Patent Publication Number: US-11396082-B2

Title: Substrate holding device and substrate processing apparatus including the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2017-218564, filed on Nov. 13, 2017, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to a substrate holding device and a substrate processing apparatus including the substrate holding device. 
     BACKGROUND 
     In a semiconductor manufacturing apparatus, when some kind of processing (chemical or mechanical processing, measurement, or the like) is performed on a pattern surface of a substrate Wf which is a process target object, the substrate Wf may be fixed onto a stage, a pedestal, or the like of a mechanism to process the substrate Wf. At this time, fixing any substrate Wf onto the same position on the stage without deviation makes possible similar processing on any substrate Wf and uniform quality in the final product. The precision requirement in each step in semiconductor device manufacturing by a semiconductor manufacturing apparatus these days has already reached a level of several nanometers, and to perform accurate processing on accurate positions on the substrate Wf, it is important to accurately position the substrate Wf. 
     There is a method of performing positional alignment between the substrate Wf and the stage with a center of the stage as a reference so that a center of the substrate Wf coincides with the center of the stage. The term “center of the stage” refers to a center of a circle in a case where the stage has a circular shape, or even if the stage does not have a circular shape, a center of rotation of the stage or a center of a holding portion provided outside the stage may be regarded as a “center of the stage” which is a reference for the positional alignment. 
     For example, PTL 1 discloses a method in which a plurality of alignment pins provided around the outer periphery of the substrate Wf are driven to move the substrate Wf toward the center of the stage, so that the center of the substrate Wf coincides with the center of the stage. Furthermore, PTL 2 discloses a method in which guides with a slope to lower in level toward the center of the stage are provided around the outer periphery of the substrate Wf so that the substrate Wf slides over the slope under gravity, whereby the center of the substrate Wf coincides with the center of the stage. There is also a method of positioning the substrate Wf on the stage by pressing the substrate Wf against a plurality of pins that are disposed at predetermined positions on the outer periphery of the stage. 
     In a semiconductor manufacturing process, a CMP (chemical mechanical polishing) apparatus may be used to polish the substrate Wf. The CMP apparatus includes a polishing unit for polishing a process target object, a cleaning unit for cleaning and drying the process target object, a loading/unloading unit that transfers the process target object to the polishing unit and receives the process target object having been cleaned and dried by the cleaning unit, and other units. The CMP apparatus further includes a transport mechanism that transports the process target object in each of the polishing unit, the cleaning unit, and the loading/unloading unit. The CMP apparatus sequentially performs the polishing, cleaning, and drying with the process target object transported by the transport mechanism. 
     The precision requirement in each step in semiconductor device manufacturing these days has already reached a level of several nanometers, and CMP is no exception. To satisfy the requirement, polishing and cleaning conditions are optimized in CMP. Even when optimum conditions are determined, however, there are inevitable changes in polishing and cleaning performance due to variations in component control and changes in consumable materials over time. Furthermore, there is also a variation in a semiconductor substrate itself, which is the process target object. There are, for example, pre-CMP variations in the thickness of a film formed on the process target object and in the shape of a device. Depending on the processing condition in the CMP process and the state of the layer below the film to be polished, the local on-substrate polishing amount distribution varies in some cases. Therefore, these variations manifest themselves in the form of a variation in residual film and incomplete step elimination during CMP and after CMP and further in the form of a remaining film in polishing of a film that should be completely removed in the first place. To address such a variation in local polishing amount, after the CMP process on the whole surface of the substrate, the local residual film on the substrate is polished and removed using a partial polisher which uses a polishing pad smaller in size than the substrate. In such a partial polisher, to polish the local protruding portion on the substrate, it is necessary to accurately press the polishing pad that is smaller in size against the protruding portion on the substrate. To do so, it is important to accurately position the substrate on the stage. 
     CITATION LIST 
     Patent Literature 
     PTL 1: Japanese Patent Laid-Open No. 2003-133275 
     PTL 2: Japanese Patent Laid-Open No. 2013-65658 
     SUMMARY 
     The method in which the plurality of alignment pins are driven to move the substrate Wf so that the center of the substrate Wf coincides with the center of the stage as disclosed in PTL 1 requires a motive power for driving the alignment pins. Therefore, an installation location of a motive power source such as a motor, and a space for a controller and wiring of the power source are required, which makes the device larger. When a positioning mechanism is incorporated in the existing substrate processing apparatus, or the like, it may be difficult to secure a space for the power source. Furthermore, if the motive power source or the like for positioning the substrate Wf is added, the cost is accordingly increased. 
     The method in which guides with a slope to lower in level toward the center of the stage are provided around the outer periphery of the substrate Wf so that the substrate Wf slides over the slope under gravity, whereby the center of the substrate Wf coincides with the center of the stage, as disclosed in PTL 2 causes a problem such as operational reliability. If a sliding surface between the substrate Wf and the guides has some abnormality (e.g., scratches, stains, or other defects), the substrate Wf does not slide over the slope as assumed and is caught on the slope, which makes it impossible to perform the positional alignment. 
     As for the method of positioning the substrate Wf on the stage by pressing the substrate Wf against a plurality of pins that are disposed at predetermined positions on the outer periphery of the stage, the center of the substrate Wf may deviate from the center of the stage due to a manufacturing error of the substrate. For example, a semiconductor substrate having 300 mm in diameter has a manufacturing error of about ±0.2 mm. When the substrate Wf is pressed from one side against the plurality of pins, the center of the substrate Wf may deviate from the center of the stage by the error of the substrate Wf. 
     An object of the present application is to provide a device and method for accurately positioning a substrate on a stage by a simple method using power of a movement mechanism provided for a movable stage. 
     [First Form] According to a first form, a substrate holding device for holding a substrate is provided. The substrate holding device includes a substrate stage for supporting the substrate, a stage drive mechanism for causing the substrate stage to move, a positioning pin for positioning the substrate on the substrate stage, first urging members each urging the positioning pin, and a stopper member capable of applying a force against the urging member to the positioning pin. The positioning pin is configured to move together with the substrate stage by the stage drive mechanism. The positioning pins moving together with the substrate stage allows the substrate to be positioned on the substrate stage. 
     [Second Form] According to a second form, the substrate holding device according to the first form further includes a base member whose position is fixed. The stopper member is fixed to the base member. 
     [Third Form] According to a third form, the substrate holding device according to the first or second form further includes a positioning pin stage. The positioning pin is fixed to the positioning pin stage, and the positioning pin stage is configured to be capable of engaging with and disengaging from the substrate stage. 
     [Fourth Form] According to a fourth form, in the substrate holding device according to the third form, the positioning pin stage is configured to be movable between (1) an engagement position at which the positioning pin stage engages with the substrate stage and (2) a disengagement position at which the positioning pin stage disengages from the substrate stage, the engagement position and the disengagement position being separate from each other in a direction perpendicular to a top surface of the substrate stage. 
     [Fifth Form] According to a fifth form, in the substrate holding device according to the fourth form, the positioning pin includes a substrate support portion, and when the positioning pin stage is at the disengagement position, the positioning pin is configured to be capable of supporting the substrate by the substrate support portion. 
     [Sixth Form] According to a sixth form, in the substrate holding device according to any one of the third to fifth form having a feature of the second form, the positioning pin stage is connected to the base member through a second urging member, and the second urging member is configured to urge the positioning pin stage in a direction opposite to a direction in which the positioning pin stage moves together with the substrate stage. 
     [Seventh Form] According to a seventh form, in the substrate holding device according to any one of the first to sixth form, the positioning pin is urged by the first urging member in a central direction of the substrate. 
     [Eighth Form] According to an eighth form, in the substrate holding device according to any one of the first to seventh form, the number of the positioning pins is three or more. 
     [Ninth Form] According to a ninth form, in the substrate holding device according to the eighth form, the number of the positioning pins is six or more. 
     [Tenth Form] According to a tenth form, in the substrate holding device according to any one of the first to ninth form, the substrate stage has a circular top surface for supporting a circular substrate. 
     [Eleventh Form] According to an eleventh form, in the substrate holding device according to the tenth form, the stage drive mechanism has a motor for rotating the substrate stage, and the positioning pin is configured to position the substrate so that a center of the substrate coincides with a rotation center of the substrate stage. 
     [Twelfth Form] According to a twelfth form, a substrate processing apparatus is provided. The substrate processing apparatus includes the substrate holding device according to any one of the first to eleventh form, and the substrate processing apparatus is configured to perform processing on a substrate held by the substrate holding device. 
     [Thirteenth Form] According to a thirteenth form, the substrate processing apparatus according to the twelfth form includes a partial polisher partially polishing the substrate held by the substrate holding device. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic view illustrating a configuration of a partial polisher including a substrate holding device according to one embodiment; 
         FIG. 2  is a perspective view illustrating positioning pins, a pin stage, a base member, and pedestals of the substrate holding device, which is illustrated in  FIG. 1 ; 
         FIG. 3A  is a perspective view illustrating a state in which the positioning pin is supported by a stopper member according to one embodiment; 
         FIG. 3B  is a perspective view illustrating a state in which the positioning pin is released from the stopper member according to one embodiment; 
         FIG. 4A  is a schematic view illustrating the substrate holding device of the partial polisher according to one embodiment as viewed from below; 
         FIG. 4B  is a schematic view illustrating the substrate holding device of the partial polisher according to one embodiment as viewed from below, and illustrates a state in which a stage and a pin stage are rotated clockwise from the state in  FIG. 4A ; 
         FIG. 5A  is a partial cross-sectional view illustrating the substrate holding device according to one embodiment in a state in which the pin stage is located at a first position (upper stage); 
         FIG. 5B  is a partial cross-sectional view illustrating the substrate holding device according to one embodiment in a state in which the pin stage is located at a second position (middle stage); 
         FIG. 5C  is a cross-sectional view illustrating the substrate holding device according to one embodiment in a state in which the pin stage is located at a third position (lower stage); 
         FIG. 6A  is a schematic view illustrating the substrate holding device of the partial polisher according to one embodiment as viewed from above; 
         FIG. 6B  is a schematic view illustrating the substrate holding device of the partial polisher according to one embodiment as viewed from above, and illustrates a state in which the stage and the pin stage are rotated counterclockwise from the state in  FIG. 6A ; 
         FIG. 7  is a schematic view illustrating a mechanism that allows a polishing head to hold a polishing pad, according to one embodiment; 
         FIG. 8A  is a schematic view for describing an example of control of the polishing using the partial polisher according to one embodiment; 
         FIG. 8B  is a schematic view for describing an example of control of the polishing using the partial polisher according to one embodiment; 
         FIG. 9A  illustrates an example of a control circuit for processing information on the thickness of a film on the substrate Wf and irregularities and height thereof according to one embodiment; 
         FIG. 9B  illustrates a circuit diagram illustrating a substrate surface state detecting section separated from a partial polishing controller illustrated in  FIG. 9A ; 
         FIG. 10  is a schematic view illustrating a substrate processing system including the partial polisher according to one embodiment; 
         FIG. 11  is a schematic view illustrating a detection section  408  illustrated in  FIG. 1 , according to one embodiment; 
         FIG. 12  is a side view illustrating a state in which a fluid jet nozzle illustrated in  FIG. 11  is made close to the peripheral edge portion of the substrate, according to one embodiment; 
         FIG. 13  is a graph showing a pressure as a physical quantity measured by a fluid measuring device, according to one embodiment; 
         FIG. 14  is a graph showing a change in difference of the pressure as a physical quantity between the latest measured value and the previous measured value along a time axis, according to one embodiment; and 
         FIG. 15  is a plan view illustrating a positional relationship among the fluid jet nozzle, a holding arm, and the stage, according to one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of a partial polisher including a substrate holding device according to the present invention are described below with reference to appended drawings. In the appended drawings, the same or similar elements are designated by the same or similar reference symbols, and in the descriptions of respective embodiments, descriptions about the same or similar elements may be omitted where such descriptions would be redundant. Additionally, unless features described in respective embodiments are contradictory to each other, the features are applicable to other embodiments. 
       FIG. 1  is a schematic view illustrating a configuration of a partial polisher  1000  including a substrate holding device  400  according to one embodiment. As illustrated in  FIG. 1 , the partial polisher  1000  is configured on a base surface  1002 . The partial polisher  1000  may be configured as an independent single apparatus, or may be configured as a module that is part of a substrate processing system  1100  including a large-diameter polisher  1200  using a large-diameter polishing pad along with the partial polisher  1000  (see  FIG. 1 ). The partial polisher  1000  is installed in an enclosure which is not illustrated. The enclosure includes an exhaust mechanism which is not illustrated, and is configured not to expose a polishing liquid and the other components to the exterior of the enclosure during polishing. 
     As illustrated in  FIG. 1 , the partial polisher  1000  includes the substrate holding device  400  for holding a substrate Wf. The substrate holding device  400  includes a stage  401  that holds the substrate Wf in such a way that the substrate Wf faces upward. The stage  401  includes a rotational drive mechanism  410 , and is configured to be rotatable around a rotation axis  401 A. In one embodiment, the substrate Wf can be placed on the stage  401  by a transporter which is not illustrated. In the substrate holding device  400  in the partial polisher  1000  illustrated in  FIG. 1 , six positioning pins  402  are provided around the stage  401  (only four positioning pins  402  are illustrated in  FIG. 1 ). Each of the six positioning pins  402  is attached to an annular pin stage  404  through a pedestal  406 . The six positioning pins  402  have the same dimensions, and are arranged at an equal distance from the annular pin stage  404  in a radial direction. In the illustrated embodiment, the six positioning pins  402  are arranged at equal intervals in the circumferential direction. However, the arrangement of the positioning pins  402  in the circumferential direction need not be necessarily arranged at the equal intervals. For example, when the positioning pins  402  are not arranged at the equal intervals, and the annular pin stage  404  is divided by any diameter into two parts, the positioning pins  402  can be arranged so that the positioning pins  402  on both halves of the annular pin stage  404  are positioned in a symmetrical pattern with respect to the diameter. Alternatively, the positioning pins  402  may be arranged at any intervals in the circumferential direction. The pin stage  404  is configured to be movable in a direction (z direction) perpendicular to a top surface of the stage  401  as described later. Therefore, the positioning pins  402  are movable in the direction (z direction) perpendicular to the top surface of the stage  401 . In addition, the pin stage  404  is configured to be rotatable together with the stage  401  as described later. Therefore, the positioning pins  402  are movable in the circumferential direction of the stage  401 . A base member  405  is arranged below the pin stage  404 . Unlike the pin stage  404 , the base member  405  is configured not to rotate together with the stage  401 . The pin stage  404  and the base member  405  are connected through a bearing  409  (see  FIGS. 5A, 5B, and 5C ), and the pin stage  404  can rotate with respect to the base member  405 . The bearing  409  can be any bearing such as a thrust ball bearing, or a single row deep groove ball bearing. The base member  405  is configured to be movable in the direction (z direction) perpendicular to the top surface of the stage  401  by a drive mechanism which is not illustrated. Since the pin stage  404  is arranged on the base member  405  through the bearing  409 , when the base member  405  is moved in the z direction, the pin stage  404  on the base member  405  is also moved together with the base member  405  in the z direction. In one embodiment, a component such as a roller, a ball, or a slide member that can guide a rotary motion may be used instead of the bearing  409 . 
       FIG. 2  is a perspective view illustrating the positioning pins  402 , the pin stage  404 , the base member  405 , and the pedestals  406  of the substrate holding device  400 , which is illustrated in  FIG. 1 .  FIG. 3A  and  FIG. 3B  each are a perspective view illustrating an enlargement of the vicinity of the one positioning pin  402 . As illustrated in  FIGS. 3A and 3B , each of the positioning pins  402  includes a cylindrical guide portion  402   a . The guide portions  402   a  are configured to push the substrate Wf toward a central direction of the substrate Wf to position the substrate Wf on the stage  401  as described later. Each of the positioning pins  402  includes a substrate support portion  402   b  having a diameter larger than that of the guide portion  402   a . As described later, the substrate Wf is supported by top surfaces of the substrate support portions  402   b  of the six positioning pins  402 . Each of the positioning pins  402  further includes an arm portion  402   c  extending in an xy plane direction, and a cylindrical shaft portion  402   d . The guide portion  402   a  and the substrate support portion  402   b  are connected to the cylindrical shaft portion  402   d  through the arm portion  402   c . A center axis of the cylindrical shaft portion  402   d  defines a rotation axis  402   z  of the positioning pin  402 , and each of the positioning pins  402  is configured to be rotatable around the rotation axis  402   z . As illustrated in  FIGS. 3A and 3B , a center axis of the cylindrical guide portion  402   a  and the substrate support portion  402   b  is not coincident with the rotation axis  402   z . Therefore, when the positioning pin  402  rotates around the rotation axis  402   z , the guide portion  402   a  and the substrate support portion  402   b  can be moved in a direction parallel to the plane (xy plane) of the stage  401 . A motion direction of the guide portion  402   a  and the substrate support portion  402   b  when the positioning pin  402  rotates is an approximate radial direction of the stage  401 . The illustrated positioning pin  402  further includes an elastic member contact portion  402   e  and a stopper contact portion  402   f . As illustrated in  FIGS. 3A and 3B , the pedestal  406  is fixed to the pin stage  404 , and an elastic member  403  serving as an urging member is arranged between the pedestal  406  and the elastic member contact portion  402   e  of the positioning pin  402 . The elastic member  403  can be any urging member. In one embodiment, the elastic member  403  can be a spring plunger or a coil spring. Note that in the illustrated embodiment, the elastic member  403  is used as an urging member, but in the other embodiments, an urging member such as a magnet which is not an elastic member may be used. The elastic member  403  is configured to rotate the positioning pin  402  to urge the positioning pin  402  in a direction in which the guide portion  402   a  moves toward the interior of the stage  401 . As illustrated in  FIG. 2 , the base member  405  is provided with six stopper members  405   a  to correspond to the respective positioning pins  402 . The stopper contact portions  402   f  of the respective positioning pins  402  are configured to be in contact with the base member  405 .  FIG. 3A  illustrates a state in which the positioning pin  402  is supported by the stopper member  405   a . In the state illustrated in  FIG. 3A , the stopper member  405   a  applies a force which counteracts against the urging force of the elastic member  403  to the positioning pin  402 , so that the guide portion  402   a  is moved toward the exterior of the stage  401 . From the state illustrated in  FIG. 3A , the pin stage  404  is rotated counterclockwise when viewed in  FIG. 2  and  FIG. 3A , so that the stopper contact portion  402   f  of the positioning pin  402  moves away from the stopper member  405   a . Then, an elastic force of the elastic member  403  pushes the elastic member contact portion  402   e  to rotate the positioning pin  402 , so that the guide portion  402   a  and the substrate support portion  402   b  move in an inward direction of the stage  401 .  FIG. 3B  illustrates such a state. 
       FIGS. 4A and 4B  each are a schematic view illustrating the substrate holding device  400  of the partial polisher  1000  illustrated in  FIG. 1  as viewed from below (in the z direction).  FIGS. 5A, 5B and 5C  each are a partial cross-sectional view of the substrate holding device  400  of the partial polisher  1000  illustrated in  FIG. 1  which is cut out in a radial direction of the stage  401 .  FIGS. 6A and 6B  each are a schematic view illustrating the substrate holding device  400  of the partial polisher  1000  illustrated in  FIG. 1  as viewed from above (in the −z direction). As illustrated in  FIGS. 4A and 4B , the stage  401  includes a stage main body  401   a  that is rotated by a motor serving as the rotational drive mechanism  410 . The stage main body  401   a  is provided with first engagement portions  401   b . In one embodiment, the first engagement portions  401   b  each are a protruding portion extending radially outwardly from the stage main body  401   a  as illustrated in  FIGS. 4A and 4B  and  FIGS. 5A, 5B, and 5C . The pin stage  404  is provided with first engagement portions  404   b  each engaging with the corresponding first engagement portion  401   b  of the stage main body  401   a . Each of the first engagement portions  404   b  of the pin stage  404  can be a protruding portion extending radially inwardly as illustrated in  FIGS. 4A and 4B  and  FIGS. 5A, 5B, and 5C . Furthermore, the pin stage  404  is provided with second engagement portions  404   c . In one embodiment, the second engagement portions  404   c  each are a protruding portion extending radially outwardly from the annular pin stage  404 . The base member  405  includes second engagement portions  405   c  each engaging with the corresponding second engagement portion  404   c  of the pin stage  404  through a corresponding elastic member  405   b  serving as an urging member. The elastic member  405   b  can be, for example, a coil spring. The elastic member  405   b  is arranged to urge the pin stage  404  in a direction opposite to the rotational direction of the stage. In other words, the elastic member  405   b  is configured to urge the pin stage  404  toward the state of the pin stage  404  illustrated in  FIG. 3A  from the state illustrated in  FIG. 3B . Note that in the illustrated embodiment, the elastic member  405   b  is used as an urging member, but in the other embodiments, an urging member such as a magnet which is not an elastic member may be used. 
     When the stage  401  is rotated by the rotational drive mechanism  410  in a state in which each of the first engagement portions  401   b  of the stage  401  is engaged with the corresponding first engagement portion  404   b  of the pin stage  404 , the pin stage  404  also rotates together with the stage  401 .  FIG. 4B  illustrates a state in which the stage  401  and the pin stage  404  are rotated clockwise when viewed in  FIG. 4B  from the state illustrated in  FIG. 4A . When a driving force to the stage  401  is stopped, the pin stage  404  is returned, by the elastic members  405   b , to the original position, i.e., the position illustrated in  FIG. 4A . Thus, the above-described positioning pins  402  can be moved using the rotational drive mechanism  410  of the stage  401 . 
     In the state illustrated in  FIG. 4A , the positioning pin  402  is in the state illustrated in  FIG. 3A , and the guide portion  402   a  and the substrate support portion  402   b  of the positioning pin  402  are moved radially outwardly by the stopper member  405   a  of the base member  405 .  FIG. 6A  is a diagram illustrating such a state as viewed from above. As illustrated in  FIG. 6A , in this state, the substrate Wf is supported by the substrate support portions  402   b  of the six positioning pins  402 . When the stage  401  is rotated from such a state as illustrated in  FIG. 4B , the pin stage  404  is rotated, each of the positioning pins  402  is released from the corresponding stopper member  405   a  as illustrated  FIG. 3B , and each of the guide portions  402   a  of the respective positioning pins  402  is moved radially inwardly by the corresponding elastic member  403 . Thus, the substrate Wf supported by the substrate support portions  402   b  of the respective positioning pins  402  is pushed by the guide portions  402   a  of the six positioning pins  402  in the central direction to be positioned so that a rotation center of the stage  401  coincides with a center of the substrate Wf.  FIG. 6B  is a diagram illustrating such a state as viewed from above. 
     As described above, the pin stage  404  is movable in a direction perpendicular to the top surface of the stage  401 , so that the pin stage  404  can engage with and disengage from the stage  401 .  FIG. 5A  is a partial cross-sectional view illustrating a state in which the pin stage  404  is located at a first position (upper stage). As illustrated in  FIG. 5A , at the first position, the first engagement portion  401   b  of the stage  401  is separated from the first engagement portion  404   b  of the pin stage  404  in the height direction (z direction), so that the first engagement portion  401   b  is not engaged with the first engagement portion  404   b . Therefore, even when the stage  401  is rotated in this state, a rotational force of the stage  401  is not transmitted to the pin stage  404 . At the first position, the substrate support portion  402   b  of the positioning pin  402  is located higher than the top surface of the stage  401 , and the substrate Wf is transferred between a transport mechanism which is not illustrated and the positioning pins  402  at the first position. 
       FIG. 5B  is a partial cross-sectional view illustrating a state in which the pin stage  404  is located at a second position (middle stage). As illustrated in  FIG. 5B , at the second position, the first engagement portion  401   b  of the stage  401  is located at the same level as the first engagement portion  404   b  of the pin stage  404 , so that the first engagement portion  401   b  can engage with the first engagement portion  404   b . At the second position, the substrate support portion  402   b  of the positioning pin  402  is slightly lower than the top surface of the stage  401 , so that the guide portion  402   a  is brought to a position capable of contacting a peripheral edge portion of the substrate Wf on the stage  401 . Thus, when the stage  401  is rotated in this state, the rotational force of the stage  401  is transmitted to the pin stage  404  to move the positioning pin  402  as described above, so that the positioning pin  402  can be released from the stopper member  405   a.    
       FIG. 5C  is a cross-sectional view illustrating a state in which the pin stage  404  is located at a third position (lower stage). As illustrated in  FIG. 5C , at the third position, the first engagement portion  401   b  of the stage  401  is separated from the first engagement portion  404   b  of the pin stage  404  in the height direction (z direction), so that the first engagement portion  401   b  is not engaged with the first engagement portion  404   b . Therefore, even when the stage  401  is rotated in this state, the rotational force of the stage  401  is not transmitted to the pin stage  404 . At the third position, the whole positioning pin  402  is located lower than the top surface of the stage  401 . At the third position, partial polishing is performed on the substrate Wf supported by the stage  401 . 
     In the substrate holding device  400  according to the present embodiment, the placement and positioning of the substrate Wf on the stage  401  are performed as follows. As illustrated in  FIG. 5A , the positioning pin  402  is moved to the first position which is the upper stage. At this position, the substrate Wf is transferred from the transporter which is not illustrated to the substrate support portions  402   b  of the six positioning pins  402  so as to be supported by the substrate support portions  402   b . After the substrate Wf is placed on the substrate support portions  402   b , the positioning pins  402  are lowered to the second position illustrated in  FIG. 5B , and the substrate Wf is temporarily placed on the stage  401 . When at this position, the stage  401  is rotated as described above, the substrate Wf is positioned on the stage  401  by the six positioning pins  402  so that the center of the substrate Wf coincides with the rotation center of the stage  401 . When the substrate Wf is positioned, the substrate Wf is fixed onto the stage  401  by means of vacuum chucking or the like. When the substrate Wf is fixed onto the stage  401 , the positioning pins  402  are lowered to the third position which is the lower stage illustrated in  FIG. 5C . At such a position, a variety of types of processing such as partial polishing can be performed on the substrate Wf fixed onto the stage  401 . 
     As described above, in the substrate holding device  400  according to the present embodiment, the motive power from the rotational drive mechanism  410  that is originally included in the stage  401  of the partial polisher  1000  is used for the positioning of the substrate Wf, as described later. Therefore, an additional motive power source is not needed to move the positioning pins  402 . Furthermore, the positioning pins  402  according to the present embodiment are also used for transfer of the substrate Wf, and therefore are not components added only for a positioning function. Since the substrate is positioned by actively moving the positioning pins  402 , the reliability of the positioning of the substrate is more improved than in the case where the substrate is positioned by a passive action as disclosed in PTL 2. In the present embodiment, the substrate Wf is positioned by moving a plurality of movable positioning pins  402  from the exterior toward the center of the substrate Wf, thereby preventing the center of the substrate Wf from deviating from the center of the stage due to the error in substrate size, the deviation being generated when the substrate Wf is positioned by being pushed from only one side of the substrate Wf. 
     In the illustrated embodiment, the number of positioning pins  402  is six, but any number of three or more positioning pins  402  can be employed. However, when the number of positioning pins  402  is three, a position of an orientation flat or a notch portion of the substrate Wf may correspond to the positioning pin  402 , and in this case, there is a possibility that the substrate Wf cannot be accurately positioned. Therefore, it is preferable that the number of positioning pins  402  is four or more, or as in the illustrated embodiment, the number of positioning pins  402  is six or more. In the illustrated embodiment, the stage  401  is rotated, and the positioning pins  402  are released from the respective stopper members  405   a , so that the guide portions  402   a  of the respective positioning pins  402  are moved inwardly using the forces of the respective elastic members  403 . On the contrary, the guide portions  402   a  of the respective positioning pins  402  may be moved inwardly by the rotation of the stage  401 , and the guide portions  402   a  of the respective positioning pins may be moved outwardly by the respective elastic members  403 . For example, the arm portion  402   c  of the positioning pin  402  illustrated in  FIGS. 3A and 3B  is configured to extend to the opposite side of the circumferential direction of the pin stage  404 , so that such an embodiment can be implemented. Note that since in such an embodiment, the positioning pins  402  are moved inwardly by the rotation of the rotational drive mechanism  410 , when abnormality occurs in the rotational drive mechanism  410 , resulting in generating large forces, the positioning pins  402  applies the large forces to the substrate Wf, which may cause breakage in the substrate Wf. Therefore, the illustrated embodiment in which the forces of the elastic members  403  urge the respective positioning pins  402  inwardly is more preferable. 
     The description will return to the partial polisher  1000  illustrated in  FIG. 1 . The partial polisher  1000  illustrated in  FIG. 1  includes a detection section  408 . The detection section  408  is intended to detect the position of the substrate Wf placed on the stage  401 . For example, the detection section  408  can detect a notch or an orientation flat formed on the substrate Wf or the outer circumference of the substrate to detect the position of the substrate Wf on the stage  401 . Using the position of the notch or the orientation flat as a reference allows identification of an arbitrary point on the substrate Wf, thereby allowing partial polishing of a desired region. Furthermore, since information on the position of the outer circumference of the substrate provides information on the position of the substrate Wf on the stage  401  (amount of deviation with respect to ideal position, for example), the position to which a polishing pad  502  is moved may be corrected by a controller  900  based on the information. Note that, to detach the substrate Wf from the stage  401 , the positioning pins  402  are moved to the position ( FIG. 5B ) where the substrate is received from the stage  401 , and the vacuum chucking via the stage  401  is then deactivated. The positioning pins  402  are then further lifted to move the substrate Wf to the position ( FIG. 5A ) where the substrate is transferred to the transporter, and the transporter which is not illustrated can then receive the substrate Wf on the positioning pins  402 . The substrate Wf can then be transported by the transporter to an arbitrary location for subsequent processing. 
       FIG. 11  is a schematic view illustrating the detection section  408  illustrated in  FIG. 1 . The detection section  408  includes a fluid jet nozzle  431  configured to jet out fluid toward the peripheral edge portion of the substrate, a fluid measuring device  433  configured to measure a physical quantity of the fluid, a fluid supply pipe  435  configured to supply the fluid to the fluid jet nozzle  431 , a pressure regulator  436  attached to the fluid supply pipe  435 , and a position detector  440  configured to detect a position of a cut formed in the peripheral edge portion of the substrate Wf based on change in the fluid physical quantity. The fluid jet nozzle  431  is disposed downward in the vertical direction so that a distal end of the fluid jet nozzle  431  faces the stage  401 , and is connected to the fluid supply pipe  435 . 
     In the present embodiment, the fluid physical quantity to be measured is the pressure or flow rate of the fluid. The fluid measuring device  433  is any one of a pressure sensor and a flow rate sensor. In one embodiment, the fluid measuring device  433  may be provided with both of the pressure sensor and the flow rate sensor. The fluid measuring device  433  is electrically connected to the position detector  440  to transmit a measured value of the fluid physical quantity to the position detector  440 . The position detector  440  is electrically connected to the controller  900 . The position detector  440  detects a position of the cut on the substrate Wf based on change in the measured value of the fluid, and transmits the information on the position of the cut on the substrate Wf to the controller  900 . 
     As indicated by an arrow in  FIG. 11 , the fluid is supplied from a fluid supply source (not illustrated) provided outside the partial polisher  1000  to the fluid jet nozzle  431  through the fluid supply pipe  435 . The fluid supply source can be, for example, a canister, or a factory fluid supply line in which the partial polisher  1000  is installed. The pressure of the fluid supplied to the fluid supply pipe  435  is stabilized and is maintained at a constant level by the pressure regulator  436 . In the present embodiment, the above-described fluid is a liquid such as pure water, but in one embodiment, the above-described fluid may be gas such as clean air, or N 2  gas. 
     Next, a method of detecting a cut (e.g. a notch or an orientation flat) by the detection section  408  will be described in detail. The substrate Wf is placed on a surface of the stage  401  by the six positioning pins  402 . The substrate Wf is held on the stage surface by means of the vacuum chucking. Then, the stage  401  is rotated together with the substrate Wf by the rotational drive mechanism  410 . The rotational drive mechanism  410  can be formed, for example, of a servo motor such as a stepping motor. 
     The fluid jet nozzle  431  is moved above the peripheral edge portion of the substrate Wf by a nozzle movement mechanism which is not illustrated with the substrate Wf rotated. Then, the fluid jet nozzle  431  is lowered by the above-described nozzle movement mechanism so as to approach the peripheral edge portion of the substrate Wf rotating as illustrated in  FIG. 12 .  FIG. 12  is a side view illustrating a state in which the fluid jet nozzle  431  is made close to the peripheral edge portion of the substrate Wf. A distance T 2  between the axis  401 A of the stage  401  and a center line  431 A of the fluid jet nozzle  431  is equal to or larger than a distance T 1  between a center O of the substrate Wf and the innermost end of a cut  450  formed on the peripheral edge portion of the substrate Wf, and is smaller than a radius R of the substrate Wf. 
     The fluid jet nozzle  431  has a jet orifice  432  of the fluid at a distal end thereof. The fluid jet nozzle  431  jets out the fluid downward in the vertical direction in the state in which the fluid jet nozzle  431  is made close to the peripheral edge portion of the substrate Wf. That is, the fluid is jetted out to the peripheral edge portion of the substrate Wf. The physical quantity such as a pressure of the fluid flowing through the fluid supply pipe  435  is measured by the fluid measuring device  433 . The above-described physical quantity is measured per a predetermined unit time during jetting out of the fluid. Since the stage  401  is rotated during jetting out of the fluid, the fluid is jetted out on the entire circumferential surface of the peripheral edge portion of the substrate Wf. The fluid measuring device  433  transmits the measured value of the fluid physical quantity to the position detector  440 . The fluid physical quantity is continuously measured while the substrate Wf rotates for a predetermined number of times. After the substrate Wf rotates for the predetermined number of times, the fluid jet nozzle  431  stops jetting out the fluid, and the fluid measuring device  433  ends the measurement of the fluid physical quantity. 
     Reducing the distance between the distal end of the fluid jet nozzle  431  and the surface of the substrate Wf leads to the improvement in the detection accuracy of the cut position. In the present embodiment, a distance dw from the distal end of the fluid jet nozzle  431  to the surface of the stage  401  is a distance obtained by adding a thickness of the substrate Wf to 0.05 mm to 0.2 mm. In one embodiment, after the pressure of the fluid supplied from the fluid supply source such as a factory fluid supply line is boosted with a pump or the like, the fluid may flow into the pressure regulator  436 . Increasing the pressure of the fluid leads to the improvement in the detection accuracy of the cut position. 
       FIG. 13  is a graph showing a pressure as a physical quantity measured by the fluid measuring device  433 . In  FIG. 13 , a vertical axis represents the fluid pressure, and a horizontal axis represents the measurement time. The surface of the stage  401  is not completely perpendicular to the axis  401 A of the stage  401 . Therefore, during the rotation of the stage  401 , the distance from the distal end of the fluid jet nozzle  431  to the peripheral edge portion of the substrate Wf (distance from the distal end of the fluid jet nozzle  431  to the surface of the substrate Wf) periodically fluctuates. During the jetting out of the fluid, the fluid pressure fluctuates in response to the above-described fluctuations in the distance. In the example shown in  FIG. 13 , this periodic fluctuation in the fluid pressure is represented as a sine wave. 
     Since the fluid is jetted out downward in the vertical direction from the fluid jet nozzle  431 , when the stage  401  is rotated and the cut such as an orientation flat or a notch comes directly under the fluid jet nozzle  431 , at least part of fluid jet passes through the cut of the substrate Wf and does not collide with the substrate Wf. As a result, the fluid physical quantity is rapidly changed (reduced). In the example shown in  FIG. 13 , the rapid reduction of pressure represents that the cut of the substrate Wf is positioned directly under the fluid jet nozzle  431 . 
       FIG. 14  is a graph showing a pressure difference as a physical quantity measured by the fluid measuring device  433 . Specifically, the graph shown in  FIG. 14  shows the change in difference of the pressure as a physical quantity between the latest measured value and the previous measured value along a time axis. The position detector  440  calculates the difference of physical quantity between the latest measured value and the previous measured value each time the position detector  440  receives the latest measured value of the physical quantity from the fluid measuring device  433 , and compares the calculated difference with a predetermined threshold value. The position detector  440  determines a cut position based on the above-described comparison result. The cut position can be identified from an angle of rotation around the axis  401 A of the stage  401 . In other words, the cut position can be indicated in terms of the angle of rotation around the axis  401 A of the stage  401 . The position detector  440  is connected to the rotational drive mechanism  410 , so that a signal indicating the angle of rotation around the axis  401 A of the stage  401  is transmitted to the position detector  440  from the rotational drive mechanism  410 . 
     The position detector  440  determines the cut position based on the angle of rotation of stage  401  when the above-described difference reaches the threshold value. In the present embodiment, the position detector  440  determines the cut position identified from the angle of rotation of the stage  401  when the above-described difference reaches the threshold value. In one embodiment, the position detector  440  may calculate a corrected angle of rotation by adding a predetermined angle to the angle of rotation of the stage  401  when the above-described difference reaches the threshold value, and determine the cut position identified from the corrected angle of rotation. 
     When the surface of the stage  401  is completely perpendicular to the axis  401 A of the stage  401 , the fluid physical quantity is not represented as a sine wave as shown in  FIG. 13 . In this case, the position detector  440  may compare the measured value of the physical quantity with the predetermined threshold value, and determine the cut position of the substrate Wf based on the comparison result. In one embodiment, the position detector  440  determines the cut position based on the angle of rotation of the stage  401  when the measured value of the physical quantity reaches the threshold value. 
     In one embodiment, the detection section  408  may jet out the fluid to the peripheral edge portion of the substrate Wf while rotating the substrate Wf and the stage  401  in a first direction (clockwise, for example), and detect a first cut position of the substrate Wf using the method described with reference to  FIG. 11  to  FIG. 14 , and further may jet out the fluid to the peripheral edge portion of the substrate Wf while rotating the substrate Wf and the stage  401  in a second direction opposite to the first direction (counterclockwise, for example), and detect a second cut position of the substrate Wf using the method described with reference to  FIG. 11  to  FIG. 14 , such that an average of the first cut position and the second cut position is determined as the above-described cut position of the substrate Wf. The first cut position and the second cut position are identified from the angle of rotation of the substrate Wf, and the average of the first cut position and the second cut position can be indicated in terms of the angle of rotation of the substrate Wf. Thus, rotating the substrate Wf in both directions enables more accurate detection of the cut position. 
     As described above, the detection section  408  detects the cut position of the substrate Wf by measuring the fluid physical quantity which is a pressure or a flow rate. The pressure and the flow rate do not fluctuate due to slurry used in the polishing process and water drops, and do not substantially fluctuate depending on the measurement environment. As a result, the detection section  408  can detect the accurate cut position. 
       FIG. 15  is a plan view illustrating a positional relationship among the fluid jet nozzle  431 , a holding arm  600 , and the stage  401 . A point at which the axis  401 A of the stage  401  intersects the surface of the stage  401  is defined as an origin CP of the stage  401 . The XY coordinate system illustrated in  FIG. 15  is an imaginary coordinate system defined on the surface of the stage  401 , and has the origin CP. The X-axis of the XY coordinate system is a horizontal line which passes through the origin CP and extends in an X direction of the partial polisher  1000 , and the Y-axis of the XY coordinate system is a horizontal line which passes through the origin CP and extends vertically to the X-axis. The X-axis direction, i.e., the X direction of the partial polisher  1000  is a direction of the movement of a polishing head  500 . 
     An angle A is an angle formed between a line extending from the origin CP and being perpendicular to the center line  431 A of the fluid jet nozzle  431  and the X-axis. The angle A is measured in advance, and is stored in the controller  900 . The holding arm  600  is disposed along the Y-axis. The polishing head  500  is disposed on the axis  401 A and above the origin CP. 
     After the polishing head  500  and the fluid jet nozzle  431  are retracted outside of the stage  401 , the transporter, which is not illustrated, places the substrate Wf on the top ends of the six positioning pins  402  (see  FIG. 1 ). Then, the six positioning pins  402  are lowered to the above-described middle stage ( FIG. 5B ), and the substrate Wf is placed on the stage  401 . As described above, the substrate Wf is positioned by the six positioning pins  402 , so that the center O of the substrate Wf coincides with the origin CP of the stage  401 . Then, the substrate Wf is fixed onto the stage  401  by means of vacuum chucking or the like. 
     After the substrate Wf is fixed onto the stage  401 , the six positioning pins  402  are lowered to the above-described lower stage ( FIG. 5C ). Then, the fluid jet nozzle  431  is moved to a position illustrated in  FIG. 15 . The stage  401  is then rotated to a rotary origin of the stage  401  by the rotational drive mechanism  410  (see  FIG. 1 ). The rotary origin of the stage  401  refers to a reference point of the angle of rotation of the stage  401 . 
     Next, the rotational drive mechanism  410  rotates the stage  401  for a predetermined number of times in a predetermined direction. The controller  900  activates the detection section  408  at the same time when the stage  401  is rotated. The detection section  408  detects a position of the cut  450  by using the above-described method of detecting the cut. That is, the fluid jet nozzle  431  jets out the fluid to the peripheral edge portion of the substrate Wf while rotating the substrate Wf and the stage  401 , and the position detector  440  detects a position of the cut  450  based on change in the fluid physical quantity (a pressure or a flow rate). The position detector  440  transmits a signal indicating the detected position of the cut  450  to the controller  900 . When the substrate Wf is rotated for the predetermined number of times, the rotational drive mechanism  410  stops rotating the stage  401 , and returns the stage  401  to the rotary origin thereof. The detection section  408  stops jetting out of the fluid from the fluid jet nozzle  431 . 
     The stage  401  of the partial polisher  1000  includes the rotational drive mechanism  410 , and is configured to be rotatable around the rotation axis  401 A. The term “rotation” means continuous motion in a fixed direction, and motion in an arbitrary direction over a predetermined angular range of less than a single rotation. Note that, as another embodiment, the stage  401  may include a movement mechanism that imparts linear motion to the held substrate Wf. 
     The partial polisher  1000  illustrated in  FIG. 1  includes the polishing head  500 . The polishing head  500  holds the polishing pad  502 .  FIG. 7  is a schematic view illustrating the mechanism that allows the polishing head  500  to hold the polishing pad  502 . The polishing head  500  includes a first holding member  504  and a second holding member  506 , as illustrated in  FIG. 7 . The polishing pad  502  is held between the first holding member  504  and the second holding member  506 . The first holding member  504 , the polishing pad  502 , and the second holding member  506  each have a disc-like shape, as illustrated in  FIG. 7 . The diameter of each of the first holding member  504  and the second holding member  506  is smaller than the diameter of the polishing pad  502 . Therefore, in the state in which the polishing pad  502  is held by the first holding member  504  and the second holding member  506 , the polishing pad  502  is exposed beyond the edges of the first holding member  504  and the second holding member  506 . The first holding member  504 , the polishing pad  502 , and the second holding member  506  each have an opening at the center thereof, and a rotary shaft  510  is inserted into the openings. One or more alignment pins  508 , which protrude toward the polishing pad  502 , are provided on a surface of the first holding member  504  facing the polishing pad  502 . On the other hand, through holes are provided in the positions on the polishing pad  502  that correspond to the alignment pins  508 , and recesses that receive the alignment pins  508  are formed in a surface of the second holding member  506  facing the polishing pad  502 . Therefore, when the rotary shaft  510  rotates the first holding member  504  and the second holding member  506 , the holding members  504  and  506  can be rotated integrally with the polishing pad  502  with no slip thereof. 
     In the embodiment illustrated in  FIG. 1 , the polishing head  500  holds the polishing pad  502  in such a way that the side surface of the disc-like shape of the polishing pad  502  faces the substrate Wf. Note that the polishing pad  502  does not necessarily have a disc-like shape, and the polishing pad  502  having an arbitrary shape smaller in size than the substrate Wf can be used. The partial polisher  1000  illustrated in  FIG. 1  includes the holding arm  600 , which holds the polishing head  500 . The holding arm  600  includes a first drive mechanism for imparting motion to the polishing pad  502  in a first motion direction with respect to the substrate Wf. The motion in the “first motion direction” used herein is motion of the polishing pad  502  for polishing the substrate Wf and is a rotary motion of the polishing pad  502  in the partial polisher  1000  in  FIG. 1 . The first drive mechanism can therefore be formed, for example, of a typical motor. In the portion where the polishing pad  502  is in contact with the substrate Wf, since the polishing pad  502  moves in parallel to the surface of the substrate Wf (a direction of tangent to the polishing pad  502 , the x direction in  FIG. 1 ), the “first motion direction,” which is actually the direction of rotary motion of the polishing pad  502 , can be considered as the direction of a fixed straight line. 
     In the partial polisher  1000  according to the embodiment illustrated in  FIG. 1 , the area where the polishing pad  502  is in contact with the substrate Wf can be reduced, and only part of the surface of the substrate Wf can be polished. Note that the region where the polishing pad  502  is in contact with the substrate Wf is determined by the diameter and thickness of the polishing pad  502 . As an example, any value of the diameter c of the polishing pad  502  ranging from about 50 to 300 mm and any value of the thickness of the polishing pad  502  ranging from about 1 to 10 mm may be used in combination. 
     As one embodiment, the first drive mechanism can change the rotational speed of the polishing pad  502  during polishing. Changing the rotational speed allows adjustment of the polishing rate. Therefore, even in a case where a large polishing amount is required in a processed region of the substrate Wf, the polishing can be efficiently performed. Furthermore, for example, even in a case where the polishing pad  502  wears by a large amount during polishing and the diameter of the polishing pad  502  therefore changes, the adjustment of the rotational speed allows the polishing rate to be maintained. Note that, in the embodiment illustrated in  FIG. 1 , the first drive mechanism imparts rotary motion to the disc-shaped polishing pad  502 , but in another embodiment, the polishing pad  502  can have another shape, and the first drive mechanism can be configured to impart linear motion to the polishing pad  502 . Note that the linear motion includes a linear reciprocating motion. 
     The partial polisher  1000  illustrated in  FIG. 1  includes a vertical drive mechanism  602  for moving the holding arm  600  in the direction perpendicular to the surface of the substrate Wf (the z direction in  FIG. 1 ). The vertical drive mechanism  602  can move the polishing head  500  and the polishing pad  502  along with the holding arm  600  in the direction perpendicular to the surface of the substrate Wf. The vertical drive mechanism  602  also functions as a pressing mechanism for pressing the polishing pad  502  against the substrate Wf when the substrate Wf is partially polished. In the embodiment illustrated in  FIG. 1 , the vertical drive mechanism  602  is a mechanism using a motor and a ball screw, but as another embodiment, the vertical drive mechanism  602  may be a drive mechanism using air pressure or liquid pressure or a drive mechanism using a spring. Furthermore, as one embodiment, a drive mechanism for coarse motion and a drive mechanism for fine motion different from each other may be used as the vertical drive mechanism  602  for the polishing head  500 . For example, the drive mechanism for coarse motion can be a drive mechanism using a motor, and the drive mechanism for fine motion, which presses the polishing pad  502  against the substrate Wf, can be a drive mechanism using an air cylinder. In this case, adjusting the air pressure in the air cylinder while monitoring the pressing force exerted by the polishing pad  502  allows controlling the pressing force exerted by the polishing pad  502  on the substrate Wf. Conversely, an air cylinder may be used as the drive mechanism for coarse motion, and a motor may be used as the drive mechanism for fine motion. In this case, controlling the motor for fine motion while monitoring the torque provided by the motor allows controlling the pressing force exerted by the polishing pad  502  on the substrate Wf. A piezoelectric element may be used as another drive mechanism, and voltage applied to the piezoelectric element can be used to adjust the amount of movement. Note that in the case where the vertical drive mechanism  602  is separated into the drive mechanism for coarse motion and the drive mechanism for fine motion, the drive mechanism for fine motion may be provided in a position where the holding arm  600  holds the polishing pad  502 , that is, the distal end of the arm  600  in the example in  FIG. 1 . 
     The partial polisher  1000  illustrated in  FIG. 1  includes a lateral drive mechanism  620  for moving the holding arm  600  in the lateral direction (the y direction in  FIG. 1 ). The lateral drive mechanism  620  can move the polishing head  500  and the polishing pad  502  along with the arm  600  in the lateral direction. Note that the lateral direction (the y direction) is a second motion direction perpendicular to the above-described first motion direction and parallel to the surface of the substrate. The partial polisher  1000  can therefore further homogenize the shapes of the processed marks on the substrate Wf by moving the polishing pad  502  in the first motion direction (the x direction) to polish the substrate Wf and causing the polishing pad  502  to move in the second motion direction (the y direction) perpendicular to the first motion direction at the same time. As described above, in the partial polisher  1000  illustrated in  FIG. 1 , in the region where the polishing pad  502  is in contact with the substrate Wf, the linear speed is constant. However, if the state in which the polishing pad  502  is in contact with the substrate is not uniform due to unevenness of the shape and material of the polishing pad  502 , the shape of each processed mark on the substrate Wf varies, particularly, the polishing rate varies in the direction perpendicular to the first motion direction on the surface where the polishing pad  502  is in contact with the substrate Wf. However, causing the polishing pad  502  during polishing to move in the direction perpendicular to the first motion direction allows reduction in the polishing variation, whereby the shapes of the processed marks can be more homogenized. Note that, in the embodiment illustrated in  FIG. 1 , the vertical drive mechanism  602  is a mechanism using a motor and a ball screw. In the embodiment illustrated in  FIG. 1 , the lateral drive mechanism  620  is configured to move the holding arm  600  by moving the vertical drive mechanism  602  as a whole. Note that the second motion direction is not necessarily exactly perpendicular to the first motion direction, but may be a direction having a component perpendicular to the first motion direction. Also, in the latter case, the effect of homogenizing the shapes of the processed marks can be provided. 
     The partial polisher  1000  according to the embodiment illustrated in  FIG. 1  includes a polishing liquid supply nozzle  702 . The polishing liquid supply nozzle  702  is fluidly connected to a supply source (not illustrated), which supplies the polishing liquid, for example, slurry. In the partial polisher  1000  according to the embodiment illustrated in  FIG. 1 , the polishing liquid supply nozzle  702  is held by the holding arm  600 . The polishing liquid can therefore be efficiently supplied only to a polished region on the substrate Wf through the polishing liquid supply nozzle  702 . 
     The partial polisher  1000  according to the embodiment illustrated in  FIG. 1  includes a cleaning mechanism  200  for cleaning the substrate Wf. In the embodiment illustrated in  FIG. 1 , the cleaning mechanism  200  includes a cleaning head  202 , a cleaning member  204 , a cleaning head holding arm  206 , and a rinse nozzle  208 . The cleaning member  204  is a member for cleaning the partially polished substrate Wf with the rotated cleaning member  204  being in contact with the substrate Wf. The cleaning member  204  can be formed of a PVA sponge as one embodiment. The cleaning member  204  can instead include a cleaning nozzle for achieving mega-sonic cleaning, high-pressure water cleaning, or two-fluid cleaning in place of or in addition to the PVA sponge. The cleaning member  204  is held by the cleaning head  202 . The cleaning head  202  is held by the cleaning head holding arm  206 . The cleaning head holding arm  206  includes a drive mechanism for rotating the cleaning head  202  and the cleaning member  204 . The drive mechanism can be formed, for example, of a motor. The cleaning head holding arm  206  further includes a swing mechanism for swinging the cleaning head  202  and the cleaning member  204  in the plane of the substrate Wf. The cleaning mechanism  200  includes the rinse nozzle  208 . The rinse nozzle  208  is connected to a cleaning liquid supply source, which is not illustrated. The cleaning liquid can, for example, be pure water or a chemical liquid. In the embodiment in  FIG. 1 , the rinse nozzle  208  may be attached to the cleaning head holding arm  206 . The rinse nozzle  208  includes a swing mechanism for swinging the rinse nozzle in the plane of Wf with the rinse nozzle  208  held by the cleaning head holding arm  206 . 
     The partial polisher  1000  according to the embodiment illustrated in  FIG. 1  includes a conditioner  800  for conditioning the polishing pad  502 . The conditioner  800  is disposed in a position outside the stage  401 . The conditioner  800  includes a dressing stage  810  that holds a dresser  820 . In the embodiment in  FIG. 1 , the dressing stage  810  is rotatable around a rotation axis  810 A. In the partial polisher  1000  in  FIG. 1 , the polishing pad  502  can be conditioned by pressing the polishing pad  502  against the dresser  820  and rotating the polishing pad  502  and the dresser  820 . Note that as another embodiment, the dressing stage  810  may be configured to move linearly (including reciprocating motion) instead of rotary motion. Note that in the partial polisher  1000  in  FIG. 1 , the conditioner  800  is primarily used to condition the polishing pad  502  after completion of partial polishing at a certain point on the substrate Wf but before partial polishing at the following point or on the following substrate. The dresser  820  can be formed, for example, as (1) a diamond dresser having a surface onto which diamond particles are fixed in an electrodeposition process, (2) a diamond dresser having a surface which comes into contact with the polishing pad and on which diamond abrasive grains are entirely or partially placed, (3) a brushed dresser having a surface which comes into contact with the polishing pad and on which resin brushes are entirely or partially placed, or (4) any of the dressers described above or an arbitrary combination thereof. 
     The partial polisher  1000  according to the embodiment illustrated in  FIG. 1  includes a second conditioner  850 . The second conditioner  850  is intended to condition the polishing pad  502  during polishing of the substrate Wf with the polishing pad  502 . The second conditioner  850  can therefore be called an in-situ conditioner. The second conditioner  850  is held by the holding arm  600  in the vicinity of the polishing pad  502 . The second conditioner  850  includes a movement mechanism for moving a conditioning member  852  in the direction in which the conditioning member  852  is pressed against the polishing pad  502 . In the embodiment in  FIG. 1 , the conditioning member  852  is held in the vicinity of the polishing pad  502  but separate from the polishing pad  502  in the x direction and is configured to be movable by the movement mechanism in the x direction. The conditioning member  852  is configured to be capable of rotating or moving linearly by means of a drive mechanism which is not illustrated. Therefore, in the course of polishing of the substrate Wf with the polishing pad  502 , the polishing pad  502  can be conditioned during the polishing of the substrate Wf by pressing the conditioning member  852  in rotary motion or any other motion against the polishing pad  502 . 
     In the embodiment illustrated in  FIG. 1 , the partial polisher  1000  includes the controller  900 . The variety of drive mechanisms of the partial polisher  1000  are connected to the controller  900 , and the controller  900  can control the action of the partial polisher  1000 . The controller includes a computation section that calculates a target polishing amount in a polished region of the substrate Wf. The controller  900  is configured to control the polisher in accordance with the target polishing amount calculated by the computation section. Note that the controller  900  can be configured by installing a predetermined program in a typical computer including a storage device, a CPU, an input/output mechanism, and other components. 
     In one embodiment, the partial polisher  1000  may include, although not shown in  FIG. 1 , a state detecting section  420  (see  FIGS. 9A and 9B ) for detecting the state of the polished surface of the substrate Wf. The state detecting section  420  can be a Wet-ITM (in-line thickness monitor) by way of example. The Wet-ITM can detect (measure) the distribution of the thickness of a film formed on the substrate Wf (or distribution of information on film thickness) by moving a noncontact detection head, which is present above the substrate Wf, across the entire surface of the substrate Wf. As the state detecting section  420 , a detector based on an arbitrary method other than the Wet-ITM can instead be used. For example, as a usable detection method, a noncontact detection method, such as a known eddy-current type or optical type, can be employed. Still instead, a contact-type detection method may be employed. As the contact-type detection method, for example, a detection head including a probe through which current can flow is prepared, and the surface of the substrate Wf is scanned with the probe which is in contact with the substrate Wf and through which current is caused to flow. Electrical resistance detection that allows detection of a film resistance distribution can thus be employed. As another contact detection method, a step detection method can also be employed. In the step detection method, the surface of the substrate Wf is scanned with a probe that is in contact with the surface of the substrate Wf, and the upward and downward motion of the probe is monitored to detect the distribution of irregularities across the surface. In each of the contact-type and noncontact-type detection methods, a detected output is the film thickness or a signal corresponding to the film thickness. In the optical detection, the amount of light projected onto the surface of the substrate Wf and reflected off the surface may be detected. In addition to this, a film thickness difference may be identified based on a difference in color tone of the surface of the substrate Wf. To detect the thickness of a film on the substrate Wf, it is desirable to detect the film thickness with the substrate Wf rotated and the detector swung in the radial direction of the substrate Wf. As a result, information on the film thickness across the entire surface of the substrate Wf and information on a step and other surface states can be obtained. Furthermore, use of the position of a notch or an orientation flat detected with the detection section  408  as a reference allows data on the film thickness and other factors to be related not only to the radial position but to the circumferential position, whereby a distribution of the film thicknesses and steps on the substrate Wf or signals relating thereto can be obtained. Furthermore, when partial polishing is performed, the actions of the stage  401  and the holding arm  600  can be controlled based on the positional data. 
     The above-described state detecting section  420  is connected to the controller  900 , and a signal detected by the state detecting section  420  is processed by the controller  900 . The controller  900  for the detector of the state detecting section  420  may use the same hardware as that used by the controller  900  that controls the actions of the stage  401 , the polishing head  500 , and the holding arm  600  or may use another piece of hardware. In the case where the controller  900  that controls the actions of the stage  401 , the polishing head  500 , and the holding arm  600  and the controller  900  for the detector use different pieces of hardware, hardware resources used in the polishing of the substrate Wf can be different from hardware resources used in the detection of the state of the surface of the substrate Wf and the subsequent signal processing, whereby the processing can be performed at high speed as a whole. 
     The timing when the state detecting section  420  performs the detection can be a timing before polishing of the substrate Wf, during the polishing, and/or after the polishing. In a case where the state detecting section  420  is independently incorporated, the detecting operation before the polishing, after the polishing, and even during the polishing but between adjacent polishing actions does not interfere with the action of the holding arm  600 . It is, however, noted that when the thickness of a film on the substrate Wf is detected during the processing of the substrate Wf and concurrently with the processing performed by the polishing head  500 , the state detecting section  420  performs the scanning in accordance with the action of the holding arm  600  to minimize a temporal delay of the thickness of a film on the substrate Wf being processed or a signal relating to the film thickness. In the present embodiment, the state detecting section  420  is incorporated in the partial polisher  1000  to detect the state of the surface of the substrate Wf. Instead, in a case where the polishing performed by the partial polisher  1000  takes time, for example, the detecting section may be disposed as a detection unit external to the partial polisher  1000  from the viewpoint of productivity. For example, as for ITM, Wet-ITM is effective in measurement during the processing, whereas in the acquisition of the film thickness or a signal corresponding thereto before or after the processing, the ITM is not necessarily required to be incorporated in the partial polisher  1000 . The ITM may be disposed in a position outside the partial polisher module, and the measurement may be performed when the substrate Wf is placed in or removed from the partial polisher  1000 . Furthermore, the polishing end point in each polished region of the substrate Wf may be determined based on the film thickness or signals relating to the film thickness, irregularities, and height acquired by the state detecting section  420 . 
       FIG. 8A  is a schematic view for describing an example of control of the polishing using the partial polisher  1000  according to one embodiment.  FIG. 8A  is a schematic view of the substrate Wf viewed from above and illustrates an example in which portions Wf- 1 , where the film thickness is greater than the film thickness in the other portion Wf- 2 , are randomly formed. It is assumed in  FIG. 8A  that the polishing pad  502  has a roughly rectangular unit processed mark  503 . The size of the unit processed mark  503  corresponds to the area where the polishing pad  502  is in contact with the substrate Wf. As illustrated in  FIG. 8A , it is assumed that the portions Wf- 1 , where the film thickness is greater than the film thickness in the other portion Wf- 2 , are randomly formed on the processed surface of the substrate Wf. In this case, the controller  900  can cause the drive mechanism that drives the stage  401  to cause the substrate Wf to rotate angularly so that the polishing amount in each of the portions Wf- 1 , where the film on the substrate Wf is thicker, is greater than the polishing amount in the other portion Wf- 2 . For example, the controller  900  can grasp the position of each of the portions Wf- 1 , where the film on the substrate Wf is thicker, with respect to a notch, an orientation flat, or a laser marker on the substrate Wf and use the drive mechanism that drives the stage  401  to cause the substrate Wf to rotate angularly in such a way that the position falls within the range over which the polishing head  500  swings. Specifically, the partial polisher  1000  illustrated in  FIG. 1  includes the detection section  408  that detects at least one of the notch, the orientation flat, and the laser marker on the substrate Wf, moves the polishing head  500  in the radial direction to a polishing position calculated based on the detected notch, orientation flat, or laser marker and the surface state distribution of the substrate Wf detected by the state detecting section  420 , and rotates the substrate Wf on the stage  401  by an arbitrary predetermined angle. Note that the controller  900  only needs to polish Wf- 1  in a case where the Wf- 2  region has a desired film thickness. In a case where both Wf- 1  and Wf- 2  are polished to achieve a desired film thickness, the polishing head  500  can be controlled such that when each of the portions Wf- 1 , where the film on the substrate Wf is thicker, falls within the range over which the polishing head  500  swings, the number of revolutions of the polishing head  500  is greater than the number of revolutions in the other portion Wf- 2 . Furthermore, the controller  900  can control the polishing head  500  in such a way that when each of the portions Wf- 1 , where the film on the substrate Wf is thicker, falls within the range over which the polishing head  500  swings, the pressing force exerted by the polishing pad  502  is greater than the force in the other portion Wf- 2 . Furthermore, the controller  900  can control the swing speed of the holding arm  600  in such a way that the polishing period (period for which the polishing pad  502  stays) for which each of the portions Wf- 1 , where the film on the substrate Wf is thicker, falls within the range over which the polishing head  500  swings is longer than the polishing period in the other portion Wf- 2 . Furthermore, the controller  900  can perform control so as to rotate the polishing head  500  with the stage  401  being stationary in the position where the polishing pad  502  is above each of the portions Wf- 1 , where the film on the substrate Wf is thicker, to polish only the portion Wf- 1 , where the film on the substrate Wf is thicker. As a result, the partial polisher  1000  can polish the polished surface into a flat surface by using the controller  900 . 
       FIG. 8B  is a schematic view for describing an example of control of the polishing using the partial polisher  1000 .  FIG. 8B  is a schematic view of the substrate Wf viewed from above and illustrates an example in which a portion Wf- 1 , where the film thickness is greater than the film thickness in the other portions Wf- 2 , is concentrically formed. It is assumed in  FIG. 8B  that the polishing pad  502  has the roughly rectangular unit processed mark  503 . The size of the unit processed mark  503  corresponds to the area where the polishing pad  502  is in contact with the substrate Wf. As illustrated in  FIG. 8B , it is assumed that the portion Wf- 1 , where the film thickness is greater than the film thickness in the other portions Wf- 2 , is concentrically formed on the processed surface of the substrate Wf. In this case, the controller  900  performs polishing by rotating the stage  401  and moving the holding arm  600  in the radial direction of the substrate Wf at the same time. Note that in a case where the Wf- 2  regions have a desired film thickness, only the Wf- 1  region of the substrate Wf is polished. In a case where both Wf- 1  and Wf- 2  are polished to achieve a desired film thickness, the number of revolutions of the polishing head  500  can be controlled to be greater in Wf- 1  than in Wf- 2 . Furthermore, the controller  900  can control the polishing head  500  in such a way that the pressing force exerted by the polishing pad  502  is greater in Wf- 1  than in Wf- 2 . Furthermore, the controller  900  can control the swing speed of the holding arm  600  in such a way that the polishing period (period for which the polishing pad  502  stays) in Wf- 1  is longer than the polishing period in Wf- 2 . As a result, the controller  900  allows the polished surface of the substrate Wf to be polished into a flat surface. 
       FIG. 9A  illustrates an example of a control circuit for processing information on the thickness of a film on the substrate Wf and irregularities and height thereof according to one embodiment. First, a partial polishing controller combines a polishing process recipe set via an HMI (human machine interface) with parameters to determine a basic partial polishing process recipe. In this process, the partial polishing process recipe and the parameters may be downloaded from a HOST to the partial polisher  1000 . A recipe server then combines the basic partial polishing process recipe with polishing process information on a process job to produce a basic partial polishing process recipe for each substrate Wf to be processed. The partial polishing recipe server combines the partial polishing process recipe for each substrate Wf to be processed, substrate surface shape data stored in a partial polishing database, and, further, data on the substrate surface shape and other factors relating to similar substrates and obtained after past partial polishing and polishing rate data on each parameter in a polishing condition acquired in advance with one another to produce a partial polishing process recipe on a substrate basis. At this point, the substrate surface shape data stored in the partial polishing database may be data on the substrate Wf measured by the partial polisher  1000  or may be data downloaded in advance from the HOST to the partial polisher  1000 . The partial polishing recipe server transmits the partial polishing process recipe via the recipe server or directly to the partial polisher  1000 . The partial polisher  1000  partially polishes the substrate Wf in accordance with the received partial polishing process recipe. 
       FIG. 9B  illustrates a circuit diagram illustrating the substrate surface state detecting section  420  separated from the partial polishing controller illustrated in  FIG. 9A . It can be expected by separating the substrate surface state detection controller, which handles a large amount of data, from the partial polishing controller that the data processing load on the partial polishing controller is reduced and the period for creating the process job and the processing period required for the generation of a partial polishing process recipe can be shortened, whereby the overall throughput of the partial polishing module can be improved. 
     In each of the partial polishers  1000  according to the embodiments described above, the first drive mechanism allows the polishing pad  502  for polishing the substrate Wf to move in the first motion direction. The first motion direction is the direction in which the polishing pad  502  moves in the region where the polishing pad  502  is in contact with the substrate Wf. For example, in the case where the polishing pad  502  has a disc-like shape and rotates, the first motion direction of the polishing pad  502  is the direction of a tangent to the polishing pad  502  in the region where the polishing pad  502  is in contact with the substrate Wf. Furthermore, in each of the partial polishers  1000  according to the embodiments described above, the lateral drive mechanism  620  allows the polishing pad  502  to move in the second motion direction having a component perpendicular to the first motion direction and parallel to the substrate Wf. Causing the polishing pad  502  to move in the second motion direction during the polishing of the substrate Wf as described above allows a further uniform shape of processed marks on the substrate Wf. The polishing pad  502  can be moved by an arbitrary amount in the second motion direction during the polishing, and the amount of movement in the second motion direction can be determined from a variety of points of view. 
       FIG. 10  is a schematic view illustrating a substrate processing system  1100  according to one embodiment, which incorporates the partial polisher  1000 . The substrate processing system  1100  includes the partial polisher  1000 , a large-diameter polisher  1200 , a cleaner  1300 , a dryer  1400 , the controller  900 , and a transport mechanism  1500 , as illustrated in  FIG. 10 . The partial polisher  1000  in the substrate processing system  1100  can be the partial polisher  1000  having any of the features described above. The large-diameter polisher  1200  is a polisher that polishes a substrate by using a polishing pad having an area greater than the area of the substrate Wf, which is a target to be polished. The large-diameter polisher  1200  can be formed of a known CMP apparatus. The cleaner  1300 , the dryer  1400 , and the transport mechanism  1500  can also be each an arbitrary known apparatus. The controller  900  can be configured to control the entire action of the substrate processing system  1100  as well as the action of the partial polisher  1000  described above. In the embodiment illustrated in  FIG. 10 , the partial polisher  1000  and the large-diameter polisher  1200  are incorporated in one substrate processing system  1100 . Therefore, combining the partial polishing performed by the partial polisher  1000 , overall polishing of the substrate Wf performed by the large-diameter polisher  1200 , and detection of the state of the surface of the substrate Wf performed by the state detecting section  420  allows a variety of types of polishing. Note that in the partial polishing performed by the partial polisher  1000 , only part of the surface of the substrate Wf instead of the entire surface thereof can be polished, or in the polishing of the entire surface of the substrate Wf performed by the partial polisher  1000 , the polishing condition can be changed in part of the surface of the substrate Wf and the polishing can be performed in accordance with the changed polishing condition. 
     A partial polishing method carried out by the substrate processing system  1100  will be described. First, the state of the surface of the substrate Wf, which is the polishing target object, is detected. The surface state is, for example, information on the thickness of a film formed on the substrate Wf and irregularities of the surface (such as position, size, and height) and can be detected by the state detecting section  420  described above. A polishing recipe is then created in accordance with the detected state of the surface of the substrate Wf. The polishing recipe is formed of a plurality of process steps. Parameters in the steps, for example, in the partial polisher  1000  include the processing period, the contact pressure or load exerted by the polishing pad  502  on the substrate Wf and the dresser  820  disposed on the dressing stage  810 , the number of revolutions of the polishing pad  502  and the substrate Wf, the movement pattern and moving speed of the polishing head  500 , the selection and flow rate of the polishing pad processing liquid, the number of revolutions of the dressing stage  810 , and the polishing end point detection condition. Furthermore, in the partial polishing, it is necessary to determine the action of the polishing head  500  on the substrate Wf based on the information on the film thickness and irregularities on the substrate Wf acquired by the state detecting section  420  described above. For example, as for the period for which the polishing head  500  stays in each polished region of the substrate Wf, examples of the parameters involved in the determination described above may include target values corresponding to a desired film thickness and a desired state of the irregularities and a polishing rate in the polishing condition described above. The polishing rate, which varies depending on the polishing condition, may be stored as a database in the controller  900  and may be automatically calculated when a polishing condition is set. In this case, a polishing rate for each basic parameter may be acquired in advance and stored as a database. The period for which the polishing head  500  stays on the substrate Wf can be calculated from the information on the parameters and the acquired film thickness and irregularities on the substrate Wf. Furthermore, as will be described later, since the order of the pre-measurement, partial polishing, overall polishing, and cleaning varies depending on the state of the substrate Wf and the processing liquid to be used, the transport order of the components described above may be set. Furthermore, a condition under which data on the film thickness and irregularities on the substrate Wf is acquired may be set. In a case where the state of the processed Wf does not reach an acceptable level, as will be described later, the polishing is required to be performed again. A processing condition (such as number of repetitions of re-polishing) in this case may be set. Partial polishing and overall polishing are then performed in accordance with the created polishing recipe. Note that in the present example and other examples described later, the substrate Wf can be cleaned at an arbitrary timing. For example, in a case where the processing liquid used in the partial polishing differs from the processing liquid used in the overall polishing, and contamination of the processing liquid in the partial polishing is not negligible in the overall polishing, the substrate Wf may be cleaned after each of the partial polishing and the overall polishing to prevent the contamination. Conversely, in a case where the same processing liquid is used or in a case where the contamination of the processing liquid is negligible, the substrate Wf may be cleaned after both the partial polishing and the overall polishing are performed. 
     In each of the embodiments described above, an example is described in which the substrate holding device  400  is used for the partial polisher  1000 , but the substrate holding device  400  can be used for a substrate processing apparatuses other than the partial polisher  1000 . For example, the substrate holding device  400  can be used for a polisher that polishes the peripheral edge portion of the substrate. 
     The embodiments of the present invention have been described based on some examples. The inventive embodiments described above are intended to allow easy understanding of the present invention and are not intended to limit the present invention. The present invention can be changed and improved to the extent that the changes or improvements do not depart from the substance of the present invention and of course encompasses equivalents of the present invention. The components described in the claims and the specification can be arbitrarily combined with one another or any of the components can be omitted to the extent that at least part of the object described above is achieved or at least part of the effects is provided. 
     REFERENCE SIGNS LIST 
     
         
           400  . . . Substrate holding device 
           401  . . . Stage 
           401   a  . . . Stage main body 
           401 A . . . Rotation axis 
           401   b  . . . First engagement portion 
           402  . . . Positioning pin 
           402   a  . . . Guide portion 
           402   b  . . . Substrate support portion 
           402   c  . . . Arm portion 
           402   d  . . . Shaft portion 
           402   e  . . . Elastic member contact portion 
           402   f  . . . Stopper contact portion 
           402   z  . . . Rotation axis 
           403  . . . Elastic member 
           404  . . . Pin stage 
           404   b  . . . First engagement portion 
           404   c  . . . Second engagement portion 
           405  . . . Base member 
           405   a  . . . Stopper member 
           405   b  . . . Elastic member 
           405   c  . . . Second engagement portion 
           406  . . . Pedestal 
           408  . . . Detection section 
           410  . . . Rotational drive mechanism 
           900  . . . Controller 
           1000  . . . Partial polisher 
         Wf . . . Substrate