Polishing apparatus

Abstract

A workpiece such as a semiconductor wafer is supported on a top ring and polished by an abrasive cloth on a turntable while the top ring is being pressed against the turntable and the turntable and the top ring are being rotated. The top ring is coupled to a top ring drive shaft, coupled to a pressure cylinder for pressing the top ring, and to a motor for rotating the top ring. A spherical bearing is interposed between the top ring and the top ring drive shaft for allowing the top ring to align with the upper surface of the moving turntable. A torque transmitting mechanism is operatively coupled between the top ring and the top ring drive shaft for rotating the top ring in synchronization with the top ring drive shaft.

1. A polishing apparatus for polishing a surface of a workpiece comprising:
 a turntable having an abrasive cloth at an upper surface thereof;  
 a workpiece supporting and pressing member for supporting the workpiece to be polished and pressing the workpiece against said abrasive cloth, said workpiece supporting and pressing member comprising a top ring positioned above said turntable;  
 a top ring drive shaft coupled to said top ring; and  
 a spherical bearing interposed between said workpiece supporting and pressing member and said top ring drive shaft, and spherical bearing comprising spherical seats formed in said workpiece supporting and pressing member and in said top ring drive shaft, respectively, and a single sphere seated in said seats so as to allow said top ring to tilt upon changes in the inclination of said upper surface of said turntable, the radius of said sphere being substantially the same as the radius of curvature of each of said spherical seats.  
 
     
     
       2. The polishing apparatus according to  claim 1 , wherein said top ring has a plurality of suction holes connected to a vacuum source, whereby the workpiece is attractable to a lower surface of said top ring under a vacuum developed by said vacuum source. 
     
     
       3. The polishing apparatus according to  claim 1 , wherein said top ring comprises a porous plate connected to a vacuum source, whereby the workpiece is attractable to a lower surface of said porous plate under a vacuum developed by said vacuum source. 
     
     
       4. The polishing apparatus according to  claim 1 , and further comprising at least one first pin mounted on said top ring drive shaft and at least one second pin mounted on said top ring, said first pin and said second pin being held in point contact with each other such that torque from said top ring drive shaft is transmitted to said top ring via said pins. 
     
     
       5. A polishing apparatus for polishing a surface of a workpiece comprising:
 a turntable having an abrasive cloth at an upper surface thereof;  
 a top ring positioned above said turntable for supporting the workpiece to be polished and pressing the workpiece against said abrasive cloth;  
 a top ring drive shaft coupled to said top ring;  
 a spherical bearing interposed between said top ring and said top ring drive shaft for allowing said top ring to tilt upon changes in the inclination of said upper surface of said turntable;  
 at least one first pin mounted on said top ring drive shaft and at least one second pin mounted on said top ring, said first pin and said second pin bearing in point contact with each other such that torque from said top ring drive shaft is transmitted to said top ring via said pins; and  
 damping means provided on at least one of said first pin and said second pin for inhibiting the transmission of vibrations from said top ring drive shaft to said top ring.  
 
     
     
       6. The polishing apparatus according to  claim 5 , wherein said damping means comprises an elastic member mounted on at least one of said first pin and said second pin. 
     
     
       7. A polishing apparatus for polishing a surface of a workpiece comprising:
 a turntable having an abrasive cloth at an upper surface thereof;  
 a top ring positioned above said turntable for supporting the workpiece to be polished and pressing the workpiece against said abrasive cloth;  
 a top ring drive shaft coupled to said top ring;  
 a stationary member supporting said top ring drive shaft;  
 a spherical bearing interposed between said top ring and said top ring drive shaft for allowing said top ring to tilt upon changes in the inclination of said upper surface of said turntable; and  
 damping means for damping said top ring drive shaft, said damping means being provided between said top ring drive shaft and said stationary member supporting said top ring drive shaft.  
 
     
     
       8. The polishing apparatus according to  claim 7 , and further comprising a radial bearing interposed between said stationary member and said top ring drive shaft, and wherein said damping means comprises an O-ring interposed between said radial bearing and said stationary member. 
     
     
       9. The polishing apparatus according to  claim 7 , wherein said damping means comprises oil supplying means for supplying oil into a space defined between said top ring drive shaft and said stationary member. 
     
     
       10. The polishing apparatus according to  claim 9 , and further comprising a radial bearing interposed between said stationary member and said top ring drive shaft, and wherein said space is defined between said radial bearing and said stationary member. 
     
     
       11. The polishing apparatus according to  claim 1 , and further comprising biasing means for resiliently holding said top ring in a predetermined plane with respect to said top ring drive shaft. 
     
     
       12. A polishing apparatus for polishing a surface of a workpiece, comprising:
 a turntable having an abrasive cloth at an upper surface thereof;  
 a top ring positioned above said turntable for supporting the workpiece to be polished and pressing the workpiece against said abrasive cloth;  
 a top ring drive shaft coupled to said top ring;  
 a spherical bearing interposed between said top ring and said top ring drive shaft for allowing said top ring to tilt upon changes in the inclination of said upper surface of said turntable; and  
 a top ring holder movably mounted on said top ring drive shaft, a plurality of retaining members extending through said top ring holder and fixed to said top ring, and a plurality of springs between said top ring holder and said retaining members, and springs resiliently urging said top ring holder against said top ring drive shaft to hold said ring in a predetermined plane with respect to said top ring drive shaft.  
 
     
     
       13. The polishing apparatus according to  claim 1 , and further comprising a transferring device provided in the vicinity of said turntable for transferring the workpiece to said top ring, said transferring device including holding means for holding said workpiece, and shock absorbing means for resiliently supporting and holding means to suppress the effect of an impact on the workpiece during the transfer process. 
     
     
       14. The polishing apparatus according to  claim 13 , wherein the holding means comprise a support member having a suction hole connected to a vacuum source for attracting said workpiece to said support member. 
     
     
       15. The polishing apparatus according to  claim 13 , wherein said shock absorbing means comprise a spring box urging said holding means upwardly. 
     
     
       16. The polishing apparatus according to  claim 1 , wherein said spherical seats have the same coefficient of friction. 
     
     
       17. A polishing apparatus for polishing a surface of a workpiece, comprising:
 a turntable having an abrasive cloth at an upper surface thereof;  
 a top ring positioned above said turntable for supporting the workpiece to be polished and pressing the workpiece against said abrasive cloth;  
 a top ring drive shaft coupled to said top ring;  
 a plate interposed between said top ring and said top ring drive shaft, said plate having an annular lower projection, at a lower surface thereof, which contacts the upper surface of said top ring, pressure distributions at the lower surface of said top ring being established by the area over which said lower projection contacts said top ring; and  
 a spherical bearing interposed between said plate and said top ring drive shaft, said spherical bearing comprising spherical seats formed in said plate and in said top ring drive shaft, respectively and a single sphere seated in said seats so as to allow said top ring to tilt upon changes in the inclination of said upper surface of said turntable.  
 
     
     
       18. The polishing apparatus according to  claim 12 , wherein said top ring has a plurality of suction holes connected to a vacuum source, whereby the workpiece is attractable to a lower surface of said top ring under a vacuum developed by said vacuum source. 
     
     
       19. The polishing apparatus according to  claim 12 , wherein said top ring comprises a porous plate connected to a vacuum source, whereby the workpiece is attractable to a lower source of said porous plate under a vacuum developed by said vacuum source. 
     
     
       20. The polishing apparatus according to  claim 12 , and further comprising at least one first pin mounted on said top ring drive shaft and at least one second pin mounted on said top ring, said first pin and said second pin being held in point contact with each other such that torque from said top ring drive shaft is transmitted to said top ring via said pins. 
     
     
       21. The polishing apparatus according to  claim 1  wherein said turntable has an axis of rotation extending parallel to and spaced from the central longitudinal axis of said top ring drive shaft; and further comprising an abrasive spray nozzle disposed above said turntable and oriented to direct abrasive slurry onto the abrasive cloth at a location spaced radially inwardly to the turntable from the location at which the surface of a workpiece is pressed against the abrasive cloth by said supporting and pressing member. 
     
     
       22. A polishing apparatus for polishing a surface of a workpiece, comprising:
   a turntable having an abrasive cloth at an upper surface thereof;        a top ring positioned above said turntable for supporting the workpiece to be polished and pressing the workpiece against said abrasive cloth;        a top ring drive shaft coupled to said top ring;        a bearing for allowing said top ring to tilt upon changes in the inclination of said upper surface of said turntable;        a plurality of biasing members rigidly attached to said top ring; and        a damper provided between said top ring drive shaft and a stationary member supporting said top ring drive shaft to dampen said top ring drive shaft.     
     
     
       23. A polishing apparatus for polishing a surface of a workpiece comprising:
   a turntable having an abrasive cloth at an upper surface thereof;        a top ring positioned above said turntable for supporting the workpiece to be polished and pressing the workpiece against said abrasive cloth;        a top ring drive shaft coupled to said top ring;        a bearing for allowing said top ring to tilt upon changes in the inclination of said upper surface of said turntable;        a plurality of biasing members rigidly attached to the periphery of said top ring; and        a damper provided between said top ring drive shaft and a stationary member supporting said top ring drive shaft to dampen said top ring drive shaft.     
     
     
       24. A polishing apparatus for polishing a surface of a workpiece, comprising:
   a turntable having an abrasive cloth at an upper surface thereof;        a top ring positioned above said turntable for supporting the workpiece to be polished and pressing the workpiece against said abrasive cloth;        a top ring drive shaft coupled to said top ring;        a bearing for allowing said top ring to tilt upon changes in the inclination of said upper surface of said turntable;        a plurality of biasing members rigidly attached to said top ring and positioned radially with respect to said drive shaft for biasing the periphery of said top ring; and        a damper provided between said top ring drive shaft and a stationary member supporting said top ring drive shaft to dampen said top ring drive shaft.     
     
     
       25. A polishing apparatus for polishing a surface of a workpiece, comprising:
   a turntable having an abrasive cloth at an upper surface thereof;        a top ring positioned above said turntable for supporting the workpiece to be polished and pressing the workpiece against said abrasive cloth;        a top ring drive shaft coupled to said top ring;        a bearing interposed between said top ring and said top ring drive shaft for allowing said top ring to tilt upon changes in the inclination of said upper surface of said turntable;        a plurality of biasing means rigidly attached to said top ring and positioned radially with respect to said drive shaft for biasing the periphery of said top ring; and        a damper provided between said top ring drive shaft and a stationary member supporting said top ring drive shaft to dampen said top ring drive shaft.     
     
     
       26. A polishing apparatus for polishing a surface of workpiece, comprising:
   a turntable having an abrasive cloth at an upper surface thereof;        a top ring positioned above said turntable for supporting the workpiece to be polished and pressing the workpiece against said abrasive cloth;        a top ring drive shaft coupled to said top ring;        a stationary member supporting said top ring drive shaft;        a bearing interposed between said top ring and said top ring drive shaft for allowing said top ring to tilt upon changes in the inclination of said upper surface of said turntable; and        a damper provided between said top ring drive shaft and said stationary member supporting said top ring drive shaft to dampen said top ring drive shaft.     
     
     
       27. A polishing apparatus for polishing a surface of a workpiece, comprising:
   a turntable with an abrasive cloth mounted on an upper surface thereof;        a top ring positioned above said turntable for supporting the workpiece to be polished and pressing the workpiece against said abrasive cloth;        a top ring drive shaft coupled to said top ring;        a bearing interposed between said top ring and said top ring drive shaft, said bearing allowing said top ring to tilt upon changes in the inclination of said upper surface of said turntable;        a torque transmitter comprising a plurality of torque transmitting members provided at a substantially lower part of said top ring drive shaft and extending radially outwardly, said torque transmitting members transmitting torque from said top ring drive shaft to said top ring at locations spaced from said top ring drive shaft while permitting said top ring to tilt relative to said top ring drive shaft; and        a damper provided between said top ring drive shaft and a stationary member for supporting said top ring drive shaft, to dampen said top ring drive shaft.     
     
     
       28. The polishing apparatus according to  claim 26  or  27 , wherein said top ring has a plurality of suction holes connected to a vacuum source for attracting the workpiece to a lower surface of said top ring under a vacuum developed by said vacuum source. 
     
     
       29. The polishing apparatus according to  claim 26  or  27  wherein said top ring has a porous plate having a number of pores connectable to a vacuum source for attracting said workpiece to a lower surface of said porous plate under a vacuum developed by said vacuum source. 
     
     
       30. A polishing apparatus for polishing a surface of a workpiece, comprising:
   a turntable with an abrasive cloth mounted on an upper surface thereof;        a top ring positioned above said turntable for supporting the workpiece to be polished and pressing the workpiece against said abrasive cloth;        a top ring drive shaft coupled to said top ring;        a bearing interposed between said top ring and said top ring drive shaft for allowing said top ring to tilt upon changes in the inclination of said upper surface of said turntable;        a torque transmitter for transmitting torque from said top ring drive shaft to said top ring while permitting said top ring to tilt relative to said top ring drive shaft, said torque transmitter comprising a plurality of torque transmitting members provided at a substantially lower part of said top ring drive shaft and extending radially outwardly, said torque transmitting members transmitting torque at locations spaced from said top ring drive shaft; and        a damper provided between said top ring drive shaft and a stationary member for supporting said top ring drive shaft to dampen said top ring drive shaft.     
     
     
       31. The polishing apparatus according to  claim 30 , wherein said damper comprises an o- ring interposed between a radial bearing for supporting said top ring drive shaft and said stationary member.   
     
     
       32. The polishing apparatus according to  claim 30 , wherein said damper comprises oil supplying means for supplying oil into a space defined between said top ring drive shaft and said stationary member. 
     
     
       33. The polishing apparatus according to  claim 32 , further comprising a radial bearing interposed between said stationary member and said top ring drive shaft, and wherein said space is defined between said radial bearing and said stationary member. 
     
     
       34. The polishing apparatus according to  claim 22  or  30 , further comprising a transferring device provided in the vicinity of said turntable for transferring said workpiece between said transferring device and said top ring, said transferring device including a holder for holding said workpiece, and a shock absorber for resiliently supporting said holder so that said workpiece is not subject to impact force during the transfer process. 
     
     
       35. A polishing apparatus for polishing a surface of workpiece, comprising:
   a turntable with an abrasive cloth mounted on an upper surface thereof;        a top ring positioned above said turntable for supporting the workpiece to be polished and pressing the workpiece against said abrasive cloth;        a top ring drive shaft coupled to said top ring;        a bearing interposed between said top ring and said top ring drive shaft, said bearing allowing said top ring to tilt upon changes in the inclination of said upper surface of said turntable;        a damper provided between said top ring drive shaft and a stationary member for supporting said top ring drive shaft to dampen said top ring drive shaft; and        a pressure adjuster provided between said bearing and said top ring for adjusting a pressure distribution of a lower surface of said top ring, said pressure adjuster including an annular portion which contacts an upper surface of said top ring.     
     
     
       36. A polishing apparatus for polishing a surface of a workpiece, comprising:
   a turntable with an abrasive cloth mounted on an upper surface thereof;        a top ring for supporting the workpiece to be polished, said top ring having an upper top ring member connected to a lower top ring member, said lower top ring member having a plurality of suction holes therethrough connectable to a vacuum source, whereby the workpiece is attractable to a lower surface of said lower top ring member under a vacuum developed by said vacuum source;        a top ring drive shaft;        a bearing interposed between said top ring and said top ring drive shaft for allowing said top ring to tilt upon changes in the inclination of said upper surface of said turntable; and        a torque transmitter for transmitting torque from said top ring drive shaft to said upper top ring member while permitting said top ring to tilt relative to said top ring drive shaft, said torque transmitter including a damper for inhibiting the transmission of vibrations.     
     
     
       37. A polishing apparatus for polishing a surface of a workpiece, comprising:
   a turntable with an abrasive cloth mounted on an upper surface thereof;        a top ring for supporting the workpiece to be polished, said top ring having an upper top ring member connected to a lower top ring member, said lower top ring member having a plurality of suction holes therethrough connectable to a vacuum source, whereby the workpiece is attractable to a lower surface of said lower top ring member under a vacuum developed by said vacuum source;        a top ring drive shaft;        a bearing interposed between said top ring and top ring drive shaft for allowing said top ring to upon changes in the inclination of said upper surface of said turntable;        a plurality of biasing members rigidly attached to said ring; and        a damper provided between said top ring drive shaft and a stationary member supporting said top ring drive shaft to dampen said top ring drive shaft.     
     
     
       38. A polishing apparatus for polishing a surface of a workpiece, comprising:
   a turntable having an abrasive cloth at an upper surface thereof;        a top ring positioned above said turntable for supporting the workpiece to be polished and pressing the workpiece against said abrasive cloth;        a top ring drive shaft coupled to said top ring;        a bearing for allowing said top ring to tilt upon changes in the inclination of said upper surface of said turntable; and        a damper provided between said top ring drive shaft and a stationary member supporting said top ring drive shaft to dampen said top ring drive shaft.     
     
     
       39. The polishing apparatus according to  claim 38 , wherein said top ring includes an upper top ring member connected to a lower top ring member, said lower top ring member having a plurality of suction holes therethrough connectable to a vacuum source, whereby the workpiece is attractable to a lower surface of said lower top ring member under a vacuum developed by said vacuum source, wherein said upper top ring member includes an annular portion which contracts an upper surface of said lower top ring member. 
     
     
       40. The polishing apparatus according to  claim 39 , further comprising a torque transmitter for transmitting torque from said top ring drive shaft to said upper top ring member while permitting said top ring to tilt relative to said top ring drive shaft. 
     
     
       41. The polishing apparatus according to  claim 38 , further comprising a transferring device for transferring the workpiece from and to said top ring, said transferring device having a holder for holding the workpiece, said holder being elevated when the workpiece is transferred from and to said top ring, wherein said holder comprises a support member having a suction hole connected to a vacuum source for attracting the workpiece to said support member. 
     
     
       42. The polishing apparatus according to  claim 41 , further comprising a washing unit to wash the workpiece after the workpiece is received by said transferring device. 
     
     
       43. The polishing apparatus according to  claim 36 ,  37 , or  39 , wherein said top ring drive shaft and upper top ring member have vacuum passages therein connected to one another and connectable to said vacuum source, and wherein said vacuum passage in said upper top ring member is connected to the suction holes in said lower top ring member. 
     
     
       44. The polishing apparatus according to  claim 43 , wherein said upper and lower top ring members are shaped and disposed so as to form a vacuum manifold therebetween, each of said suction holes in said lower top ring member and said vacuum passage in said upper top ring member opening into said manifold. 
     
     
       45. A method of polishing a workpiece, comprising:
   holding a workpiece by a top ring;        rotating said top ring with respect to a turntable;        polishing said workpiece by pressing said workpiece against said turntable by said top ring;        moving said top ring holding said workpiece to a transfer device after polishing, said transferring device including a support member;        moving said transferring device so that said support member contacts said workpiece; and        transferring said workpiece from said top ring to said transferring device.     
     
     
       46. The method according to  claim 44 , wherein said support member has a suction hole connected to a vacuum source, so that the workpiece is attracted to said support member when said transferring device is moved toward said workpiece. 
     
     
       47. The method according to  claim 44 , wherein said support member has a pad thereon so that said pad contacts the workpiece when said transferring device is moved toward said workpiece. 
     
     
       48. The method according to  claim 45 , further comprising resiliently holding said top ring in a predetermined plane with respect to a top ring drive shaft while moving said top ring to said transferring device so that said support member contacts said workpiece.