Patent Publication Number: US-2019193242-A1

Title: Magnetic element and eddy current sensor using the same

Description:
TECHNICAL FIELD 
     The present invention relates to a magnetic element and an eddy current sensor using the magnetic element. 
     BACKGROUND ART 
     The trend of a semiconductor device in recent years has been a highly integrated structure, which entails finer interconnects of a circuit and a smaller distance between the interconnects. Thus, the surface of a semiconductor wafer which is an object needs to be planarized, and polishing by a polishing apparatus is performed as means for planarizing. 
     The polishing apparatus includes a polishing table for holding a polishing pad thereon for polishing an object and a top ring for holding the object and pressing the object against the polishing pad. The polishing table and the top ring are driven to rotate by a drive section (e.g., motor) respectively. The object is polished by causing a liquid containing an abrasive agent (slurry) to flow onto the polishing pad and pressing the object held to the top ring against the polishing pad. 
     When polishing of an object is not sufficient, the polishing apparatus cannot ensure insulation between circuits, which may result in a short-circuit. On the other hand, when excessive polishing occurs, a cross-sectional area of wiring decreases, the resistance thereby increases or the wiring itself is completely removed, resulting in a problem that the circuit itself is not formed. Therefore, the polishing apparatus is required to detect an optimum polishing end point. 
     One such technique is described in Japanese Patent Application Laid-Open No. 2017-58245. This technique uses an eddy current sensor using a so-called pod-shaped coil to detect a polishing end point. 
     CITATION LIST 
     Patent Literature 
     PTL 1: Japanese Patent Application Laid-Open No. 2017-58245 
     SUMMARY OF INVENTION 
     Technical Problem 
     On the surface of an object, metal may be widely distributed in a planar shape (bulk shape) or fine wiring of copper or the like may partially exist on the surface. In the case where the wiring partially exists on the surface, the density of eddy current flowing through the object needs to be greater than in the case where metal is widely distributed in a planar shape, that is, it is necessary to increase the strength of the magnetic field formed by an eddy current sensor in the object. 
     An embodiment of the present invention has been implemented to solve such a problem, and it is an object of the present invention to provide a magnetic element for increasing the strength of a magnetic field formed in the object and an eddy current sensor using the magnetic element. 
     Solution to Problem 
     In order to solve the above-described problem, a first aspect adopts a configuration of a magnetic element including a bottom magnetic body, a central magnetic body provided in a middle of the bottom magnetic body, a peripheral magnetic body provided on a periphery of the bottom magnetic body, an internal coil disposed on an outer periphery of the central magnetic body and capable of generating a magnetic field and an external coil disposed on an outer periphery of the peripheral magnetic body and capable of generating a magnetic field. 
     The present embodiment includes the external coil disposed on an outer periphery of the peripheral magnetic body and capable of generating a magnetic field. For this reason, there is conventionally only the internal coil disposed on an outer periphery of the central magnetic body and capable of generating a magnetic field, whereas according to the present embodiment, it is possible to increase the strength of the magnetic field more than in the prior arts. 
     A second aspect adopts a configuration of the magnetic element according to the first aspect, in which the bottom magnetic body has a columnar shape and the peripheral magnetic body is disposed at both ends of the columnar shape. The magnetic element can be, for example, an E-shaped coil. 
     A third aspect adopts a configuration of the magnetic element according to the first aspect, in which the peripheral magnetic body is provided in plurality on the periphery of the bottom magnetic body. The number of peripheral magnetic bodies can be two, three, four or six or the like and a multipolar coil can be adopted. 
     A fourth aspect adopts a configuration of the magnetic element according to the first aspect, in which the peripheral magnetic body is a wall portion provided on the periphery of the bottom magnetic body so as to surround the central magnetic body. The peripheral magnetic body can be cylindrical, rectangular cylindrical shape or the like. These shapes are identical to the shapes of conventional pod-shaped coils. However, the conventional pod-shaped coil includes no external coil disposed on an outer periphery of a peripheral magnetic body and capable of generating a magnetic field. Therefore, the fourth aspect can increase the strength of the magnetic field more than the conventional pod-shaped coil. 
     A fifth aspect adopts a configuration of the magnetic element according to any one of the first to fourth aspects in which the internal coil and the external coil can be electrically connected in parallel. 
     A sixth aspect adopts a configuration of the magnetic element according to any one of the first to fifth aspects in which the direction of the magnetic field generated by the internal coil in the central magnetic body can be the same as the direction of the magnetic field generated by the external coil in the central magnetic body. 
     A seventh aspect adopts a configuration of the magnetic element according to any one of the first to sixth aspects, further including a detection coil disposed on an outer periphery of the central magnetic body and/or on an outer periphery of the peripheral magnetic body and capable of detecting a magnetic field. 
     An eighth aspect adopts a configuration of the magnetic element according to the seventh aspect, further including a dummy coil disposed on an outer periphery of the central magnetic body and/or on an outer periphery of the peripheral magnetic body and capable of detecting a magnetic field. 
     A ninth aspect adopts a configuration of the magnetic element according to any one of the first to sixth aspects, further including a detection coil disposed on an outer periphery of the central magnetic body and capable of detecting a magnetic field and a dummy coil disposed on an outer periphery of the central magnetic body and capable of detecting a magnetic field. The present embodiment exhibits the following effects. There may be cases where the detection coil and the dummy coil may not be essential on an outer periphery of the peripheral magnetic body. For example, there may be cases where it may be preferable to limit a range of acquiring interlinkage flux caused by an eddy current generated by the external coil and the internal coil by using the magnetic element without any detection coil or dummy coil provided in the peripheral magnetic body. That is, it may be preferable to limit a range of interlinkage flux that can be acquired by the detection coil and the dummy coil disposed on an outer periphery of the central magnetic body. 
     A tenth aspect adopts a configuration of an eddy current sensor including the magnetic element according to any one of the seventh to ninth aspects. 
     An eleventh aspect adopts a configuration of a polishing apparatus including a polishing table on which a polishing pad for polishing an object can be mounted, a drive section that can drive to rotate the polishing table, a holding section that holds the object and can press the object against the polishing pad, the eddy current sensor according to the tenth aspect disposed inside the polishing table and capable of detecting an eddy current formed by the internal coil and the external coil in the object as the polishing table rotates using the detection coil and an end point detection section that can detect a polishing end point indicating an end of polishing of the object from the detected eddy current. 
     A twelfth aspect adopts a configuration of the polishing apparatus according to the eleventh aspect, in which the end point detection section determines a polishing rate of the object from the detected eddy current, calculates an estimated polishing amount when the object is polished at the polishing rate and can thereby detect the polishing end point. 
     A thirteenth aspect adopts a configuration of the polishing apparatus according to the twelfth aspect, in which the end point detection section compares data relating to a film thickness obtained from the eddy current and data relating to a film thickness predicted from the polishing rate, and can prevent use of the data relating to the film thickness obtained from the eddy current when the comparison result is greater than a predetermined value. 
     A fourteenth aspect adopts a configuration of the polishing apparatus according to the twelfth or thirteenth aspect, in which the end point detection section can detect the polishing end point from the estimated polishing amount and a threshold relating to the film thickness corresponding to the polishing end point. 
     A fifteenth aspect adopts a configuration of a polishing method for polishing between a polishing pad and an object disposed opposed to the polishing pad, the polishing method including holding the polishing pad using a polishing table, driving to rotate the polishing table, driving to rotate a holding section for holding the object and pressing the object against the polishing pad, disposing the eddy current sensor according to the tenth aspect inside the polishing table and detecting an eddy current formed in the object by the internal coil and the external coil as the polishing table rotates using the detection coil and detecting a polishing end point indicating an end of polishing of the object from the detected eddy current. 
     A sixteenth aspect adopts a configuration of the polishing method according to the fifteenth aspect, in which the strength of a magnetic field generated by the internal coil and/or the external coil is changed when conductivity of the object changes. 
     A seventeenth aspect adopts a configuration of the polishing method according to the fifteenth or sixteenth aspect, in which the eddy current sensor according to the tenth aspect is disposed in plurality inside the polishing table and the plurality of eddy current sensors have different levels of detection sensitivity. 
     An eighteenth aspect adopts a configuration of a computer-readable recording medium that records a program for causing a computer to control a polishing apparatus that polishes an object, the polishing apparatus including a polishing table on which a polishing pad for polishing the object can be mounted, a drive section that can drive to rotate the polishing table, a holding section that holds the object and can press the object against the polishing pad, the eddy current sensor according to the tenth aspect disposed inside the polishing table and capable of detecting an eddy current formed in the object by the internal coil and the external coil as the polishing table rotates using the detection coil, the program causing the computer to function as end point detection section means that can detect a polishing end point indicating an end of polishing of the object from the detected eddy current and control means for controlling polishing by the polishing apparatus. 
     A nineteenth aspect adopts a configuration of the polishing apparatus according to any of the eleventh to fourteenth aspects, the polishing apparatus including an optical system that irradiates the polishable surface (i.e., surface to be polished) of the object with light from an optical fiber through a through hole provided in the polishing pad and receives reflected light through the optical fiber and analysis processing means for analyzing and processing the reflected light received by the optical system, analysis processing means analyzing and processing the reflected light, an object film thickness monitoring apparatus that monitors a polishing progress situation of a thin film formed on the polishable surface of the object, in which the polishing apparatus provides a liquid supply hole for supplying a transparent liquid into the through hole provided in the polishing pad in the polishing table, the liquid supply hole is disposed and formed so as to form a flow of a transparent liquid supplied therefrom advancing perpendicularly to the polishable surface of the object and fill the through hole, the optical fiber is disposed so that the radiation light and the reflected light pass through the transparent liquid of the flow portion advancing perpendicularly to the polishable surface, a liquid discharge hole for discharging the transparent liquid of the through hole is provided, the liquid discharge hole is positioned in the rear in the moving direction of the polishing table with respect to the liquid supply hole and is open toward an end face opposite to the object of the through hole. 
     A twentieth aspect adopts a configuration of the polishing apparatus according to the nineteenth aspect, in which a middle point of a line segment connecting the center of the liquid supply hole and the center of the liquid discharge hole is located ahead of the central point of the through hole in the moving direction of the polishing table. 
     A twenty-first aspect adopts a configuration of the polishing apparatus according to the nineteenth or twentieth aspect, in which the through hole is a hole having a substantially elliptic cross section so that the outer periphery of the end face surrounds the end faces of the liquid supply hole and the liquid discharge hole. 
     A twenty-second aspect adopts a configuration of the polishing apparatus according to any of the nineteenth to twenty-first aspects, including a forced liquid discharge mechanism, in which the forced liquid discharge mechanism forcibly discharges a liquid from the liquid discharge hole. 
     A twenty-third aspect adopts a configuration of the polishing method according to any of the fifteenth to seventeenth aspects, including a translucent liquid nozzle and a translucent liquid receiving section disposed on the peripheral portion of the translucent liquid nozzle so as to surround the translucent liquid nozzle, in which a columnar translucent liquid flow is brought into contact with the polishable surface of the object from the translucent liquid nozzle, the translucent liquid flow is received by the translucent liquid receiving section, the translucent liquid in the translucent liquid nozzle and the translucent liquid in the translucent liquid receiving section thereby communicate with each other, a translucent liquid flow hermetically sealed from outside is formed, the translucent liquid flow is passed via an optical system, the polishable surface of the object is irradiated with light, the translucent liquid flow is passed therethrough, light reflected by the polishable surface of the object is received by the optical system and a film thickness of the polishable surface is measured from the intensity of the received reflected light. 
     A twenty-fourth aspect adopts a configuration of the polishing method according to the twenty-third aspect, in which the optical system includes at least one optical fiber, a distal end portion of the optical fiber is inserted into the translucent liquid flow, the optical fiber and the translucent liquid flow are passed therethrough, the polishable surface of the object is irradiated with light, and light reflected by the polishable surface is received via the translucent liquid flow and the optical fiber. 
     A twenty-fifth aspect adopts a configuration of the polishing apparatus according to any one of the eleventh to fourteenth and nineteenth to twenty-second aspects, including a plurality of processing areas in which a plurality of light-shielded processing units are disposed in upper and lower parts and housed therein, and transfer areas in which a transporter is housed and arranged between the processing areas, in which the processing areas are light-shielded from the transfer areas by a light-shielding wall and the front of the transfer area is light-shielded by a maintenance door and the processing unit is connected to the light-shielding wall in a light-shielded state. 
     A twenty-sixth aspect adopts a configuration of the polishing apparatus according to the twenty-fifth aspect, in which the processing unit includes a substrate insertion port having an openable/closable shutter, the light-shielding wall is provided with a light-shielding film that surrounds the object insertion port and an opening is provided in a region of the light-shielding wall surrounded by the light-shielding film. 
     A twenty-seventh aspect adopts a configuration of the polishing apparatus according to the twenty-fifth or twenty-sixth aspect, in which the processing area is a cleaning area and processing on an object is cleaning of an object. 
     A twenty-eighth aspect adopts a configuration of the polishing apparatus according to any one of the eleventh to fourteenth, nineteenth to twenty-second and twenty-fifth to twenty-seventh aspects, including a polishing section that polishes the object, a cleaning section that cleans and dries the object, a barrier that separates the polishing section from the cleaning section, a transfer mechanism that transfers the object subjected to polishing from the polishing section to the cleaning section through an opening of the barrier, and a housing having a side wall to house the polishing section, the cleaning section and the transfer mechanism therein, in which the cleaning section includes cleaning means for cleaning the object subjected to polishing with a cleaning liquid, drying means for drying the cleaned object and transfer means that can transfer the object so as to be horizontally and vertically movable between the cleaning means and the drying means, and the polishing section includes the polishing table, the holding section, the drive section, the eddy current sensor and the end point detection section. Note that U.S. Pat. No. 5,885,138 is incorporated in the present specification by reference in its entirety. 
     A twenty-ninth aspect adopts a configuration of the polishing method according to any of the fifteenth to seventeenth, twenty-third and twenty-fourth aspects using a polishing apparatus including a polishing section that polishes the object, a cleaning section that cleans and dries the object, a barrier that separates the polishing section from the cleaning section, a transfer mechanism that transfers the object subjected to polishing from the polishing section to the cleaning section through the opening of the barrier, and a housing having a side wall to house the polishing section, the cleaning section and the transfer mechanism, in which the cleaning section cleans the polished object with a cleaning liquid, dries the cleaned object and transfers the object between the cleaning step and the drying step so as to be horizontally and vertically movable to transfer the object. 
     A thirtieth aspect adopts a configuration of the polishing apparatus according to any one of the eleventh to fourteenth, nineteenth to twenty-second and twenty-fifth to twenty-eighth aspects, including an optical sensor that irradiates the object with light and measures intensity of reflected light from the object, in which the optical sensor detects a polishing end point indicating an end of the polishing based on the eddy current and the intensity of reflected light from the object measured by the optical sensor. 
     A thirty-first aspect adopts a configuration of the polishing apparatus according to the thirtieth aspect, including a window incorporated at a position in the polishing table where the window can face the object during polishing, in which the optical sensor is disposed below the window. 
     A thirty-second aspect adopts a configuration of the polishing apparatus according to the thirtieth aspect, in which the polishing table includes an opening at a position in the polishing table where the opening can face the object during polishing, the optical sensor is disposed below the window and the optical sensor includes a fluid supply section that supplies a cleaning fluid into the opening. 
     A thirty-third aspect adopts a configuration of the polishing apparatus according to any one of the eleventh to fourteenth aspects, the nineteenth to twenty-second aspects, the twenty-fifth to twenty-eighth aspects and the thirtieth to thirty-second aspects, in which the eddy current sensor generates a magnetic field in the object, detects the strength of the generated magnetic field, and the polishing apparatus further includes a second electric motor for driving to rotate the holding section, a swing arm for holding the holding section, a third electric motor for swinging the swing arm around a swing center on the swing arm and a detection section that detects a current value of one electric motor of the drive section (first electric motor) and the second and third electric motors and/or a torque command value of the one electric motor and generates a first output, and detects a polishing end point indicating an end of the polishing based on the first output and the strength of the magnetic field measured by the eddy current sensor. 
     A thirty-fourth aspect adopts a configuration of a program for controlling a polishing apparatus that polishes an object, the polishing apparatus including a holding section for holding the object, a swing arm for holding the holding section and an arm torque detection section that directly or indirectly detects arm torque applied to the swing arm, the program causing a computer to function as end point detection means for detecting an end of the polishing based on the arm torque detected by the arm torque detection section and control means for controlling polishing by the polishing apparatus. 
     A thirty-fifth aspect adopts a configuration of the program according to the thirty-fourth aspect, in which the program is updatable. 
     A thirty-sixth aspect adopts a configuration of a polishing apparatus including a substrate processing apparatus that polishes a substrate and acquires a polishing-related signal and a data processing apparatus that is connected to the substrate processing apparatus via communication means, in which the data processing apparatus updates parameters relating to a polishing process based on the signal acquired by the substrate processing apparatus. Here, the signal is an analog signal and/or a digital signal. 
     Examples of the polishing parameters include (1) pressing forces on four regions of a semiconductor wafer, that is, a central part, an inside intermediate part, an outside intermediate part and a peripheral edge, (2) a polishing time, (3) the number of revolutions of the polishing table or the top ring, (4) a threshold for determining a polishing end point or the like. Parameter updating means updating these parameters. 
     A thirty-seventh aspect adopts a configuration of the polishing apparatus according to the thirty-sixth aspect, in which the signal is acquired by one type of sensor or a plurality of different types of sensors. Examples of the different types of sensors used in the present aspect include the following sensors. That is, (1) a sensor that acquires a measurement signal relating to torque fluctuation of a swing shaft motor, (2) SOPM (optical sensor), (3) eddy current sensor and (4) a sensor for acquiring a measurement signal relating to a fluctuation in the motor current of the polishing table rotation motor. 
     A thirty-eighth aspect adopts a configuration of a polishing method, including a step of connecting a substrate processing apparatus and a data processing apparatus via communication means, a step of polishing a substrate using the substrate processing apparatus and acquiring a polishing-related signal and a step of updating parameters relating to a polishing process by the data processing apparatus based on the signal acquired by the substrate processing apparatus. 
     A thirty-ninth aspect adopts a configuration of a polishing apparatus, including a substrate processing apparatus that polishes a substrate and acquires a polishing-related signal, an intermediate processing apparatus and a data processing apparatus, in which the substrate processing apparatus and the intermediate processing apparatus are connected by first communication means, the intermediate processing apparatus and the data processing apparatus are connected by second communication means, the intermediate processing apparatus creates a data set relating to a polishing process based on the signal acquired by the substrate processing apparatus, the data processing apparatus monitors a polishing processing state of the substrate processing apparatus based on the data set, and the intermediate processing apparatus or the data processing apparatus detects a polishing end point indicating an end of the polishing based on the data set. 
     A fortieth aspect can adopt a configuration of the polishing apparatus according to the thirty-ninth aspect, in which the signal is acquired by one type of sensor or a plurality of different types of sensors. Examples of the different types of sensors used in the present aspect include the following sensors. That is, (1) a sensor for acquiring a measurement signal relating to a torque fluctuation of a swing shaft motor, (2) SOPM (optical sensor), (3) an eddy current sensor, and (4) a sensor for acquiring a measurement signal relating to a motor current fluctuation of a polishing table rotation motor. 
     A forty-first aspect corresponds to the thirty-ninth aspect, in which examples of the data set include the following. The sensor signal outputted from the sensor and necessary control parameters can be configured as a data set. That is, the data set can include a pressure of the top ring on the semiconductor wafer, a current of the swing shaft motor, a motor current of the polishing table, a measurement signal of the optical sensor, a measurement signal of the eddy current sensor, the position of the top ring on the polishing pad, a flow rate/type of slurry and chemical liquid and correlation calculation data thereof. 
     A forty-second aspect corresponds to the thirty-ninth aspect, in which examples of the method of transmitting the data set include the following. The data set can be transmitted using a transmission system that transmits one-dimensional data in parallel or a transmission system that transmits one-dimensional data sequentially. Furthermore, the one-dimensional data can be processed into two-dimensional data to be used as a data set. 
     A forty-third aspect corresponds to the thirty-ninth aspect, in which signals having a large fluctuation in signal values can be extracted to update polishing parameters. Examples of the method of updating the polishing parameters include the following. An influence ratio is defined between a sensor as a master and a sensor as a slave by providing priority ratio coefficients (weighting factors) in target values for both the master sensor and the slave sensor. Signals having a large fluctuation in signal values are extracted and the priority ratio coefficients are changed. Fluctuations in signal values include fluctuations lasting only for a short time and fluctuations lasting for a long time. A fluctuation in a signal value means a differential value of the signal value with respect to time or a difference value of a signal value with respect to time or the like. 
     A forty-fourth aspect adopts a configuration of a polishing method, including a step of connecting a substrate processing apparatus and an intermediate processing apparatus that polish a substrate and acquire a polishing-related signal using first communication means, a step of connecting the intermediate processing apparatus and the data processing apparatus using second communication means, a step for the intermediate processing apparatus to create a data set relating to a polishing process based on the signal acquired by the substrate processing apparatus, a step for the data processing apparatus to monitor a state of the polishing process of the substrate processing apparatus based on the data set and a step for the intermediate processing apparatus or the data processing apparatus to detect a polishing end point indicating an end of the polishing based on the data set. 
     A forty-fifth aspect adopts a configuration of a polishing method for polishing between a polishing pad and an object disposed opposed to the polishing pad, the polishing method including a step of holding the polishing pad using a polishing table, a step of driving to rotate the polishing table, a step of driving to rotate a holding section for holding the object and pressing the object against the polishing pad, a step of disposing the eddy current sensor according to the tenth aspect inside the polishing table, a step of detecting an eddy current formed in the object using a detection coil according to at least one of a first step of detecting an eddy current formed by the internal coil in the object as the polishing table rotates using the detection coil, a second step of detecting an eddy current formed by the external coil in the object using the detection coil and a third step of detecting an eddy current formed by both the internal coil and the external coil in the object using the detection coil, and a step of detecting a polishing end point indicating an end of polishing of the object from the detected eddy current. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a plan view illustrating an overall configuration of a substrate processing apparatus according to an embodiment of the present invention; 
         FIG. 2  is a perspective view schematically illustrating a first polishing unit; 
         FIG. 3  is a cross-sectional view schematically illustrating a structure of a top ring; 
         FIG. 4  is a cross-sectional view schematically illustrating another structure example of the top ring; 
         FIG. 5  is a cross-sectional view for describing a mechanism for causing the top ring to rotate and swing; 
         FIG. 6  is a cross-sectional view schematically illustrating an inner structure of a polishing table; 
         FIG. 7  is a schematic diagram illustrating a polishing table provided with an optical sensor; 
         FIG. 8  is a schematic diagram illustrating the polishing table provided with a microwave sensor; 
         FIG. 9  is a perspective view illustrating a dresser; 
         FIG. 10A  is a perspective view illustrating an atomizer and  FIG. 10B  is a schematic diagram illustrating a bottom of an arm; 
         FIG. 11A  is a side view illustrating an inner structure of the atomizer and  FIG. 11B  is a plan view illustrating the atomizer; 
         FIG. 12A  is a plan view illustrating a cleaning section and  FIG. 12B  is a side view illustrating the cleaning section; 
         FIG. 13  is a schematic diagram illustrating an example of a cleaning line; 
         FIG. 14  is a longitudinal cross-sectional view illustrating an upper drying module; 
         FIG. 15  is a plan view illustrating the upper drying module; 
         FIG. 16  is a schematic diagram illustrating an overall configuration of a polishing apparatus according to an embodiment of the present invention; 
         FIGS. 17A and 17B  are diagrams illustrating a configuration of an eddy current sensor;  FIG. 17A  is a block diagram illustrating a configuration of the eddy current sensor and  FIG. 17B  is an equivalent circuit diagram of the eddy current sensor; 
         FIG. 18  is a schematic diagram illustrating a configuration example of the eddy current sensor according to the present embodiment; 
         FIG. 19  is a schematic diagram illustrating a connection example of an excitation coil in the eddy current sensor; 
         FIG. 20  is a diagram illustrating a magnetic field in the eddy current sensor; 
         FIG. 21  is a schematic diagram illustrating another connection example of the excitation coil in the eddy current sensor; 
         FIG. 22  is a diagram illustrating the magnetic field by the eddy current sensor; 
         FIGS. 23A, 23B and 23C  are schematic diagrams illustrating a connection example of each coil in the eddy current sensor; 
         FIG. 24  is a block diagram illustrating a coherent detection circuit of the eddy current sensor; 
         FIG. 25  illustrates an example of an end point detection method using the eddy current sensor; 
         FIG. 26  illustrates an example where the peripheral magnetic body is not a wall portion provided on the periphery of the bottom face portion so as to surround the magnetic core portion; 
         FIG. 27  illustrates an example where the peripheral magnetic body is not a wall portion provided on the periphery of the bottom face portion so as to surround the magnetic core portion; 
         FIG. 28  illustrates an example where the peripheral magnetic body is not a wall portion provided on the periphery of the bottom face portion so as to surround the magnetic core portion; 
         FIG. 29  is a block diagram for describing an arm torque detection method by an arm torque detection section; 
         FIG. 30  is diagram illustrating another embodiment having an optical sensor; 
         FIG. 31  is diagram illustrating a further embodiment having an optical sensor; 
         FIG. 32  is diagram illustrating an example of a case where the film structure of an end point section is a state in which a metal and an insulating film are mixed; 
         FIG. 33  is diagram illustrating an example of a case where the film structure of an end point section is a state in which a metal and an insulating film are mixed; 
         FIG. 34  is diagram illustrating an example of a case where the film structure of an end point section is a state in which a metal and an insulating film are mixed; 
         FIG. 35  is a diagram illustrating an embodiment as a modification of  FIG. 16 ; 
         FIG. 36  is a diagram illustrating overall control by a control section; 
         FIG. 37  is a diagram illustrating a configuration of another embodiment; 
         FIG. 38  is a diagram illustrating a modification of the embodiment in  FIG. 27 ; 
         FIGS. 39A and 39B  are diagrams illustrating another schematic configuration of the sensor of the polishing apparatus according to the present invention;  FIG. 39A  illustrating a plan view and  FIG. 39B  illustrating a cross-sectional side view; 
         FIG. 40  is a diagram illustrating a schematic configuration example of a further embodiment; 
         FIG. 41  is a diagram illustrating a schematic configuration example of a still further embodiment; 
         FIG. 42  is a diagram illustrating a configuration example of a polishing apparatus of a still further embodiment; 
         FIG. 43  is a diagram illustrating a cross section along an arrow Y-Y in  FIG. 42 ; 
         FIG. 44  is a cross-sectional view illustrating an example of PN connection; 
         FIG. 45  is a schematic side view illustrating a relationship between a multihead type top ring and a polishing table supported by a carousel; 
         FIG. 46  is a schematic side view illustrating a relationship between a multihead type top ring supported by a carousel including an arm drive section and the polishing table; 
         FIG. 47  is a top view of the embodiment shown in  FIG. 46 . 
         FIGS. 48A, 48B and 48C  are diagrams describing an embodiment in which the strength of a magnetic field generated by the excitation coil is changed when conductivity of a semiconductor wafer changes; 
         FIG. 49  illustrates an example where the peripheral magnetic body is not a wall portion provided on the periphery of the bottom face portion so as to surround the magnetic core portion; and 
         FIG. 50  illustrates an example where the peripheral magnetic body is not a wall portion provided on the periphery of the bottom face portion so as to surround the magnetic core portion. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that in the following respective embodiments, identical or corresponding members are assigned identical reference numerals and overlapping description may be omitted. Furthermore, features shown in the respective embodiments are also applicable to other embodiments unless the features are inconsistent with one another. 
       FIG. 1  is a plan view illustrating a whole arrangement of a substrate processing apparatus according to an embodiment of the present invention. As shown in  FIG. 1 , the substrate processing apparatus is provided with a housing, that is, substantially rectangular housing  61  in the present embodiment. The housing  61  includes a side wall  700 . An interior of the housing  61  is partitioned into a load/unload section  62 , a polishing section  63  and a cleaning section  64  by barriers  1   a  and  1   b . These load/unload section  62 , polishing section  63  and cleaning section  64  are assembled independently and a gas therein is exhausted independently. Furthermore, the substrate processing apparatus includes a control section  65  that controls substrate processing operation. 
     The load/unload section  62  is provided with two or more (four in the present embodiment) front load sections  20  on which wafer cassettes for stocking many semiconductor wafers (substrates) are placed. The front load sections  20  are arranged adjacent to the housing  61  and arrayed along a width direction of the substrate processing apparatus (direction perpendicular to a longitudinal direction). The front load section  20  can mount an open cassette, a SMIF (standard manufacturing interface) pod or a FOUP (front opening unified pod). Here, the SMIF and the FOUP are airtight containers that house a wafer cassette, cover it with a barrier and can thereby maintain an environment independent of an external space. 
     A traveling mechanism  21  is laid on the load/unload section  62  along a direction in which the front load sections  20  are arranged side by side. Two transfer robots (loaders)  22  which are movable along a wafer cassette array direction are laid on the traveling mechanism  21 . The transfer robots  22  can access the wafer cassettes mounted on the front load sections  20  by moving on the traveling mechanism  21 . Each transfer robot  22  is provided with two hands, upper and lower. The upper hand is used to return a processed semiconductor wafer to the wafer cassette. The lower hand is used to unload a wafer before processing from the wafer cassette. In this way, the upper and lower hands are used for different purposes. The semiconductor wafer can be turned over by causing the lower hand of the transfer robot  22  to turn around its shaft center. 
     The load/unload section  62  is a region that must be kept most clean. Therefore, the interior of the load/unload section  62  is always kept to a higher pressure than the outside of the substrate processing apparatus, the polishing section  63  and the cleaning section  64 . The polishing section  63  uses slurry as a polishing liquid, and is therefore the dirtiest region. Therefore, a negative pressure is formed inside the polishing section  63  and the pressure thereof is kept lower than the inner pressure of the cleaning section  64 . The load/unload section  62  is provided with a filter fan unit (not shown) including a clean air filter such as a HEPA filter, ULPA filter or chemical filter. Clean air stripped of particles, poisonous vapor or poisonous gas is always blown from the filter fan unit. 
     The polishing section  63  is a region where a semiconductor wafer is polished (planarized) and is provided with a first polishing unit  3 A, a second polishing unit  3 B, a third polishing unit  3 C and a fourth polishing unit  3 D. The first polishing unit  3 A, second polishing unit  3 B, third polishing unit  3 C and fourth polishing unit  3 D are arrayed along the longitudinal direction of the substrate processing apparatus as shown in  FIG. 1 . 
     As shown in  FIG. 1 , the first polishing unit  3 A is provided with a polishing table  30 A, a top ring  31 A, a polishing liquid supply nozzle  32 A, a dresser  33 A, and an atomizer  34 A. A polishing pad  10  having a polishing surface is attached to the polishing table  30 A. The top ring (holding section)  31 A holds the semiconductor wafer and polishes the semiconductor wafer while pressing the semiconductor wafer against the polishing pad  10  on the polishing table  30 A. The polishing liquid supply nozzle  32 A supplies a polishing liquid or a dressing liquid (e.g., pure water) to the polishing pad  10 . The dresser  33 A performs dressing on the polishing surface of the polishing pad  10 . The atomizer  34 A atomizes a fluid in which a liquid (e.g., pure water) and a gas (e.g., nitrogen gas) are mixed or a liquid (e.g., pure water) and jets the fluid or liquid onto the polishing surface. 
     Similarly, the second polishing unit  3 B is provided with a polishing table  30 B to which the polishing pad  10  is attached, a top ring  31 B, a polishing liquid supply nozzle  32 B, a dresser  33 B and an atomizer  34 B. The third polishing unit  3 C is provided with a polishing table  30 C to which the polishing pad  10  is attached, a top ring  31 C, a polishing liquid supply nozzle  32 C, a dresser  33 C and an atomizer  34 C. The fourth polishing unit  3 D is provided with a polishing table  30 D to which the polishing pad  10  is attached, a top ring  31 D, a polishing liquid supply nozzle  32 D, a dresser  33 D and an atomizer  34 D. 
     The first polishing unit  3 A, the second polishing unit  3 B, the third polishing unit  3 C and the fourth polishing unit  3 D have identical configurations, and so the details of the polishing units will be described using the first polishing unit  3 A as a target. 
       FIG. 2  is a perspective view schematically illustrating the first polishing unit  3 A. The top ring  31 A is supported by a top ring shaft  111 . The polishing pad  10  is mounted on the top surface of the polishing table  30 A and the top surface of the polishing pad  10  constitutes a polishing surface for polishing a semiconductor wafer  16 . Note that fixed abrasive grains may also be used instead of the polishing pad  10 . The top ring  31 A and the polishing table  30 A are configured to rotate around the shaft center as shown by an arrow. The semiconductor wafer  16  is held to the undersurface of the top ring  31 A by vacuum suction. During polishing, a polishing liquid is supplied from the polishing liquid supply nozzle  32 A to the polishing surface of the polishing pad  10 , and the semiconductor wafer  16  which is the object is pressed against the polishing surface by the top ring  31 A and is polished. 
       FIG. 3  is a cross-sectional view schematically illustrating a structure of the top ring  31 A. The top ring  31 A is connected to a bottom end of the top ring shaft  111  via a universal joint  637 . The universal joint  637  is a ball joint that transmits the rotation of the top ring shaft  111  to the top ring  31 A while allowing mutual tilting of the top ring  31 A and the top ring shaft  111 . The top ring  31 A is provided with a substantially disk-shaped top ring body  638  and a retainer ring  640  disposed below the top ring body  638 . The top ring body  638  is formed of a material with high strength and rigidity such as metal or ceramics. The retainer ring  640  is formed of a resin material or ceramics with high rigidity. Note that the retainer ring  640  may be formed integrally with the top ring body  638 . 
     A circular elastic pad  642  in contact with the semiconductor wafer  16 , a ring-shaped pressuring sheet  643  made of an elastic film and a substantially disk-shaped chucking plate  644  for holding the elastic pad  642  are housed in a space formed inside the top ring body  638  and the retainer ring  640 . An upper circumferential edge of the elastic pad  642  is held to the chucking plate  644 , and four pressure chambers (airbags) P 1 , P 2 , P 3  and P 4  are provided between the elastic pad  642  and the chucking plate  644 . The pressure chambers P 1 , P 2 , P 3  and P 4  are formed of the elastic pad  642  and the chucking plate  644 . The pressure chambers P 1 , P 2 , P 3  and P 4  are respectively supplied with a pressurized fluid such as pressurized air or evacuated via fluid channels  651 ,  652 ,  653  and  654 . The pressure chamber P 1  in the center is circular and the pressure chambers P 2 , P 3  and P 4  are annular. The pressure chambers P 1 , P 2 , P 3  and P 4  are concentrically arranged. 
     Inner pressures of the pressure chambers P 1 , P 2 , P 3  and P 4  can be changed independently by a pressure adjusting section, which will be described later, and it is possible to thereby adjust pressing forces on four regions of the semiconductor wafer  16 , that is, a central part, an inside intermediate part, an outside intermediate part and a peripheral edge independently. The retainer ring  640  can be pressed against the polishing pad  10  with a predetermined pressing force by causing the entire top ring  31 A to ascend or descend. A pressure chamber P 5  is formed between the chucking plate  644  and the top ring body  638 , a pressurized fluid is supplied to the pressure chamber P 5  or evacuated via a fluid channel  655 . This allows the chucking plate  644  and the elastic pad  642  as a whole to move in the vertical direction. 
     The peripheral edge of the semiconductor wafer  16  is surrounded by the retainer ring  640  so that the semiconductor wafer  16  does not slip out of the top ring  31 A during polishing. An opening (not shown) is formed in the region of the elastic pad  642  making up the pressure chamber P 3 , and by forming vacuum in the pressure chamber P 3 , the semiconductor wafer  16  is suctioned and held to the top ring  31 A. Furthermore, by supplying a nitrogen gas, dry air, compressed air or the like to the pressure chamber P 3 , the semiconductor wafer  16  can be released from the top ring  31 A. 
       FIG. 4  is a cross-sectional view schematically illustrating another structure example of the top ring  31 A. In this example, no chucking plate is provided and the elastic pad  642  is attached to an undersurface of the top ring body  638 . No pressure chamber P 5  is provided between the chucking plate and the top ring body  638 , either. Instead, an elastic bag  646  is disposed between the retainer ring  640  and the top ring body  638 , and a pressure chamber P 6  is formed inside the elastic bag  646 . The retainer ring  640  is designed to be movable relative to the top ring body  638  in the vertical direction. A fluid channel  656  communicates with the pressure chamber P 6  and a pressurized fluid such as pressurized air is supplied to the pressure chamber P 6  via the fluid channel  656 . An inner pressure of the pressure chamber P 6  can be adjusted by a pressure adjusting section, which will be described later. Therefore, it is possible to adjust the pressing force of the retainer ring  640  on the polishing pad  10  independently of the pressing force on the semiconductor wafer  16 . Other components and operations are the same as the components of the top ring shown in  FIG. 20 . Either type of top ring in  FIG. 20  or  FIG. 21  can be used in the present embodiment. 
       FIG. 5  is a cross-sectional view for describing a mechanism for causing the top ring  31 A to rotate and swing. The top ring shaft (e.g., spline shaft)  636  is rotatably supported by a top ring head  660 . Furthermore, the top ring shaft  111  is connected to a rotation shaft of a motor M 1  via pulleys  661  and  662 , and a belt  663 , and the motor M 1  causes the top ring shaft  111  and the top ring  31 A to rotate around a shaft center thereof. The motor M 1  is attached above the top ring head  660 . The top ring head  660  and the top ring shaft  111  are connected via an air cylinder  665  as a vertical drive source. Air (compressed gas) supplied to the air cylinder  665  causes the top ring shaft  111  and the top ring  31 A to integrally move in the vertical direction. Note that a mechanism including a ball screw and a servo motor may also be used as the vertical drive source instead of the air cylinder  665 . 
     The top ring head  660  is rotatably supported by a support shaft  667  via a bearing  672 . The support shaft  667  is a fixed shaft and has a non-rotating structure. A motor M 2  is installed in the top ring head  660 , and relative positions of the top ring head  660  and the motor M 2  are fixed. The rotation shaft of the motor M 2  is connected to the support shaft  667  via a rotation transmission mechanism (gear or the like) which is not shown, and by causing the motor M 2  to rotate, the top ring head  660  swings around the support shaft  667 . Therefore, through swing motion of the top ring head  660 , the top ring  31 A supported at a distal end thereof moves between a polishing position above the polishing table  30 A and a transfer position on a side of the polishing table  30 A. Note that the swing mechanism for causing the top ring  31 A to swing is constructed of the motor M 2  in the present embodiment. 
     A through hole (not shown) extending in a longitudinal direction is formed inside the top ring shaft  111 . The fluid channels  651 ,  652 ,  653 ,  654 ,  655  and  656  of the aforementioned top ring  31 A pass through the through hole and are connected to a rotary joint  669  provided at a top end of the top ring shaft  111 . A fluid such as a pressurized gas (clean air) or nitrogen gas is supplied to the top ring  31 A via the rotary joint  669  and a gas is evacuated from the top ring  31 A. A plurality of fluid pipes  670  communicating with the above-described fluid channels  651 ,  652 ,  653 ,  654 ,  655  and  656  (see  FIG. 20  and  FIG. 21 ) are connected to the rotary joint  669  and the fluid pipes  670  are connected to a pressure adjusting section  675 . A fluid pipe  671  that supplies pressurized air to the air cylinder  665  is also connected to the pressure adjusting section  675 . 
     The pressure adjusting section  675  includes an electropneumatic regulator that adjusts a pressure of the fluid supplied to the top ring  31 A, pipes connected to the fluid pipes  670  and  671 , air operation valves provided in these pipes, an electropneumatic regulator that adjusts a pressure of air which becomes an operation source of the air operation valves and an ejector that forms vacuum in the top ring  31 A, and these components are congregated together to form one block (unit). The pressure adjusting section  675  is fixed to the upper part of the top ring head  660 . The pressures of the pressurized gas supplied to the pressure chambers P 1 , P 2 , P 3 , P 4  and P 5  (see  FIG. 20 ) of the top ring  31 A and pressurized air supplied to the air cylinder  665  are adjusted by the electropneumatic regulator of the pressure adjusting section  675 . Similarly, a vacuum is formed by an ejector of the pressure adjusting section  675  in the airbags P 1 , P 2 , P 3  and P 4  of the top ring  31 A and the pressure chamber P 5  between the chucking plate  644  and the top ring body  638 . 
     Since the electropneumatic regulator which is a pressure adjusting device or a valve is installed near the top ring  31 A in this way, controllability of the pressure in the top ring  31 A is improved. More specifically, since the distances from the electropneumatic regulator to the pressure chambers P 1 , P 2 , P 3 , P 4  and P 5  are small, responsivity to a pressure change command from the control section  65  improves. Since the ejector which is a vacuum source is also installed near the top ring  31 A, responsivity when a vacuum is formed in the top ring  31 A improves likewise. Furthermore, it is possible to use a reverse side of the pressure adjusting section  675  as a pedestal for mounting electrical equipment and thereby eliminate the necessity for a mounting frame which is conventionally required. 
     The top ring head  660 , the top ring  31 A, the pressure adjusting section  675 , the top ring shaft  111 , the motor M 1 , the motor M 2  and the air cylinder  665  are configured as one module (hereinafter referred to as a “top ring assembly”). That is, the top ring shaft  111 , the motor M 1 , the motor M 2 , the pressure adjusting section  675  and the air cylinder  665  are attached to the top ring head  660 . The top ring head  660  is configured to be removable from the support shaft  667 . Therefore, by separating the top ring head  660  from the support shaft  667 , it is possible to remove the top ring assembly from the substrate processing apparatus. Such a configuration can improve maintainability of the support shaft  667 , the top ring head  660  or the like. For example, when an abnormal sound is generated from the bearing  672 , the bearing  672  can be easily replaced and when replacing the motor M 2  or the rotation transmission mechanism (reduction gear), adjacent devices need not be removed. 
       FIG. 6  is a cross-sectional view schematically illustrating an inner structure of the polishing table  30 A. As shown in  FIG. 6 , a sensor  676  for detecting a state of the film of the semiconductor wafer  16  is embedded in the polishing table  30 A. In this example, an eddy current sensor is used as the sensor  676 . A signal of the sensor  676  is transmitted to the control section  65  and the control section  65  generates a monitoring signal indicating a film thickness. Although the value of the monitoring signal (and the sensor signal) does not indicate the film thickness itself, the value of the monitoring signal varies in accordance with the film thickness. Therefore, the monitoring signal can be said to be a signal indicating a film thickness of the semiconductor wafer  16 . 
     The control section  65  determines inner pressures of the respective pressure chambers P 1 , P 2 , P 3  and P 4  based on the monitoring signal and issues a command to the pressure adjusting section  675  so that the determined inner pressures are formed in the respective pressure chambers P 1 , P 2 , P 3  and P 4 . The control section  65  functions as a pressure control section that operates the inner pressures of the respective pressure chambers P 1 , P 2 , P 3  and P 4  and an end point detection section that detects a polishing end point based on the monitoring signal. 
     As in the case of the first polishing unit  3 A, the sensor  676  is also provided in each polishing table of the second polishing unit  3 B, the third polishing unit  3 C and the fourth polishing unit  3 D. The control section  65  generates a monitoring signal from signals sent from each sensor  676  of the respective polishing units  3 A to  3 D and monitors the progress of polishing of the semiconductor wafer in the respective polishing units  3 A to  3 D. When a plurality of semiconductor wafers are polished in the polishing units  3 A to  3 D, the control section  5  monitors the monitoring signal indicating the film thickness of the semiconductor wafer during polishing and controls the pressing forces of the top rings  31 A to  31 D based on the monitoring signals so that polishing times in the polishing units  3 A to  3 D become substantially identical. By adjusting the pressing forces of the top rings  31 A to  31 D during polishing based on the monitoring signals in this way, it is possible to level the polishing times in the polishing units  3 A to  3 D. 
     The semiconductor wafer  16  may be polished by any one of the first polishing unit  3 A, the second polishing unit  3 B, the third polishing unit  3 C and the fourth polishing unit  3 D or may be polished consecutively by a plurality of polishing units selected in advance from among the polishing units  3 A to  3 D. For example, the semiconductor wafer  16  may be polished in order of the first polishing unit  3 A, and the second polishing unit  3 B or may be polished in order of the third polishing unit  3 C, and the fourth polishing unit  3 D. Moreover, the semiconductor wafer  16  may be polished in order of the first polishing unit  3 A, the second polishing unit  3 B, the third polishing unit  3 C, and the fourth polishing unit  3 D. In all cases, it is possible to improve a throughput by leveling polishing times of all the polishing units  3 A to  3 D. 
     An eddy current sensor is preferably used when the film of the semiconductor wafer is a metal film. When the film of the semiconductor wafer is a film having a light transmissive property such as an oxide film, an optical sensor can be used as the sensor  76 . Alternatively, a microwave sensor may be used as the sensor  76 . A microwave sensor can also be used for both a metal film and a non-metal film. Hereinafter, examples of an optical sensor and a microwave sensor will be described. 
       FIG. 7  is a schematic view illustrating a polishing table provided with an optical sensor. As shown in  FIG. 7 , the optical sensor  676  for detecting a film state of the semiconductor wafer  16  is embedded in the polishing table  30 A. The sensor  676  irradiates the semiconductor wafer  16  with light and detects the film state (film thickness or the like) of the semiconductor wafer  16  from the intensity (reflection intensity or reflection factor) of reflected light from the semiconductor wafer  16 . 
     The polishing pad  10  is provided with a light transmitting section  677  for transmitting light from the sensor  676 . The light transmitting section  677  is formed of a material with high transmittance such as non-foaming polyurethane. Alternatively, the light transmitting section  677  may also be configured by providing a through hole in the polishing pad  10  and causing a transparent liquid to flow from below while the through hole is closed by the semiconductor wafer  16 . The light transmitting section  677  is disposed at a position corresponding to the center of the semiconductor wafer  16  held to the top ring  31 A. 
     As shown in  FIG. 7 , the sensor  676  is provided with a light source  678   a , a light-emitting optical fiber  678   b  as a light-emitting section that irradiates a polishable surface of the semiconductor wafer  16  with light from the light source  678   a , a light-receiving optical fiber  678   c  as a light-receiving section that receives light reflected from the polishable surface, a spectroscope unit  678   d  that incorporates a spectroscope that disperses the light received by the light-receiving optical fiber  678   c  and a plurality of light-receiving devices that store the light dispersed by the spectroscope as electrical information, an operation control section  678   e  that controls lighting on/off of the light source  678   a  and read start timing or the like of the light-receiving device in the spectroscope unit  678   d , and a power supply  678   f  that supplies power to the operation control section  678   e . Note that power is supplied to the light source  678   a  and the spectroscope unit  678   d  via the operation control section  678   e.    
     A light-emitting end of the light-emitting optical fiber  678   b  and a light-receiving end of the light-receiving optical fiber  678   c  are configured so as to be substantially perpendicular to the polishable surface of the semiconductor wafer  16 . As the light-receiving device in the spectroscope unit  678   d , for example, a photodiode array of  128  elements can be used. The spectroscope unit  678   d  is connected to the operation control section  678   e . Information from the light-receiving device in the spectroscope unit  678   d  is sent to the operation control section  678   e  and spectral data of the reflected light is generated based on this information. That is, the operation control section  678   e  reads electrical information stored in the light-receiving device and generates spectral data of the reflected light. The spectral data indicates the intensity of the reflected light decomposed according to the wavelength and varies depending on the film thickness. 
     The operation control section  678   e  is connected to the aforementioned control section  65 . The spectral data generated in the operation control section  678   e  is transmitted to the control section  65 . The control section  65  calculates a characteristic value associated with the film thickness of the semiconductor wafer  16  based on the spectral data received from the operation control section  678   e  and uses the characteristic value as a monitoring signal. 
       FIG. 8  is a schematic view illustrating the polishing table provided with a microwave sensor. The sensor  676  is provided with an antenna  680   a  that irradiates the polishable surface of the semiconductor wafer  16  with a microwave, a sensor body  680   b  that supplies microwave to the antenna  680   a , and a waveguide  681  that connects the antenna  680   a  and the sensor body  680   b . The antenna  680   a  is embedded in the polishing table  30 A and is disposed opposed to the center position of the semiconductor wafer  16  held to the top ring  31 A. 
     The sensor body  680   b  is provided with a microwave source  680   c  that generates a microwave and supplies the microwave to the antenna  680   a , a separator  680   d  that separates the microwave (incident wave) generated from the microwave source  680   c  from the microwave (reflected wave) reflected from the surface of the semiconductor wafer  16  and a detection section  680   e  that receives the reflected wave separated by the separator  680   d  and detects the amplitude and the phase of the reflected wave. Note that a directional coupler is preferably used as the separator  680   d.    
     The antenna  680   a  is connected to the separator  680   d  via the waveguide  681 . The microwave source  680   c  is connected to the separator  680   d , and a microwave generated by the microwave source  680   c  is supplied to the antenna  680   a  via the separator  680   d  and the waveguide  681 . The microwave is radiated from the antenna  680   a  onto the semiconductor wafer  16 , passes (penetrates) through the polishing pad  10  and reaches the semiconductor wafer  16 . The reflected wave from the semiconductor wafer  16  passes through the polishing pad  10  again and is then received by the antenna  680   a.    
     The reflected wave is sent from the antenna  680   a  to the separator  680   d  via the waveguide  681  and separated into an incident wave and a reflected wave by the separator  680   d . The reflected wave separated by the separator  680   d  is transmitted to the detection section  680   e . The detection section  680   e  detects the amplitude and the phase of the reflected wave. The amplitude of the reflected wave is detected as power (dbm or W) or a voltage (V) and the phase of the reflected wave is detected by a phase measuring instrument (not shown) incorporated in the detection section  680   e . The amplitude and the phase of the reflected wave detected by the detection section  680   e  are sent to the control section  65 , where the film thickness of a metal film or non-metal film or the like of the semiconductor wafer  16  is analyzed based on the amplitude and the phase of the reflected wave. The analyzed values are monitored by the control section  65  as monitoring signals. 
       FIG. 9  is a perspective view illustrating the dresser  33 A usable as an embodiment of the present invention. As shown in  FIG. 9 , the dresser  33 A is provided with a dresser arm  685 , a dressing member  686  rotatably attached to a distal end of the dresser arm  685 , a swing shaft  688  connected to the other end of the dresser arm  685  and a motor  689  as a drive mechanism that causes the dresser arm  685  to swing around the swing shaft  688 . The dressing member  686  has a circular dressing surface and rigid grains are fixed to the dressing surface. Examples of the rigid grains include diamond grains and ceramic grains. The dresser arm  685  incorporates a motor which is not shown and the motor causes the dressing member  686  to rotate. The swing shaft  688  is connected to an ascending/descending mechanism which is not shown and the dresser arm  685  descends through the ascending/descending mechanism, whereby the dressing member  686  presses the polishing surface of the polishing pad  10 . 
       FIG. 10A  is a perspective view illustrating the atomizer  34 A. The atomizer  34 A is provided with an arm  690  provided with one or a plurality of jet holes below, a fluid channel  691  connected to the arm  690  and a swing shaft  694  that supports the arm  690 .  FIG. 10B  is a schematic view illustrating a lower part of the arm  690 . In the example shown in  FIG. 10B , a plurality of jet holes  690   a  are formed at equal intervals in the lower part of the arm  690 . The fluid channel  691  can be made up of a tube or a pipe or a combination thereof. 
       FIG. 11A  is a side view illustrating an inner structure of the atomizer  34 A and  FIG. 11B  is a plan view illustrating the atomizer  34 A. An opening end portion of the fluid channel  691  is connected to a fluid supply pipe which is not shown and a fluid is supplied from the fluid supply pipe to the fluid channel  691 . Examples of the fluid used include a liquid (e.g., pure water), or a fluid as a liquid and gas mixture (e.g., a fluid with a mixture of pure water and nitrogen gas). The fluid channel  691  communicates with the jet holes  690   a  of the arm  690  and the fluid is atomized and jetted out from the jet holes  690   a  onto the polishing surface of the polishing pad  10 . 
     The arm  690  is turnable around the swing shaft  694  between a cleaning position and a retracted position as shown by dotted lines in  FIG. 10A  and  FIG. 11B . A movable angle of the arm  690  is approximately 90°. The arm  690  is normally located at the cleaning position and disposed along the diameter direction of the polishing surface of the polishing pad  10  as shown in  FIG. 1 . During maintenance such as replacement of the polishing pad  10 , the arm  690  is manually moved to the retracted position. Therefore, the arm  690  need not be removed during maintenance, and it is thereby possible to improve maintainability. Note that a rotation mechanism may be connected to the swing shaft  694  so that the rotation mechanism may cause the arm  690  to turn. 
     As shown in  FIG. 11B , two reinforcement members  696 ,  696  having different shapes are provided on both sides of the arm  690 . The reinforcement members  696 ,  696  provided in this way prevent, when the arm  690  is turned between the cleaning position and the retracted position, the shaft center of the arm  690  from shaking by a large margin and allows an atomizing operation to be effectively performed. The atomizer  34 A is provided with a lever  695  for fixing the turning position of the arm  690  (angle range within which the arm  690  can turn). That is, it is possible to adjust the turnable angle of the arm  690  according to conditions by operating the lever  695 . When the lever  695  is turned, the arm  690  can turn freely and the arm  690  can be manually moved between the cleaning position and the retracted position. When the lever  695  is tightened, the position of the arm  690  is fixed at either the cleaning position or the retracted position. 
     The arm  690  of the atomizer can have a foldable structure. More specifically, the arm  690  can be constructed of at least two arm members which are connected via a joint. In this case, an angle formed by the arm members when the arm  690  is folded is set to be equal to or greater than 1° and equal to or less than 45°, or preferably set to be equal to or greater than 5° and equal to or less than 30°. When the angle formed between the arm members is equal to or greater than 45°, the space occupied by the arm  690  increases, and on the other hand, when the angle formed between the arm members is less than 1°, the width of the arm  690  cannot help but be reduced and the mechanical strength is weakened. In this example, the arm  690  may be configured so as not to rotate around the swing shaft  694 . By folding the arm  690  during maintenance such as replacement of the polishing pad  10 , it is possible to prevent the atomizer from disturbing the maintenance operation. The arm  690  of the atomizer can have an expandable structure as another modification. In this example, if the arm  690  is contracted during maintenance, the atomizer never becomes a hindrance. 
     An object of providing the atomizer  34 A is to wash away polishing waste or abrasive grains or the like remaining on the polishing surface of the polishing pad  10  using a high pressure fluid. It is possible to achieve more preferable dressing, that is, regeneration of the polishing surface through cleaning of the polishing surface using a fluid pressure of the atomizer  34 A and dressing of the polishing surface using the dresser  33 A which is a mechanical contact. Normally, the polishing surface is often regenerated using the atomizer after performing dressing using a contact type dresser (diamond dresser or the like). 
     Next, a transfer mechanism for conveying a semiconductor wafer will be described using  FIG. 1 . The transfer mechanism is provided with a lifter  11 , a first linear transporter  66 , a swing transporter  12 , a second linear transporter  67  and a temporary placement table  180 . 
     The lifter  11  receives a semiconductor wafer from the transfer robot  22 . The first linear transporter  66  transfers the semiconductor wafer received from the lifter  11  between a first transfer position TP 1 , a second transfer position TP 2 , a third transfer position TP 3  and a fourth transfer position TP 4 . The first polishing unit  3 A and the second polishing unit  3 B receive the semiconductor wafer from the first linear transporter  66  and polish it. The first polishing unit  3 A and the second polishing unit  3 B hand over the polished semiconductor wafer to the first linear transporter  66 . 
     The swing transporter  12  transfers the semiconductor wafer between the first linear transporter  66  and the second linear transporter  67 . The second linear transporter  67  transfers the semiconductor wafer received from the swing transporter  12  among a fifth transfer position TP 5 , a sixth transfer position TP 6  and a seventh transfer position TP 7 . The third polishing unit  3 C and the fourth polishing unit  3 D receive the semiconductor wafer from the second linear transporter  67  and polish it. The third polishing unit  3 C and the fourth polishing unit  3 D hand over the polished semiconductor wafer to the second linear transporter  67 . The semiconductor wafer polished by the polishing unit  3  is placed on the temporary placement table  180  by the swing transporter  12 . 
       FIG. 12A  is a plan view illustrating the cleaning section  64  and  FIG. 12B  is a side view illustrating the cleaning section  64 . As shown in  FIG. 12A  and  FIG. 12B , the cleaning section  64  is partitioned into a first cleaning chamber  190 , a first transfer chamber  191 , a second cleaning chamber  192 , a second transfer chamber  193 , and a drying chamber  194 . An upper primary cleaning module  201 A and a lower primary cleaning module  201 B arrayed in a longitudinal direction are arranged in the first cleaning chamber  190 . The upper primary cleaning module  201 A is disposed above the lower primary cleaning module  201 B. Similarly, an upper secondary cleaning module  202 A and a lower secondary cleaning module  202 B arrayed in the longitudinal direction are arranged in the second cleaning chamber  192 . The upper secondary cleaning module  202 A is disposed above the lower secondary cleaning module  202 B. The primary and secondary cleaning modules  201 A,  201 B,  202 A and  202 B are cleaners for cleaning a semiconductor wafer using a cleaning liquid. Since the primary and secondary cleaning modules  201 A,  201 B,  202 A and  202 B are arrayed along the vertical direction, they provide an advantage that a footprint area is small. 
     A temporary semiconductor wafer placement table  203  is provided between the upper secondary cleaning module  202 A and the lower secondary cleaning module  202 B. In the drying chamber  194 , an upper drying module  205 A and a lower drying module  205 B arrayed along the longitudinal direction are arranged. The upper drying module  205 A and the lower drying module  205 B are separated from each other. Filter fan units  207 ,  207  for supplying clean air to the drying modules  205 A and  205 B are provided on the upper drying module  205 A and the lower drying module  205 B respectively. The upper primary cleaning module  201 A, the lower primary cleaning module  201 B, the upper secondary cleaning module  202 A, the lower secondary cleaning module  202 B, the temporary placement table  203 , the upper drying module  205 A and the lower drying module  205 B are fixed to a frame, which is not shown, via bolts or the like. 
     A vertically movable first transfer robot  209  is disposed in the first transfer chamber  191  and a vertically movable second transfer robot  210  is disposed in the second transfer chamber  193 . The first transfer robot  209  and the second transfer robot  210  are movably supported respectively by support shafts  211  and  212  extending in the longitudinal direction. The first transfer robot  209  and the second transfer robot  210  incorporate a drive mechanism such as a motor therein and are vertically movable along the support shafts  211  and  212 . As in the case of the transfer robot  22 , the first transfer robot  209  includes two hands, upper and lower. The first transfer robot  209  is disposed at a position where the lower hand thereof can access the aforementioned temporary placement table  180  as shown by a dotted line in  FIG. 12A . When the lower hand of the first transfer robot  209  accesses the temporary placement table  180 , a shutter (not shown) provided in the barrier  1   b  is designed to be opened. 
     The first transfer robot  209  operates so as to transfer the semiconductor wafer  16  between the temporary placement table  180 , the upper primary cleaning module  201 A, the lower primary cleaning module  201 B, the temporary placement table  203 , the upper secondary cleaning module  202 A and the lower secondary cleaning module  202 B. The first transfer robot  209  uses the lower hand when transferring a semiconductor wafer before cleaning (semiconductor wafer to which slurry is adhered) and uses the upper hand when transferring a semiconductor wafer after cleaning. The second transfer robot  210  operates so as to transfer the semiconductor wafer  16  between the upper secondary cleaning module  202 A, the lower secondary cleaning module  202 B, the temporary placement table  203 , the upper drying module  205 A and the lower drying module  205 B. The second transfer robot  210  is provided with only one hand because it transfers only a cleaned semiconductor wafer. Using the upper hand, the transfer robot  22  shown in  FIG. 1  unloads a semiconductor wafer from the upper drying module  205 A or the lower drying module  205 B and returns the semiconductor wafer to the wafer cassette. When the upper hand of the transfer robot  22  accesses the drying modules  205 A and  205 B, a shutter (not shown) provided in the barrier  1   a  is designed to be opened. 
     Since the cleaning section  64  is provided with the two primary cleaning modules and the two secondary cleaning modules, it is possible to form a plurality of cleaning lines whereby a plurality of semiconductor wafers are cleaned in parallel. The “cleaning line” means a moving path inside the cleaning section  64  when one semiconductor wafer is cleaned by a plurality of cleaning modules. For example, as shown in  FIG. 13 , it is possible to convey one semiconductor wafer in order of the first transfer robot  209 , the upper primary cleaning module  201 A, the first transfer robot  209 , the upper secondary cleaning module  202 A, the second transfer robot  210  and the upper drying module  205 A (see a cleaning line  1 ), and convey another wafer in parallel to this, in order of the first transfer robot  209 , the lower primary cleaning module  201 B, the first transfer robot  209 , the lower secondary cleaning module  202 B, the second transfer robot  210  and the lower drying module  205 B (see a cleaning line  2 ). Thus, it is possible to substantially simultaneously clean and dry a plurality of (typically two) semiconductor wafers using the two parallel cleaning lines. 
     Next, configurations of the upper drying module  205 A and the lower drying module  205 B will be described. Both the upper drying module  205 A and the lower drying module  205 B are dryers that perform rotagoni drying. Since the upper drying module  205 A and the lower drying module  205 B have identical configurations, the upper drying module  205 A will be described hereinafter.  FIG. 14  is a longitudinal cross-sectional view illustrating the upper drying module  205 A and  FIG. 15  is a plan view illustrating the upper drying module  205 A. The upper drying module  205 A is provided with a base  401  and four cylindrical substrate support members  402  supported by the base  401 . The base  401  is fixed to a top end of a rotation shaft  406  and the rotation shaft  406  is rotatably supported by a bearing  405 . The bearing  405  is fixed to an inner circumferential surface of a cylindrical body  407  that extends parallel to the rotation shaft  406 . A bottom end of the cylindrical body  407  is attached to a frame  409  and the position thereof is fixed. The rotation shaft  406  is connected to a motor  415  via pulleys  411  and  412 , and a belt  414 , and the base  401  is designed to rotate around its shaft center by driving the motor  415 . 
     A rotation cover  450  is fixed to a top surface of the base  401 . Note that  FIG. 14  illustrates a longitudinal cross section of the rotation cover  450 . The rotation cover  450  is disposed so as to surround a whole circumference of the semiconductor wafer  16 . The longitudinal cross-sectional shape of the rotation cover  450  is inclined inward in the diameter direction. The longitudinal cross section of the rotation cover  450  is formed of a smooth curve. A top end of the rotation cover  450  is proximate to the semiconductor wafer  16  and an inner diameter of the top end of the rotation cover  450  is set to be slightly greater than the diameter of the semiconductor wafer  16 . A notch  450   a  that follows an outer circumferential surface shape of the substrate support member  402  is formed at the top end of the rotation cover  450  so as to correspond to each substrate support member  402 . A liquid discharge hole  451  which extends diagonally is formed in a bottom surface of the rotation cover  450 . 
     A front nozzle  454  that supplies pure water as a cleaning liquid onto a surface (front surface) of the semiconductor wafer  16  is disposed above the semiconductor wafer  16 . The front nozzle  454  is disposed oriented toward the center of the semiconductor wafer  16 . The front nozzle  454  is connected to a pure water supply source (cleaning liquid supply source), which is not shown, and pure water is supplied to the center of the surface of the semiconductor wafer  16  through the front nozzle  454 . As the cleaning liquid, a chemical liquid can also be used in addition to pure water. Two nozzles  460  and  461  are disposed in parallel above the semiconductor wafer  16  to execute rotagoni drying. The nozzle  460  is intended to supply IPA vapor (a mixture of isopropyl alcohol and N 2  gas) to the surface of the semiconductor wafer  16  and the nozzle  461  is intended to supply pure water to prevent the surface of the semiconductor wafer  16  from drying. The nozzles  460  and  461  are configured to be movable along the diameter direction of the semiconductor wafer  16 . 
     A back nozzle  463  connected to a cleaning liquid supply source  465  and a gas nozzle  464  connected to a drying gas supply source  466  are disposed inside the rotation shaft  406 . Pure water is stored in the cleaning liquid supply source  465  as a cleaning liquid and the pure water is designed to be supplied to the reverse side of the semiconductor wafer  16  through the back nozzle  463 . An N 2  gas or dry air or the like is stored in the drying gas supply source  466  as a drying gas and the drying gas is supplied to the reverse side of the semiconductor wafer  16  through the gas nozzle  464 . 
     Next, the supply of pure water from the front nozzle  454  is stopped, the front nozzle  454  is moved to a predetermined standby position away from the semiconductor wafer  16  and the two nozzles  460  and  461  are moved to working positions above the semiconductor wafer  16 . The IPA vapor from the nozzle  460  and the pure water from the nozzle  461  are supplied onto the surface of the semiconductor wafer  16  while causing the semiconductor wafer  16  to rotate at a low speed of 30 to 150 min −1 . At this time, pure water is also supplied to the reverse side of the semiconductor wafer  16  from the back nozzle  463 . The two nozzles  460  and  461  are simultaneously moved along the diameter direction of the semiconductor wafer  16 . The surface (top surface) of the semiconductor wafer  16  is thereby dried. 
     After that, the two nozzles  460  and  461  are moved to the predetermined standby position and the supply of pure water from the back nozzle  463  is stopped. The semiconductor wafer  16  is caused to rotate at a high speed of 1000 to 1500 min −1  to shake off pure water adhered to the reverse side of the semiconductor wafer  16 . At this time, a drying gas from the gas nozzle  464  is sprayed over the reverse side of the semiconductor wafer  16 . The reverse side of the semiconductor wafer  16  is dried in this way. The dried semiconductor wafer  16  is unloaded from the drying module  205 A by the transfer robot  22  shown in  FIG. 1  and returned to the wafer cassette. Thus, the wafer is subjected to a series of processes including polishing, cleaning and drying. The drying module  205 A configured as described above can dry both sides of the semiconductor wafer  16  speedily and effectively, and can also accurately control the end time point of drying processing. Therefore, the processing time for drying processing never becomes a rate-determining step of the whole cleaning process. Since processing times on a plurality of aforementioned cleaning lines formed in the cleaning section  4  can be leveled, it is possible to improve the throughput of the entire process. 
     According to the present embodiment, when the semiconductor wafer is transferred (before loading) to the polishing apparatus, the semiconductor wafer is in a dried state, and after completion of polishing and cleaning, the semiconductor wafer is in a dried state before unloading and unloaded to the substrate cassette. The semiconductor wafer in a dried state can be unloaded from the polishing apparatus into the cassette. That is, dry in/dry out is possible. 
     The semiconductor wafer placed on the temporary placement table  180  is transferred to the first cleaning chamber  190  or the second cleaning chamber  192  via the first transfer chamber  191 . The semiconductor wafer is subjected to cleaning processing in the first cleaning chamber  190  or the second cleaning chamber  192 . The semiconductor wafer subjected to the cleaning processing in the first cleaning chamber  190  or the second cleaning chamber  192  is transferred to the drying chamber  194  via the second transfer chamber  193 . The semiconductor wafer is subjected to drying processing in the drying chamber  194 . The semiconductor wafer subjected to the drying processing is unloaded from the drying chamber  194  and returned to the cassette by the transfer robot  22 . 
       FIG. 16  is a schematic diagram illustrating a whole arrangement of a polishing unit (polishing apparatus) according to an embodiment of the present invention. As shown in  FIG. 16 , the polishing apparatus is provided with the polishing table  30 A and the top ring  31 A (holding section) that holds a substrate such as a semiconductor wafer, which is an object, and presses the substrate against the polishing surface on the polishing table. 
     The first polishing unit  3 A is a polishing unit for polishing between the polishing pad  10  and the semiconductor wafer  16  disposed opposed to the polishing pad  10 . The first polishing unit  3 A includes the polishing table  30 A for holding the polishing pad  10  and the top ring  31 A for holding the semiconductor wafer  16 . The first polishing unit  3 A includes the swing arm  110  for holding the top ring  31 A, a swing shaft motor  14  for causing the swing arm  110  to swing and a driver  18  that supplies drive power to the swing shaft motor  14 . Furthermore, the first polishing unit  3 A includes an arm torque detection section  26  that detects arm torque applied to the swing arm  110  and an end point detection section  28  that detects a polishing end point indicating an end of polishing based on the arm torque  26   a  detected by the arm torque detection section  26 . The end point detection section  28  detects a polishing end point indicating an end of polishing using at least one of the output of the arm torque detection section  26  and the output of a current detection section  810  which will be described later. 
     According to the present embodiment which will be described using  FIG. 16  to  FIG. 48 , it is possible to improve accuracy of polishing end point detection in the scheme in which the top ring is held at an end portion of the swing arm. In the present embodiment, various types of polishing end point detection means are available such as a method based on an eddy current, a method based on arm torque and a method of detecting and using a drive load of a drive section that drives to rotate the polishing table or top ring. The present embodiment will be described by focusing on polishing end point detection based on an eddy current in a scheme in which the top ring is held at an end portion of the swing arm, but it is also possible to detect a polishing end point based on eddy current arm torque or detect a polishing end point by detecting a drive load of the drive section that drives to rotate the polishing table or the top ring. 
     The holding section, the swing arm, the arm drive section and the end point detection section form a set and sets of the same configuration are provided in the first polishing unit  3 A, the second polishing unit  3 B, the third polishing unit  3 C and the fourth polishing unit  3 D respectively. 
     The polishing table  30 A is connected to a motor M 3  (see  FIG. 2 ), which is a drive section, disposed therebelow via a table shaft  102  and is rotatable around the table shaft  102 . The polishing pad  10  is mounted on the top surface of the polishing table  30 A and a surface  101  of the polishing pad  10  constitutes a polishing surface for polishing the semiconductor wafer  16 . A polishing liquid supply nozzle (not shown) is provided above the polishing table  30 A and the polishing liquid supply nozzle supplies a polishing liquid Q to the polishing pad  10  on the polishing table  30 A. As shown in  FIG. 16 , an eddy current sensor  50  that can detect a polishing end point by generating an eddy current in the semiconductor wafer  16  and detecting the eddy current is embedded in the polishing table  30 A. 
     The top ring  31 A is constructed of a top ring body  24  that presses the semiconductor wafer  16  against the polishing surface  101  and a retainer ring  23  that holds an outer circumferential edge of the semiconductor wafer  16  so that the semiconductor wafer  16  does not slip out of the top ring. 
     The top ring  31 A is connected to a top ring shaft  111 . The top ring shaft  111  is caused by a vertical motion mechanism, which is not shown, to move in the vertical direction relative to the swing arm  110 . The vertical motion of the top ring shaft  111  causes the entire top ring  31 A to ascend or descend and causes it to be positioned relative to the swing arm  110 . 
     The top ring shaft  111  is connected to a rotary cylinder  112  via a key (not shown). The rotary cylinder  112  is provided with a timing pulley  113  on its circumferential portion. A top ring motor  114  is fixed to the swing arm  110 . The timing pulley  113  is connected to a timing pulley  116  provided for the top ring motor  114  via a timing belt  115 . As the top ring motor  114  rotates, the rotary cylinder  112  and the top ring shaft  111  integrally rotate via the timing pulley  116 , the timing belt  115  and the timing pulley  113 , and the top ring  31 A rotates. 
     The swing arm  110  is connected to the rotation shaft of the swing shaft motor  14 . The swing shaft motor  14  is fixed to a swing arm shaft  117 . Therefore, the swing arm  110  is rotatably supported by the swing arm shaft  117 . 
     The top ring  31 A can hold a substrate such as the semiconductor wafer  16  to an undersurface thereof. The swing arm  110  can turn around the swing arm shaft  117 . The top ring  31 A that holds the semiconductor wafer  16  to its undersurface is moved from a position at which it receives the semiconductor wafer  16  to a position above the polishing table  30 A as the swing arm  110  turns. The top ring  31 A is caused to descend to press the semiconductor wafer  16  against the surface (polishing surface)  101  of the polishing pad  10 . At this time, the top ring  31 A and the polishing table  30 A are caused to rotate respectively. At the same time, a polishing liquid is supplied onto the polishing pad  10  from the polishing liquid supply nozzle provided above the polishing table  30 A. In this way, the surface of the semiconductor wafer  16  is polished by causing the semiconductor wafer  16  to slide on the polishing surface  101  of the polishing pad  10 . 
     The first polishing unit  3 A includes a table drive section (not shown) that drives to rotate the polishing table  30 A. The first polishing unit  3 A may include a table torque detection section (not shown) that detects table torque applied to the polishing table  30 A. The table torque detection section can detect table torque from a current of the table drive section which is a rotary motor. The end point detection section  28  may also detect a polishing end point indicating an end of polishing only from the eddy current detected by the eddy current sensor  50  or detect a polishing end point indicating an end of polishing also by taking into consideration the arm torque  26   a  detected by the arm torque detection section  26  or the table torque. 
     Next, the eddy current sensor  50  provided for the polishing apparatus according to the present invention will be described in more detail with reference to the accompanying drawings.  FIGS. 17A and 17B  are diagrams illustrating a configuration of the eddy current sensor  50 ;  FIG. 17A  is a block diagram illustrating a configuration of the eddy current sensor  50  and  FIG. 17B  is an equivalent circuit diagram of the eddy current sensor  50 . 
     As shown in  FIG. 17A , the eddy current sensor  50  is disposed in the vicinity of a metal film (or conductive film) mf which is an object to be detected and an AC signal source  52  is connected to a coil thereof. Here, the metal film (or conductive film) mf to be detected is a thin film of, for example, Cu, Al, Au or W formed on a semiconductor wafer W. The eddy current sensor  50  is disposed in the vicinity on the order of, for example, 1.0 to 4.0 mm of the metal film (or conductive film) to be detected. 
     When an eddy current is generated on the metal film (or conductive film) mf, an oscillating frequency or an impedance thereby changes, and examples of the eddy current sensor include a frequency type sensor that detects a metal film (or conductive film) from the frequency change and an impedance type sensor that detects a metal film (or conductive film) from the impedance change. That is, in the case of the frequency type sensor, when an eddy current I 2  changes in the equivalent circuit shown in  FIG. 17B , an impedance Z changes and the oscillating frequency of the signal source (variable frequency oscillator)  52  changes, and the detection circuit  54  detects the change of the oscillating frequency, and can thereby detect a change in the metal film (or conductive film). In the case of the impedance type, when the eddy current I 2  changes in the equivalent circuit shown in  FIG. 17B , the impedance Z changes and the impedance Z seen from the signal source (fixed frequency oscillator)  52  changes, and the detection circuit  54  detects the change in the impedance Z, and can thereby detect a change in the metal film (or conductive film). 
     The impedance type eddy current sensor extracts signal outputs X and Y, phase and joint impedance Z as will be described later. It is possible to obtain measurement information on a metal film (or conductive film) of Cu, Al, Au or W from a frequency F or the impedance X or Y or the like. The eddy current sensor  50  can be incorporated in the vicinity of the inner surface of the polishing table  30 A as shown in  FIG. 16 , is positioned so as to face a semiconductor wafer as an object to be polished via the polishing pad and can detect a change in the metal film (or conductive film) from the eddy current flowing through the metal film (or conductive film) on the semiconductor wafer. 
     Regarding the frequency of the eddy current sensor, a single radio wave, mixed radio wave, AM modulated radio wave, FM modulated radio wave, sweeping output of a function generator or a plurality of oscillating frequency sources can be used and it is preferable to select a high sensitivity oscillating frequency or modulation scheme adapted to the film type of the metal film. 
     Hereinafter, an impedance type eddy current sensor will be described more specifically. The AC signal source  52  is an oscillator with a fixed frequency on the order of 2 to 30 MHz, and, for example, a crystal oscillator is used. A current I 1  flows through the eddy current sensor  50  by an AC voltage supplied from the AC signal source  52 . When the current flows through the eddy current sensor  50  disposed in the vicinity of the metal film (or conductive film) mf, a magnetic flux thereof crosses the metal film (or conductive film) mf and thereby forms a mutual inductance M therebetween, which causes the eddy current I 2  to flow through the metal film (or conductive film) mf. Here, R 1  is equivalent resistance on a primary side including the eddy current sensor and L 1  is a self-inductance on the primary side including the eddy current sensor likewise. On the metal film (or conductive film) mf side, R 2  is equivalent resistance corresponding to an eddy current loss and L 2  is a self-inductance thereof. The impedance Z on the eddy current sensor side viewed from terminals a and b of the AC signal source  52  changes depending on the magnitude of the eddy current loss formed in the metal film (or conductive film) mf. 
       FIGS. 18 and 19  are schematic diagrams illustrating a configuration example of the eddy current sensor  50  of the present embodiment. The eddy current sensor  50  disposed in the vicinity of a substrate on which the conductive film is formed is constructed of a pot core  60 , six coils  860 ,  862 ,  864 ,  866 ,  868  and  870 . The pot core  60  which is a magnetic body includes bottom face portion  61   a  (bottom magnetic body), a magnetic core portion  61   b  (central magnetic body) provided at the middle of the bottom face portion  61   a  and a peripheral wall portion  61   c  (peripheral magnetic body) provided on the periphery of the bottom face portion  61   a . The peripheral wall portion  61   c  is a wall portion provided on the periphery of the bottom face portion  61   a  so as to surround the magnetic core portion  61   b . In the present embodiment, the bottom face portion  61   a  has a circular disk shape, the magnetic core portion  61   b  has a solid columnar shape and the peripheral wall portion  61   c  has a cylinder shape that surrounds the bottom face portion  61   a.    
     Among the six coils  860 ,  862 ,  864 ,  866 ,  868  and  870 , the central coils  860  and  862  are excitation coils connected to the AC signal source  52 . The excitation coils  860  and  862  form an eddy current in the metal film (or conductive film) mf on the semiconductor wafer W disposed in the vicinity through a magnetic field formed by a voltage supplied from the AC signal source  52 . The detection coils  864  and  866  are disposed on the metal film side of the excitation coils  860  and  862  to detect a magnetic field generated by the eddy current formed on the metal film. The dummy coils  868  and  870  are disposed on the opposite side of the detection coils  864  and  866  across the excitation coils  860  and  862 . 
     The excitation coil  860  is disposed on an outer periphery of the magnetic core portion  61   b , and is an internal coil that can generate a magnetic field and forms an eddy current in a conductive film. The excitation coil  862  is disposed on an outer periphery of the peripheral wall portion  61   c , is an external coil that can generate a magnetic field and forms an eddy current in the conductive film. The detection coil  864  is disposed on an outer periphery of the magnetic core portion  61   b , can detect a magnetic field and detects an eddy current formed in the conductive film. The detection coil  866  is disposed on an outer periphery of the peripheral wall portion  61   c , can detect a magnetic field and detects an eddy current formed in the conductive film. 
     The eddy current sensor includes dummy coils  868  and  870  that detect an eddy current formed in a conductive film. The dummy coil  868  is disposed on an outer periphery of the magnetic core portion  61   b  and can detect a magnetic field. The dummy coil  870  is disposed on an outer periphery of the peripheral wall portion  61   c  and can detect a magnetic field. The detection coil and the dummy coil according to the present embodiment are disposed on an outer periphery of the bottom face portion  61   a  and on an outer periphery of the peripheral wall portion  61   c , but the detection coil and the dummy coil may also be disposed only one of the outer periphery of the bottom face portion  61   a  and the outer periphery of the peripheral wall portion  61   c.    
     An axial direction of the magnetic core portion  61   b  is orthogonal to the conductive film on the substrate, the detection coils  864  and  866 , the excitation coils  860  and  862 , and the dummy coils  868  and  870  are disposed at different positions in the axial direction of the magnetic core portion  61   b , and the detection coils  864  and  866 , the excitation coils  860  and  862 , and the dummy coils  868  and  870  are disposed in that order from a position closer to the conductive film on the substrate to a position far from the conductive film in the axial direction of the magnetic core portion  61   b . Lead wires (not shown) for connections with the outside are led from the detection coils  864  and  866 , the excitation coils  860  and  862 , and the dummy coils  868  and  870 . 
       FIG. 18  is a cross-sectional view on a plane passing through a central axis  872  of the magnetic core portion  61   b . The pot core  60  which is a magnetic body includes the bottom face portion  61   a  in a disk shape, the magnetic core portion  61   b  in a columnar shape provided at the middle of the bottom face portion  61   a  and the peripheral wall portion  61   c  in a cylindrical shape provided on the periphery of the bottom face portion  61   a . As an example of the size of the pot core  60 , a diameter L 1  of the bottom face portion  61   a  is approximately 1 cm to 5 cm, a height L 2  of the eddy current sensor  50  is approximately 1 cm to 5 cm. Although the peripheral wall portion  61   c  has a cylindrical shape, an outside diameter of which is the same in the height direction in  FIG. 18 , the peripheral wall portion  61   c  may also have a tapered shape which becomes narrower in the direction away from the bottom face portion  61   a , that is, toward the top end. 
     The lead wires used for the detection coils  864  and  866 , the excitation coils  860  and  862 , and the dummy coils  868  and  870  are copper wires, manganin wires or nichrome wires. Using the manganin wires or nichrome wires reduces a temperature variation of electric resistance or the like and improves temperature characteristics. 
     Since the excitation coils  860  and  862  are formed by winding a wire member around the outside of the magnetic core portion  61   b  which is made of ferrite or the like and the outside of the peripheral wall portion  61   c  in the present embodiment, it is possible to increase a density of the eddy current flowing through an object to be measured in the present embodiment. Since the detection coils  864  and  866  are also formed outside the magnetic core portion  61   b  and outside the peripheral wall portion  61   c , it is possible to efficiently collect an inverse magnetic field (interlinkage magnetic flux) generated. 
     In order to increase the density of the eddy current flowing through the object to be measured in the present embodiment, the excitation coil  860  and the excitation coil  862  are connected in parallel as shown in  FIG. 19 . That is, the internal coil and the external coil are electrically connected in parallel. The coils are connected in parallel for the following reason. When connected in parallel, a voltage applicable to the excitation coil  860  and the excitation coil  862  increases compared to when connected in series, causing the current flowing through the excitation coil  860  and the excitation coil  862  to increase. This results in an increase of the magnetic field. On the other hand, when the coils are connected in series, an inductance of the circuit increases and a frequency of the circuit decreases. It is therefore difficult to apply a necessary high frequency to the excitation coils  860  and  862 . An arrow  874  represents an orientation of the current flowing through the excitation coil  860  and the excitation coil  862 . 
     As shown in  FIG. 19 , the excitation coil  860  and the excitation coil  862  are connected such that the excitation coil  860  and the excitation coil  862  have the same magnetic field direction. That is, currents are made to flow through the excitation coil  860  and the excitation coil  862  in different directions. A magnetic field  876  is a magnetic field generated by the inside excitation coil  860  and a magnetic field  878  is a magnetic field generated by the outside excitation coil  862 . As shown in  FIG. 20 , the excitation coil  860  and the excitation coil  862  have the same magnetic field direction. That is, the direction of the magnetic field generated by the internal coil in the magnetic core portion  61   b  is the same as the direction of the magnetic field generated by the external coil in the magnetic core portion  61   b.    
     Since the magnetic field  876  and the magnetic field  878  shown in the region  880  have the same orientation, the two magnetic fields are added up into a greater magnetic field. Compared to a conventional case where only the magnetic field  876  from the excitation coil  860  exists, the magnetic field becomes greater by an amount corresponding to the magnetic field  878  from the excitation coil  862  in the present embodiment. 
     Next, unlike  FIG. 19 , a case will be described where as shown in  FIG. 21 , the excitation coil  860  and the excitation coil  862  are connected such that the excitation coil  860  and the excitation coil  862  have mutually opposite magnetic field directions. That is, currents are caused to flow through the excitation coil  860  and the excitation coil  862  in the same direction. The magnetic field  876  is a magnetic field generated by the inside excitation coil  860  and the magnetic field  878  is a magnetic field generated by the outside excitation coil  862 . As shown in  FIG. 22 , the excitation coil  860  and the excitation coil  862  have mutually opposite magnetic field directions. That is, the direction of the magnetic field generated by the internal coil in the magnetic core portion  61   b  is opposite to the direction of the magnetic field generated by the external coil in the magnetic core portion  61   b.    
     Since the magnetic field  876  and the magnetic field  878  shown in a region  880  have opposite directions, the two magnetic fields cancel each other out into a smaller magnetic field. The magnetic field  878  from the outside excitation coil  862  suppresses the magnetic field  876  from the inside excitation coil  860 , which causes the flow of magnetic force line in the magnetic core portion  61   b  to change. Note that the magnetic field shown in  FIG. 22  corresponds to a case where the current flowing through the excitation coil  862  which is located outside is greater. When the current is greater, the magnetic field from the excitation coil  862  is greater in strength than the magnetic field from the excitation coil  860  inside the peripheral wall portion  61   c , and therefore the magnetic field  878  suppresses the magnetic field  876 . As a result, a magnetic field shown in  FIG. 22  is generated. 
     When  FIG. 20  is compared to  FIG. 22 , the following can be known. The eddy current density generated in the semiconductor wafer  16  by the magnetic field shown in  FIG. 20  is generated strongly in a narrow range. The eddy current density generated in the semiconductor wafer  16  by the magnetic field shown in  FIG. 22  is generated strongly in a wide range. 
       FIG. 23  is a schematic diagram illustrating a connection example of the respective coils in the eddy current sensor. As shown in  FIG. 23A , the detection coils  864  and  866  and the dummy coils  868  and  870  are connected in mutually opposite phases. The detection coil  864  and the detection coil  866  are connected in series. The dummy coil  868  and the dummy coil  870  are connected in series. In  FIG. 23 , the excitation coils  860  and  862 , the detection coils  864  and  866  and the dummy coils  868  and  870  are represented by one coil. 
     The detection coils  864  and  866  and the dummy coils  868  and  870  constitute an inverse phase series circuit as described above and both ends thereof are connected to a resistor bridge circuit  77  including a variable resistor  76 . The excitation coils  860  and  862  are connected to the AC signal source  52 , generate an alternating magnetic flux and thereby form an eddy current in the metal film (or conductive film) mf disposed in the vicinity. Adjusting the resistance value of the variable resistor  76  makes it possible to adjust the output voltage of the series circuit from the detection coils  864  and  866  and the dummy coils  868  and  870  so as to become 0 when no metal film (or conductive film) exists. The variable resistors  76  (VR 1 , VR 2 ) inserted in parallel to the detection coils  864  and  866  and the dummy coils  868  and  870  respectively adjust signals L 1  and L 3  so as to be in-phase with each other. That is, in the equivalent circuit in  FIG. 23B , variable resistor VR 1  (=VR 1-1 +VR 1-2 ) and VR 2  (=VR 2-1 +VR 2-2 ) are adjusted so as to satisfy: 
       VR 1-1 ×(VR 2-2   +jωL   3 )=VR 1-2 ×(VR 2−1   +jωL   1 )   (1)
 
     Thus, as shown in  FIG. 23C , the signals L 1  and L 3  before adjustment (shown by a dotted line in  FIG. 23 ) are assumed to be in-phase signals with the same amplitude (shown by a solid line in  FIG. 23 ). 
     When the metal film (or conductive film) is located in the vicinity of the detection coils  864  and  866 , a magnetic flux generated by an eddy current formed in the metal film (or conductive film) crosses the detection coils  864  and  866  and the dummy coils  868  and  870 , but since the detection coils  864  and  866  are disposed at positions closer to the metal film (or conductive film), a balance in induced voltages between the detection coils  864  and  866  and the dummy coils  868  and  870  is lost, which makes it possible to detect an interlinkage flux formed by the eddy current in the metal film (or conductive film). That is, a zero point can be adjusted by separating the series circuit of the detection coils  864  and  866  and the dummy coils  868  and  870  from the excitation coils  860  and  862  connected to the AC signal source and adjusting the balance using the resistor bridge circuit. Therefore, it is possible to detect an eddy current flowing through the metal film (or conductive film) from a zero state, which can increase the detection sensitivity of the eddy current in the metal film (or conductive film). This makes it possible to detect the magnitude of the eddy current formed in the metal film (or conductive film) in a wide dynamic range. 
       FIG. 24  is a block diagram illustrating a coherent detection circuit of the eddy current sensor. The present drawing shows an example of a measuring circuit of an impedance Z when the eddy current sensor  50  side is seen from the AC signal source  52  side. In the measuring circuit for the impedance Z shown in the present drawing, it is possible to extract a resistance component (R), a reactance component (X), an amplitude output (Z) and a phase output (tan −1 R/X) associated with a change in film thickness. 
     As described above, the signal source  52  that supplies an AC signal to the eddy current sensor  50  disposed in the vicinity of the semiconductor wafer W on which the metal film (or conductive film) mf as an object to be detected is formed is an oscillator with a fixed frequency consisting of a crystal oscillator and supplies voltages with fixed frequencies of 2 MHz, 8 MHz, 16 MHz, for example. An AC voltage formed in the signal source  52  is supplied to the eddy current sensor  50  via a bandpass filter  82 . A signal detected by a terminal of the eddy current sensor  50  is passed through a high-frequency amplifier  83  and a phase shift circuit  84 , and a cos component and a sin component of the detection signal are extracted by a coherent detection section constructed of a cos coherent detection circuit  85  and a sin coherent detection circuit  86 . Here, the phase shift circuit  84  forms two signals: an in-phase component (0°) and a quadrature component (90°) of the signal source  52  from the oscillating signal formed in the signal source  52  and both components are introduced into the cos coherent detection circuit  85  and the sin coherent detection circuit  86  and subjected to the aforementioned coherent detection. 
     Low-pass filters  87  and  88  remove unnecessary high-frequency components equal to or higher than the frequency of the signal component from the coherent-detected signal, and extract a resistance component (R) output which is a cos coherent detection output and a reactance component (X) output which is a sin coherent detection output respectively. A vector operation circuit  89  obtains an amplitude output (R 2 +X 2 ) 1/2  from the resistance component (R) output and the reactance component (X) output. A vector operation circuit  90  likewise obtains a phase output (tan −1 R/X) from the resistance component output and the reactance component output. Here, the measuring apparatus body is provided with various filters to remove noise components of a sensor signal. Corresponding cut-off frequencies are set for the various filters, and, for example, by setting the cut-off frequencies of the low-pass filters within a range of 0.1 to 10 Hz, it is possible to remove noise components mixed in the sensor signal during polishing and measure the metal film (or conductive film) to be measured with high accuracy. 
     Next, an example of the end point detection method using the eddy current sensor  50  shown in  FIG. 18  will be described using  FIG. 25 .  FIG. 25  shows a film thickness (mm) of the semiconductor wafer  16  on the vertical axis and a polishing time (sec) after polishing starts on the horizontal axis. The horizontal axis also shows how many times the table has rotated with an integer when the eddy current sensor  50  performs measurement. “1” represents a first rotation and “N” represents an N-th rotation. The end point detection section  28  determines a polishing rate of the semiconductor wafer  16  from the detected eddy current and creates an approximate line (initial polishing rate expression  882 ) based on the polishing rate. The initial polishing rate expression  882  is created using the eddy current obtained for a period during which the polishing table  30 A rotates several times in an initial stage of polishing. 
     An estimated polishing amount when the semiconductor wafer  16  is polished at a polishing rate according to the initial polishing rate expression  882  is calculated and a time required to reach the polishing end point  884  is detected. The end point detection section  28  detects the polishing end point  884  from the estimated polishing amount and a threshold  886  relating to a film thickness corresponding to the polishing end point  884 . At this time, when a change of output of the eddy current sensor  50  is small relative to a change in the wiring height in the semiconductor wafer  16 , it is difficult to obtain the change of the output value of the eddy current sensor  50  accurately. In such a case, a cancellation algorithm of the output value of the eddy current sensor  50  shown below is executed. 
     Using the cancellation algorithm, the end point detection section  28  compares the data relating to the film thickness obtained from the eddy current and the data relating to the film thickness estimated from the polishing rate and does not use the data relating to the film thickness obtained from the eddy current when the comparison result is greater than a predetermined value. For example, the end point detection section  28  compares data collected every one rotation and data relating to the film thickness estimated from the initial polishing rate expression  882  and does not adopt the collected data when both values are considerably different from a predetermined value. For example, when data is collected on the (N+2)-th rotation, if a difference between the data collected on the (N+2)-th rotation and the data collected on the (N+1)-th rotation is greater (or smaller) than a difference (predetermined value) between the data collected on the (N+1)-th rotation and the data collected on the N-th rotation, the data collected on the (N+2)-th rotation is not used. Instead, the value obtained from the initial polishing rate expression  882  is used. Whether the data is not used when it is greater than a predetermined value or the data is not used when it is smaller than a predetermined value depends on polishing conditions such as properties of the film. 
     There are also the following cases as other cases where the collected data is not adopted. For example, when data is collected on the (N+2)-th rotation, if the data collected on the (N+2)-th rotation is greater than data collected on the (N+1)-th rotation, the data collected on the (N+2)-th rotation is not used. Instead, data obtained from the initial polishing rate expression  882  is used. 
     When the data collected on the (N+2)-th rotation is not used, if a value close to an approximation line is acquired from the (N+3)-th rotation onward, the data is adopted. As mentioned above, the initial polishing rate expression  882  is created using several rotations after polishing starts and can be recreated using several latest rotations, for example, every tenth rotation. 
     Next, a case where the peripheral magnetic body is not a wall portion provided on the periphery of the bottom face portion  61   a  so as to surround the magnetic core portion  61   b  will be described using  FIGS. 26 to 28 .  FIGS. 26 and 27  illustrate the eddy current sensor  50  (magnetic element) in which the bottom face portion  61   a  has a columnar shape and the peripheral wall portion  61   c  is disposed at both ends having a columnar shape.  FIG. 26  is a top view.  FIG. 27  is an AA cross-sectional view of  FIG. 26 . Two peripheral magnetic bodies  61   d  are provided on the periphery of the bottom face portion  61   a . As is clear from  FIG. 27 , the eddy current sensor  50  is an E-shaped magnetic element.  FIG. 28  is a top view of the eddy current sensor  50  (magnetic element) in which four peripheral magnetic bodies  61   d  are provided on the periphery of the bottom face portion  61   a . Five or more peripheral magnetic bodies  61   d  may be provided. 
     In the case of the E-shaped magnetic element, a coil arrangement shown in  FIGS. 49 and 50  is also possible in addition to the coil arrangement shown in  FIGS. 26 and 27 .  FIG. 49  is a top view.  FIG. 50  is an AA cross-sectional view of  FIG. 49 . In the embodiment shown in  FIGS. 49 and 50 , detection coils  864   a  and  864   b , excitation coils  860   a  and  860   b , and dummy coils  868   a  and  868   b  are further provided on an outer periphery of a portion  61   e  located between the magnetic core portion  61   b  and the peripheral magnetic body  61   d  of the bottom face portion  61   a . At least one of the detection coils  864   a  and  864   b , excitation coils  860   a  and  860   b , and dummy coils  868   a  and  868   b  may be provided in the portion  61   e . In the embodiment shown in  FIGS. 49 and 50 , only the excitation coils  860   a  and  860   b , and the dummy coils  868   a  and  868   b  may be provided as the excitation coils and dummy coils without providing the excitation coil  860  or the dummy coil  868 . 
     The detection coil  864   a  and the detection coil  864   b  may be electrically connected via a lead wire or may be electrically independent without being connected via a lead wire. The excitation coil  860   a  and excitation coil  860   b , and the dummy coil  868   a  and dummy coil  868   b  may also be electrically connected via a lead wire or may be electrically independent without being connected via a lead wire. 
     Next, an embodiment will be described using  FIG. 48  in which strengths of the magnetic fields generated by the excitation coil  860  and/or excitation coil  862  are changed when the conductivity of the semiconductor wafer  16  is changed. Hereinafter, an embodiment will be described in which strengths of the magnetic fields generated by the excitation coil  860  and the excitation coil  862  are changed, but strength of a magnetic field generated by only one of the excitation coil  860  and the excitation coil  862  may be changed. 
     In  FIGS. 48A, 48B and 48C , an insulating layer  888  (barrier) is formed in the semiconductor wafer  16  and a conductive layer  890  of copper or the like is formed on the insulating layer  888 . Polishing is performed from a state in  FIG. 48A , through a state in  FIG. 48B  to a state in  FIG. 48C . The conductive layer  890  is used as, for example, wiring. 
     In the state in  FIG. 48A , since the conductive layer  890  exists on the front of the semiconductor wafer  16 , the conductive layer  890  generates many eddy currents. In the state in  FIG. 48C , since the conductive layer  890  only exists in a small portion of the semiconductor wafer  16 , the conductive layer  890  generates a smaller eddy current. From the state in  FIG. 48A  to the state in  FIG. 48B , strengths of the magnetic fields generated by the excitation coils  860  and  862  are small. When the state in  FIG. 48B  is reached, the strengths of the magnetic fields generated by the excitation coils  860  and  862  are increased. This is because when the state in  FIG. 48B  is reached, the conductivity of the semiconductor wafer  16  changes. 
     The timing at which the strengths of the magnetic fields generated by the excitation coils  860  and  862  are changed when the conductivity of the semiconductor wafer  16  changes may not be timing at which the state in  FIG. 48B  is reached but may be timing at which polishing of a portion  892  of the insulating layer  888  shown in  FIG. 48A  is finished. 
     In order to increase the strengths of the magnetic fields generated by the excitation coils  860  and  862 , currents flowing through the excitation coils  860  and  862  are increased or voltages applied to the excitation coils  860  and  862  are increased. As another method for increasing the strength of a magnetic field, the state in which only one of the excitation coil  860  and the excitation coil  862  is used may be changed to a state in which both the excitation coil  860  and the excitation coil  862  are used. 
     Note that a plurality of eddy current sensors may be disposed in the polishing table instead of changing the strength of a magnetic field generated by the excitation coil  860  and/or the excitation coil  862  when the conductivity of the semiconductor wafer  16  changes. The plurality of eddy current sensors have different levels of detection sensitivity. An eddy current sensor  50  having a low level of detection sensitivity is used from the state in  FIG. 48A  to the state in  FIG. 48B . When the state in  FIG. 48B  is reached, an eddy current sensor  50  having a higher level of detection sensitivity is used. 
     Here, “having different levels of detection sensitivity” means “having magnetic fields of different strengths generated” and/or “having magnetic fields of different spreads generated”. Examples of a case where a plurality of eddy current sensors of different levels of detection sensitivity are necessary include the following cases: (a) a case where it is necessary to measure film thicknesses of a plurality of chips having different ratios of conductive films within a single chip, (b) a case where it is necessary to measure film thicknesses of a plurality of chips having different resolution requirements in a height direction  896  shown in  FIG. 48A , and (c) a case where it is necessary to measure film thicknesses of a plurality of chips having different polishing amounts in the height direction  896  shown in  FIG. 48A . 
     The case in (c) where it is necessary to measure film thicknesses of a plurality of chips having different polishing amounts in the height direction  896  is such a case as shown below. The conductive layer  890  (Cu wiring) has a distance LL in the height direction shown in  FIG. 48A  when polishing starts. When polishing is finished, the conductive layer  890  has a distance LS in the height direction  896  shown in  FIG. 48C . There are various combinations of the distance LL and the distance LS. Depending on the range of distance LL, a plurality of sensors having different resolutions may be necessary. 
     The method whereby a plurality of eddy current sensors are disposed in the polishing table has been described as the method of changing detection sensitivity, but only one of the excitation coil  860  and the excitation coil  862  shown in  FIG. 18  may be used as the method of changing detection sensitivity. That is, as the method of changing detection sensitivity, it is possible to adopt a method including a step of detecting an eddy current formed in the semiconductor wafer  16  using the detection coil  864  and/or the detection coil  866  according to at least one of a first step of detecting an eddy current formed by the excitation coil  860  in the semiconductor wafer  16  as the polishing table  30 A rotates using the detection coil  864  and/or the detection coil  866 , a second step of detecting an eddy current formed by the excitation coil  862  in the semiconductor wafer  16  using the detection coil  864  and/or detection coil  866  and a third step of detecting an eddy current formed by both the excitation coil  860  and the excitation coil  862  in the semiconductor wafer  16  using the detection coil  864  and/or the detection coil  866 , and a step of detecting a polishing end point indicating an end of polishing of the semiconductor wafer  16  from the detected eddy current. 
     The excitation coil  860  has a smaller outside diameter than the excitation coil  862 . Therefore, when the spread of the magnetic field generated singly by the excitation coil  860  is compared to the spread of the magnetic field generated singly by the excitation coil  862 , the spread of the magnetic field generated singly by the excitation coil  862  is greater. Therefore, the excitation coil  860  can measure a film thickness in a narrow region. The excitation coil  862  can measure a film thickness in a wide region. 
     When both the excitation coil  860  and the excitation coil  862  are used, it is possible to perform control by combining (synthesizing) the magnetic fields generated by the excitation coil  860  and the excitation coil  862  respectively. Control combining magnetic fields makes it possible to achieve wider control of both the spreading region of the magnetic field and the strength of the magnetic field compared to the case where only one of the excitation coil  860  and the excitation coil  862  is used. 
     Which of the first, second or third step should be adopted can be determined depending on the configuration of the micro circuit on the semiconductor wafer  16  or an approximate die size. 
     The relationship between the size of the eddy current sensor  50  and the chip size of the object to be measured can be preferably set as follows. For example, when the chip has a square or rectangular shape, the eddy current sensor  50  is preferably a circumscribed circle circumscribing the square or the rectangle. The size of the eddy current sensor  50  is not preferably excessively smaller or excessively larger than the size of the circumscribed circle. When the chip size is extremely larger or smaller than the size of the eddy current sensor  50 , the eddy current may not be able to be detected, and in such a case, a plurality of eddy current sensors  50  in different sizes may have to be disposed. 
     Note that since the intensity of an eddy current is increased by only adding excitation coils, when the bulk (film) shown in  FIG. 48A  is detected, an addition of excitation alone has an effect. The “bulk (film)” means a film covering the whole surface of the semiconductor wafer  16  such as a region  894  of the conductive layer  890 . Furthermore, the “addition of the excitation coil alone” means providing the excitation coil  862  which is an outside coil for only the excitation coils  860  and  862  and not providing the detection coil  866  which is an outside coil and the dummy coil  870  for the detection coils  864 ,  866  and the dummy coils  868  and  870 . 
     When detecting the conductive layer  890  (Cu wiring) shown in  FIG. 48B  and  FIG. 48C , the detection sensitivity of the eddy current sensor  50  needs to be greater than that when detecting the state in  FIG. 48A , and therefore it may be preferable to provide the detection coil  866  which is an outside coil and the dummy coil  870  also for the detection coils  864  and  866 , and the dummy coils  868  and  870 . 
     Next, an example will be described where the end point detection section  28  detects a polishing end point indicating an end of polishing by also taking into account the arm torque  26   a  detected by the arm torque detection section  26  and table torque. The arm torque detection section  26  detects arm torque  26   a  applied to the swing arm  110  at the connection part of the swing arm  110  to the swing shaft motor  14  in  FIG. 16 . More specifically, the arm drive section is the swing shaft motor (rotation motor)  14  that causes the swing arm  110  to rotate and the arm torque detection section  26  detects the arm torque  26   a  applied to the swing arm  110  from the current value of the swing shaft motor  14 . The current value of the swing shaft motor  14  is an amount that depends on arm torque at the connection part of the swing arm  110  to the swing shaft motor  14 . The current value of the swing shaft motor  14  is a current value  18   b  supplied from the driver  18  to the swing shaft motor  14  in the present embodiment. 
     A method of detecting the arm torque  26   a  by the arm torque detection section  26  will be described using  FIG. 29 . The driver  18  receives a position command  65   a  relating to the position of the swing arm  110  from the control section  65 . The position command  65   a  is data corresponding to an angle of rotation of the swing arm  110  with respect to the swing arm shaft  117 . The driver  18  also receives an angle of rotation  36   a  of the swing arm shaft  117  from an encoder  36  incorporated in and attached to the swing shaft motor  14 . 
     The encoder  36  can detect the angle of rotation  36   a  of the rotation shaft of the swing shaft motor  14 , that is, the angle of rotation  36   a  of the swing arm shaft  117 . Although the swing shaft motor  14  and the encoder  36  are illustrated independently of each other in the drawing, the swing shaft motor  14  and the encoder  36  are integrated together. An example of such an integrated motor is a synchronization type AC servo motor with a feedback encoder. 
     The driver  18  includes a deviation circuit  38 , a current generation circuit  40  and a PWM circuit  42 . The deviation circuit  38  obtains a deviation  38   a  between the position command  65   a  and the angle of rotation  36   a  from the position command  65   a  and the angle of rotation  36   a . The deviation  38   a  and the current value  18   b  are inputted to the current generation circuit  40 . The current generation circuit  40  generates a current command  18   a  corresponding to the deviation  38   a  from the deviation  38   a  and the present current value  18   b . The PWM circuit  42  receives the current command  18   a  and generates the current value  18   b  under PWM (pulse width modulation) control. The current value  18   b  is a three-phase (U-phase, V-phase, and W-phase) current capable of driving the swing shaft motor  14 . The current value  18   b  is supplied to the swing shaft motor  14 . 
     The current command  18   a  is an amount that depends on the current value of the swing shaft motor  14  and an amount that depends on arm torque. The arm torque detection section  26  applies processing such as at least one of AD conversion, amplification, rectification and effective value conversion to the current command  18   a , and then outputs the processed current command to the end point detection section  28  as the arm torque  26   a.    
     The current value  18   b  is a current value of the swing shaft motor  14  itself and is also a value that depends on arm torque. The arm torque detection section  26  may detect arm torque  26   a  applied to the swing arm  110  from the current value  18   b . The arm torque detection section  26  can use a current sensor such as a Hall sensor to detect the current value  18   b.    
     With reference to  FIG. 29 , a description is given about a method of detecting a motor current by a current detection section  810  (detection section) that detects a current value of one electric motor among a motor M 3  (first electric motor, see  FIG. 2 ) for driving to rotate the polishing table, a motor M 1  (second electric motor, see  FIG. 5 ) for driving to rotate the top ring  31 A and a motor M 2  (third electric motor, see  FIG. 5 ) for swinging the swing arm, and generates a first output. In the present embodiment, the current detection section  810  detects a current value of the motor M 2  and generates a first output  810   a . A three-phase (U-phase, V-phase and W-phase) current value  18   b  is inputted to the current detection section  810 . 
     The current detection section  810  samples the U-phase, V-phase and W-phase current values  18   b  respectively, for example, every 10 msec and obtains moving average of 100 msec for the sampled current values  18   b  respectively. An object of obtaining moving average is noise reduction. After that, the U-phase, V-phase and W-phase current values  18   b  are subjected to full-wave rectification and effective values are then obtained through effective value conversion respectively. After calculating the effective values, the three values are added up to generate a first output  810   a . The current detection section  810  outputs the generated first output  810   a  to the end point detection section  28 . 
     Note that noise reduction processing is not limited to the aforementioned moving average processing, but various kinds of noise reduction processing are possible. The current detection section  810  may also carry out processing other than effective value calculation on the current values  18   b . For example, after calculating respective absolute values of the current values  18   b , these three values may be added up to generate the first output  810   a . Furthermore, the current detection section  810  may also generate the sum of squares of the absolute values of three-phase current values of the electric motor as a first output. The current detection section  810  may also calculate an effective value for only one phase or two phases of the three U-phase, V-phase and W-phase current values  18   b . The first output can take any given amount as long as it is an amount that can represent a torque change. The end point detection section  28  that detects a polishing end point indicating an end of polishing based on a first output can also detect a polishing end point indicating an end of polishing from a change of the first output (frictional force). 
     The swing arm  110  that swings on the plane of the polishing table  30 A in the horizontal direction (circumferential direction) has been described in the present embodiment. However, the present embodiment is also applicable to an arm that moves back and forth on the plane of the polishing table  30 A between the rotation center of the polishing table  30 A and the end portion of the polishing table  30 A in a linear direction in the radius direction. 
     Note that the end point detection section  28  can be configured as a computer including a CPU, a memory and input/output means. In that case, it is possible to store a program in a memory, for causing the computer to function as end point detection section means capable of detecting a polishing end point indicating an end of polishing of the semiconductor wafer  16  from the detected eddy current and control means for controlling polishing by the polishing apparatus. 
     Next, another embodiment having an optical sensor will be described using  FIG. 30 . The present embodiment simultaneously uses detection of a torque fluctuation in the swing shaft motor  14  that swings the polishing table  30 A and detection of a reflection factor of the polishing surface of the semiconductor wafer  16  using an optical sensor. A sensor is incorporated in the polishing table  30 A to detect an end point. The sensor is an optical sensor  724 . A sensor using a fiber or the like is used as the optical sensor  724 . Note that an eddy current sensor can also be used instead of the optical sensor  724 . 
     The embodiment in  FIG. 30  can solve the following problems. When only one of a torque fluctuation detection scheme and an optical detection scheme is used to detect an end point, if polishing of an object involves a mixture of polishing: polishing of a metal film and polishing of an insulating film, this results in the following problem. The torque fluctuation detection scheme is suitable for detection of a boundary between a metal film and an insulating film, and the optical detection scheme is suitable for detection of a change in a thickness of a film. Thus, when both detection of a boundary of films and detection of a thickness of the remaining film are necessary, use of only one scheme cannot achieve sufficient detection accuracy. This problem can be solved by selectively using either torque fluctuation detection or optical detection depending on which of detection of a boundary of films or detection of a thickness of the remaining film corresponds to the case. 
     In the case of an optical sensor, the end point detection section of the polishing apparatus exposes the semiconductor wafer  16  to light and measures the intensity of reflected light from the semiconductor wafer  16 . The end point detection section detects a polishing end point indicating an end of polishing based on arm torque detected by the arm torque detection section and the intensity of the reflected light from the semiconductor wafer  16  measured by the optical sensor  724 . The output of the optical sensor  724  is sent to the control section  65  via a wiring  726 . 
     In the case of the optical sensor, an opening  720  is provided in part of the polishing pad  10 . The opening  720  is provided with a view port  722  which is a window. Radiation of light and detection of reflected light are achieved via the view port  722 . The view port  722  is incorporated at a position inside the polishing table  30 A which can face the semiconductor wafer  16  during polishing. The optical sensor  724  is disposed below the view port  722 . When the optical sensor  724  is a fiber sensor, the view port  722  may not be provided. 
     When there is no view port  722 , pure water may be discharged from around the fiber sensor to remove slurry supplied from the nozzle  728  and perform end point detection. The optical sensor includes a fluid supply section (not shown) that supplies pure water (or high purity gas, fluid such as a liquid-gas mixture) to clean slurry into the opening  720 . 
     There can be a plurality of sensors. For example, as shown in  FIG. 30 , sensors are provided at a center and an end portion to monitor detection signals at both the center and end portion.  FIG. 30A  illustrates the location of the optical sensor  724  and  FIG. 30B  is an enlarged view of the optical sensor  724 . The end point detection section  28  selects a detection signal unaffected by polishing conditions (or optimum for the polishing conditions) according to a change in the polishing conditions (material, polishing time or the like of the semiconductor wafer  16 ) from among a plurality of signals, determines an end point and stops polishing. 
     This point will be described further. A combination of torque fluctuation detection (measurement of motor current fluctuation) by the above-described swing shaft motor  14  and optical detection is effective if it is used to detect a polishing end point of an inter-layer insulating film (ILD) or an element separation film by STI (shallow trench isolation). In optical detection such as SOPM (spectrum optical endpoint monitoring), the thickness of the remaining film is detected and an end point is detected. For example, in a manufacturing process of a multilayer film of LSI, it may be necessary to form the remaining film through polishing of a metal film and polishing of an insulating film. It is necessary to perform polishing of the metal film and polishing of the insulating film, and it is possible to selectively use torque fluctuation detection or optical detection depending on which of polishing of the metal film or polishing of the insulating film is performed. 
     When the film structure of the end point portion is one in which the metal and the insulating film are present in a mixed state, it is difficult to detect an end point accurately using only one of torque fluctuation detection and optical detection schemes. Therefore, the film thickness is measured through torque fluctuation detection and optical detection, whether or not a certain point is an end point is determined based on both detection results and polishing is completed at an optimum time point. In a mixed state, measurement accuracy deteriorates because a measured signal is weak in both torque fluctuation detection and optical detection. However, it is possible to determine an optimum end point position by making determinations using signals obtained through two or more types of measurement methods. An end point is determined, for example, when all the determinations made using the signals obtained through two or more types of measurement methods have results indicating that an end point is found. 
     Next, another embodiment having an optical sensor will be described using  FIG. 31 . The present embodiment simultaneously uses detection of a torque fluctuation (friction fluctuation of the polishing table  30 A) in the swing shaft motor  14  that swings the polishing table  30 A, detection of a reflection factor of the polishing surface of the semiconductor wafer  16  using an optical sensor and detection of an eddy current in the object of the semiconductor wafer  16  using an eddy current sensor. Three types of detection methods are used simultaneously. 
     In the case of the embodiment in  FIG. 31 , the following problems can be solved. The torque fluctuation detection scheme and the optical detection scheme according to the embodiment in  FIG. 30  have a problem of having difficulty in detecting a change in the thickness of a metal film. The embodiment in  FIG. 31  is intended to solve this problem and further uses detection of an eddy current in addition to the embodiment in  FIG. 30 . Since an eddy current in the metal film is detected, it is easier to detect a change in the thickness of a metal film. 
       FIG. 31A  illustrates arrangements of the optical sensor  724  and an eddy current sensor  730 ,  FIG. 31B  is an enlarged view of the optical sensor  724  and  FIG. 31C  is an enlarged view of the eddy current sensor  730 . The eddy current sensor  730  is disposed in the polishing table  30 A. The eddy current sensor  730  generates a magnetic field in the semiconductor wafer  16  and detects the intensity of the generated magnetic field. The end point detection section  28  detects a polishing end point indicating an end of polishing based on arm torque detected by the arm torque detection section  26 , the intensity of reflected light from the semiconductor wafer  16  measured by the optical sensor  724  and the intensity of the magnetic field measured by the eddy current sensor  730 . 
     The present embodiment is an example of combining torque fluctuation detection of the swing shaft motor  14  and detection of physical quantities of the semiconductor wafer  16  by the optical sensor  724  and the eddy current sensor  730  incorporated in the polishing table  30 A to detect an end point. The torque fluctuation detection (measurement of motor current fluctuation) by the swing shaft motor  14  excels in detection of an end point in a region where the film quality of a sample to be polished changes. The optical scheme excels in detection of the amount of remaining film of an insulating film such as ILD and STI and detection of an end point thereby. End point detection by the eddy current sensor excels in end point detection at a time point at which polishing is performed up to the insulating film of the lower layer which is an end point by polishing, for example, a plated metal film. 
     In manufacturing processes of a semiconductor having multiple layers of LSI or the like, multiple layers made of various materials are polished, and so three types of end point detection methods are used to perform polishing of a variety of films and end point detection with high accuracy. Three or more types of end point detection methods can also be used in the present embodiment. For example, torque fluctuation detection (motor current fluctuation measurement (TCM)) of a motor that rotates the polishing table  30 A can also be used simultaneously. 
     It is possible to perform high function control and high accuracy end point detection using a combination of four types of detections of end points. For example, when the top ring  31 A moves (swings) on the polishing table  30 A to perform polishing, a torque fluctuation of the polishing table  30 A due to a change in the position of the top ring  31 A is detected using TCM. Thus, it is possible to find a factor whereby a pressure of the top ring  31 A on a sample is different due to a torque fluctuation when the top ring  31 A is located at the center of the polishing table  30 A, when the top ring  31 A moves to one end of the polishing table  30 A or when the top ring  31 A moves to the other end of the polishing table  30 A. When the factor is found, it is possible to perform feedback such as adjusting a pressure on the surface of the top ring  31 A in order to uniformize the pressure on the sample. 
     Examples of the factors for a torque fluctuation in the polishing table  30 A due to a change in the position of the top ring  31 A include a difference in the horizontal level between the top ring  31 A and the polishing table  30 A, a difference in the horizontal level between the sample face and the surface of the polishing pad  10  or the frictional force being different when the top ring  31 A is located at the center and when the top ring  31 A is located at a position deviated from the center due to a difference in the abrasion degree of the polishing pad  10 . 
     Note that when the film structure of the polishing end point of the film of the semiconductor wafer  16  is one in which a metal and insulating film are present in a mixed state, it is difficult to perform accurate end point detection using only one detection scheme, and therefore the end point state is determined using a scheme of detecting an arm torque fluctuation and an optical detection method, or a scheme of detecting an arm torque fluctuation and a scheme of detecting an eddy current or from detection of all the three types of signals, and polishing is completed at an optimal time point. In the mixed state, since the measured signal is weak in any of the torque fluctuation detection, the optical scheme and the scheme of detecting a detection eddy current, the measurement accuracy deteriorates. However, by making determinations using signals obtained using three or more types of measurement methods, it is possible to determine an optimum end point position. For example, when all the determinations using signals obtained using the three or more types of measurement methods have results indicating that an end point is found, the end point is determined. 
     These combinations can be enumerated as follows: i. Arm torque detection+table torque detection ii. Arm torque detection+optical detection iii. Arm torque detection+eddy current detection iv. Arm torque detection+optical detection by microwave sensor v. Arm torque detection+optical detection+table torque detection vi. Arm torque detection+optical detection+eddy current detection vii. Arm torque detection +optical detection+optical detection by microwave sensor viii. Arm torque detection+eddy current detection+table torque detection ix. Arm torque detection+eddy current detection+optical detection by microwave sensor x. Arm torque detection+table torque detection+optical detection by microwave sensor xi. In addition, any combination of sensors combined with arm torque detection is included. 
       FIGS. 32, 33 and 34  show examples where the film structure of the end point portion is one in which a metal and an insulating film are present in a mixed state. In the following examples, examples of the metal include metals such as Cu, Al, W and Co, and examples of the insulating film include insulating materials such as SiO 2 , SiN, glass material (SOG (spin-on glass), BPSG (boron phosphorus silicon glass) or the like), Lowk material, resin material and other insulating members. SiO 2 , SOG, BPSG or the like are manufactured using CVD or coating.  FIGS. 32A and 32B  are examples where an insulating film is polished.  FIG. 32A  illustrates a state before polishing and  FIG. 32B  illustrates a state after polishing. A film  732  is silicon. A film  734  which is an insulating film such as SiO 2  (thermal oxide film) and SiN is formed on the film  732 . A film  736  which is an insulating film such as an oxide film (SiO 2 ) or glass material (SOG, BPSG) is formed on the film  734  through film formation. The film  736  is polished to a state shown in  FIG. 32B . 
     The film thickness of the film  736  is measured through optical detection. A boundary  758  between the film  736  and the film  734 , and a boundary between the film  734  and the film  732  are sensitive to reflection of light. Therefore, optical detection is preferable. When the film  736  and the film  734  are made of different materials, a change in friction may be large during polishing. In this case, optical detection+torque detection is preferable. 
       FIGS. 33A and 33B  illustrate examples where a metal film is polished.  FIG. 33A  illustrates a state before polishing and  FIG. 33B  illustrates a state after polishing. An embedded part  737  is an STI. A film  738  similar to the film  736  is formed on the film  734 . A gate electrode  740  is formed on the film  734 . A diffusion layer  744  which is a drain or source is formed below the film  734 . The diffusion layer  744  is connected to a longitudinal wiring  742  such as a via or plug. The gate electrode  740  is connected to the longitudinal wiring  742 , which is not shown. The longitudinal wiring  742  penetrates the film  738 . A metal film  746  is formed on the film  738 . The longitudinal wiring  742  and the metal film  746  are of the same metal. The metal film  746  is polished to a state shown in  FIG. 33B . Note that although the gate electrode  740  and the diffusion layer  744  are formed in  FIGS. 33A and 33B , other circuit elements may also be formed. 
     Being a metal film, the metal film  746  detects an eddy current by taking advantage of the fact that there is a large change in the waveform of an eddy current in the metal film  746  when the metal film is drastically reduced. It is also possible to use optical detection taking advantage of the fact that the metal film is reduced from a state in which the amount of reflection of the metal film is large and the amount of reflection drastically changes, together with eddy current detection. Since the film  738  is an insulating film, the film thickness thereof is measured through optical detection. 
       FIGS. 34A and 34B  illustrate examples where a metal film is polished.  FIG. 34A  illustrates a state before polishing and  FIG. 34B  illustrates a state after polishing. The embedded part  737  is an STI. The film  738  is formed on the film  734 . The gate electrode  740  is formed on the film  734 . The diffusion layer  744  which is a drain or source is formed below the film  734 . The diffusion layer  744  is connected to the longitudinal wiring  742  such as a via or plug. The gate electrode  740  is connected to the longitudinal wiring  742 , which is not shown. The longitudinal wiring  742  penetrates the film  738 . A metallic lateral wiring  750  is formed on the via  742 . The metal film  748  and the lateral wiring  750  are of the same metal. The metal film  748  is polished to a state shown in  FIG. 34B . 
     Being a metal film, the metal film  748  detects an eddy current using an eddy current sensor. Since the film  738  is an insulating film, its film thickness is measured through optical detection. Note that the embodiment shown in  FIG. 32  and subsequent drawings is applicable to all the embodiments in  FIG. 1  to  FIG. 31 . 
     Next, an embodiment as the modification in  FIG. 16  will be described using  FIG. 35 . In the present embodiment, the swing arm  110  is constructed of a plurality of arms. In  FIG. 35 , the swing arm  110  is constructed of, for example, an arm  752  and an arm  754 . The arm  752  is attached to the swing shaft motor  14  and the top ring  31 A is attached to the arm  754 . An end point is detected by detecting a torque fluctuation in the swing arm at a joint between the arm  752  and the arm  754 . 
     In the case of the embodiment in  FIG. 35 , the following problems can be solved. In the case of  FIG. 16 , regarding end point detection, there is a problem that the accuracy of end point detection deteriorates due to influences of clearance vibration, which will be described later, or the like. In the case of the embodiment in  FIG. 35 , it is possible to reduce the influences of clearance vibration or the like, and thereby solve this problem. 
     A torque sensor for detecting a torque fluctuation in the swing arm is disposed at the joint  756  between the arm  752  and the arm  754 . The torque sensor includes the load cell  706  and a distortion gauge. At the joint  756 , the arm  752  and the arm  754  are mutually fixed by the metal fitting  710 . The arm  752  can be caused to swing by the swing shaft motor  14 . When a torque change is measured based on a fluctuation in the aforementioned swing motor current, the swing operation may be preferably stopped temporarily and a torque change may be measured. This is because noise in the motor current of the swing motor may increase along with the swing operation. 
     In the case of the present embodiment, when a fluctuation in polishing torque occurs due to a friction fluctuation in a part where the film quality changes such as the boundary  758  in  FIG. 32A , it is possible to detect the boundary  758  using the torque sensor at the joint  756 . A fluctuation in polishing torque can also be detected by detecting a current fluctuation in the swing shaft motor  14 . Compared to the torque fluctuation detection based on a current fluctuation, torque fluctuation detection by the torque sensor at the joint  756  has the following merits. 
     The torque fluctuation detection through detection of a current fluctuation is affected by an error in rotation operation (swing) of the swing shaft motor  14  such as clearance vibration of the swing arm  110  by the swing shaft motor  14 . The “clearance vibration” is vibration caused by slight backlash generated at the part of the swing arm  110  attached to the swing shaft motor  14  during rotation operation of the swing shaft motor  14 . In torque fluctuation detection by the torque sensor at the joint  756 , the joint  756  has no clearance vibration and can detect a torque fluctuation corresponding to a friction change of the polishing section. Thus, more accurate end point detection is made possible. It is necessary to stop swinging of the swing arm  110  to reduce clearance vibration. However, in torque fluctuation detection by the torque sensor at the joint  756 , accurate end point detection is made possible without stopping swinging of the swing arm  110 . 
     The present embodiment is applicable to a case where there are a plurality of top rings  31 A or also applicable to a carousel scheme. As multilayer films of LSI become thinner or functional elements become finer, more accurate polishing end point detection needs to be performed than the prior art in order to make performance more stable and maintain yield. The present embodiment is effective as a technique capable of meeting such requirements. 
     Next, control of the entire substrate processing apparatus by the control section  65  will be described using  FIG. 36 . The control section  65  which is a main controller includes a CPU, a memory, a recording medium and software recorded in the recording medium or the like. The control section  65  performs monitoring or control of the entire substrate processing apparatus, exchanges signals therefor, records information or carries out calculations. The control section  65  exchanges signals mainly with a unit controller  760 . The unit controller  760  also includes a CPU, a memory, a recording medium and software recorded in the recording medium or the like. In the case of  FIG. 36 , the control section  65  incorporates a program that functions as end point detection means for detecting a polishing end point indicating an end of polishing and control means for controlling polishing by the polishing unit. Note that the unit controller  760  may incorporate a part or a whole of the program. The program is updatable. Note that the program may not be updatable. 
     The embodiment described in  FIG. 36  to  FIG. 38  can solve the following problems. The control schemes of the polishing apparatuses described so far have the following typical problems. Regarding end point detection, before polishing a target, a plurality of tests are conducted, polishing conditions or end point determination conditions are determined from the data obtained and a recipe which is the polishing conditions is created. A partial signal analysis may be used but processing of determining end point detection is performed using one sensor signal for the semiconductor wafer structure. In this way, however, sufficient accuracy cannot be achieved to meet the following requirements. In order to improve yield of devices or chips to be manufactured, it is necessary to detect an end point with higher accuracy and minimize fluctuations among lots and chips in manufacturing the devices or chips. To meet such requirements, by using a system that carries out end point detection to which the embodiments described in  FIG. 36  and subsequent drawings are applied, it is possible to perform more accurate end point detection, improve yield and minimize fluctuations in the amount of polishing among chips. 
     Particularly, it is possible to achieve high-speed data processing, signal processing using many sensors of many types, data normalized from these signals, learning from data using artificial intelligence (AI), creation of a data set used to determine end point detection, learning through storage of determination examples using the created data set, improvement of accuracy using learning effects, polishing parameters determined and updated by the learned determination function, a high-speed communication processing system that reflects the polishing parameters in a high-speed control system, or the like. These are applicable to all the embodiments shown in  FIG. 35  and therebefore. 
     The unit controller  760  controls a unit  762  (one or in plurality) mounted on the substrate processing apparatus. According to the present embodiment, the unit controller  760  is provided for each unit  762 . The load/unload section  62 , the polishing section  63  and the cleaning section  64  or the like are provided as the unit  762 . The unit controller  760  controls operation of the unit  762 , exchanges signals with the monitoring sensor, exchanges control signals and performs high-speed signal processing or the like. The unit controller  760  is constructed of an FPGA (field-programmable gate array), an ASIC (application specific integrated circuit) or the like. 
     The unit  762  operates according to a signal from the unit controller  760 . The unit  762  receives a sensor signal from the sensor and transmits the sensor signal to the unit controller  760 . The sensor signal may be further transmitted from the unit controller  760  to the control section  65 . The sensor signal is processed (including calculation processing) by the control section  65  or the unit controller  760  and a signal for the next operation is sent from the unit controller  760 . The unit  762  operates according to the signal. For example, the unit controller  760  detects a torque fluctuation of the swing arm  110  from a current change in the swing shaft motor  14 . The unit controller  760  sends a detection result to the control section  65 . The control section  65  performs end point detection. 
     Examples of the software include the following. The software determines the type of the polishing pad  10  and the amount of slurry supplied according to the data recorded in the control device (control section  65  or unit controller  760 ). Next, the software specifies maintenance timing of the polishing pad  10  or the polishing pad  10  usable until the maintenance timing, obtains the amount of slurry supplied and outputs the data. The software may also be software that can be installed in the substrate processing apparatus  764  after shipment of the substrate processing apparatus  764 . 
     Communication between the control section  65 , unit controller  760  and unit  762  can be carried out wiredly or wirelessly. Communication via the Internet or communication using other communication means (high-speed communication using a dedicated channel) is available for communication between the substrate processing apparatus  764  and the outside. Regarding data communication, it is possible to use a cloud through cloud cooperation and exchange data via smartphones in the substrate processing apparatus through smartphone cooperation. It is thereby possible to exchange an operation situation of the substrate processing apparatus and setting information of substrate processing with the outside of the substrate processing apparatus. A communication network may be formed between sensors as a communication device and this communication network may be used. 
     Automated operation of the substrate processing apparatus may be performed using the above-described control function and communication function. It is possible to standardize a control pattern of the substrate processing apparatus and use a threshold in determination of a polishing end point for automated operation. 
     It is possible to predict/determine/display an abnormality/life of the substrate processing apparatus. It is also possible to perform control to make performance more stable. 
     It is possible to automatically extract feature values of various types of data and polishing data (film thickness and end point of polishing) during operation of the substrate processing apparatus, automatically learn the operation state and polishing state, automatically standardize a control pattern and predict/determine/display an abnormality/life. 
     For a communication scheme, device interface or the like, it is possible to standardize, for example, a format, use it for information communication between apparatuses/devices to manage the apparatuses/devices. 
     Next, an embodiment will be described in which the substrate processing apparatus  764  acquires information from the semiconductor wafer  16  via a sensor, data is stored in a data processing apparatus (cloud or the like) installed inside/outside a factory in which the substrate processing apparatus is installed via communication means such as the Internet, the data stored in the cloud or the like is analyzed and the substrate processing apparatus is controlled according to the analysis result.  FIG. 37  is a diagram illustrating a configuration of this embodiment. 
     1. The information acquired from the semiconductor wafer  16  via the sensor can be as follows: ●Measured signal or measured data relating to a torque fluctuation of the swing shaft motor  14  ●Measured signal or measured data of an SOPM (optical sensor) ●Measured signal or measured data of an eddy current sensor ●Measured signal or measured data of one or a plurality of combination 2. Communication means such as the Internet can have the following functions and configurations: ●Signals or data including the above-described measured signal or measured data are transmitted to the data processing apparatus  768  connected to the network  766 . ●The network  766  can be communication means such as the Internet or high-speed communication. For example, it is possible to implement the network  766 , in which the substrate processing apparatus, gateway, Internet, cloud, Internet, and data processing apparatus are connected in that order. Examples of high-speed communication include high-speed optical communication, high-speed radio communication, or the like. As high-speed radio communication, Wi-Fi (registered trademark), Bluetooth (registered trademark), Wi-Max (registered trademark), 3G, LTE or the like are conceivable. Other high-speed radio communications are also applicable. Note that a cloud may be used as the data processing apparatus. ●When the data processing apparatus  768  is installed in a factory, it is possible to process signals from one or a plurality of substrate processing apparatuses in the factory. ●When the data processing apparatus  768  is installed outside the factory, it is possible to transmit signals from one or a plurality of substrate processing apparatuses in the factory to the outside of the factory and process the signals. In this case, connections with data processing apparatuses installed in and outside Japan are possible. 3. Regarding the above description that the data processing apparatus  768  analyzes data stored in the cloud or the like and controls the substrate processing apparatus  764  according to the analysis result, the following is possible: ●After the measured signal or measured data is processed, they can be transmitted to the substrate processing apparatus  764  as a control signal or control data. ●The substrate processing apparatus  764  that has received the data updates polishing parameters relating to polishing processing based on the data and performs polishing operation. When the data from the data processing apparatus  768  is a signal/data indicating that an end point is detected, polishing is completed by determining that an end point is detected. The polishing parameters include (1) pressing forces on four regions of the semiconductor wafer  16 , that is, central part, inside intermediate part, outside intermediate part and peripheral edge, (2) polishing time, (3) the number of revolutions of the polishing table  30 A and the top ring  31 A, and (4) a threshold for determination of a polishing end point. 
     Next, another embodiment will be described using  FIG. 38 .  FIG. 38  is a diagram illustrating a modification of the embodiment in  FIG. 37 . The present embodiment has a configuration with the substrate processing apparatus, the intermediate processing apparatus, the network  766 , and the data processing apparatus connected in that order. The intermediate processing apparatus is constructed of, for example, an FPGA or ASIC, and has a filtering function, a calculation function, a data processing function and a data set creation function. 
     Usage of the Internet and high-speed optical communication can be classified into the following three cases: (1) case where the substrate processing apparatus and the intermediate processing apparatus are connected via the Internet and the network  766  is the Internet; (2) case where the substrate processing apparatus and the intermediate processing apparatus are connected via high-speed optical communication and the network  766  is high-speed optical communication; (3) case where the substrate processing apparatus and the intermediate processing apparatus are connected via high-speed optical communication and the intermediate processing apparatus and outside thereof is the Internet. 
     Case (1): This is a case where the data communication speed and the data processing speed in the entire system can be a communication speed of the Internet. The data sampling speed is on the order of about 1 to 1000 mS and it is possible to carry out data communication of a plurality of polishing condition parameters. In this case, the intermediate processing apparatus  770  creates a data set to be sent to the data processing apparatus  768 . Details of the data set will be described later. The data processing apparatus  768  that receives the data set performs data processing, calculates changed values of polishing condition parameters up to the position of an end point, creates a polishing process plan and returns them to the intermediate processing apparatus  770  via the network  766 . The intermediate processing apparatus  770  sends the changed values of the polishing condition parameters and necessary control signals to the substrate processing apparatus  764 . 
     Case (2): Communication of sensor signals between the substrate processing apparatus and the intermediate processing apparatus and between the intermediate processing apparatus and the data processing apparatus, and communication between the state management devices correspond to high-speed communication. High-speed communication allows communication at a communication speed of 1 to 1000 Gbps. Data, data sets, commands and control signals or the like can be communicated in high-speed communication. In this case, the intermediate processing apparatus  770  creates a data set and transmits the data set to the data processing apparatus  768 . The intermediate processing apparatus  770  extracts data necessary for processing in the data processing apparatus  768 , processes the data and creates a data set. For example, a plurality of sensor signals for end point detection are extracted to create a data set. 
     The intermediate processing apparatus  770  sends the data set created to the data processing apparatus  768  through high-speed communication. The data processing apparatus  768  calculates parameter changed values up to the polishing end point and creates a process plan based on the data set. The data processing apparatus  768  receives data sets from a plurality of substrate processing apparatuses  764 , calculates parameter updated values and creates a process plan in the next step for the respective apparatuses and transmits the updated data sets to the intermediate processing apparatus  770 . The intermediate processing apparatus  770  converts the updated data sets to control signals based on the updated data sets and transmits the control signals to the control section  65  of the substrate processing apparatus  764  through high-speed communication. The substrate processing apparatus  764  applies polishing according to the updated control signals and performs accurate end point detection. 
     Case (3): The intermediate processing apparatus  770  receives a plurality of sensor signals of the substrate processing apparatus  764  through high-speed communication. In high-speed optical communication, communication at a communication speed of 1 to 1000 Gbps is possible. In this case, on-line polishing condition control is possible through high-speed communication between the substrate processing apparatus  764 , the sensor, the control section  65  and the intermediate processing apparatus  770 . Data is processed in order of, for example, reception of a sensor signal (from the substrate processing apparatus  764  to the intermediate processing apparatus  770 ), creation of a data set, data processing, calculation of a parameter updated value, transmission of updated parameter signals, polishing control by the control section  65  and detection of the updated end point. 
     In this case, the intermediate processing apparatus  770  performs high-speed end point detection control through high-speed communication. The intermediate processing apparatus  770  periodically transmits a status signal to the data processing apparatus  768 , and the data processing apparatus  768  monitors a control state. The data processing apparatus  768  receives status signals from a plurality of substrate processing apparatuses  764  and creates a plan in the next process step for the respective substrate processing apparatuses  764 . The data processing apparatus  768  sends a plan signal of the process step based on the plan to the respective substrate processing apparatuses  764  and the respective substrate processing apparatuses  764  prepare for the polishing process and execute the polishing process independently of each other. In this way, the intermediate processing apparatus  770  performs high-speed end point detection control through high-speed communication and the data processing apparatus  768  manages states of the plurality of substrate processing apparatuses  764 . 
     Next, examples of data sets will be described. A sensor signal and necessary control parameters can be formed into a data set. The data set can include a pressure of the top ring  31 A on the semiconductor wafer  16 , a current of the swing shaft motor  14 , a motor current of the polishing table  30 A, a measured signal of an optical sensor, a measured signal of an eddy current sensor, the position of the top ring  31 A on the polishing pad  10 , flow rates/types of slurry and a chemical liquid, correlation calculation data thereof or the like. 
     The above-described types of data sets can be transmitted using a transmission system whereby one-dimensional data is transmitted in parallel or a transmission system whereby one-dimensional data is transmitted sequentially. As for the data set, the above-described one-dimensional data can be processed into two-dimensional data to form a data set. For example, when it is assumed that the X-axis shows time and the Y-axis shows many data strings, a plurality of pieces of parameter data at the same time are processed into one data set. The two-dimensional data can be handled as something like two-dimensional image data. The merit is that a two-dimensional data transfer allows data associated with time to be exchanged and handled with a smaller amount of wiring than a one-dimensional data transfer. More specifically, when one-dimensional data is formed into one signal, one line as is, many wires are necessary, whereas in the case of a two-dimensional data transfer, a plurality of signals can be transmitted with one line. Furthermore, when a plurality of lines are used, the interface with the data processing apparatus  768  that receives transmitted data becomes complicated and data reassembly in the data processing apparatus  768  becomes complicated. 
     When such a time-associated two-dimensional data set exists, comparisons with a data set during polishing under a standard polishing condition performed previously and a data set under a standard polishing condition currently being performed become easier. Furthermore, mutual differences between two-dimensional pieces of data can be easily known through difference processing or the like. It is also easy to extract differences and detect a sensor or a parameter signal in which an abnormality occurs. Furthermore, a data set corresponding to a previous standard polishing condition is compared with a data set currently being polished, and it is easier to detect an abnormality by extracting parameter signals in a region where a difference from surroundings differs. 
       FIGS. 39A and 39B  are diagrams illustrating another schematic configuration example of a sensor (embodiment described in the nineteenth to twenty-second aspects),  FIG. 29A  is a plan view and  FIG. 29B  is a cross-sectional side view. As illustrated, a liquid supply hole  1042  and a liquid discharge hole  1046  are arranged (the liquid discharge hole  1046  and the liquid supply hole  1042  are arranged in that order in the moving direction of the polishing table  30 A) so that a midpoint of a line segment connecting the center of the liquid supply hole  1042  and the center of the liquid discharge hole  1046  is located ahead of the center of the through hole  1041  in the moving direction (arrow D direction) of the polishing table  30 A, and the through hole  1041  has a substantially elliptic cross section so that the outer periphery of the bottom end face of the through hole  1041  surrounds the top end surfaces of the liquid supply hole  1042  and the liquid discharge hole  1046 . By adopting such a configuration, the flow of a transparent liquid Q supplied from the liquid supply hole  1042  into the through hole  1041  becomes a flow moving perpendicularly to the polishable surface  16   a  of the semiconductor wafer  16 . By causing the through hole  1041  to have a substantially elliptic cross section, it is possible to minimize the area of the through hole  1041  and reduce influences on a polishing characteristic. 
     Note that a radiation light optical fiber  1043  and a reflected light optical fiber  1044  are arranged in the liquid supply hole  1042  so that the center lines thereof are parallel to the center line of the liquid supply hole  1042 . Note that one radiation light/reflected light optical fiber may be used instead of the radiation light optical fiber  1043  and the reflected light optical fiber  1044 . 
     Next, the embodiments corresponding to the twenty-third and twenty-fourth aspects will be described based on the accompanying drawings.  FIG. 40  is a diagram illustrating a schematic configuration of an embodiment of the present invention. In  FIG. 40 , a water jet nozzle  1005  jets a columnar water flow onto a processing surface  1002   a  of the semiconductor wafer  16 , on a surface of which a thin film  1002  is formed and causes the water flow to come into contact therewith. Distal end portions of a radiation fiber  1007  and a light receiving fiber  1008  are inserted and disposed in the water jet nozzle  1005 . 
     In the above-described configuration, a pressurized water flow  1006  is supplied to the water jet nozzle  1005 , a fine columnar water flow  1004  is brought from the distal end thereof into contact with the processing surface  1002   a  of the semiconductor wafer  16  at a predetermined position to form a measurement spot  1003 . In this condition, a measurement calculation section  1009  transmits light into the water flow  1004  via the radiation fiber  1007 , causes the light to pass through the water flow  1004  and irradiates the polishing surface in the measurement spot  1003  of the semiconductor wafer  16  with the light. In this case, the optical axis in the water flow  1004  is preferably substantially perpendicular to the polishing surface in terms of the apparatus configuration. However, depending on the case, if there is a positional relationship in which the light receiving fiber  1008  can receive reflected light from the polishing surface of light from the radiation fiber, a configuration in which the optical axis is set to be diagonal with respect to the polishing surface in the water flow  1004 . 
     The light reflected by the processing surface (polishing surface)  1002   a  passes through the water flow  1004  and the light receiving fiber  1008  and is guided to the measurement calculation section  1009 . The measurement calculation section  1009  measures a film thickness of the thin film  1002  from the reflected light. At this time, the inner surface of the water jet nozzle  1005  is mirror-finished and improved so as to efficiently guide radiation/reflected light to the radiation/light receiving fibers  1007  and  1008 . 
     Furthermore, water droplets may be occasionally trapped in an area where the thin film  1002  and the water flow  1004  come into contact with each other and disturb the measurement spot  1003 . Therefore, as shown in  FIG. 41 , a water discharge member  1138  which is spirally wound and which extends from the water jet nozzle  1005  to the measurement spot  1003  of the thin film  1002  may be provided to remove water droplets. Furthermore, when the water flow  1004  is set diagonally relative to the semiconductor wafer or in a mechanism whereby the water flow  1004  is supplied in an upward or downward direction, means for removing water droplets may be combined as appropriate. Note that as shown in  FIG. 41 , the water discharge member may be one having a spring-like structure and using surface tension of water or one using a suction nozzle (not shown) set so as to surround the water jet nozzle  1005 . 
       FIGS. 42 and 43  are diagrams illustrating a configuration example of a polishing apparatus that polishes a polishing surface of the semiconductor wafer  16  through relative motion between the semiconductor wafer  16  and the polishing pad  10  in a case where a film thickness of the film being polished is detected in real time.  FIG. 42  is a partial cross-sectional side view and  FIG. 43  is a figure viewing from the arrow direction of a Y-Y line in  FIG. 42 . 
     The water jet nozzle  1005  is similar to that shown in  FIG. 40  and  FIG. 41 , a pressurized water flow pipe  1136  is connected to the water jet nozzle  1005 , the water of the water flow  1004  jetted from the water jet nozzle  1005  is received by a water receiver  1135  and discharged through a water discharge pipe  1137 . The top end of the water receiver  1135  is open to the top surface of the polishing pad  10  and the water flow  1004  jetted from the water jet nozzle  1005  forms the measurement spot  1003  on the polishing surface of the semiconductor wafer  16  as in the case of  FIG. 40  and  FIG. 41 . Note that although the water jet nozzle  1005  is depicted larger than it actually is in the figure to facilitate an understanding, the diameter of the water jet nozzle  1005  is actually small to form a tiny spot (0.4 mm to 0.7 mm). 
     As in the case of  FIG. 40  and  FIG. 41 , the distal end portions of the radiation fiber  1007  and the light receiving fiber  1008  are inserted into the water jet nozzle  1005  and light passes through the radiation fiber  1007  from the measurement calculation section  1009 , is guided into the water jet nozzle  1005 , passes through the water flow  1004  jetted from the water jet nozzle  1005  and is projected into the measurement spot  1003  on the polishing surface with which the water flow  1004  comes into contact. The light reflected by the polishing surface passes through the water flow  1004  and the light receiving fiber  1008  and is guided into the measurement calculation section  9 . 
     The twenty-fifth aspect is the processing apparatus for polishing an object, including a plurality of processing areas housing a plurality of light-shielded processing units arranged on upper and lower rows and transfer areas housing transporters and arranged between the processing areas, the processing areas are light-shielded from the transfer areas by a light-shielding wall and the front of the transfer area is light-shielded by a maintenance door and the processing units are connected to the light-shielding wall in a light-shielded state. 
     Thus, by applying a light-shielding process to the processing unit and by light-shielding the processing area in which the processing unit is disposed from the transfer area using the light-shielding wall and light-shielding the front of the transfer area using the maintenance door, it is possible to prevent light from entering from the outside into the transfer area even when the maintenance door of the processing unit is left open and process the object in a light-shielding state by the lower processing unit even when, for example, the upper processing unit of the processing units disposed on the upper and lower rows is under maintenance. Thus, even when some processing units are under maintenance, it is possible to process the object by another processing unit other than the processing unit in question without stopping the apparatus. 
     The twenty-sixth aspect is the processing apparatus according to the eighteenth aspect, in which the processing unit is provided with an object insertion port having an openable/closable shutter, the light-shielding wall is provided with a light-shielding film that surrounds the object insertion port and an opening is provided in a region of the light-shielding wall surrounded by the light-shielding film. 
     In this way, it is possible to transfer the object with the shutter of the processing unit left open and while maintaining the light-shielding state in the processing unit and the transfer area, and prevent light from the outside from entering the transfer area through the opening of the light-shielding wall during maintenance, for example. 
     The twenty-seventh aspect is the processing apparatus for polishing an object according to the twenty-fourth or twenty-fifth aspect, in which the processing area is a cleaning area and processing on an object is cleaning of an object. 
     According to the twenty-fifth to twenty-seventh aspects, it is possible to prevent photocorrosion of copper wiring or the like due to irradiation of the processed surface of the object with light and process the object, preventing photocorrosion of copper wiring or the like due to irradiation of the processed surface of the object with light although the number of objects processed temporarily decreases. 
     The twenty-fifth to twenty-seventh aspects can have the following features: (1) An apparatus that reduces electrolysis between metal features in a semiconductor material (that is, substrate) including a sealing mechanism for eliminating exposure of the semiconductor material to light having energy equal to or greater than bandgap energy of the semiconductor material. (2) The apparatus described in (1) above in which the sealing mechanism is disposed around a semiconductor processing tool selected from the group consisting of chemical mechanical polishing apparatuses and brush cleaning apparatuses. (3) The apparatus described in (2) above further including a light source capable of generating light having energy lower than bandgap energy. (4) The apparatus described in (3) above further including a process monitoring video camera capable of detecting light having energy lower than bandgap energy. (5) The apparatus described in (4) above, in which the semiconductor material is silicon-based, the sealing mechanism excludes light having a wavelength of approximately 1.1 μm or less, the light source generates light having a wavelength exceeding approximately 1.1 μm, the video camera detects such light. The apparatus may be preferably adapted so as to detect an end point in a polishing process of a silicon-based object in the polishing apparatus described above using, for example, light having a wavelength in the relevant region, for example, infrared light. (6) The apparatus described in (4) above, in which the semiconductor material is gallium arsenide-based, the sealing mechanism excludes light having a wavelength of approximately 0.9 μm or less, the light source generates light having a wavelength exceeding approximately 0.9 μm, and the video camera detects the light. The apparatus may be preferably adapted so as to detect an end point in a polishing process of a gallium arsenide-based object in the polishing apparatus described above using, for example, light having a wavelength in the relevant region, for example, infrared light. (7) An apparatus that reduces electrolysis between metal features in a semiconductor material, including a semiconductor processing tool capable of combining at least one electrolysis inhibitor with the metal features in the semiconductor material. (8) The apparatus described in (7) above, in which the semiconductor material is silicon-based, the sealing mechanism excludes light having a wavelength of approximately 1.1 μm or less, the light source generates light having a wavelength exceeding approximately 1.1 μm and the video camera detects the light. The apparatus may be preferably adapted so as to detect an end point in a polishing process of a silicon-based object in the polishing apparatus described above using, for example, light having a wavelength in the relevant region, for example, infrared light. 
     In crystalline solids such as materials constituting an integrated circuit, atomic orbits are practically combined to become a continuous “zone” of “crystal” orbits or electronic energy levels. A maximum occupied bandwidth is called a “valence band” and a lowest bandwidth is called a “conduction band.” The amount of energy necessary to excite one electron from a maximum point of the valence band to a minimum point of the conduction band is called “bandgap energy (Eg).” Bandgap energy of silicon is Eg=1.12 eV at a room temperature and bandgap energy of gallium arsenide is Eg=1.42 eV. A semiconductor material such as silicon is known to exhibit photoconductivity in which light radiation gives energy enough to excite electrons to the conduction band and increase conductivity of a semiconductor. Light energy is associated with a frequency or wavelength according to equation E=hv or E=hc/λ, where h is Planck&#39;s constant, c is the velocity of light, v is a frequency and λ is a wavelength. For most silicon-based semiconductors at a room temperature, the light energy necessary to achieve photoconductivity needs to reach approximately 1.12 eV, that is, the light needs to have a wavelength of approximately 1.1 μm or less. For gallium arsenide semiconductors, the light needs to have a wavelength of approximately 0.9 μm or less to achieve photoconductivity. For other semiconductors, Eg can be easily obtained from general reference documents and wavelengths can be calculated using the above-described equations. The following description is given focusing on silicon-based semiconductor elements, but those skilled in the art will easily understand that the present invention is likewise applicable to devices manufactured using other semiconductor materials such as gallium arsenide. 
     The photoconductivity discussed above forms a basis of a photoelectric effect in a PN junction  300  shown in  FIG. 44 . An n-type semiconductor  320  is silicon doped with a donor impurity such as phosphor or arsenic, which supplies electrons to the silicon conduction band and generates extra negative charge carriers. Therefore, many charge carriers in the n-type semiconductor  320  are negatively charged particles. The p-type semiconductor  310  is silicon doped with an acceptor impurity such as boron which receives electrons from the valence band of silicon and generates extra positive holes or positive charge carriers. Therefore, many charge carriers in the p-type semiconductor  310  are positively charged positive holes. When the PN junction  300  is irradiated with photons of the light  350  having sufficient energy, electrons in both the p-type  310  and the n-type  320  semiconductors are excited from the valence band to the conduction band and positive holes remain. Many of the additional positive charge carriers generated in the n-type semiconductor  320  in this way move toward the p-type  310  side of positive (positive hole) junction  300 . Many of the additional negative charge carriers generated in the p-type semiconductor  310  in this way move toward the n-type  320  side of negative (electron) junction  300 . The movement of these charge carriers produces a photoelectric effect and generates a similar current source for the battery. 
     When the PN junction functioning as a current source is connected to metal conductors such as mutual connections  330  and  340  exposed to an electrolyte  230 , all elements necessary for electrolysis are present and dissolution of anode metal components takes place if the potential is sufficient. The electrochemical dissolution in  FIG. 44  generated by a photoelectric voltage is similar to electrochemical dissolution. Oxidation reaction in the anode  330  generates free cations  250  dissolved into the electrolyte  230  and electrons that flow into the current source (PN junction  300 ) via an inner connection reaching the cathode  340 . This oxidation reaction gives rise to a most outstanding sign of the electrolysis, that is, dissolution of the anode  330  or pitching, but reduction reaction also has to take place. The reduction reaction at the cathode causes electrons to couple with a reactant  260  in the electrolyte  230  and generates a reduced reaction product. It should be noted that some of the metal conductors become cathodes and some other metal conductors become anodes depending on to which of the p side or then side of the PN junction they are connected. 
     For cancellation or reduction of electrochemical dissolution, a preferred embodiment of the present invention provides a method and an apparatus for eliminating or reducing electrochemical dissolution of global wiring, mutual connection, contacts and other metal features. The preferred embodiment reduces dissolution by eliminating exposure of the PN junction to light which may cause a photoelectric effect or prevent either oxidation or reduction induced by a photoelectric effect or both of oxidation and reduction. 
     Note that examples of a scheme for holding the top ring and the drive section of the top ring include not only the aforementioned scheme for holding them at an end portion of the swing arm (cantilever arm) but also a scheme for holding a plurality of drive sections for driving each top ring to one carousel. When the first embodiment of the present invention is applied to a carousel, it is also possible to provide a polishing apparatus with reduced differences in the measurement results of the current sensor among a plurality of polishing apparatuses. These top rings and drive sections constitute a set (of polishing apparatuses) and one carousel can be provided with a plurality of sets thereof. By applying the aforementioned embodiment to current values of motor currents of a plurality of drives sections (top ring motor  114 ), it is possible to implement a polishing apparatus with reduced differences in the measurement results of the current sensor among a plurality of sets of polishing apparatuses. 
     The carousel will be described with reference to  FIG. 45 . The carousel is rotatable around an axis of rotation  704  and a top ring motor  114  is attached to the carousel  702 .  FIG. 45  is a schematic side view illustrating a relationship between a multihead type top ring  31 A supported by the carousel  702 , the top ring motor  114  and the polishing table  30 A. As shown in  FIG. 45 , a plurality of top ring units are disposed on one polishing table  30 A. One top ring may be disposed on the carousel and there may be two or more tables. A plurality of top rings may be disposed in the carousel and there may be a plurality of tables. In this case, one top ring may be placed on one table or a plurality of top rings may be placed on one table. The carousel may perform movement such as rotation or the top ring may move to another table at the next stage and perform polishing. 
     The carousel  702  is rotatable. A rotation mechanism is provided in the vicinity of the center of the carousel  702 . The carousel  702  is supported by pillars (not shown). The carousel  702  is supported by a main rotation shaft of a motor (not shown) attached to the pillars. Therefore, the carousel  702  can rotate around a vertical rotation shaft center  704  through rotation of the main rotation shaft. Note that as a scheme similar to the carousel scheme, for example, a circular rail may be used instead of the carousel. A plurality of drive sections (top ring motors  114 ) are disposed on the rail. At this time, the drive sections can move on the rail. 
     Next, an embodiment will be described using  FIGS. 46 and 47  in which the polishing apparatus includes a carousel which is rotatable around an axis of rotation and the arm drive section is attached to the carousel.  FIG. 46  is a schematic side view illustrating a relationship among a multihead-type top rings  31 A and swing arms  110  supported by the carousel  702  and the polishing table  30 A, and  FIG. 47  is a top view. 
     According to the embodiment shown in  FIG. 46  in which the top rings are attached to the carousel  702 , it is possible to solve the following problems. When a plurality of top rings  31 A are disposed on the large carousel  702 , as one of the polishing end point detection means, a method of monitoring a torque fluctuation of the polishing table rotation drive motor or the top ring rotation drive motor is available in addition to the method based on arm torque. According to these methods, a change of rotational resistance force (frictional force) of the top ring  31 A is detected. However, a frictional force detection signal involves errors due to errors caused by swinging of the arm, fluctuation of rotation of the top ring and fluctuation of rotation of the table, and it has been conventionally difficult to perform end point detection with high accuracy. Furthermore, when one rotation table includes a plurality of top rings, the table rotation fluctuates in a complicated manner under the influence of the plurality of top rings  31 A, and so it has been conventionally difficult to catch exact fluctuation of frictional force of each top ring  31 A. 
     In the polishing apparatus in  FIG. 46 , the swing arm  110  is attached to the carousel  702  and the top ring  31 A is attached to the swing arm  110 . A unit is constructed of one swing arm  110  and one top ring  31 A (hereinafter, referred to as a “TR unit”), and there is a case where one such unit is set up on the carousel  702  and there is a case where a plurality of such units are set up on the carousel  702  (multihead type).  FIG. 46  shows a case where a plurality of such units are set up on the carousel  702 . 
     Note that in  FIGS. 45 and 46 , the top ring motor  114  is disposed above the swing arm  110 , but the top ring motor  114   a  may be disposed below the swing arm  110  as shown by a dotted line in  FIG. 46 . Note that as shown in  FIG. 45 , when there are a plurality of top rings  31 A on one polishing table  30 A, the swing direction or the moving direction of the plurality of top rings  31 A needs to be such that the plurality of top rings  31 A move so as not to interfere with each other. For example, in the case of an arrangement in which if the plurality of top rings  31 A move in such a way as to come closer to each other, the plurality of top rings  31 A may interfere with each other, but interference is prevented by moving the plurality of top rings  31 A so as not to come closer to each other or moving the top rings  31 A in the same direction. 
     As another embodiment, the swing arm  110  may move on a track. For example, the polishing apparatus includes a support frame, a track attached to the support frame to define a conveyance path of the top ring motor  114  and a carriage that conveys the top ring motor  114  along the path defined by the track, the carriage being connected to the track and movable along the track. 
     A linear motor drive scheme can also be used for the track and the mechanism (carriage) that moves along the track. A track mechanism using a motor and a bearing is also available. As a further embodiment, a mode in which the track itself can rotate is available. In this mode, the track itself can rotate and move the top ring to another table section. The carriage makes a small adjustment to the movement at that time. 
     In  FIGS. 45 and 46 , it is also possible to use a mechanism (carriage) that moves linearly using a linear motor drive scheme instead of the swing arm  110 . The linear movement direction may be a direction in which the carriage moves on a radius between the center  704  of the carousel  702  and a terminal portion. Alternatively, the carriage may include a mechanism for moving in the X direction, a mechanism for moving in the Y direction and a mechanism for moving in the Z direction as shown in  FIG. 47  and move in directions combining these movement directions. Examples of combination of directions include (X direction or Y direction)+Z direction, or directions other than the X direction or Y direction. 
     In the aspect shown in  FIGS. 45 to 47 , the arm or the carriage swings or moves and performs polishing while swinging or moving. When the arm or the carriage swings or moves, a motor current signal fluctuates even when the frictional force does not change during polishing. In such a case, the embodiment shown in  FIG. 16  and subsequent drawings is effective. In the embodiment shown in  FIG. 16  and subsequent drawings, it is possible to detect a change of the material of the surface of the semiconductor wafer  16  along with the progress of polishing and a change of the frictional force caused by a change of the circuit pattern. End point detection is performed based on the detected change of the frictional force. 
     Although the embodiments of the present invention have been described so far, the aforementioned embodiments are intended to facilitate an understanding of the present invention, but not intended to limit the present invention. The present invention can be changed or improved without departing from the spirit and scope of the present invention, and it goes without saying that the present invention includes its equivalent components. Furthermore, within a scope in which at least some of the aforementioned problems can be solved or within a scope in which at least some effects can be exerted, the scope of patent claims and the respective components described in the specification can be arbitrarily combined or omitted. 
     This application claims priority under the Paris Convention to Japanese Patent Application No. 2017-249699 filed on Dec. 26, 2017 and Japanese Patent Application No. 2018-195990 filed on Oct. 17, 2018. The entire disclosure of Japanese Patent Laid-Open No. 2017-58245 including specification, claims, drawings and summary is incorporated herein by reference in its entirety. 
     REFERENCE SIGNS LIST 
     
         
           61   a  . . . Bottom face portion 
           61   b  . . . Magnetic core portion 
           61   c  . . . Peripheral wall portion 
           61   d  . . . Peripheral magnetic body 
           860 ,  862  . . . Excitation coil 
           864 ,  866  . . . Detection coil 
           868 ,  870  . . . Dummy coil 
           876 ,  878  . . . Magnetic field 
           882  . . . Initial polishing rate expression 
           884  . . . Polishing end point