Patent Publication Number: US-10777417-B2

Title: Dressing device, polishing apparatus, holder, housing and dressing method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Japanese Priority Patent Application JP 2016-158456 filed on Aug. 12, 2016, the entire contents of which are incorporated herein by reference. 
     FIELD 
     This technique is related to a dressing device, a polishing apparatus, a holder, a housing and a dressing method. 
     BACKGROUND AND SUMMARY 
     As semiconductor miniaturization advances, the vertical structure has been complicated, in addition to the reduction in the horizontal dimensions. Therefore, there is an increased need for techniques of flattening the surface of a semiconductor substrate (wafer) and facilitating the processing. Among such flattening techniques, particularly, a chemical mechanical polishing (CMP) technique has become more important. 
     A polishing apparatus using the CMP technique polishes a semiconductor substrate held by a polishing head, by sliding a polishing pad, while dropping polishing liquid. When the polishing of the substrate is performed, the polishing performance gradually deteriorates, due to abrasive grains and polishing chips adhering to the surface of the polishing pad or due to the change in the property of the polishing pad. Hence, in the CMP, generally, a process called a dressing (conditioning), in which adhering substances on the surface of the polishing pad are removed, the dressing is performed and the surface state is recovered, is performed, during polishing or after polishing. 
     For example, U.S. Pat. No. 6,508,697 discloses a polishing system including a dresser that includes a supply port for supplying process liquid to a hollow rotation shaft of the dresser and a fixed cover that includes a suction port for sucking the process liquid to the outer circumference side of the dresser. Further, the rotation shaft of the dresser passes through a hole provided on the cover. 
     However, the hollow structure of the rotation shaft of the dresser as shown in U.S. Pat. No. 6,508,697 has the following practical problem. A contact seal between the hole provided on the cover and the rotation shaft of the dresser deteriorates due to polishing liquid (also referred to as slurry), and therefore, the maintenance frequency increases. For practical use, it is necessary to dispose a rotary joint on the rotation shaft, in order to avoid a hose inserted into the suction port from tangling due to the rotation. Therefore, it is not possible to dispose a cylinder that generates a pressing force on the rotation shaft. Accordingly, a load acting axis is offset horizontally from the rotation shaft, a moment acts on the rotation shaft, and a sliding resistance force increases. Therefore, it is not possible to smoothly control the pressing force. 
     Further, in the case where the suction port for sucking the process liquid is provided on the outer circumference side of the dresser as shown in U.S. Pat. No. 6,508,697, there is a problem in that it is not possible to sufficiently remove the polishing liquid and debris stuck near the center of the dresser. 
     It is desired to provide a dressing device, a polishing apparatus, a holder, a housing and a dressing method that make it possible to reduce the maintenance frequency and to smoothly control the pressing force, and that make it possible to enhance the ability of the removal of the polishing liquid and debris stuck near the center. 
     A dressing device according to one aspect of this technique, a dressing device comprising: a disk that has an opening on an inside, the disk dressing a polishing surface for polishing a substrate; a rotatable holder, the disk being coupled to a lower surface side of the holder, the holder being provided with a first flow passage that passes from a lower surface to an upper surface, the lower surface being inside an outer edge of the opening of the disk; and a housing that is provided with a distance from the upper surface of the holder, the housing being provided with a second flow passage in an interior, the housing being fixed such that an opening of the second flow passage faces the upper surface of the holder, the second flow passage being connected with a supply source and a suction source of process liquid, wherein the process liquid is supplied from the supply source to the polishing surface, through the second flow passage and the first flow passage in order, and the process liquid on the polishing surface is sucked by the suction source, through the first flow passage and the second flow passage in order. 
     A holder according to one aspect of this technique, a holder that is a component to be used together with a housing fixed in a dressing device, wherein the holder is rotatable, a disk is capable of being coupled to a lower surface side of the holder, and the holder is provided with a flow passage that passes from a lower surface to an upper surface, the lower surface being inside an outer edge of the opening of the disk when the disk is coupled. 
     A housing according to one aspect of this technique, a housing that is a component to be used together with a holder that is rotatable in a dressing device, wherein the housing is provided with a distance from an upper surface of the holder, the housing is provided with a second flow passage in an interior, the housing is fixed such that one end of the second flow passage faces the upper surface of the holder, and the second flow passage is connected with a supply source and a suction source of process liquid. 
     A dressing method according to one aspect of this technique, a dressing method that is executed by a dressing device, the dressing device comprising: a disk that has an opening on an inside, the disk dressing a polishing surface for polishing a substrate; a rotatable holder, the disk being coupled to a lower surface side of the holder, the holder being provided with a first flow passage that passes from a lower surface to an upper surface, the lower surface being inside an outer edge of the opening of the disk; and a housing that is provided with a distance from the upper surface of the holder, the housing being provided with a second flow passage in an interior, the housing being fixed such that one end of the second flow passage faces the upper surface of the holder, the dressing method comprising: a step of supplying pure water to the polishing surface, through the second flow passage and the first flow passage in order, during dressing; and a step of sucking process liquid on the polishing surface, through the first flow passage and the second flow passage in order, during the dressing. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a plan view showing the whole configuration of the polishing apparatus  100  according to the embodiment of the technique. 
         FIG. 2  is a configuration diagram showing the outline of the dressing device according to the embodiment. 
         FIG. 3  is a perspective view showing the outline of the dresser  33 . 
         FIG. 4  is a schematic diagram of an A-A cross-section in  FIG. 3 . 
         FIG. 5  is a perspective view of a portion of the dresser  33 . 
         FIG. 6  is a perspective view of the housing  54  as viewed from the upper side. 
         FIG. 7  is a perspective view of the housing  54  as viewed from the back side. 
         FIG. 8  is a cross-sectional view of a BB cross-section in  FIG. 5 . 
         FIG. 9  is a perspective view of the holder  55 . 
         FIG. 10  is a plan view of the holder  55  as viewed from the upper side. 
         FIG. 11  is a plan view of the holder  55  as viewed from the lower side. 
         FIG. 12  is a plan view when the straightening plate  130  is removed in  FIG. 11 . 
         FIG. 13  is a cross-sectional view of a CC cross-section in  FIG. 5 . 
         FIG. 14  is an enlarged view of a region R in  FIG. 13 . 
         FIG. 15  is a cross-sectional view of a DD cross-section in  FIG. 13 . 
         FIG. 16  is a flowchart showing an exemplary process method according to the embodiment. 
         FIG. 17  is a configuration diagram showing the outline of a dressing device according to a modification of the embodiment. 
     
    
    
     DETAILED DESCRIPTION OF NON-LIMITING EXAMPLE EMBODIMENTS 
     Hereinafter, an embodiment according to the technique will be described with reference to the drawings. A polishing apparatus  100  according to the embodiment polishes a polished surface of a polishing object by the relative slide between the polished surface and a polishing member. The polishing object according to the embodiment is a substrate, and the description will be made taking a wafer as an example of the substrate. Further, in the embodiment, the polishing member will be described taking a polishing pad as an example. 
     A dressing device according to a 1st aspect of this technique, a dressing device comprising: a disk that has an opening on an inside, the disk dressing a polishing surface for polishing a substrate; a rotatable holder, the disk being coupled to a lower surface side of the holder, the holder being provided with a first flow passage that passes from a lower surface to an upper surface, the lower surface being inside an outer edge of the opening of the disk; and a housing that is provided with a distance from the upper surface of the holder, the housing being provided with a second flow passage in an interior, the housing being fixed such that an opening of the second flow passage faces the upper surface of the holder, the second flow passage being connected with a supply source and a suction source of process liquid, wherein the process liquid is supplied from the supply source to the polishing surface, through the second flow passage and the first flow passage in order, and the process liquid on the polishing surface is sucked by the suction source, through the first flow passage and the second flow passage in order. 
     According to this configuration, since the contact seal is not provided between the first flow passage and second flow passage through which the polishing liquid passes, the deterioration of the contact seal does not occur, and the maintenance frequency can be reduced. Pipes (for example, hoses) to be connected with the supply source and the suction source are connected with the fixed housing, and therefore, it is not necessary to dispose a rotary joint on the rotation shaft for the holder. Accordingly, it is possible to dispose a member that generates a pressing force on the rotation shaft for the holder, and therefore, it is possible to smoothly control the pressing force. Furthermore, the inside of the outer edge of the opening of the disk tends to have a negative pressure due to the suction by the suction source, and a pressing force by which the disk surface follows the polishing surface is generated. Therefore, it is possible to expect the enhancement of the dressing efficiency. Further, it is possible to perform the suction from the inside of the outer edge of the opening of the disk, and therefore, it is possible to enhance the efficiency of the removal of the polishing liquid and debris stuck near the center. Further, even if the process liquid overflows from between the holder and the housing, it is possible to supply the process liquid to the circumference of the dresser, along the holder (specifically, along an upper surface inclined portion), and therefore, it is possible to uniformly supply the process liquid to the pad surface, compared to the conventional supply method. Furthermore, as the supply of the process liquid for dressing, it is possible to perform both the supply of the process liquid from the interior of the dresser through the holder and the supply of the process liquid to the circumference of the dresser by the overflow of the process liquid from between the holder and the housing, and it is possible to uniformly supply the process liquid in a wide range and in the vicinity of the dressing process surface. 
     A dressing device according to a 2nd aspect of this technique, the dressing device according to the 1st aspect, wherein the housing includes a projecting portion that forms the opening of the second flow passage and that projects downward, and a groove is formed on an upper surface side of the holder, the groove forming a part of the first flow passage and surrounding at least a part of a periphery of the projecting portion. 
     According to this configuration, between the downward projecting portion of the housing and the groove of the holder, a labyrinth structure with a downward convex shape and a concave shape is formed, and a non-contact seal is configured. Thereby, as long as the flow rate is regulated such that a pressure exceeding a pressure corresponding to the depth of the groove is not generated in the downward flow passage in the holder, it is possible to supply the process liquid without the overflow from the groove. Further, since the seal is not provided between the first flow passage and second flow passage through which the polishing liquid passes, the deterioration of the seal does not occur, and the maintenance frequency can be reduced. 
     A dressing device according to a 3rd aspect of this technique, the dressing device according to the 1st aspect, further comprising a switching unit that switches a communication point of the second flow passage of the housing between the supply source and the suction source. 
     According to this configuration, when the communication point is switched to the supply source, even for the debris that is difficult to remove, it is possible to float the debris from the polishing surface by injecting a high-pressure process liquid (for example, a chemical). Thereafter, when the communication point is switched to the suction source without moving the position of a dressing head including the disk, it is possible to suck and discharge the floated debris together with the process liquid. 
     A dressing device according to a 4th aspect of this technique, the dressing device according to the 3rd aspect, further comprising a control unit that controls the switching unit such that the second flow passage of the housing communicates with either the supply source or the suction source. 
     According to this configuration, it is possible to automatically switch the communication point of the flow passage of the housing, and therefore, it is possible to enhance the dressing efficiency. 
     A dressing device according to a 5th aspect of this technique, the dressing device according to the 1st aspect, wherein a chamber is provided on the second flow passage of the housing, the chamber being capable of temporarily storing the process liquid. 
     According to this configuration, it is possible to continuously supply the process liquid stored in the chamber, to the polishing surface. Further, it is possible to continuously discharge the process liquid stored in the chamber, to the exterior. 
     A dressing device according to a 6th aspect of this technique, the dressing device according to the 5th aspect, wherein a plurality of holes are formed on the housing, the plurality of holes communicating with the chamber, being formed on a lower surface side of the housing and being arranged substantially radially at intervals from each other, and a plurality of the second flow passages are provided, each of the plurality of the second flow passages being formed by one of the holes and the chamber. 
     According to this configuration, it is possible to uniformly drop the process liquid from the plurality of holes to the upper surface of the holder, and it is possible to uniformly supply the process liquid to a region on the inside of the disk. 
     A dressing device according to a 7th aspect of this technique, the dressing device according to the 5th aspect, wherein the chamber surrounds a rotation shaft for the holder, and has a substantially annular shape. 
     According to this configuration, it is possible to temporarily store the process liquid around the rotation shaft for the holder, and to supply the process liquid to the polishing surface more uniformly. 
     A dressing device according to an 8th aspect of this technique, the dressing device according to the second aspect, wherein a plurality of holes are formed on the holder, the plurality of holes being arranged substantially radially at intervals from each other, the groove communicates with the plurality of holes and has an annular shape, a plurality of the first flow passages are provided, each of the plurality of the first flow passages being formed by one of the holes and the groove, and a distance between an end of the projecting portion and a bottom of the groove is longer than a distance between a portion of a lower surface of the housing and the upper surface of the holder, the portion of the lower surface of the housing being a portion where the projecting portion is not provided. 
     According to this configuration, it is possible to avoid the process liquid from flowing out of the groove, by keeping the process liquid in the groove as much as possible. 
     A dressing device according to a 9th aspect of this technique, the dressing device according to the 1st aspect, wherein the first flow passage is inclined so as to be closer to a rotation shaft of the holder as it goes to the lower surface side. 
     According to this configuration, it is possible to smoothly supply the process liquid in the direction of the rotation shaft. 
     A dressing device according to a 10th aspect of this technique, the dressing device according to the 1st aspect, wherein a straightening plate is provided on the lower surface side of the holder, the straightening plate being provided with a plurality of holes and covering the opening of the first flow passage. 
     According to this configuration, when the process liquid is supplied to the polishing surface, the process liquid, after passing through the first flow passage, is supplied to the polishing surface through the straightening plate. Thereby, the process liquid dropped from the first flow passage drops from the plurality of holes formed on the straightening plate, so that the process liquid is supplied to the polishing surface more uniformly. Further, when the process liquid is sucked from the polishing surface, the process liquid, after passing through the straightening plate, is sucked through the first flow passage. Thereby, it is possible to constantly suck the process liquid on the polishing surface evenly in the circumferential direction, and it is possible to suck the process liquid from the polishing surface more uniformly. 
     A dressing device according to an 11th aspect of this technique, the dressing device according to the 1st aspect, further comprising a rotatable rotation shaft, wherein the holder is coupled to the rotation shaft in a detachable manner. 
     According to this configuration, the holder can be detached from the dressing device, and therefore, even if the polishing liquid sticks to the first flow passage in the holder, the polishing liquid can be easily removed. Therefore, the maintenance property for the removal of the polishing liquid is enhanced. 
     A dressing device according to a 12th aspect of this technique, the dressing device according to the 1st aspect, further comprising a turnable arm, wherein the housing is coupled to the arm in a detachable manner. 
     According to this configuration, the housing can be detached from the dressing device, and therefore, even if the polishing liquid sticks to the second flow passage in the housing, the polishing liquid can be easily removed. Therefore, the maintenance property for the removal of the polishing liquid is enhanced. 
     A polishing apparatus according to a 13th aspect of this technique, a polishing apparatus comprising the dressing device according to any one of aspects 1 to 12. 
     According to this configuration, in the polishing apparatus, it is possible to reduce the maintenance frequency, and to smoothly control the pressing force, and it is possible to enhance the ability of the removal of the polishing liquid and debris stuck near the center. 
     A holder according to a 14th aspect of this technique, a holder that is a component to be used together with a housing fixed in a dressing device, the holder comprising: a connect portion that connects with a disk, the connect portion being located on a lower surface side of the holder, wherein a flow passage that passes from the lower surface to an upper surface is provided in the holder, one end of the flow passage on the lower surface is located inside an outer edge of the opening of the disk when the disk is connected with the holder. 
     A housing according to a 15th aspect of this technique, a housing that is a component to be used together with a holder that is rotatable in a dressing device, wherein the housing is provided with a distance from an upper surface of the holder, the housing is provided with a second flow passage in an interior, the housing is fixed such that one end of the second flow passage faces the upper surface of the holder, and the second flow passage is connected with a supply source and a suction source of process liquid. 
     A dressing method according to a 16th aspect of this technique, a dressing method that is executed by a dressing device, the dressing device comprising: a disk that has an opening on an inside, the disk dressing a polishing surface for polishing a substrate; a rotatable holder, the disk being coupled to a lower surface side of the holder, the holder being provided with a first flow passage that passes from a lower surface to an upper surface, the lower surface being inside an outer edge of the opening of the disk; and a housing that is provided with a distance from the upper surface of the holder, the housing being provided with a second flow passage in an interior, the housing being fixed such that one end of the second flow passage faces the upper surface of the holder, the dressing method comprising: a first supplying pure water to the polishing surface, through the second flow passage and the first flow passage in order, during dressing; and a first sucking process liquid on the polishing surface, through the first flow passage and the second flow passage in order, during the dressing. 
     According to this configuration, it is possible to supply the process liquid during the dressing, and therefore, it is possible to perform the stable supply of the water quantity to a dressing process point. Therefore, it is possible to expect the enhancement of the dressing effect, and it is possible to contribute to the enhancement of the productivity. Further, since the process liquid is sucked during the dressing, it is possible to remove the debris on the polishing surface. It is possible to efficiently perform the conditioning of the polishing surface, to reduce the residue of scratch sauce, and to contribute to the enhancement of the productivity. 
     A dressing method according to a 17th aspect of this technique, the dressing method according to the 16th aspect, further comprising: a second supplying polishing liquid to the polishing surface, through the second flow passage and the first flow passage in order, during polishing by a polishing head; and a second sucking the process liquid on the polishing surface, through the first flow passage and the second flow passage in order, during supply of washing water by an atomizer. 
     According to this configuration, it is possible to supply the polishing liquid while performing a light dressing. Further, during the supply of the washing water by the atomizer, it is possible to suck the process liquid containing dressing dregs and/or polishing dregs, from the polishing surface, and discharge the process liquid. 
       FIG. 1  is a plan view showing the whole configuration of the polishing apparatus  100  according to the embodiment of the technique. As shown in  FIG. 1 , the polishing apparatus  100  includes a housing  1  having a substantially rectangular shape, and the interior of the housing  1  is sectioned into a loading/unloading unit  2 , a polishing unit  3  and a washing unit  4 , by partition walls  1   a ,  1   b . The loading/unloading unit  2 , the polishing unit  3  and the washing unit  4  are assembled independently of each other, and are vented independently of each other. The washing unit  4  is sectioned into a first washing chamber  190 , a first transport chamber  191 , a second washing chamber  192 , a second transport chamber  193  and a drying chamber  194 . Further, the polishing apparatus  100  includes a control unit  5  that controls a substrate processing operation. 
     The loading/unloading unit  2  includes two or more (four in the embodiment) front loading units  20  in each of which a wafer cassette to stock many wafers (substrates) is placed. The front loading units  20  are arranged so as to be adjacent to the housing  1 , and are arrayed along the width direction (the direction perpendicular to the longitudinal direction) of the polishing apparatus  100 . The front loading unit  20  allows the mounting of an open cassette, a SMIF (Standard Manufacturing Interface) pod or a FOUP (Front Opening Unified Pod). Here, each of the SMIF and the FOUP is a closed container that contains a wafer cassette in the interior and that can keep an environment independent of the external space by the covering with a partition wall. 
     Further, in the loading/unloading unit  2 , a travelling mechanism  21  is laid along the array of the front loading units  20 , and a transport robot (loader)  22  that can move along the direction of the array of the wafer cassettes is disposed on the travelling mechanism  21 . The transport robot  22  moves on the travelling mechanism  21 , and thereby, can access the wafer cassette mounted on the front loading unit  20 . The transport robot  22  includes two hands that are vertically arranged. The upper and lower hands are used for different purposes such that the upper hand is used when a wafer after processing is returned to the wafer cassette and the lower hand is used when a wafer before processing is taken from the wafer cassette. Furthermore, the lower hand of the transport robot  22  is configured to be capable of reversing the wafer by rotating around the shaft center. 
     The loading/unloading unit  2  is a region that requires keeping the cleanest state, and therefore, the interior of the loading/unloading unit  2  is constantly maintained at a higher pressure than all of the exterior of the polishing apparatus  100 , the polishing unit  3  and the washing unit  4 . The polishing unit  3  is the dirtiest region because slurry is used as the polishing liquid. Therefore, in the interior of the polishing unit  3 , a negative pressure is applied, and the pressure is maintained at a lower pressure than the inner pressure of the washing unit  4 . The loading/unloading unit  2  is provided with a filter fan unit (not illustrated) including a clean air filter such as a HEPA filter, a ULPA filter or a chemical filter. The filter fan unit constantly jets out clean air in which particles, toxic vapor and toxic gas are removed. 
     The polishing unit  3  is a region where the polishing (flattening) of a wafer is performed, and includes a first polishing unit  3 A, a second polishing unit  3 B, a third polishing unit  3 C and a fourth polishing unit  3 D. As shown in  FIG. 1 , the first polishing unit  3 A, the second polishing unit  3 B, the third polishing unit  3 C and the fourth polishing unit  3 D are arrayed along the longitudinal direction of the polishing apparatus  100 . 
     As shown in  FIG. 1 , the first polishing unit  3 A includes a table  30 A to which a polishing pad  10  having a polishing surface is attached, a top ring (polishing head)  31 A for holding the wafer and polishing the wafer while pressing the wafer to the polishing pad  10  on the table  30 A, a polishing liquid supply nozzle (polishing liquid supply unit)  32 A for supplying polishing liquid or dressing liquid (for example, pure water) to the polishing pad  10 , a dresser  33 A for dressing the polishing surface of the polishing pad  10 , and an atomizer  34 A for injecting a fluid to the polishing surface and sucking the fluid on the polishing surface. For example, the fluid is a gas (for example, nitrogen gas), a fluid mixture of a liquid (for example, pure water) and a gas (for example, nitrogen gas), or a liquid (for example, pure water). The fluid may be a misty fluid. 
     Similarly, the second polishing unit  3 B includes a table  30 B to which the polishing pad  10  is attached, a top ring (polishing head)  31 B, a polishing liquid supply nozzle  32 B, a dresser  33 B, and an atomizer  34 B. The third polishing unit  3 C includes a table  30 C to which the polishing pad  10  is attached, a top ring (polishing head)  31 C, a polishing liquid supply nozzle  32 C, a dresser  33 C, and an atomizer  34 C. The fourth polishing unit  3 D includes a table  30 D to which the polishing pad  10  is attached, a top ring (polishing head)  31 D, a polishing liquid supply nozzle  32 D, a dresser  33 D, and an atomizer  34 D. 
     The atomizers  34 A,  34 B,  34 C,  34 D are nozzles that inject a high-pressure washing water, and inject the high-pressure washing water to the polishing pad surface, after the polishing or at the time of water polishing in an end phase of the polishing. 
     Next, a transport mechanism for transporting the wafer will be described. As shown in  FIG. 1 , a first linear transporter  6  is arranged so as to be adjacent to the first polishing unit  3 A and the second polishing unit  3 B. The first linear transporter  6  is a mechanism that transports the wafer among four transport positions along a direction in which the first polishing unit  3 A and the second polishing unit  3 B are arrayed (the order of a first transport position TP 1 , a second transport position TP 2 , a third transport position TP 3  and a fourth transport position TP 4  from the loading/unloading unit side). 
     Further, a second linear transporter  7  is arranged so as to be adjacent to the third polishing unit  3 C and the fourth polishing unit  3 D. The second linear transporter  7  is a mechanism that transports the wafer among three transport positions along a direction in which the third polishing unit  3 C and the fourth polishing unit  3 D are arrayed (the order of a fifth transport position TP 5 , a sixth transport position TP 6  and a seventh transport position TP 7  from the loading/unloading unit side). 
     By the first linear transporter  6 , the wafer is transported to the first polishing unit  3 A and the second polishing unit  3 B. As described above, the top ring  31 A of the first polishing unit  3 A is moved between the polishing position and the second transport position TP 2  by the swing action of a top ring head (not illustrated). Therefore, the transfer of the wafer to the top ring  31 A is performed at the second transport position TP 2 . Similarly, the top ring  31 B of the second polishing unit  3 B is moved between the polishing position and the third transport position TP 3 , and the transfer of the wafer to the top ring  31 B is performed at the third transport position TP 3 . The top ring  31 C of the third polishing unit  3 C is moved between the polishing position and the sixth transport position TP 6 , and the transfer of the wafer to the top ring  31 C is performed at the sixth transport position TP 6 . The top ring  31 D of the fourth polishing unit  3 D is moved between the polishing position and the seventh transport position TP 7 , and the transfer of the wafer to the top ring  31 D is performed at the seventh transport position TP 7 . 
     At the first transport position TP 1 , a lifter  11  for receiving the wafer from the transport robot  22  is arranged. The wafer is transferred from the transport robot  22  to the first linear transporter  6  through the lifter  11 . Between the lifter  11  and the transport robot  22 , a shutter (not illustrated) is provided on the partition wall  1   a . At the time of the transport of the wafer, the shutter is opened, and the wafer is transferred from the transport robot  22  to the lifter  11 . Further, a swing transporter  12  is arranged among the first linear transporter  6 , the second linear transporter  7  and the washing unit  4 . The swing transporter  12  includes a hand that can move between the fourth transport position TP 4  and the fifth transport position TP 5 , and the transfer of the wafer from the first linear transporter  6  to the second linear transporter  7  is performed by the swing transporter  12 . By the second linear transporter  7 , the wafer is transported to the third polishing unit  3 C and/or the fourth polishing unit  3 D. Further, a temporary placement table  180  for the wafer W that is disposed in an unillustrated frame is arranged on a lateral side of the swing transporter  12 . As shown in  FIG. 1 , the temporary placement table  180  is arranged so as to be adjacent to the first linear transporter  6 , and is positioned between the first linear transporter  6  and the washing unit  4 . The wafer W polished in the polishing unit  3  is placed on the temporary placement table  180  through the swing transporter  12 , and thereafter, the wafer W is transported to the washing unit  4  by the transport robot of the washing unit  4 . 
     The dressers  33 A,  33 B,  33 C,  33 D have the same configuration as each other. Hereinafter, the dressers  33 A,  33 B,  33 C,  33 D are collectively referred to as a dresser  33 . In the following, a dressing device included in the polishing apparatus  100  will be described. 
       FIG. 2  is a configuration diagram showing the outline of the dressing device according to the embodiment. As shown in  FIG. 2 , a dressing device  40  according to the embodiment includes the dresser  33 , a supply source  41 , a suction source  42 , a switching unit  43 , and the control unit  5 . 
     The dresser  33  includes a housing  54  that is fixed, a rotatable holder  55 , and a disk  56  that is coupled to the lower surface side of the holder. 
     The supply source  41  is a supply source of a process liquid. Examples of the process liquid include pure water (DIW), washing liquid and/or slurry. 
     The suction source  42  is a suction source of the process liquid. Examples of the suction source  42  include a vacuum pump, an ejector, an accumulator and a cyclone steam-water separation device. 
     The switching unit  43  switches the communication point of the flow passage of the housing  54  between the supply source  41  and the suction source  42 . Thereby, when the communication point is switched to the supply source  41 , even for the debris that is difficult to remove, it is possible to float the debris from the polishing surface by injecting a high-pressure process liquid (for example, a chemical). Thereafter, when the communication point is switched to the suction source  42  without moving the position of a dressing head including the disk, it is possible to suck and discharge the floated debris together with the process liquid. In the embodiment, as an example, the switching unit  43  includes a first valve  431  and a second valve  432  as shown in  FIG. 2 . 
     The control unit  5  controls the switching unit  43  such that the flow passage of the housing  54  communicates with either the supply source  41  or the suction source  42 . Thereby, it is possible to automatically switch the communication point of the flow passage of the housing  54 , and therefore, it is possible to enhance the dressing efficiency. For example, when the process liquid is supplied to the polishing surface, the control unit  5  controls the switching unit  43  such that the first valve  431  is opened and the second valve  432  is closed. On the other hand, for example, when the process liquid on the polishing surface is sucked, the control unit  5  controls the switching unit  43  such that the first valve  431  is closed and the second valve  432  is opened. 
     Subsequently, the structure of the dresser will be described with use of  FIG. 3  to  FIG. 15 .  FIG. 3  is a perspective view showing the outline of the dresser  33 . As shown in  FIG. 3 , the dresser  33  includes a support shaft  51 , an arm  52  that is coupled on the support shaft  51  and that is capable of turning substantially horizontally, and a head  53  that is coupled on the arm  52 . Further, the dresser  33  includes the housing  54  that is coupled to the arm  52 , the holder  55  that faces the housing  54  at an interval, and the disk  56  that is coupled to the lower surface of the holder  55 . 
       FIG. 4  is a schematic diagram of an A-A cross-section in  FIG. 3 . The dresser  33  further includes a rotatable rotation shaft  57 . In U.S. Pat. No. 6,508,697, the polishing liquid sticks to the rotation shaft for the dresser, but there is a problem in that the maintenance for the removal is difficult. On the other hand, the holder  55  according to the embodiment is coupled to the rotation shaft  57  in a detachable manner, and rotates together with the rotation shaft  57 , as shown in  FIG. 4 . Thereby, the holder  55  can be detached from the dressing device  40 , and therefore, even if the polishing liquid sticks to the later-described first flow passage in the holder  55 , the polishing liquid can be easily removed. Therefore, the maintenance property for the removal of the polishing liquid is enhanced. 
     Further, as shown in  FIG. 4 , the housing  54  according the embodiment is fixed by being coupled to the arm  52  in a detachable manner, and therefore, does not rotate even if the holder  55  rotates. Thereby, the housing  54  can be detached from the dressing device  40 , and therefore, even if the polishing liquid sticks to the later-described second flow passage in the housing  54 , the polishing liquid can be easily removed. Therefore, the maintenance property for the removal of the polishing liquid is enhanced. The disk  56  has an opening on the inside, and sets the polishing surface for polishing the wafer W. As shown in  FIG. 4 , the disk  56  according to the embodiment has an annular shape, as an example. 
     The rotation shaft  57  is coupled to a rotation and elevation mechanism unit  58  that includes an unillustrated cylinder. The rotation and elevation mechanism unit  58  rotates and elevates the rotation shaft  57 . Thereby, the cylinder of the rotation and elevation mechanism unit  58  can weight the rotation shaft  57  downward along the long axis of the rotation shaft  57 . Thereby, the load acting axis coincides with the rotation shaft  57 , and therefore, it is possible to smoothly press the disk  56  onto the polishing surface. 
       FIG. 5  is a perspective view of a portion of the dresser  33 . As shown in  FIG. 5 , the housing  54  includes a supply port  541  that is connected with the supply source  41  through the first valve  431 , and a discharge port  542  that is connected with the suction source  42  through the second valve  432 . Further, in the interior of the housing  54 , a chamber CB that communicates with the supply port  541  and the discharge port  542  is provided. Thereby, the process liquid flows into the chamber CB through the supply port  541 . The process liquid is discharged from the chamber CB through the discharge port  542 . 
       FIG. 6  is a perspective view of the housing  54  as viewed from the upper side.  FIG. 7  is a perspective view of the housing  54  as viewed from the back side.  FIG. 8  is a cross-sectional view of a BB cross-section in  FIG. 5 . As shown in  FIG. 5  and  FIG. 6 , the chamber CB surrounds the rotation shaft  57  for the holder  55 , and has a substantially annular shape. Thereby, the chamber CB can temporarily store the process liquid around the rotation shaft  57  for the holder  55 , and can supply the process liquid to the polishing surface more uniformly. 
     As shown in  FIG. 6  to  FIG. 8 , the housing  54  is provided with a plurality of holes L 1  to L 18  that communicate with the chamber CB, that are formed on the lower surface side of the housing  54  and that are arranged substantially radially at intervals from each other. Thereby, the process liquid supplied to the chamber CB drops to the upper surface of the holder  55  through the plurality of holes L 1  to L 18 . Thereby, it is possible to uniformly drop the process liquid from the plurality of holes L 1  to L 18  to the upper surface of the holder  55 , and to supply the process liquid to the region on the inside of the disk  56 . The process liquid sucked through the plurality of holes L 1  to L 18  is discharged from the discharge port  542  through the chamber CB. 
       FIG. 9  is a perspective view of the holder  55 .  FIG. 10  is a plan view of the holder  55  as viewed from the upper side. As shown in  FIG. 9  and  FIG. 10 , on the holder  55 , holes  121  to  124  are radially formed. Furthermore, on the outer side of the holder  55 , a plurality of holes H 1  to H 16  that are arranged substantially radially at intervals from each other are formed. Further, as shown in  FIG. 9 , an annular groove DP that communicates with the plurality of holes H 1  to H 16  is formed on the upper surface side of the holder. 
     In this way, the holder  55  is rotatable, the disk  56  is coupled to the lower surface side of the holder  55 , and a plurality of first flow passages each of which passes, to the upper surface, from the lower surface inside the outer edge of the opening of the disk  56  are formed. In the embodiment, as an example, each first flow passage is formed by one of the holes H 1  to H 16  and the groove DP, and in total, 16 first flow passages are formed. 
       FIG. 11  is a plan view of the holder  55  as viewed from the lower side. As shown in  FIG. 11 , the annular disk  56  is fixed to the lower surface of the holder  55 . As shown in  FIG. 11 , a straightening plate  130  is fixed to the lower surface side of the holder  55 , by screws  131  to  134 . Each of the screws  131  to  134  is fixed to the corresponding one of the hole  121  to  124  (see  FIG. 10 ), so that the straightening plate  130  is fixed. On the straightening plate  130 , a plurality of holes are formed substantially evenly. 
       FIG. 12  is a plan view when the straightening plate  130  is removed in  FIG. 11 . As shown in  FIG. 12 , one end of each of the holes H 1  to H 16 , which is a part of the first flow passage, is exposed on the inside of the disk  56 . 
     In this way, the straightening plate  130  that is provided with the plurality of holes and that covers the opening of the first flow passage is provided on the lower surface side of the holder  55 . Thereby, when the process liquid is supplied to the polishing surface, the process liquid, after passing through the first flow passage, is supplied to the polishing surface through the straightening plate  130 . Thereby, the process liquid dropped from the first flow passage drops from the plurality of holes formed on the straightening plate  130 , so that the process liquid is supplied to the polishing surface more uniformly. Further, when the process liquid is sucked from the polishing surface, the process liquid, after passing through the straightening plate  130 , is sucked through the first flow passage. Thereby, it is possible to constantly suck the process liquid on the polishing surface evenly in the circumferential direction, and it is possible to suck the process liquid from the polishing surface more uniformly. 
       FIG. 13  is a cross-sectional view of a CC cross-section in  FIG. 5 . As shown in  FIG. 13 , the holder  55  is rotatable around the rotation shaft  57 , the disk  56  is coupled to the lower surface side of the holder  55 , and the first flow passage that passes, to the upper surface, from the lower surface inside the outer edge of the opening of the disk  56  is provided. 
     As shown in  FIG. 13 , the first flow passage is inclined o as to be closer to the rotation shaft  57  of the holder  55  as it goes to the lower surface side. Thereby, it is possible to smoothly supply the process liquid in the direction of the rotation shaft  57 . 
     As shown in  FIG. 13 , the housing  54  is provided with a distance from the upper surface of the holder  55 . The second flow passage is provided in the interior of the housing  54 , and the housing  54  is fixed such that the opening of the second flow passage faces the upper surface of the holder  55 . The second flow passage is connected with the supply source  41  and the suction source  42  of the process liquid. 
     In the housing  54 , the chamber CB capable of temporarily storing the process liquid is provided on the second flow passage. In this way, in the embodiment, as an example, the second flow passage is formed by one of the holes L 1  to L 16  and the chamber CB, and in total, 16 second flow passages are formed. Thereby, it is possible to continuously supply the process liquid stored in the chamber CB, to the polishing surface. Further, it is possible to continuously discharge the process liquid stored in the chamber CB, to the exterior. 
     During the operation of the dresser  33 , the rotation shaft  57  rotates at a predetermined rotation speed, so that the holder  55  rotates. Therefore, at certain timings, the hole L 14  of the second flow passage faces the hole H 13  of the first flow passage as shown in the cross-sectional view of  FIG. 13 , but at many other timings, the hole L 14  of the second flow passage does not face the hole H 13  of the first flow passage. Therefore, when the process liquid is supplied to the polishing surface, at many timings, the process liquid dropped through the second flow passage is once received by the groove DP. Then, the process liquid moves horizontally along the groove DP, and drops from one of the holes H 1  to H 16 . 
       FIG. 14  is an enlarged view of a region R in  FIG. 13 .  FIG. 15  is a cross-sectional view of a DD cross-section in  FIG. 13 . In U.S. Pat. No. 6,508,697, since the seal between the hole provided on the cover and the rotation shaft of the dresser deteriorates due to the polishing liquid, there is a problem in that the maintenance frequency increases. On the other hand, in the embodiment, the housing  54  includes a projecting portion  543  that forms the opening of the second flow passage and that projects downward, as shown in  FIG. 14 . The groove DP that forms a part of the first flow passage and that surrounds at least a part of the periphery of the projecting portion  543  is formed on the upper surface side of the holder  55 . 
     According to this configuration, between the downward projecting portion  543  of the housing  54  and the groove of the holder  55 , a labyrinth structure with a downward convex shape and a concave shape is formed, and a non-contact seal is configured. Thereby, as long as the flow rate is regulated such that a pressure exceeding a pressure corresponding to the depth of the groove DP is not generated in the downward flow passage in the holder, it is possible to supply the process liquid without the overflow from the groove DP. Further, since a contact seal is not provided between the first flow passage and second flow passage through which the polishing liquid passes, the deterioration of the contact seal does not occur, and the maintenance frequency can be reduced. 
     Even if the process liquid overflows from between the holder  55  and the housing  54 , it is possible to supply the process liquid to the circumference of the dresser  33 , along the upper surface inclined portion of the holder  55 , and therefore, it is possible to uniformly supply the process liquid to the pad surface, compared to the conventional supply method. Furthermore, as the supply of the process liquid for dressing, it is possible to perform both the supply of the process liquid from the interior of the dresser  33  through the holder  55  and the supply of the process liquid to the circumference of the dresser  33  by the overflow of the process liquid from between the holder  55  and the housing  54 , and it is possible to uniformly supply the process liquid in a wide range and in the vicinity of the dressing process surface. 
     Specifically, as shown in  FIG. 15 , the groove DP is provided in an annular shape, and the projecting portion  543  is also provided in an annular shape. The projecting portion  543  penetrates into the groove DP, and the groove DP and the projecting portion  543  face each other at an interval. Thereby, it is possible to surely drop the process liquid into the groove DP, and it is possible to avoid the process liquid from flowing to the exterior (in the direction of an arrow A 1 ). 
     A distance d 1  between the end of the projecting portion  543  and the bottom of the groove DP is longer than a distance d 2  between a portion of the lower surface of the housing  54  where the projecting portion  543  is not provided and the upper surface of the holder  55 . Thereby, it is possible to avoid the process liquid from flowing out of the groove DP (in the direction of the arrow A 1 ), by keeping the process liquid in the groove DP as much as possible. 
       FIG. 16  is a flowchart showing an exemplary process method according to the embodiment. 
     (Step S 101 ) First, in a polishing step, during the polishing by the polishing head  31 A,  31 B,  31 C or  31 D, the polishing liquid is supplied from the dresser  33 A,  33 B,  33 C or  33 D to the polishing surface. Thereby, it is possible to supply the polishing liquid while performing a light dressing. 
     (Step S 102 ) Next, in a water polishing step, during the supply of the washing water by the atomizer  34 A,  34 B,  34 C or  34 D, the dressers  33 A,  33 B,  33 C or  33 D sucks the process liquid containing dressing dregs and/or polishing dregs, from the polishing surface, and discharges the process liquid, while the dresser  33 A,  33 B,  33 C or  33 D scans the polishing surface. 
     (Step S 103 ) Next, in a dressing step (pad conditioning step), during the dressing, the dresser  33 A,  33 B,  33 C or  33 D supplies the pure water (DIW) to the polishing surface, while the dresser  33 A,  33 B,  33 C or  33 D scans the polishing surface. 
     Here, during the dressing, in some cases, the washing water is supplied by the atomizer  34 A,  34 B,  34 C or  34 D. In that case, the dresser  33 A,  33 B,  33 C or  33 D may suck the process liquid containing dressing dregs and/or polishing dregs, from the polishing surface, and may discharge the process liquid. 
     (Step S 104 ) Next, in the final step of the dressing step (pad conditioning step), during the dressing, the dresser  33 A,  33 B,  33 C or  33 D sucks the process liquid on the polishing surface and discharges the process liquid, while the dresser  33 A,  33 B,  33 C or  33 D scans the polishing surface. Thereby, the water on the polishing surface is removed, and therefore, it is possible to shorten the time for the replacement of the water on the polishing surface with the polishing liquid. Further, since the water on the polishing surface is removed, it is possible to prevent the polishing liquid from being unnecessarily diluted. Thereby, it is possible to reduce the supply quantity of the polishing liquid and shorten the time for the supply of the polishing liquid in the next polishing preparation step, and it is possible to contribute to the enhancement of the productivity. 
     (Step S 105 ) Next, in the polishing preparation step (a preload step for the polishing liquid), the polishing liquid is supplied from the polishing liquid supply nozzle  32 A,  32 B,  32 C or  32 D to the polishing surface. Here, the polishing liquid may be supplied from the dresser  33 A,  33 B,  33 C or  33 D to the polishing surface. After the process of step S 105 , the process flow returns to the process of step S 101 , and the processes of steps S 101  to S 105  are repeated. 
     Thus, the dressing device  40  according to the embodiment includes the disk  56  that includes the opening on the inside and that sets the polishing surface for polishing the substrate. Further, the dressing device  40  includes the rotatable holder  55 , that has the disk  56  coupled to the lower surface side, and that is provided with the first flow passage passing from the lower surface inside the outer edge of the opening of the disk  56  to the upper surface. Further, the dressing device  40  includes the housing  54  that is provided with a distance from the upper surface of the holder  55 , that is provided with the second flow passage in the interior, that is fixed such that the opening of the second flow passage faces the upper surface of the holder  55 , and that has the second flow passage connected with the supply source  41  and the suction source  42  of the process liquid. The process liquid is supplied from the supply source  41  to the polishing surface, through the second flow passage and the first flow passage in order, and the process liquid on the polishing surface is sucked by the suction source  42 , through the first flow passage and the second flow passage in order. 
     According to this configuration, the holder  55  can be detached from the dressing device  40 , and therefore, even if the polishing liquid sticks to the first flow passage in the holder  55 , the polishing liquid can be easily removed. Further, the housing  54  can be detached from the dressing device  40 , and therefore, even if the polishing liquid sticks to the second flow passage in the housing  54 , the polishing liquid can be easily removed. Therefore, the maintenance property for the removal of the polishing liquid is enhanced. Further, since the seal is not provided between the first flow passage and second flow passage through which the polishing liquid passes, the deterioration of the seal does not occur, and the maintenance frequency can be reduced. Further, pipes (for example, hoses) to be connected with the supply source  41  and the suction source  42  are connected with the fixed housing, and therefore, it is not necessary to dispose a rotary joint on the rotation shaft for the holder  55 . Accordingly, it is possible to dispose the cylinder, which is a member for generating the pressing force on the rotation shaft for the holder  55 , and therefore, it is possible to smoothly control the pressing force. Furthermore, the inside of the outer edge of the opening of the disk  56  tends to have a negative pressure due to the suction by the suction source  42 , and a pressing force by which the surface of the disk  56  follows the polishing surface is generated. Therefore, it is possible to expect the enhancement of the dressing efficiency. Further, it is possible to perform the suction from the inside of the outer edge of the opening of the disk  56 , and therefore, it is possible to enhance the efficiency of the removal of the polishing liquid and debris stuck near the center. 
     The dressing method according to the embodiment includes the step of supplying the pure water to the polishing surface, through the second flow passage and the first flow passage in order, during the dressing, as shown in step S 103  of  FIG. 16 , and the step of sucking the process liquid on the polishing surface, through the first flow passage and the second flow passage in order, during the dressing. 
     Thereby, it is possible to supply the process liquid during the dressing, and therefore, it is possible to perform the stable supply of the water quantity to the dressing process point. Therefore, it is possible to expect the enhancement of the dressing effect, and it is possible to contribute to the enhancement of the productivity. Further, since the process liquid is sucked during the dressing, it is possible to remove the debris on the polishing pad  10 . It is possible to efficiently perform the conditioning of the surface of the polishing pad  10 , to reduce the residue of scratch sauce, and to contribute to the enhancement of the productivity. 
     The dressing method according to the embodiment includes the step of supplying the polishing liquid to the polishing surface, through the second flow passage and the first flow passage in order, during the polishing by the polishing head, as shown in step S 101  of  FIG. 16 . Furthermore, the dressing method according to the embodiment includes the step of sucking the process liquid on the polishing surface, through the first flow passage and the second flow passage in order, during the supply of the washing water by the atomizer, as shown in step S 102  of  FIG. 16 . 
     Thereby, it is possible to supply the polishing liquid while performing a light dressing. Further, during the supply of the washing water by the atomizer, it is possible to suck the process liquid containing dressing dregs and/or polishing dregs, from the polishing surface, and discharge the process liquid. 
     Here, the housing  54  according to the embodiment includes the two ports of the supply port  541  and the discharge port  542 , but without being limited to this, may include a single united port that functions as both the supply port  541  and the discharge port  542 . In that case, the dressing device  40  according to the embodiment may be configured as shown in  FIG. 17 . 
       FIG. 17  is a configuration diagram showing the outline of a dressing device according to a modification of the embodiment. As shown in  FIG. 17 , compared to the dressing device  40  according to the embodiment, in a dressing device  40   b  according to the modification, the switching unit  43  is changed into a switching unit  43   b . The switching unit  43   b  includes a three-way valve  433  that is connected with the supply source  41 , the suction source  42  and the above united port of the housing  54  of the dresser  33 . The control unit  5  controls the three-way valve  433  such that the second flow passage of the housing  54  communicates with either the supply source  41  or the suction source  42 . 
     Thus, the technique is not limited to the above embodiment itself, and can be realized by modifying constituent elements in the implementation phase, in a range without departing from the spirit. Further, various techniques can be formed by appropriate combinations of the plurality of constituent elements disclosed in the above embodiment. For example, some constituent elements of all constituent elements shown in the embodiment may be excluded. Furthermore, among different embodiments, constituent elements may be appropriately combined.