Apparatus for and method for polishing workpiece

Abstract

A polishing apparatus for polishing a workpiece such as a semiconductor wafer has a turntable with a polishing surface, and a top ring for holding a workpiece and pressing the workpiece against the polishing surface under a first pressing. The polishing apparatus has a pressurized fluid source for supplying pressurized fluid, and a plurality of openings provided in the holding surface of the top ring for ejecting the pressurized fluid supplied from the pressurized fluid source. A plurality of areas each having the openings are defined on the holding surface so that the pressurized fluid is selectively ejectable from the openings in the respective areas.

1. A polishing apparatus for polishing a surface of a workpiece comprising:
 a turntable having a polishing surface thereon;    a top ring for supporting the workpiece to be polished and pressing the workpiece against said polishing surface under a first pressing force, said top ring having a holding surface for holding the workpiece;    a pressurized fluid source for supplying pressurized fluid;    a plurality of openings provided in said holding surface of said top ring for ejecting said pressurized fluid supplied from said pressurized fluid source, a plurality of areas each having said openings being defined in said holding surface so that said pressurized fluid is selectively ejectable from said openings in said respective areas.    
     
     
       2. An apparatus according to  claim 1 , wherein said plurality of areas comprises concentric annular areas. 
     
     
       3. An apparatus according to  claim 1 , wherein said plurality of areas are defined by communicating with a plurality of chambers, respectively formed in said top ring through said openings. 
     
     
       4. An apparatus according to  claim 1 , wherein said first pressing force and a pressure of said pressurized fluid are variable independently of each other. 
     
     
       5. An apparatus according to  claim 1 , wherein a pressure of said pressurized fluid is variable in each of said areas. 
     
     
       6. An apparatus according to  claim 1 , further comprising: a presser ring vertically movably disposed around said top ring; and
 a pressing device for pressing said presser ring against said polishing surface under a second pressing force which is variable.    
     
     
       7. An apparatus according to  claim 1 , wherein said top ring has a recess defined therein for accommodating the workpiece therein. 
     
     
       8. A method of polishing a workpiece, comprising the steps of:
 holding a workpiece between a polishing surface of a turntable and a holding surface of a top ring disposed above said turntable;    pressing the workpiece by said top ring against said polishing surface under a first pressing force; and    ejecting pressurized fluid from openings in a plurality of areas in said holding surface of said top ring toward the workpiece held by said top ring, said pressurized fluid being selectively ejectable from said openings in said respective areas; and    polishing the workpiece in such a state that a pressing force applied to the workpiece by said pressurized fluid is variable in a central portion and an outer circumferential portion of the workpiece, respectively.    
     
     
       9. A method according to  claim 8 , further comprising the step of:
 pressing a presser ring vertically movably disposed around said top ring against said polishing surface around the workpiece under a second pressing force which is determined based on said first pressing force.    
     
     
       10. A method according to  claim 8 , said second pressing force is determined on the basis of a pressure distribution on the workpiece caused by said pressurized fluid ejected from said openings in said respective areas. 
     
     
       11. A top ring for supporting the workpiece to be polished, for use in a polishing apparatus, comprising:
 a holding surface for holding the workpiece; and    a plurality of openings, provided in said holding surface, from which pressurized fluid is ejected, a plurality of areas each having said openings being defined in said holding surface so that said pressurized fluid is selectively ejectable from said openings in said respective areas.    
     
     
       12. A method of polishing a surface of a workpiece, comprising:
   holding a workpiece by a top ring; and        pressing the workpiece against a polishing surface of a turntable to polish a surface of the workpiece so that an annular area of said workpiece is selectively pressed,        wherein polishing pressures applied to said workpiece are controlled on the basis of pressures detected by pressure sensors.     
     
     
       13. A method according to  claim 12 , wherein said annular area of said workpiece is an outer circumferential portion of said workpiece. 
     
     
       14. A method according to  claim 12 , further comprising applying a pressure to a presser ring vertically movably disposed around said top ring for pressing and polishing surface. 
     
     
       15. A method according to  claim 12 , wherein each of said pressures applied to the workpiece and said presser ring is produced by air pressure. 
     
     
       16. A method of polishing a surface of a workpiece, comprising:
   holding a workpiece by a top ring;        pressing the workpiece against a polishing surface of a turntable so that a polishing pressure applied to a central portion of the workpiece is different from a polishing pressure applied to an outer circumferential portion of the workpiece to polish a surface of the workpiece; and        applying a pressure which is independently variable to a presser ring vertically movably disposed around said top ring for pressing said polishing surface,        wherein said polishing pressure applied to the central portion of the workpiece and said polishing pressure applied to the outer circumferential portion of the workpiece as controlled on the basis of pressures detected by pressure sensors.     
     
     
       17. A method of polishing a surface of a workpiece, comprising:
   holding a workpiece on an elastic pad attached to a lower surface of a top ring; and        pressing the workpiece against a polishing surface of a turntable to polish a surface of the workpiece by applying at least two pressures through said elastic pad to substantially concentric circular areas of the workpiece, respectively.     
     
     
       18. A method of polishing a surface of a workpiece, comprising:
   holding a workpiece on an elastic pad attached to a lower surface of a top ring; and        pressing the workpiece against a polishing surface of a turntable to polish a surface of the workpiece by applying at least two pressures to two chambers configured above a central portion and an outer circumferential portion of the workpiece, respectively, and through said elastic pad.     
     
     
       19. A method of polishing a surface of a workpiece, comprising:
   holding a workpiece by a top ring;        pressing the workpiece against a polishing surface of a turntable to polish a surface of the workpiece so that at least two pressures are applied to the workpiece and are different in a central portion and in an outer circumferential portion of the workpiece; and        applying a pressure to a presser ring vertically movably disposed around said top ring by air pressure for pressing said polishing surface,        wherein said at least two pressures are controlled on the basis of pressures detected by pressure sensors.     
     
     
       20. A method of polishing a surface of a workpiece, comprising:
   holding a workpiece by a top ring;        applying air pressure to an interior of said top ring so that the polishing pressures applied to the workpiece are different at different radial portions of said workpiece; and        applying a pressure to a presser ring vertically movably disposed around said top ring by air pressure for pressing and polishing surface,        wherein said polishing pressures are controlled on the basis of pressures detected by pressure sensors.     
     
     
       21. A polishing apparatus for polishing a surface of a workpiece comprising:
   a turntable having a polishing surface thereon;        a top ring supporting the workpiece to be polished to polish a surface of the workpiece on said polishing surface,        a presser ring vertically movably disposed around said top ring, said presser ring being movable with respect to said top ring; and        a pressing mechanism for providing polishing pressures on the workpiece by air pressure,        wherein said polishing pressures are different in a central portion and an outer circumferential portion of the workpiece, and        wherein said presser ring is pressed against said polishing surface under a variable pressure independently of said polishing pressures.     
     
     
       22. A polishing apparatus according to  claim 21 , wherein said pressing force has gradient so as to be higher or lower progressively from the central area to the outer circumferential area of the workpiece. 
     
     
       23. A polishing apparatus according to  claim 21 , wherein the pressure applied to a central portion of the workpiece is larger than the pressure applied to an outer circumferential portion of the workpiece. 
     
     
       24. A polishing apparatus according to  claim 21 , wherein the pressure applied to an outer circumferential portion of the workpiece is larger than the pressure applied to a central portion of the workpiece. 
     
     
       25. A polishing apparatus for polishing a surface of a workpiece comprising:
   a turntable having a polishing surface thereon;        a top ring for supporting the workpiece to be polished on a holding surface of said top ring and        pressing the workpiece against said polishing surface;        a first pressing device for pressing said top ring against said polishing surface under a first pressing force;        a presser ring vertically movable disposed around said top ring;        a second pressing device for pressing said presser ring against said polishing surface under a second pressing force, said second pressing force being variable with respect to said first pressing force; and        a pressing mechanism for providing a third pressing force onto the workpiece, said third pressing force being different in a central portion and an outer circumferential portion of the workpiece,        wherein said third pressing force is controlled on the basis of pressures detected by pressure sensors.     
     
     
       26. A polishing apparatus according to  claim 25 , wherein said pressing force has gradient force so as to be higher or lower progressively from the central area to the outer circumferential area of the workpiece. 
     
     
       27. A polishing apparatus according to  claim 25 , wherein the pressure applied to a central portion of the workpiece is larger than the pressure applied to an outer circumferential portion of the workpiece. 
     
     
       28. A polishing apparatus according to  claim 25 , wherein the pressure applied to an outer circumferential portion of the workpiece is larger than the pressure applied to a central portion of the workpiece. 
     
     
       29. A polishing apparatus according to  claim 25 , wherein said pressing mechanism provides said third pressing force by air pressure. 
     
     
       30. A polishing apparatus according to  claim 25 , wherein said first pressing device and second pressing device provide said first and second forces by air pressure. 
     
     
       31. A polishing apparatus for polishing a surface of a workpiece comprising:
   a turntable having a polishing surface thereon;        a top ring for supporting the workpiece to be polished on a holding surface of said top ring;        a pressing mechanism for pressing the workpiece against said polishing surface of said turntable so that a polishing pressure applied to a central portion of the workpiece is different from a polishing pressure applied to an outer circumferential portion of the workpiece to polish a surface of the workpiece; and        a presser ring vertically movably disposed around said top ring, said presser ring being movable with respect to said top ring, and pressed against said polishing surface by air pressure,        wherein said polishing pressure applied to said central portion and said polishing pressure applied to said outer circumferential portion are controlled on the basis of pressures detected by pressure sensors.     
     
     
       32. A workpiece carrier for holding a workpiece and pressing the workpiece against a polishing surface, and workpiece carrier comprising:
   a top ring for supporting the workpiece to be polished; and        at least two pressurized chambers provided in said top ring and to which pressurized fluid is supplied, said at least two pressurized chambers comprising a central circular chamber and an annular chamber located outside of said central circular chamber,        said central circular chamber and said annular chamber being positionable over a central circular area and an annular area of the workpiece, respectively,        wherein a first polishing pressure applied to the central circular area of the workpiece and a second polishing pressure applied to the annular area of the workpiece are created by said pressurized fluid supplied to said central circular chamber and said annular chamber, respectively,        wherein said first polishing pressure and second polishing pressure are controlled on the basis of pressures detected by pressure sensors.     
     
     
       33. A polishing apparatus for polishing a surface of a workpiece, said polishing apparatus comprising:
   a turntable having a polishing surface thereon;        a top ring for supporting the workpiece to be polished; and        a pressing mechanism for pressing the workpiece against said polishing surface, said pressure mechanism being capable of applying a first polishing pressure to a central circular area of the workpiece and a second polishing pressure to a first annular area of the workpiece located outside of the central circular area, said first polishing pressure and said second polishing pressure being controllable independently of each other on the basis of pressures detected by pressure sensors.     
     
     
       34. The polishing apparatus is claimed in  claim 33 , wherein said pressing mechanism comprises at least two pressurized chambers to which pressurized fluid is supported, said at least two pressurized chambers comprising a central circular chamber and a first annular chamber located outside of said central circular chamber,
   wherein said central circular chamber and said first annular chamber are configured to correspond to the central circular area and the first annular area of the workpiece, respectively,        wherein the first polishing pressure and the second polishing pressure can be created by the pressurized fluid being supplied to said central circular chamber and said first annular chamber, respectively.     
     
     
       35. The polishing apparatus as claimed in  claim 34 , wherein said first polishing pressure and said second polishing pressure are controllable independently of each other during polishing. 
     
     
       36. The polishing apparatus as claimed in  claim 33 , wherein said first polishing pressure and said second polishing pressure can be substantially uniformly applied in each of said areas of the workpiece. 
     
     
       37. The polishing apparatus as claimed in  claim 33 , wherein said first polishing pressure and said second polishing pressure are controllable by varying fluid pressure. 
     
     
       38. The polishing apparatus as claimed in  claim 34 , wherein said pressurized fluid comprises pressurized air. 
     
     
       39. The polishing apparatus as claimed in  claim 34 , further comprising a second annular chamber located outside of said first annular chamber and configured to correspond to a second annular area of the workpiece that is located outside of the first annular area of the workpiece, wherein a third polishing pressure can be applied to said second annular area and is created by pressurized fluid being supplied to said second annular chamber. 
     
     
       40. The polishing apparatus as claimed in  claim 39 , wherein the pressurized fluid supplied to said second annular chamber comprises pressurized air. 
     
     
       41. A polishing apparatus for polishing a surface of a workpiece, said polishing apparatus comprising:
   a turntable having a polishing surface thereon;        a top ring for supporting the workpiece to be polished;        three pressurized chambers provided in said top ring to which pressurized fluid is supplied, said three pressurized chambers comprising a central circular chamber, a first annular chamber located outside of said central circular chamber, and a third annular chamber located outside of said first annular chamber,        wherein said pressurized chambers can be positioned above the workpiece so that a first polishing pressure can be applied to a central circular area of the workpiece, a second polishing pressure can be applied to a first annular area of the workpiece located outside of the central circular area, and a third polishing pressure can be applied to a second annular area of the workpiece located outside of the first annular area of the workpiece,        wherein the first, second and third polishing pressures can be created by pressurizing fluid being supplied to said first central circular chamber, said annular chamber and said third annular chamber, respectively, and        wherein at least one of said three pressurized chambers has an opening defined in a surface on which the workpiece is held.     
     
     
       42. A polishing apparatus for polishing a surface of a workpiece, said polishing apparatus comprising:
   a turntable having a polishing surface thereon;        a top ring for supporting the workpiece to be polished;        at least two pressurized chambers provided in said top ring to which pressurized fluid is supplied,        said at least two pressurized chambers comprising a central circular chamber and an annular chamber located outside of said central circular chamber,        wherein said central circular chamber and said annular chamber are configured so as to be positionable over a central circular area and an annular area of the workpiece, respectively,        wherein a first polishing pressure can be applied to said central circular area of the workpiece and a second polishing pressure can be applied to the annular area of the workpiece, said first and second polishing pressures being created by said pressurized fluid being supplied to said central circular chamber and said first annular chamber, respectively; and        a presser ring vertically movable with respect to said top ring, wherein said presser ring is adapted to be pressed against said polishing surface,        wherein at least one of said at least two pressurized chambers has an opening defined in a surface on which the workpiece is held.     
     
     
       43. A method for polishing a surface of a workpiece, the method comprising:
   holding a workpiece by a top ring;        pressurizing a central circular chamber in the top ring to apply a first pressure to a central circular area of the workpiece;        pressurizing a first annular chamber in the top ring to apply a second pressure to a first annular area of the workpiece located outside of the central circular area of the workpiece;        pressurizing a second annular chamber in the top ring to apply a third pressure to a second annular area of the workpiece located outside of the first annular area of the workpiece; and        controlling the first pressure and the second pressure and the third pressure on the basis of pressures detected by pressure sensors.     
     
     
       44. A polishing apparatus for polishing a surface of a workpiece, comprising:
   a turntable having a polishing surface thereon;        a top ring to support the workpiece to be polished on a holding surface of said top ring;        a presser ring vertically movably disposed around said top ring;        a mechanism to move said top ring vertically so that said top ring moves toward and away from said polishing surface;        a pressing mechanism to provide a first pressing force onto the workpiece, said first pressing force being different in a central portion and an outer circumferential portion of the workpiece; and        a pressing ticket to press and presser ring against said polishing surface under a second pressing force, said second pressing force being independently controllable with respect to said first pressing force,        wherein said first pressing force is controlled on the basis of pressures detected by pressure sensors.     
     
     
       45. A polishing apparatus for polishing a surface comprising:
   a turntable having a polishing surface thereon;        a top ring for supporting the workpiece to be polished and pressing the workpiece against said polishing surface under a first pressing force, said top ring having a surface area facing downward to be directed toward the workpiece when the workpiece is held by said top ring;        a pressurized fluid source for supplying pressurized fluid;        a plurality of openings provided in said surface area of said top ring for ejecting said pressurized fluid supplied from said pressurized fluid source, a plurality of areas each having said openings being defined so that said pressurized fluid is selectively ejectable from said openings in said respective areas.     
     
     
       46. The polishing apparatus of  claim 45 , and further comprising a material disposed at said surface for pressing against the wafer. 
     
     
       47. The polishing apparatus of  claim 46 , wherein said material comprises an elastic pad. 
     
     
       48. The polishing of  claim 47 , wherein said elastic pad comprises through holes therein for communication with said plurality of openings in said surface of said top ring. 
     
     
       49. A polishing apparatus for polishing a surface of a workpiece comprising:
   a turntable having a polishing surface thereon;        a pressurized fluid source;        a top ring connected with said pressurized fluid source and having upper side and a lower side for facing and applying pressure to a workpiece to be polished;        fluid openings on said lower side of said top ring body provided in a plurality of areas on said lower side and connected with said pressurized fluid source so as to be capable of selectively and independently providing a fluid pressure to said plurality of areas on said lower side.     
     
     
       50. The polishing apparatus of  claim 49 , and further comprises a material disposed at said lower side for pressing against the wafer. 
     
     
       51. The polishing apparatus of  claim 50 , wherein said material comprises an elastic pad. 
     
     
       52. The polishing apparatus of  claim 51 , wherein said elastic pad comprises through holes therein for communication with said plurality of openings in said lower side of said top ring. 
     
     
       53. The polishing apparatus for polishing a surface of a workpiece comprising:
   a turntable having a polishing surface thereon;        a top ring for supporting the workpiece to be polished and pressing the workpiece against said polishing surface, said top ring comprising:        a holding surface for holding the workpiece;        a plurality of openings provided in said holding surface; and        a plurality of chambers connected to a pressurized fluid source, each of said chambers is communicated with at least one of said openings so that said holding surface is divided to a plurality of areas, each of which related to each of said chambers respectively.     
     
     
       54. An apparatus according to  claim 53 , wherein said plurality of areas comprises concentric annular areas. 
     
     
       55. An apparatus according to  claim 53 , further comprising:
   a plurality of regulators through which said chambers are connected to said pressurized fluid source so that pressures supplied to said chambers are independently controllable.     
     
     
       56. An apparatus according to  claim 53 , further comprising:
   a presser ring disposed around and holding surface; and        a pressing device for pressing said pressing ring against said polishing surface by a pressure of a pressurized fluid.     
     
     
       57. A workpiece supporting and pressing apparatus comprising:
   a holding surface made of an elastic material for holding a workpiece to be polished;        a circular chamber positioned above a central area of said holding surface;        a first annular chamber positioned above an annular area surrounding said central area of said holding surface; and        a plurality of openings provided in said holding surface and communicated with each of said circular chamber and said first annular chamber respectively;        wherein each pressure of said circular chamber and said first annular chamber is independently controllable.     
     
     
       58. A workpiece supporting and pressing apparatus according to  claim 57 , further comprising:
   a second annular chamber positioned above an annular area surrounding said annular area of said holding surface;        wherein some of said plurality of openings are communicated with said second annular chamber, and pressure of said annular chamber is independently controllable.     
     
     
       59. A workpiece supporting and pressing apparatus comprising:
   a holding surface made of an elastic material for holding a workpiece to be polished;        a first chamber positioned above said holding surface;        a second chamber positioned above said holding surface;        a first group of openings provided in said holding surface and communicated with said first chamber; and        a second group of openings provided in said holding surface and communicated with said second chamber.