Patent Publication Number: US-11638980-B2

Title: Laminated membrane, substrate holder including laminated membrane, and substrate processing apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2019-70612, filed on Apr. 2, 2019, the entire content of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to a laminated membrane, a substrate holder including the laminated membrane, and a substrate processing apparatus. 
     BACKGROUND ART 
     For manufacturing a semiconductor device, a chemical mechanical polishing (CMP) apparatus is used for flattening a surface of a substrate. The substrate used in manufacturing the semiconductor device is often in a circular plate shape. Not limited to the semiconductor device, there is an increasing request for a flatness when a surface of a square-shaped substrate, such as a Copper Clad Laminate substrate (CCL substrate), a Printed Circuit Board (PCB) substrate, a photomask substrate, and a display panel, is flattened. There is also an increasing request for flattening a surface of a package substrate on which an electronic device, such as a PCB substrate, is disposed. 
     CITATION LIST 
     Patent Literature 
     PTL 1: Japanese Unexamined Patent Application Publication No. 2018-183820 
     PTL 2: Japanese Unexamined Patent Application Publication No. 2009-131946 
     SUMMARY OF INVENTION 
     Technical Problem 
     In the CMP apparatus, a substrate as a polishing object is held by a top ring, and while the substrate is pressed onto a polishing pad disposed on a polishing table, the substrate and the polishing pad are relatively moved (for example, rotated), and thus, the substrate is polished. In order to uniformly polish the substrate, contact pressures onto the polishing pad are sometimes controlled for each region of the substrate. for example, the contact pressures onto the polishing pad can be controlled for each region of the substrate by disposing an elastic member including a plurality of pressure chambers on a substrate holding surface of the top ring and controlling pressures of the respective pressure chambers (for example, PTL 1 and 2) 
     Such an elastic member is required to be formed so as to include the plurality of pressure chambers, thereby having a complicated shape in many cases. The elastic member having a complicated shape can be manufactured by a mold having a corresponding shape. However, a fabrication of a mold having a complicated shape costs money and time. The substrate polished by the CMP apparatus as described above has atypical variously-sized square-shaped substrates, not only a standardized fixed-sized semiconductor substrate as conventional. Designing elastic members so as to correspond to variously-sized substrates and fabricating molds so as to correspond to the respective designs greatly increase a cost and a time load. Therefore, manufacturing an elastic member including a plurality of pressure chambers without using a mold having a complicated shape provides a benefit. 
     Solution to Problem 
     According to one embodiment, a laminated membrane used in a substrate holder of a substrate processing apparatus is provided. Such a laminated membrane includes a first sheet material, and a second sheet material disposed on the first sheet material. A part of the first sheet material is secured to a part of the second sheet material. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a plan view illustrating an overall configuration of a substrate processing apparatus according to one embodiment; 
         FIG.  2    is a side view schematically illustrating a loading unit according to one embodiment; 
         FIG.  3    is a side view schematically illustrating a conveyance unit according to one embodiment; 
         FIG.  4    is a perspective view schematically illustrating a configuration of a polishing unit according to one embodiment; 
         FIG.  5    is a schematic cross-sectional view of a top ring that presses a substrate onto a polishing surface on a polishing pad by holding a substrate as a polishing object according to one embodiment; 
         FIG.  6    is a drawing viewing the top ring from a side of a polishing table according to one embodiment; 
         FIG.  7    is a perspective view schematically illustrating bonded regions of three sheet materials of a laminated membrane according to one embodiment; 
         FIG.  8    is a drawing for describing a method for manufacturing the laminated membrane according to one embodiment; 
         FIG.  9    is a flowchart illustrating a method for manufacturing the laminated membrane according to one embodiment; 
         FIG.  10    is a drawing for describing a method for manufacturing the laminated membrane according to one embodiment; 
         FIG.  11    is a flowchart illustrating a method for manufacturing the laminated membrane according to one embodiment; 
         FIG.  12    is a drawing for describing a method for manufacturing the laminated membrane according to one embodiment; 
         FIG.  13    is a flowchart illustrating a method for manufacturing the laminated membrane according to one embodiment; 
         FIG.  14    is a cross-sectional view illustrating a part of the top ring including the laminated membrane according to one embodiment; 
         FIG.  15 A  is a cross-sectional view schematically illustrating bonded regions of the laminated membrane according to one embodiment; 
         FIG.  15 B  is a cross-sectional view schematically illustrating bonded regions of the laminated membrane according to one embodiment; 
         FIG.  15 C  is a cross-sectional view schematically illustrating bonded regions of the laminated membrane according to one embodiment; 
         FIG.  15 D  is a cross-sectional view schematically illustrating bonded regions of the laminated membrane according to one embodiment; 
         FIG.  16 A  is a cross-sectional view schematically illustrating bonded regions of the laminated membrane according to one embodiment; and 
         FIG.  16 B  is a cross-sectional view schematically illustrating bonded regions of the laminated membrane according to one embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The following describes a laminated membrane, a method for manufacturing the laminated membrane, and a substrate processing apparatus including the laminated membrane according to the present invention with the attached drawings. In the attached drawings, identical or similar reference numerals are attached to identical or similar components, and overlapping description regarding the identical or similar components may be omitted in the description of the respective embodiments. Features illustrated in the respective embodiments are applicable to other embodiments in so far as they are consistent with one another. Note that, in the description, a “substrate” includes a magnetic recording medium, a magnetic recording sensor, a mirror, an optical element, a micro mechanical element, or a partially fabricated integrated circuit, not only a semiconductor substrate, a glass substrate, or a printed circuit board. 
       FIG.  1    is a plan view illustrating an overall configuration of a substrate processing apparatus  1000  according to one embodiment. The substrate processing apparatus  1000  illustrated in  FIG.  1    includes a loading unit  100 , a conveyance unit  200 , a polishing unit  300 , a drying unit  500 , and an unloading unit  600 . In the illustrated embodiment, the conveyance unit  200  includes two conveyance units  200 A and  200 B, and the polishing unit  300  includes two polishing units  300 A and  300 B. In one embodiment, these units can be each independently formed. Independently forming these units ensures easily forming the substrate processing apparatus  1000  in a different configuration by conveniently combining the number of respective units. The substrate processing apparatus  1000  includes a controller  900 , and each configuration member of the substrate processing apparatus  1000  is controlled by the controller  900 . In one embodiment, the controller  900  can be configured of a general computer that includes, for example, an input/output device, an arithmetic device, and a storage device. 
     &lt;Loading Unit&gt; 
     The loading unit  100  is a unit for introducing a substrate WF before processes, such as polishing and cleaning, are performed into the substrate processing apparatus  1000 .  FIG.  2    is a side view schematically illustrating the loading unit  100  according to one embodiment. In one embodiment, the loading unit  100  includes a housing  102 . The housing  102  has an inlet opening  104  on a side from which the substrate WF is received. In the embodiment illustrated in  FIG.  2   , the right side is the inlet side. The loading unit  100  receives the substrate WF as a process target from the inlet opening  104 . The loading unit  100  has an upper stream (the right side in  FIG.  2   ) where a processing apparatus is arranged. The processing apparatus is where treatment processes before the process of the substrate WF by the substrate processing apparatus  1000  according to the disclosure is performed. In the embodiment illustrated in  FIG.  2   , the loading unit  100  includes an ID reader  106 . The ID reader  106  reads an ID of the substrate received from the inlet opening  104 . The substrate processing apparatus  1000  performs various processes on the substrate WF corresponding to the read ID. In one embodiment, the ID reader  106  is not necessarily disposed. In one embodiment, the loading unit  100  is configured so as to be compliant to a mechanical equipment interface standard (IPC-SMEMA-9851) of Surface Mount Equipment Manufacturers Association (SMEMA). 
     In the embodiment illustrated in  FIG.  2   , the loading unit  100  includes a plurality of conveyance rollers  202  for conveying the substrate WF. Rotating the conveyance rollers  202  with a configuration similar to a rotation mechanism in the conveyance unit described below ensures conveying the substrate WF on the conveyance rollers  202  in a predetermined direction (the left direction in  FIG.  2   ). In the illustrated drawing, the housing  102  of the loading unit  100  has an outlet opening  108  of the substrate WF. The loading unit  100  includes a sensor  112  for sensing a presence/absence of the substrate WF at a predetermined position on the conveyance rollers  202 . The sensor  112  can be a sensor of any format, for example, can be an optical sensor. In the embodiment illustrated in  FIG.  2   , three sensors  112  are disposed in the housing  102 . One is a sensor  112   a  disposed in the proximity of the inlet opening  104 , one is a sensor  112   b  disposed in the proximity of a center of the loading unit  100 , and the other one is a sensor  112   c  disposed in the proximity of the outlet opening  108 . In one embodiment, corresponding to the detection of the substrate WF by these sensors  112 , an operation of the loading unit  100  can be controlled. For example, when the sensor  112   a  near the inlet opening  104  detects the presence of the substrate WF, the conveyance roller  202  inside the loading unit  100  may start to rotate, or a rotation speed of the conveyance roller  202  may be changed. When the sensor  112   c  near the outlet opening  108  detects the presence of the substrate WF, an inlet shutter  218  of the conveyance unit  200 A, which is a subsequent unit, may open. 
     In the illustrated embodiment, a conveying mechanism of the loading unit  100  includes the plurality of conveyance rollers  202  and a plurality of roller shafts  204  on which the conveyance rollers  202  are mounted. In the embodiment according to  FIG.  1   , three conveyance rollers  202  are mounted on each of the roller shafts  204 . The substrate WF is disposed on the conveyance rollers  202 , and the rotation of the conveyance rollers  202  conveys the substrate WF. Installation positions of the conveyance rollers  202  on the roller shaft  204  can be anywhere as long as the substrate WF can be stably conveyed with the positions. However, since the conveyance rollers  202  are brought into contact with the substrate WF, the conveyance rollers  202  should be disposed so as to be in a contact with a region without any problem of contacting the substrate WF as the process target. In one embodiment, the conveyance rollers  202  of the loading unit  100  can be constituted of a conductive polymer. In one embodiment, the conveyance rollers  202  are electrically grounded via the roller shafts  204  and the like. This is for avoiding the substrate WF from being charged to cause a damage in the substrate WF. In one embodiment, the loading unit  100  may include an ionizer (not illustrated) for avoiding the substrate WF from being charged. 
     As illustrated in  FIG.  2   , the loading unit  100  includes auxiliary rollers  214  in the proximity of the inlet opening  104  and the outlet opening  108 . The auxiliary rollers  214  are arranged at a height approximately the same as that of the conveyance rollers  202 . The auxiliary roller  214  supports the substrate WF such that the substrate WF during conveyance does not fall between the unit and another unit. The auxiliary roller  214  is configured to freely rotate without being coupled to a power source. 
     &lt;Conveyance Unit&gt; 
       FIG.  3    is a side view schematically illustrating the conveyance unit  200  according to one embodiment. The substrate processing apparatus  1000  illustrated in  FIG.  1    includes the two conveyance units  200 A and  200 B. Since the two conveyance units  200 A and  200 B can have identical configurations, the following collectively gives a description as the conveyance unit  200 . 
     The illustrated conveyance unit  200  includes the plurality of conveyance rollers  202  for conveying the substrate WF. Rotating the conveyance rollers  202  ensures conveying the substrate WF on the conveyance rollers  202  in a predetermined direction. The conveyance rollers  202  of the conveyance unit  200  may be formed of a conductive polymer or may be formed of a polymer without a conductive property. The conveyance rollers  202  are mounted on the roller shafts  204 , and are driven by a motor  208  via a gear  206 . In one embodiment, the motor  208  can be a servo motor. Using the servo motor can control a rotation speed of the roller shafts  204  and the conveyance rollers  202 , that is, a conveyance speed of the substrate WF. In one embodiment, the gear  206  can be a magnet gear. Since the magnet gear has a non-contact power transmission mechanism, no microparticles are caused by an abrasion as is the case for a contact type gear, and the maintenance, such as refueling, is not necessary. The illustrated conveyance unit  200  includes a sensor  216  for detecting a presence/absence of the substrate WF at a predetermined position on the conveyance rollers  202 . The sensor  216  can be a sensor of any format, for example, can be an optical sensor. In the embodiment illustrated in  FIG.  3   , seven sensors  216  ( 216   a  to  216   g ) are disposed in the conveyance unit  200 . In one embodiment, corresponding to the detection of the substrate WF by these sensors  216   a  to  216   g , the operation of the conveyance unit  200  can be controlled. As illustrated in  FIG.  3   , the conveyance unit  200  includes the openable/closable inlet shutter  218  for receiving the substrate WF in the conveyance unit  200 . 
     As illustrated in  FIG.  3   , the conveyance unit  200  includes a stopper  220 . The stopper  220  is coupled to a stopper moving mechanism  222 , and the stopper  220  can enter inside a conveyance path of the substrate WF that moves on the conveyance rollers  202 . When the stopper  220  is positioned within the conveyance path of the substrate WF, the substrate WF that moves on the conveyance rollers  202  has a side surface brought into contact with the stopper  220  to ensure stopping the substrate WF on the move at the position of the stopper  220 . When the stopper  220  is at a position retreated from the conveyance path of the substrate WF, the substrate WF can move on the conveyance rollers  202 . The stop position of the substrate WF by the stopper  220  is a position where a pusher  230  described below can receive the substrate WF on the conveyance rollers  202  (a substrate delivery and receipt position). 
     As illustrated in  FIG.  3   , the conveyance unit  200  includes the pusher  230 . The pusher  230  is configured to lift the substrate WF on the plurality of conveyance rollers  202  so as to be separated from the plurality of conveyance rollers  202 . The pusher  230  is configured to hand over the substrate WF that is held to the conveyance rollers  202  of the conveyance unit  200 . 
     The pusher  230  includes a first stage  232  and a second stage  270 . The first stage  232  is a stage for supporting a retainer member  3  of a top ring  302  when the substrate WF is handed over to the top ring  302  described later from the pusher  230 . The first stage  232  includes a plurality of support pillars  234  for supporting the retainer member  3  of the top ring  302 . The second stage  270  is a stage for receiving the substrate WF on the conveyance rollers  202 . The second stage  270  includes a plurality of support pillars  272  for receiving the substrate WF on the conveyance rollers  202 . The first stage  232  and the second stage  270  are movable in a height direction with a first elevating mechanism. The second stage  270  is further movable in the height direction with respect to the first stage  232  with a second elevating mechanism. When the first stage  232  and the second stage  270  are elevated by the first elevating mechanism and the second elevating mechanism, a part of the support pillars  234  of the first stage  232  and the support pillars  272  of the second stage  270  passes between the conveyance rollers  202  and the roller shafts  204  and is brought to a position higher than the conveyance rollers  202 . The substrate WF conveyed on the conveyance rollers  202  is stopped at the substrate delivery and receipt position by the stopper  220 . Afterwards, the first stage  232  and the second stage  270  are elevated by the first elevating mechanism and the substrate WF on the conveyance rollers  202  is lifted up by the support pillars  272  of the second stage  270 . Afterwards, while supporting the retainer member  3  of the top ring  302  with the support pillars  234  of the first stage  232 , the second stage  270  that holds the substrate WF is elevated with the second elevating mechanism. By vacuum suctioning or the like, the top ring  302  receives and holds the substrate WF on the second stage  270 . 
     In one embodiment, the conveyance unit  200  includes a cleaning unit. As illustrated in  FIG.  3   , the cleaning unit includes a cleaning nozzle  284 . The cleaning nozzle  284  includes an upper cleaning nozzle  284   a  arranged in an upper side of the conveyance rollers  202  and a lower cleaning nozzle  284   b  arranged in a lower side. The upper cleaning nozzle  284   a  and the lower cleaning nozzle  284   b  are coupled to a supply source of a cleaning liquid (not illustrated). The upper cleaning nozzle  284   a  is configured to supply the cleaning liquid to an upper surface of the substrate WF conveyed on the conveyance rollers  202 . The lower cleaning nozzle  284   b  is configured to supply the cleaning liquid to a lower surface of the substrate WF conveyed on the conveyance rollers  202 . The upper cleaning nozzle  284   a  and the lower cleaning nozzle  284   b  have widths as same as or greater than a width of the substrate WF conveyed on the conveyance rollers  202 , and whole surfaces of the substrate WF are configured to be cleaned by the substrate WF being conveyed on the conveyance rollers  202 . As illustrated in  FIG.  3   , the cleaning unit is positioned in a downstream side with respect to the substrate delivery and receipt position of the pusher  230  of the conveyance unit  200 . 
     &lt;Polishing Unit&gt; 
       FIG.  4    is a perspective view schematically illustrating a configuration of the polishing unit  300  according to one embodiment. The substrate processing apparatus  1000  illustrated in  FIG.  1    includes the two polishing units  300 A and  300 B. Since the two polishing units  300 A and  300 B can have identical configurations, the following collectively gives a description as the polishing unit  300 . 
     As illustrated in  FIG.  4   , the polishing unit  300  includes a polishing table  350  and the top ring  302  that configures a polishing head that holds the substrate as the polishing object to press onto a polishing surface on the polishing table  350 . The polishing table  350  is coupled, via a table shaft  351 , to a polishing table rotating motor (not illustrated) arranged below the table shaft  351 , and is rotatable about the table shaft  351 . The polishing table  350  has an upper surface on which a polishing pad  352  is attached, and the polishing pad  352  has a surface  352   a  that configures a polishing surface that polishes the substrate. In one embodiment, the polishing pad  352  may be attached via a layer for facilitating a separation from the polishing table  350 . Such a layer is, for example, a silicone layer and a fluorine-based resin layer, and, for example, one that is disclosed in Japanese Unexamined Patent Application Publication No. 2014-176950 and the like may be used. 
     A polishing liquid supply nozzle  354  is disposed above the polishing table  350 , and this polishing liquid supply nozzle  354  supplies the polishing liquid onto the polishing pad  352  on the polishing table  350 . As illustrated in  FIG.  4   , the polishing table  350  and the table shaft  351  have a passage  353  for supplying the polishing liquid. The passage  353  is communicated with an opening portion  355  on a surface of the polishing table  350 . The polishing pad  352  has a through-hole  357  formed at a position corresponding to the opening portion  355  of the polishing table  350 . The polishing liquid passing through the passage  353  is supplied to the surface of the polishing pad  352  from the opening portion  355  of the polishing table  350  and the through-hole  357  of the polishing pad  352 . Note that the opening portion  355  of the polishing table  350  and the through-hole  357  of the polishing pad  352  may be one or may be plural. The positions of the opening portion  355  of the polishing table  350  and the through-hole  357  of the polishing pad  352  may be anywhere, but are arranged in the proximity of a center of the polishing table  350  in one embodiment. 
     While it is not illustrated in  FIG.  4   , in one embodiment, the polishing unit  300  includes an atomizer  358  for injecting a liquid or a mixture fluid of a liquid and a gas toward the polishing pad  352  (see  FIG.  1   ). The liquid injected from the atomizer  358  is, for example, a pure water, and the gas is, for example, a nitrogen gas. 
     The top ring  302  is coupled to a top ring shaft  18 , and this top ring shaft  18  moves up and down with respect to a swing arm  360  by an up-and-down motion mechanism. By this up and down motion of the top ring shaft  18 , the whole top ring  302  is moved up and down with respect to the swing arm  360  to determine a position. The top ring shaft  18  rotates by the driving of a top ring rotational motor (not illustrated). The rotation of the top ring shaft  18  rotates the top ring  302  about the top ring shaft  18 . 
     Note that various kinds of polishing pads are available in a market, and there are, for example, SUBA800 (“SUBA” is a registered trademark), IC-1000, and IC-1000/SUBA400 (two-layer cloth) manufactured by Nitta Haas Incorporated, and Surfin xxx-5, Surfin 000, and the like (“Surfin” is a registered trademark) manufactured by FUJIMI INCORPORATED. SUBA800, Surfin xxx-5, and Surfin 000 are nonwoven fabrics made of fibers hardened with a urethane resin, and IC-1000 is a hard foamed-polyurethane (single layer). The foamed polyurethane is porous (porous form), and has multiple fine depressions or pores on its surface. 
     The top ring  302  can hold a square shaped substrate on its lower surface. The swing arm  360  is configured to be turnable about a spindle  362 . The top ring  302  is movable between the substrate delivery and receipt position and an upper side of the polishing table  350  of the above-described conveyance unit  200  by the turn of the swing arm  360 . Moving the top ring shaft  18  down moves the top ring  302  down to ensure pressing the substrate onto the surface (polishing surface)  352   a  of the polishing pad  352 . At this time, the top ring  302  and the polishing table  350  are each rotated, and the polishing liquid is supplied onto the polishing pad  352  from the polishing liquid supply nozzle  354  disposed above the polishing table  350  and/or from the opening portion  355  disposed on the polishing table  350 . Thus, the surface of the substrate can be polished by pressing the substrate onto the polishing surface  352   a  of the polishing pad  352 . During the polishing of the substrate WF, the swing arm  360  may be fixed or swung such that the top ring  302  passes through the center of the polishing pad  352  (such that the through-hole  357  of the polishing pad  352  is covered). 
     The polishing unit  300  according to one embodiment includes a dressing unit  356  that dresses the polishing surface  352   a  of the polishing pad  352 . This dressing unit  356  includes a dresser  50  that is brought into sliding contact with the polishing surface  352   a , a dresser shaft  51  to which the dresser  50  is coupled, and a swing arm  55  that rotatably supports the dresser shaft  51 . The dresser  50  has a lower portion configured of a dressing member  50   a , and this dressing member  50   a  has a lower surface on which needle shaped diamond particles are attached. 
     The swing arm  55  is configured to turn about a spindle  58  by being driven by a motor (not illustrated). The dresser shaft  51  rotates by the driving of a motor (not illustrated). This rotation of the dresser shaft  51  causes the dresser  50  to rotate about the dresser shaft  51 . The dresser shaft  51  is configured to move up and down, and via the dresser shaft  51 , the dresser  50  can be moved up and down to press the dresser  50  onto the polishing surface  352   a  of the polishing pad  352  with a predetermined pressing force. 
     The dressing of the polishing surface  352   a  of the polishing pad  352  is performed as follows. The dresser  50  is pressed onto the polishing surface  352   a  by an air cylinder or the like, and simultaneously with this, a pure water is supplied to the polishing surface  352   a  from a pure water supplying nozzle (not illustrated). In this state, the dresser  50  rotates about the dresser shaft  51 , and the lower surface of the dressing member  50   a  (the diamond particles) is brought into sliding contact with the polishing surface  352   a . Thus, the polishing pad  352  is scraped by the dresser  50  to dress the polishing surface  352   a.    
     Next, the top ring  302  in the polishing unit  300  according to one embodiment will be described.  FIG.  5    is a schematic cross-sectional view of the top ring  302  that presses the substrate onto the polishing surface on the polishing pad by holding the substrate as the polishing object according to one embodiment. In  FIG.  5   , only main configuration members configuring the top ring  302  are schematically illustrated.  FIG.  6    is a drawing viewing the top ring  302  from a side of the polishing table  350  according to one embodiment. 
     As illustrated in  FIG.  5   , the top ring  302  includes a top ring main body  2  that presses the substrate WF onto the polishing surface  352   a  and the retainer member  3  for preventing the substrate held by the top ring main body  2  from falling out from the top ring main body  2  during the polishing. The retainer member  3  may be configured to directly press the polishing surface  352   a . The retainer member  3  may be configured not to be in contact with the polishing surface  352   a . The top ring main body  2  is coupled to the top ring shaft  18 , and is configured to be rotatable with the rotation of the top ring shaft  18 . The top ring main body  2  may be configured by combining a plurality of members. The top ring main body  2  is formed of a flat plate-shaped member in a schematically square shape, and the retainer member  3  is installed on an outer peripheral portion of the top ring main body  2 . 
     In one embodiment, the retainer member  3  is a member in an elongated rectangular plate shape as illustrated in  FIG.  6   . In the embodiment according to  FIG.  6   , the retainer member  3  has four plate-shaped members disposed on outer peripheral portions of respective sides of the square-shaped top ring main body  2 . In one embodiment, the retainer member  3  has a plurality of grooves  3   a  as illustrated in  FIG.  6   . The retainer member  3  illustrated in  FIG.  6    has the grooves  3   a  formed to extend outward from an inside of the top ring  302 . Note that, in one embodiment, the retainer member  3  without the grooves  3   a  may be employed. The top ring main body  2  is formed of a metal, such as stainless steel (SUS), and a resin, such as an engineering plastic (e.g. PEEK). The top ring main body  2  has a lower surface on which an elastic film (membrane) that is brought into contact with a back surface of the substrate is mounted. Note that the top ring main body  2  may be configured by combining a plurality of members. 
     In one embodiment, the elastic film (membrane) is a laminated membrane  320  on which a plurality of sheet materials as illustrated are laminated. In this disclosure, the “sheet material” means a material formed of a two-dimensional structure in a natural state without any addition of force, excluding a thickness of the material. That is, the sheet material does not have a structural or geometric feature in a thickness direction in the natural state without any addition of force. In one embodiment, each of the sheet materials that configures the laminated membrane  320  is formed of a rubber material high in strength and durability, such as ethylene propylene rubber (EPDM), polyurethane rubber, and silicone rubber. 
     As illustrated in  FIG.  5   , in the laminated membrane  320 , parts of neighboring sheet materials are mutually adhered. Therefore, the laminated membrane  320  includes a plurality of pressure chambers. In the embodiment illustrated in  FIG.  5   , the laminated membrane  320  is formed of three sheet materials  320   a ,  320   b , and  320   c , and includes a first pressure chamber  322   a , a second pressure chamber  322   b , and a third pressure chamber  322   c . In the embodiment illustrated in  FIG.  5   , the three sheet materials are described as a first sheet material  320   a , a second sheet material  320   b , and a third sheet material  320   c  from a side of the substrate. In the embodiment illustrated in  FIG.  5   , the first sheet material  320   a  has an end portion held by the retainer member  3  and a first membrane holder  325 . The second sheet material  320   b  has an end portion held by the first membrane holder  325  and a second membrane holder  327 . The third sheet material  320   c  has an end portion held by the second membrane holder  327  and the top ring main body  2 . As illustrated, the first pressure chamber  322   a  is defined between the first sheet material  320   a  and the second sheet material  320   b , the second pressure chamber  322   b  is defined between the second sheet material  320   b  and the third sheet material  320   c , and the third pressure chamber  322   c  is defined between the third sheet material  320   c  and the top ring main body  2 . In the embodiment illustrated in  FIG.  5   , a flow passage  11  is coupled to the first pressure chamber  322   a , a flow passage  12  is coupled to the second pressure chamber  322   b , and a flow passage  13  is coupled to the third pressure chamber  322   c . Each of the flow passages  11 ,  12 , and  13  is connectable to a fluid source (for example, highly compressed air or nitrogen) and/or a vacuum source, and pressures of the respective pressure chambers  322   a ,  322   b , and  322   c  can be respectively and independently controlled. 
     In one embodiment, the laminated membrane  320  can have vacuum suction holes  328  as illustrated in  FIG.  5   . The vacuum suction hole  328  is used for vacuum suctioning the substrate WF under the laminated membrane  320 . The vacuum suction hole  328  can also be used to remove the substrate from the top ring  302 . For example, supplying a fluid (for example, air or nitrogen) from the vacuum suction hole  328  can remove the substrate WF held under the laminated membrane  320 . 
       FIG.  7    is a perspective view illustrating bonded regions of the three sheet materials  320   a ,  320   b , and  320   c  of the laminated membrane  320  according to one embodiment. In the embodiment illustrated in  FIG.  7   , the first sheet material  320   a  is disposed on the lowermost contacting the substrate, the second sheet material  320   b  is disposed on the first sheet material  320   a , and the third sheet material  320   c  is disposed on the uppermost. In the illustrated embodiment, the hatched region in the second sheet material  320   b  and the first sheet material  320   a  are bonded. The hatched region in the third sheet material  320   c  and the second sheet material  320   b  are bonded. As illustrated in  FIG.  7   , four vacuum suction holes  328  are formed on the first sheet material  320   a , and further, the respective vacuum suction holes  328  are formed at corresponding positions on the second sheet material  320   b  and the third sheet material  320   c . As illustrated in  FIG.  7   , bonding the three sheet materials  320   a ,  320   b , and  320   c  for lamination ensures forming the three pressure chambers  322   a ,  322   b , and  322   c  illustrated in  FIG.  5   . Note that the configuration of the laminated membrane  320  illustrated in  FIGS.  5  and  7    is one example, and the number of sheet materials and the bonded region are not limited. 
       FIG.  8    is a drawing for describing a method for manufacturing the laminated membrane  320  according to one embodiment.  FIG.  9    is a flowchart illustrating the method for manufacturing the laminated membrane  320  according to one embodiment. First, sheet materials to be laminated are prepared. In the illustrated example, the first sheet material  320   a  and the second sheet material  320   b  are prepared. The first sheet material  320   a  can be the sheet material disposed on the lowermost contacting the substrate. The first sheet material  320   a  and the second sheet material  320   b  can, for example, be a vulcanized rubber material. In one example, silicone rubber can be used as the first sheet material  320   a  and the second sheet material  320   b . Note that the second sheet material  320   b  may be a material identical to that of the first sheet material  320   a , or may be a different material. 
     Next, a part of an upper surface of the first sheet material  320   a  and a part of a lower surface of the second sheet material  320   b  undergo a surface reforming process. The surface reforming process is performed on the regions to be bonded of the first sheet material  320   a  and the second sheet material  320   b . Generally, a rubber material is difficult to bond with an adhesive, and therefore, the surface of the sheet material is reformed so as to be easily bonded with the adhesive. The surface reforming process can, for example, be performed by forming a silicon oxide film high in hydrophilicity on the surfaces of the first sheet material  320   a  and the second sheet material  320   b . As the surface reforming process, for example, Flame Bond (registered trademark) can be applied. 
     Next, an adhesive is applied on the region on which the surface reforming process has been performed of the first sheet material  320   a  and/or the region on which the surface reforming process has been performed of the second sheet material  320   b . The adhesive is preferred to be an elastic adhesive so as to be able to maintain the elasticity of the sheet materials. 
     Next, the second sheet material  320   b  is disposed on the first sheet material  320   a , and the first sheet material  320   a  and the second sheet material  320   b  are bonded. While in the illustrated example, the method that bonds the first sheet material  320   a  and the second sheet material  320   b  is described, more sheet materials can be laminated with the similar method. In such procedures, any number of a plurality of the sheet materials are bonded and laminated to form the laminated membrane  320 . In the above-described method, any regions of the neighboring sheet materials can be bonded. In the method according to the above-described embodiment, only the sheet materials having a two-dimensional structure without having a complicated three-dimensional structure are used, and therefore, the laminated membrane  320  including a plurality of pressure chambers  322  can be formed without using a mold having a complicated shape. 
       FIG.  10    is a drawing for describing a method for manufacturing the laminated membrane  320  according to one embodiment.  FIG.  11    is a flowchart illustrating the method for manufacturing the laminated membrane  320  according to the one embodiment. First, the first sheet material  320   a  is disposed in a mold. This mold is only necessary to be in a shape where the first sheet material  320   a  and the second sheet material  320   b  laminated thereafter can be stably disposed, and therefore, the mold can be in a simple shape. For example, the mold can be a mold that defines a depressed portion having a flat bottom surface that fits an outer shape of the first sheet material  320   a . The first sheet material  320   a  can be a sheet material disposed on the lowermost contacting the substrate. The first sheet material  320   a  can be, for example, a vulcanized rubber material. In one example, silicone rubber can be used as the first sheet material  320   a.    
     Next, a sheet made of fluororesin is disposed on a part of the upper surface of the first sheet material  320   a . The sheet made of fluororesin can be, for example, a sheet of polytetrafluoroethylene (a PTFE sheet). The PTFE sheet is disposed on a region that is not bonded on the second sheet material  320   b . Next, the second sheet material  320   b  is disposed on the first sheet material  320   a . In one embodiment, the second sheet material  320   b  can be an unvulcanized rubber material. Afterwards, a vulcanizing process is performed on the second sheet material  320   b . The vulcanizing process can, for example, be performed by pressurizing and heating the second sheet material  320   b . Performing the vulcanizing process ensures bonding the first sheet material  320   a  and the second sheet material  320   b  at a region other than the region on which the PTFE sheet is disposed. After performing the vulcanizing process, the PTFE sheet is removed. 
     In the method described in  FIG.  10    and  FIG.  11   , the laminated membrane  320  can be formed by laminating any number of the sheet materials. In the above-described method, any regions of the neighboring sheet materials can be bonded. For example, any regions of any number of the sheet materials can be bonded by repeating disposing the PTFE sheet on the second sheet material  320   b  undergone the vulcanizing process, disposing the sheet material made of an unvulcanized rubber material on the PTFE sheet, performing the vulcanizing process, and removing the PTFE sheet. In the method according to the above-described embodiment, only the sheet materials having a two-dimensional structure without having a complicated three-dimensional structure are used, and therefore, the laminated membrane  320  including the plurality of pressure chambers  322  can be formed only by using a simple shaped mold, without using a mold having a complicated shape. 
       FIG.  12    is a drawing for describing a method for manufacturing the laminated membrane  320  according to one embodiment.  FIG.  13    is a flowchart illustrating the method for manufacturing the laminated membrane  320  according to the one embodiment. First, the first sheet material  320   a  and the second sheet material  320   b  are prepared. The first sheet material  320   a  can be a sheet material disposed on the lowermost contacting the substrate. The first sheet material  320   a  and the second sheet material  320   b  can be, for example, a vulcanized rubber material. In one example, silicone rubber can be used as the first sheet material  320   a  and the second sheet material  320   b.    
     Next, a part of the upper surface of the first sheet material  320   a  and/or a part of the lower surface of the second sheet material  320   b  are coated with fluororesin. The fluororesin coating can be, for example, a PTFE coating. The PTFE coating can be applied on a region that is not bonded to the second sheet material  320   b  on the first sheet material  320   a . The PTFE coating can be applied on a region not bonded to the first sheet material  320   a  on the second sheet material  320   b.    
     Next, the first sheet material  320   a  is disposed in the mold. This mold is only necessary to be in a shape where the first sheet material  320   a  and the second sheet material  320   b  laminated thereafter can be stably disposed, and therefore, the mold can be in a simple shape. For example, the mold can be a mold that defines a depressed portion having a flat bottom surface that fits an outer shape of the first sheet material  320   a.    
     Next, an unvulcanized rubber material is disposed on a part of the upper surface of the first sheet material  320   a  and/or a part of the lower surface of the second sheet material  320   b . The unvulcanized rubber material can be disposed in regions where the first sheet material  320   a  and the second sheet material  320   b  are bonded. Afterwards, the second sheet material  320   b  is disposed on the first sheet material  320   a  such that the lower surface of the second sheet material  320   b  are in contact with the upper surface of the first sheet material  320   a . Next, performing the vulcanizing process bonds the first sheet material  320   a  and the second sheet material  320   b . The vulcanizing process can, for example, be performed by pressurizing and heating on the second sheet material  320   b . Performing the vulcanizing process ensures bonding the first sheet material  320   a  and the second sheet material  320   b  in a region applied with the unvulcanized rubber other than the region coated with PTFE. 
     In the method described in  FIG.  12    and  FIG.  13   , the laminated membrane  320  can be formed by laminating any number of the sheet materials. In the above-described method, any regions of the neighboring sheet materials can be bonded. In the method according to the above-described embodiment, only the sheet materials having a two-dimensional structure without having a complicated three-dimensional structure are used, and therefore, the laminated membrane  320  including the plurality of pressure chambers  322  can be formed only by using a simple shaped mold, without using a mold having a complicated shape. While in  FIG.  12    and  FIG.  13   , the case where two sheet materials are bonded has been described, three or more sheet materials may be laminated by disposing an unvulcanized rubber material in a region where the neighboring sheet materials are bonded, and applying a PTFE coating in a region that is not bonded in one embodiment. In such a case, performing the vulcanizing process after laminating all the three or more sheet materials ensures bonding all the sheet materials with one vulcanizing process. 
       FIG.  14    is a cross-sectional view illustrating a part of the top ring  302  including the laminated membrane  320  according to one embodiment. In the embodiment illustrated in  FIG.  14   , the top ring  302  includes the top ring main body  2  and the retainer portion  380 . The top ring main body  2  has an approximately square shape as a whole (see  FIG.  4   ), and has a square plate-shaped upper member  303 , an intermediate member  304  installed on a lower surface of the upper member  303 , and a lower member  306  installed on a lower surface of the intermediate member  304 . The retainer portion  380  is installed on an outer peripheral portion of the upper member  303 . The upper member  303  is coupled to the top ring shaft  18  ( FIG.  4   ) with a bolt or the like. The intermediate member  304  is coupled to the upper member  303  with a bolt or the like. The lower member  306  is coupled to the upper member  303  with a bolt or the like. The upper member  303 , the intermediate member  304 , and the lower member  306  can be formed of a metallic material and a plastic material. In one embodiment, the upper member  303  is formed of stainless steel (SUS), and the intermediate member  304  and the lower member  306  are formed of the plastic material. 
     As illustrated in  FIG.  14   , on lower surface of the lower member  306 , the laminated membrane  320  that is brought into contact with the back surface of the substrate WF is installed. This laminated membrane  320  is formed of the sheet materials as described above. In the embodiment illustrated in  FIG.  14   , the laminated membrane  320  is formed of four sheet materials  320   a ,  320   b ,  320   c , and  320   d . As illustrated, the first sheet material  320   a  on the lowermost contacting the substrate is held by being sandwiched between the retainer member  3  and a retainer guide  416 . The second sheet material  320   b  disposed on the first sheet material  320   a  is held by being sandwiched between a holder  316   b  and the lower member  306  and also sandwiched between the retainer guide  416  and a retainer support guide  412 . The third sheet material  320   c  disposed on the second sheet material  320   b  is held by being sandwiched between a holder  316   c  and the lower member  306 . A fourth sheet material  320   d  disposed on the third sheet material  320   c  is held by being sandwiched between a holder  316   d  and the lower member  306 . In the embodiment illustrated in  FIG.  14   , the first pressure chamber  322   a  is defined between the first sheet material  320   a  and the second sheet material  320   b , the second pressure chamber  322   b  is defined between the second sheet material  320   b  and the third sheet material  320   c , the third pressure chamber  322   c  is defined between the third sheet material  320   c  and the fourth sheet material  320   d , and a fourth pressure chamber  322   d  is defined between the fourth sheet material  320   d  and the lower member  306 . The sheet materials  320   a ,  320   b ,  320   c , and  320   d  are sandwiched between each of the members, such as a holder, and serve as portions to seal a fluid supplied to each of the pressure chambers  322   a ,  322   b ,  322   c , and  322   d . The first pressure chamber  322   a , the second pressure chamber  322   b , the third pressure chamber  322   c , and the fourth pressure chamber  322   d  are communicated with respective flow passages (not illustrated). The respective flow passages can be coupled to fluid sources (for example, highly compressed air or nitrogen) and/or vacuum sources, and can respectively and independently control the respective pressure chambers  322   a  to  322   d . Therefore, when polishing the substrate WF, contact pressures to the polishing pad  352  can be controlled for each of area regions of the substrate WF. 
     In the embodiment illustrated in  FIG.  14   , the first sheet material  320   a  to the fourth sheet material  320   d  are secured in an inner side or in a center side of the top ring main body  2  with approaching from the first sheet material  320   a  in a side close to the substrate WF (the lower side in  FIG.  14   ) to the fourth sheet material  320   d  in a side far from the substrate WF (the upper side in  FIG.  14   ). The sheet materials have dimensions that decrease with approaching from the first sheet material  320   a  in the side close to the substrate WF to the fourth sheet material  320   d  in the side far from the substrate WF. 
     In the embodiment illustrated in  FIG.  14   , the retainer portion  380  is disposed on the outer peripheral portion of the upper member  303 . As illustrated, the outer peripheral portion of the upper member  303  has a lower surface to which an upper housing  402  is coupled. In one embodiment, the upper housing  402  can be secured to the upper member  303  with a bolt or the like via a seal packing or the like. The upper housing  402  has a lower surface on which a lower housing  404  is disposed. In one embodiment, the upper housing  402  and the lower housing  404  are square circular members as a whole, and can be formed of polyphenylene sulfide (PPS) resin. The lower housing  404  internally defines a cylinder-shaped cylinder  406 . In the cylinder  406 , a diaphragm  408  is disposed. In one embodiment, the diaphragm  408  is formed of a rubber material. The diaphragm  408  is secured by being sandwiched between the upper housing  402  and the lower housing  404 . The cylinder  406  has an internal space partitioned into an upper space and a lower space by the diaphragm  408 . In the diaphragm  408  of the lower housing  404 , a piston  410  is disposed. The piston  410  has one end in contact with a lower surface of the diaphragm  408 . The piston  410  has the other end in contact with the retainer support guide  412  by sticking out from a lower side of the lower housing  404 . In one embodiment, the piston  410  can be formed of PPS resin. 
     The upper housing  402  has a passage  403 . The passage  403  is coupled to a fluid source (not illustrated). A pressurized fluid (for example, air or nitrogen) can be supplied into the upper space of the cylinder  406  of the lower housing  404  from the fluid source through the passage  403 . When the fluid is supplied into the upper space of the cylinder  406 , the diaphragm  408  bulges downward to move the piston  410  downward. The piston  410  moving downward ensures moving the retainer support guide  412  downward. 
     In one embodiment, as illustrated in  FIG.  14   , a band  414  is installed from an outer side surface of the upper housing  402  to an outer side surface of the retainer support guide  412 . The band  414  allows a displacement of the retainer support guide  412  with respect to the lower housing  404 , and prevents ingress of the polishing liquid and the like into the space between the lower housing  404  and the retainer support guide  412 . 
     As illustrated, the retainer support guide  412  has a lower surface on which the retainer guide  416  is installed. In one embodiment, as illustrated, the end portion of the second sheet material  320   b  is held between the retainer support guide  412  and the retainer guide  416 . As illustrated, the retainer guide  416  has a lower surface on which the retainer member  3  is installed. The retainer support guide  412 , the retainer guide  416 , and the retainer member  3  can be secured with a bolt or the like. The retainer support guide  412  and the retainer guide  416  are square circular members that fit an entire shape of the top ring  302  as a whole. In one embodiment, the retainer support guide  412  and the retainer guide  416  are formed of stainless steel (SUS), and the retainer member  3  is formed of PPS resin, polyvinyl chloride resin, or the like. As described above, the retainer support guide  412  is moved downward by the piston  410  in the lower housing  404 , and thus, the retainer member  3  is moved downward. 
     In one embodiment, the top ring  302  includes a retainer guiding device that guides the retainer member  3  such that the retainer member  3  can displace in an up and down direction, and supports the retainer member  3  such that the retainer member  3  is inhibited from displacing in a lateral direction. In one embodiment, as illustrated in  FIG.  14   , the retainer support guide  412 , the retainer guide  416 , and the retainer member  3  are supported and guided by a support roller  450  to be movable in the up and down direction. As illustrated, the retainer support guide  412  has an inner side surface where a support pad  418  is secured. As illustrated, in a state where the support pad  418  secured to the retainer support guide  412  is in contact with and supported by the support roller  450 , the retainer support guide  412 , the retainer guide  416 , and the retainer member  3  move in the up and down direction. Note that, in one embodiment, between the support pad  418  secured to the retainer support guide  412  and the support roller  450 , a slight clearance may be configured be provided. In one embodiment, the support pad  418  can be formed of PPS resin, vinyl chloride resin, or PEEK resin. 
     In one embodiment, the lower housing  404  has a circumferential direction (a direction perpendicular to the paper surface) in which a plurality of the cylinders  406  are formed, and each of the cylinders  406  includes the diaphragm  408  and the piston  410 . Using the cylinders  406 , the diaphragms  408 , and the pistons  410  in the identical shapes ensures reducing a cost for manufacturing them. For example, even when the case where the top ring main body  2  having a different dimension is manufactured, the diaphragm  408  and the piston  410 , which are the same components, are usable, and a design can be employed to change the used number depending on a size of the top ring main body  2 . 
     As illustrated in  FIG.  14   , a retainer support frame  420  is secured to the lower member  306  of the top ring main body  2 . The retainer support frame  420  is secured to the lower member  306  with a bolt or the like. 
     In one embodiment, a plurality of the support rollers  450  are disposed along each of sides of the square circular retainer portion  380 . For example, three support rollers  450  are disposed on each of the sides of the square retainer support frame  420 . While in one embodiment, three each of the support rollers  450  are disposed on each of the sides, one each of the support roller  450  may be disposed on each of the sides, or two or more each may be disposed in another embodiment. 
     In the above-described embodiment, the support roller  450  can support a load in a horizontal direction applied from the substrate WF during polishing. For example, in a state illustrated in  FIG.  14   , assume that force is applied in a left direction from the substrate WF to the retainer member  3 . In such a case, the support pad  418  installed on the retainer support guide  412  of the retainer portion  380  ( FIG.  14   ) in the right side of the top ring  302  presses the support roller  450  in the left direction. The support roller  450  has a shaft  424  secured to the retainer support frame  420 , and the retainer support frame  420  is secured to the lower member  306 . Therefore, it is possible to prevent the support roller  450  from receiving the load to move the retainer member  3  in the horizontal direction when the force in the horizontal direction is applied to the retainer member  3 . 
     In the above-described embodiment, the top ring shaft  18  has rotational force that is transmitted to the upper member  303 , the intermediate member  304 , and the lower member  306 . Furthermore, the rotational force is transmitted to the support roller  450  from the retainer support frame  420  secured to the lower member  306 , and is transmitted to the retainer portion  380  from the support roller  450  through the support pad  418 . Therefore, rotational force of the top ring main body  2  of the top ring  302  is transmitted to the retainer portion  380  through the support roller  450 . 
     In the above-described embodiment, the fluid is supplied to the cylinder  406  through the passage  403 , and the diaphragm  408  drives the piston  410 , and thus, the retainer member  3  is moved in the up and down direction such that the retainer member  3  can be pressed onto the polishing pad  352 . The pressure of the fluid supplied to the cylinder  406  can control the pressure that presses the retainer member  3  to the polishing pad  352 . In the above-described embodiment, when the retainer member  3  moves in the up and down direction, the retainer member  3  moves guided by the support roller  450 . Therefore, resistance between the support roller  450  and the support pad  418  can be decreased. 
     In the embodiment illustrated in  FIG.  14   , the bonded regions of the respective sheet materials  320   a ,  320   b ,  320   c , and  320   d  of the laminated membrane  320  are not limited.  FIG.  15 A  to  FIG.  15 D  are drawings illustrating examples of the bonded regions of the laminated membrane  320 . The laminated membrane  320  according to the embodiment illustrated in  FIG.  15 A  has four sheet materials  320   a ,  320   b ,  320   c , and  320   d  laminated. The laminated membrane  320  illustrated in  FIG.  15 A  has the lower surface of the second sheet material  320   b  bonded on the upper surface of the first sheet material  320   a  excluding the region where the first pressure chamber  322   a  is formed. The lower surface of the third sheet material  320   c  is bonded on the upper surface of the second sheet material  320   b  excluding the region where the second pressure chamber  322   b  is formed. The lower surface of the fourth sheet material  320   d  is bonded on the upper surface of the third sheet material  320   c  excluding the region where the third pressure chamber  322   c  is formed. Note that  FIG.  15 A  does not illustrate the vacuum suction hole  328  for vacuum suctioning the substrate WF, the vacuum suction hole may be provided or does not have to be provided. In the embodiment illustrated in  FIG.  15 A , the first pressure chamber  322   a  is defined between the first sheet material  320   a  and the second sheet material  320   b , the second pressure chamber  322   b  is defined between the second sheet material  320   b  and the third sheet material  320   c , the third pressure chamber  322   c  is defined between the third sheet material  320   c  and the fourth sheet material  320   d , and the fourth pressure chamber  322   d  is defined between the fourth sheet material  320   d  and the lower member  306 . In the embodiment illustrated in  FIG.  14 A , the first pressure chamber  322   a , the second pressure chamber  322   b , the third pressure chamber  322   c , and the fourth pressure chamber  322   d  are defined from the outside toward the center. Therefore, controlling the pressures of the respective pressure chambers  322   a ,  322   b ,  322   c , and  322   d  ensures controlling pressing force to the polishing pad  352  of the substrate WF held under the laminated membrane  320  for each of the regions. 
     In the embodiment illustrated in  FIG.  15 B , the laminated membrane  320  has four sheet materials  320   a ,  320   b ,  320   c , and  320   d  laminated. The laminated membrane  320  illustrated in  FIG.  15 B  has a part of the lower surface of the second sheet material  320   b  is coupled to a part of the upper surface of the first sheet material  320   a . The bonded region illustrated in  FIG.  15 B  extends in the circumferential direction of the sheet material. Accordingly, in the embodiment illustrated in  FIG.  15 B , the coupled region between the first sheet material  320   a  and the second sheet material  320   b  makes a boundary of the first pressure chamber  322   a . In the embodiment illustrated in  FIG.  15 B , no bonding is made between the second sheet material  320   b , the third sheet material  320   c , and the fourth sheet material  320   d . In the embodiment illustrated in  FIG.  15 B , the laminated membrane  320  is not provided with the vacuum suction hole for vacuum suctioning the substrate WF. 
     In the embodiment illustrated in  FIG.  15 B , the substrate WF is held on a front side surface (lower side surface) of the first sheet material  320   a  during polishing. During the polishing, when the pressures in the pressure chambers are controlled to increase in the order of the fourth pressure chamber  322   d , the third pressure chamber  322   c , and the second pressure chamber  322   b  from the center side toward the outside of the substrate, the pressing force onto the polishing pad  352  of the substrate WF can be controlled for each pressure chamber without the bonding between the sheet materials. On the other hand, when the substrate WF is pulled away from the polishing pad  352  after finishing the polishing of the substrate WF, providing a positive pressure to the first pressure chamber  322   a  and providing a negative pressure to the second pressure chamber  322   b , the third pressure chamber  322   c , and the fourth pressure chamber  322   d  ensures holding the substrate WF under the first sheet material  320   a  like a suction cup to pull the substrate WF away from the polishing pad  352 . 
     In the embodiment illustrated in  FIG.  15 C , the laminated membrane  320  has four sheet materials  320   a ,  320   b ,  320   c , and  320   d  laminated. The laminated membrane  320  illustrated in  FIG.  15 C  is provided with the vacuum suction holes  328  that pass through the second sheet material  320   b  and the first sheet material  320   a . In the embodiment of  FIG.  15 C , the second sheet material  320   b  and the first sheet material  320   a  are bonded in peripheral areas of the vacuum suction holes  328 . In the embodiment of  FIG.  15 C , vacuum drawing the second pressure chamber  322   b  ensures holding the substrate WF under the laminated membrane  320 . Furthermore, in one embodiment, as illustrated in  FIG.  15 C , in the region that serves as a boundary between the second pressure chamber  322   b  and the third pressure chamber  322   c , the third sheet material  320   c  and the second sheet material  320   b  are bonded across the circumferential direction as illustrated. Such a bonding is for preventing a liquid including slurry and the like from entering into the second pressure chamber  322   b  from the vacuum suction hole  328 , and further ingressing between the third sheet material  320   c  and the second sheet material  320   b  when the second pressure chamber  322   b  is vacuum drawn. 
     In the embodiment illustrated in  FIG.  15 C , the substrate WF is held on a front side surface of the first sheet material  320   a  during polishing. During the polishing, when the pressures in the pressure chambers are controlled to increase in the order of the fourth pressure chamber  322   d , the third pressure chamber  322   c , the second pressure chamber  322   b , and the first pressure chamber  322   a  from the center side toward the outside of the substrate, the pressing force onto the polishing pad  352  of the substrate WF can be controlled for each pressure chamber. On the other hand, when the substrate WF is pulled away from the polishing pad  352  after finishing the polishing of the substrate WF, providing a negative pressure to all the pressure chambers including the second pressure chamber  322   b  ensures holding the substrate WF under the first sheet material  320   a  by vacuum suctioning to pull the substrate WF away from the polishing pad  352 . Note that when the substrate WF is pulled away from the polishing pad  352 , as long as a negative pressure is provided to the second pressure chamber  322   b , the first pressure chamber  322   a , the third pressure chamber  322   c , and the fourth pressure chamber  322   d  may have atmospheric pressures. 
     In the embodiment illustrated in  FIG.  15 D , the laminated membrane  320  has four sheet materials  320   a ,  320   b ,  320   c , and  320   d  laminated. The laminated membrane  320  illustrated in  FIG.  15 D  is provided with the vacuum suction holes  328  that pass through the second sheet material  320   b  and the first sheet material  320   a . In the embodiment of  FIG.  15 D , the second sheet material  320   b  and the first sheet material  320   a  are bonded in peripheral areas of the vacuum suction holes  328 . As illustrated in  FIG.  15 D , in the region that serves as a boundary between the second pressure chamber  322   b  and the third pressure chamber  322   c , the third sheet material  320   c  and the second sheet material  320   b  are bonded across the circumferential direction as illustrated. Furthermore, as illustrated in  FIG.  15 D , in the region that serves as a boundary between the second pressure chamber  322   b  and the first pressure chamber  322   a , the second sheet material  320   b  and the first sheet material  320   a  are bonded as illustrated. The embodiment illustrated in  FIG.  15 D  is said to be a combination of the embodiments in  FIG.  15 B  and  FIG.  15 C . 
     In the embodiment illustrated in  FIG.  15 D , the substrate WF is held on a front side surface of the first sheet material  320   a  during polishing. Increasing the pressure in the fourth pressure chamber  322   d  greater than that in the third pressure chamber  322   c  during polishing ensures controlling the pressing force onto the polishing pad  352  of the substrate WF for each of the pressure chambers without a bonded layer between the fourth sheet material  320   d  and the third sheet material  320   c . On the other hand, when the substrate WF is pulled away from the polishing pad  352  after finishing the polishing of the substrate WF, providing a positive pressure to the first pressure chamber  322   a  and providing a negative pressure to the second pressure chamber  322   b , the third pressure chamber  322   c , and the fourth pressure chamber  322   d  ensures vacuum suctioning the substrate WF and holding the substrate WF under the first sheet material  320   a  like a suction cup to pull the substrate WF away from the polishing pad  352 . Note that when the substrate WF is pulled away from the polishing pad  352 , the third pressure chamber  322   c  and the fourth pressure chamber  322   d  may have atmospheric pressures. 
       FIG.  16 A  is a drawing illustrating an example of bonded regions of the laminated membrane  320  according to one embodiment. In the laminated membrane  320  according to the embodiment illustrated in  FIG.  16 A , the plurality of sheet materials  320   a ,  320   b ,  320   c ,  320   d , and  320   e  are laminated. As illustrated in  FIG.  16 A , a part of the upper surface of the first sheet material  320   a  is bonded on a part of the lower surface of the second sheet material  320   b . Therefore, the first sheet material  320   a  and the second sheet material  320   b  define the first pressure chamber  322   a . As illustrated in  FIG.  16 A , a part of the upper surface of the first sheet material  320   a  is bonded on a part of the lower surface of the third sheet material  320   c . Therefore, the first sheet material  320   a , the second sheet material  320   b , and the third sheet material  320   c  define the second pressure chamber  322   b . The bonded region illustrated in  FIG.  16 A  extends in the circumferential direction of the sheet materials. Note that, as illustrated in  FIG.  16 A , the second pressure chamber  322   b  is adjacent to the first pressure chamber  322   a , and the second pressure chamber  322   b  is located inside with respect to the first pressure chamber  322   a . As illustrated in  FIG.  16 A , in the proximity of the center of the first sheet material  320   a , the fourth sheet material  320   d  is disposed in an upper side of the first sheet material  320   a . As illustrated, the first sheet material  320   a , the third sheet material  320   c , and the fourth sheet material  320   d  define the third pressure chamber  322   c . Note that the first sheet material  320   a  and the fourth sheet material  320   d  are not bonded. As illustrated in  FIG.  16 A , in the proximity of the center of the first sheet material  320   a  and the fourth sheet material  320   d , a fifth sheet material  320   e  is disposed in an upper side of the fourth sheet material  320   d . As illustrated, the fourth sheet material  320   d  and the fifth sheet material  320   e  define the fourth pressure chamber  322   d . As illustrated, the fifth sheet material  320   e  defines a fifth pressure chamber  322   e . Note that the fourth sheet material  320   d  and the fifth sheet material  320   e  are not bonded. As illustrated in  FIG.  16 A , a part of the first sheet material  320   a  that defines the second pressure chamber  322   b  is provided with the vacuum suction holes  328 . 
       FIG.  16 B  is a drawing illustrating an example of bonded regions of the laminated membrane  320  according to one embodiment. The laminated membrane  320  according to the embodiment illustrated in  FIG.  16 B  has the plurality of sheet materials  320   a ,  320   b ,  320   c ,  320   d , and  320   e  laminated. As illustrated in  FIG.  16 B , a part of the upper surface of the first sheet material  320   a  is bonded on a part of the lower surface of the second sheet material  320   b . Therefore, the first sheet material  320   a  and the second sheet material  320   b  define the first pressure chamber  322   a . As illustrated in  FIG.  16 B , the second sheet material  320   b  and the third sheet material  320   c  define the second pressure chamber  322   b . Note that the second sheet material  320   b  and the third sheet material  320   c  may be an identical sheet material, and in the example illustrated in  FIG.  16 B , an outer portion from the bonded region is the second sheet material  320   b , and an inner portion from the bonded region is the third sheet material  320   c . As illustrated in  FIG.  16 B , a part of the upper surface of the first sheet material  320   a  is bonded on a part of the lower surface of the fourth sheet material  320   d . Therefore, the first sheet material  320   a , the third sheet material  320   c , and the fourth sheet material  320   d  define the third pressure chamber  322   c . Note that the bonded region illustrated in  FIG.  16 B  extends in the circumferential direction of the sheet material. As illustrated in  FIG.  16 B , in the proximity of the center of the first sheet material  320   a , the fifth sheet material  320   e  is disposed in an upper side of the first sheet material  320   a . As illustrated, the first sheet material  320   a , the fourth sheet material  320   d , and the fifth sheet material  320   e  define the fourth pressure chamber  322   d . Note that the first sheet material  320   a  and the fifth sheet material  320   e  are not bonded. As illustrated, the fifth sheet material  320   e  defines the fifth pressure chamber  322   e . As illustrated in  FIG.  16 B , a part of the first sheet material  320   a  that defines the third pressure chamber  322   c  is provided with the vacuum suction holes  328 . 
     The embodiment of the present invention has been described above based on some examples in order to facilitate understanding of the present invention without limiting the present invention. The present invention can be changed or improved without departing from the gist thereof, and of course, the equivalents of the present invention are included in the present invention. It is possible to arbitrarily combine or omit respective components according to claims and description in a range in which at least a part of the above-described problems can be solved, or a range in which at least a part of the effects can be exhibited. Note that, while in the above-mentioned examples, the top ring has been described as for holding a square shaped substrate, and the laminated membrane has also been illustrated and described as having a shape corresponding to the square shaped substrate, the top ring may be for holding a circular shaped substrate, and the laminated membrane may also have a shape corresponding to the circular shaped substrate. 
     From the above-described embodiments, at least the following technical ideas are obtained. 
     [Configuration 1] 
     According to a configuration 1, a laminated membrane used in a substrate holder of a substrate processing apparatus is provided. Such a laminated membrane includes a first sheet material, and a second sheet material disposed on the first sheet material. A part of the first sheet material is secured to a part of the second sheet material. 
     [Configuration 2] 
     According to a configuration 2, in the laminated membrane according to the configuration 1, the part of the first sheet material is secured to the part of the second sheet material with an adhesive. 
     [Configuration 3] 
     According to a configuration 3, in the laminated membrane according to the configuration 1, the part of the first sheet material is secured to the part of the second sheet material by vulcanization bonding. 
     [Configuration 4] 
     According to a configuration 4, a substrate holder of a substrate processing apparatus is provided. Such a substrate holder includes the laminated membrane according to any one of the configurations 1 to 3. The laminated membrane has a substrate holding surface configured to hold a substrate. 
     [Configuration 5] 
     According to a configuration 5, the substrate holder according to the configuration 4 includes a first holder configured to position the first sheet material, and a second holder configured to position the second sheet material. A first pressure chamber is defined between the first sheet material and the second sheet material. 
     [Configuration 6] 
     According to a configuration 6, a method for manufacturing a laminated membrane used in a substrate holder of a substrate processing apparatus is provided. Such a method for manufacturing includes a step of preparing a first sheet material and a second sheet material, a step of performing a surface reforming process on a part of an upper surface of the first sheet material and a part of a lower surface of the second sheet material, a step of disposing an adhesive on the part of the upper surface of the first sheet material and/or the part of the lower surface of the second sheet material, and a step of disposing the lower surface of the second sheet material on the upper surface of the first sheet material. 
     [Configuration 7] 
     According to a configuration 7, a method for manufacturing a laminated membrane used in a substrate holder of a substrate processing apparatus is provided. Such a method for manufacturing includes a step of disposing a first sheet material in a mold that specifies an outer shape of the laminated membrane, a step of disposing a fluororesin sheet on a part of an upper surface of the first sheet material, a step of disposing a second sheet material including unvulcanized rubber on the upper surface of the first sheet material, a step of performing a vulcanizing process on the second sheet material, and a step of removing the fluororesin sheet. 
     [Configuration 8] 
     According to a configuration 8, a method for manufacturing a laminated membrane used in a substrate holder of a substrate processing apparatus is provided. Such a method for manufacturing includes a step of coating fluororesin on a part of a first sheet material and/or a second sheet material, a step of disposing the first sheet material in a mold that specifies an outer shape of the laminated membrane, a step of disposing unvulcanized rubber on a part of an upper surface of the first sheet material and/or a part of a lower surface of the second sheet material, a step of disposing the second sheet material on the first sheet material on which the unvulcanized rubber is disposed, and a step of performing a vulcanizing process on the unvulcanized rubber. 
     [Configuration 9] 
     According to a configuration 9, a substrate processing apparatus is provided. Such a substrate processing apparatus includes a rotatable table, and the substrate holder according to the configuration 4 or 5. The substrate processing apparatus is configured to polish a substrate by rotating the table in a state where a polishing pad disposed on the table is brought into contact with the substrate held by the substrate holder. 
     REFERENCE SIGNS LIST 
     
         
         
           
               2  . . . top ring main body 
               3  . . . retainer member 
               50  . . . dresser 
               100  . . . loading unit 
               200  . . . conveyance unit 
               300  . . . polishing unit 
               302  . . . top ring 
               303  . . . upper member 
               304  . . . intermediate member 
               306  . . . lower member 
               316   b  . . . holder 
               316   c  . . . holder 
               316   d  . . . holder 
               320  . . . laminated membrane 
               320   a  . . . first sheet material 
               320   b  . . . second sheet material 
               320   c  . . . third sheet material 
               320   d  . . . fourth sheet material 
               320   e  . . . fifth sheet material 
               322  . . . pressure chamber 
               322   a  . . . first pressure chamber 
               322   b  . . . second pressure chamber 
               322   c  . . . third pressure chamber 
               322   d  . . . fourth pressure chamber 
               322   e  . . . fifth pressure chamber 
               325  . . . first membrane holder 
               327  . . . second membrane holder 
               328  . . . vacuum suction hole 
               350  . . . polishing table 
               352  . . . polishing pad 
               356  . . . dressing unit 
               360  . . . swing arm 
               362  . . . spindle 
               380  . . . retainer portion 
               500  . . . drying unit 
               600  . . . unloading unit 
               900  . . . controller 
               1000  . . . substrate processing apparatus 
             WF . . . substrate