Wafer polishing method and apparatus

Abstract

A wafer polishing apparatus includes a wafer polishing assembly having a plurality of wafer carriers for substantially simultaneously polishing a plurality of wafers against a rotating polishing surface. A plurality of wafers to be polished are substantially simultaneously loaded into the plurality of wafer carriers by wafer holding apparatus of an index table. Similarly, a plurality of wafer carriers are substantially simultaneously unloaded into wafer holding apparatus of the index table. The wafer carriers are individually computer controlled for exact polishing and different polishing requirements can be met at the same time by different wafer carriers.

What is claimed is:  
     
       1. Computer controlled apparatus for polishing a surface of a thin wafer material comprising: 
       a rotating polishing surface;  
       means for measuring the rotation rate of said polishing surface;  
       a wafer carrier for securing a thin wafer of material to a surface thereof;  
       air cylinder means for pressing a wafer secured to said wafer carrier against said polishing surface;  
       pressure sensing means for measuring the pressure applied by said wafer carrier to said polishing surface;  
       means for rotating said wafer carrier while said wafer of material is being pressed against said polishing surface;  
       means for measuring the rotation rate of said carrier;  
       means for establishing ranges of wafer carrier pressure, polishing table rotation rate and wafer carrier rotation rate; and  
       computer means responsive to said pressure sensing means, said means for sensing the polishing surface rotation rate and said means for sensing wafer carrier rotation rate for substantially continuously maintaining the pressure, polishing surface rotation rate and wafer carrier rotation rate within the ranges established by the means for establishing.  
     
     
       2. Apparatus in accordance with  claim 1  wherein said means for establishing ranges comprises a data input means responsive to operator interaction for establishing ranges of wafer carrier pressure, polishing surface rotation rate and wafer carrier rotation rate  module. 
     
     
       3. Apparatus in accordance with  claim 1  comprising means for oscillating said wafer carrier on said polishing surface; 
       oscillation measurement means for measuring the distance and rate of such wafer carrier oscillation; and  
       said computer means comprises means responsive to said oscillation measurement means for maintaining said wafer carrier oscillation within predetermined ranges.  
     
     
       4. The apparatus in accordance with  claim 2 , wherein said data input module further comprises an operator input interface. 
     
     
       5. The apparatus in accordance with  claim 1 , wherein said computer means is configured to maintain the wafer carrier pressure, the polishing surface rotation rate and the wafer carrier rotation rate within the established ranges by comparing an actual wafer carrier pressure, an actual polishing surface rotation rate and an actual wafer carrier rotation rate with the established ranges, and adjusting the actual wafer carrier pressure, the actual polishing surface rotation rate and the actual wafer carrier rotation rate to keep the actual wafer carrier pressure, the actual polishing surface rotation rate and the actual wafer carrier rotation rate within the established ranges. 
     
     
       6. The apparatus in accordance with  claim 1 , further comprising: 
       
         a load station for loading and securing the wafer to the surface of the wafer carrier prior to polishing the wafer, and an unload station for subsequently unloading the wafer from the wafer carrier after the wafer has been polished;  
       
       
         a polishing station which includes the rotating polishing surface, for polishing the surface of the workpiece; and  
       
       
         an airflow system for keeping particles that may exist in said polishing station from entering said load and unload station, so that said load and unload station is maintained at a cleaner clean room environment class than said polishing station. 
       
     
     
       7. The apparatus in accordance with  claim 1 , wherein said polishing surface comprises at least one polishing surface. 
     
     
       8. The apparatus in accordance with  claim 1 , further comprising a plurality of wafer carriers. 
     
     
       9. The apparatus in accordance with  claim 8 , wherein said computer means, said pressure sensing means and said air cylinder means are configured to control the pressure applied by each of said wafer carriers against said polishing surface independent of the pressure applied by the other wafer carriers. 
     
     
       10. The apparatus in accordance with  claim 8 , wherein said computer means, said means for measuring the rotation rate of said wafer carriers and said means for rotating said wafer carriers are configured to control the rotation rate of each of said wafer carriers independent of the rotation rate of the other wafer carriers. 
     
     
       11. The apparatus in accordance with  claim 8 , wherein at least one of said plurality of wafer carriers has a pressure or a rotation rate which is different from a pressure or rotation rate of at least one other of said plurality of wafer carriers. 
     
     
       12. The apparatus in accordance with  claim 3 , wherein said computer means is configured to maintain the wafer carrier pressure, the polishing surface rotation rate, the wafer carrier rotation rate, and the wafer carrier oscillation rate and distance within the established ranges by comparing an actual wafer carrier pressure, an actual polishing surface rotation rate, an actual wafer carrier rotation rate, and an actual wafer carrier oscillation rate and distance with the established ranges, and adjusting the actual wafer carrier pressure, the actual polishing surface rotation rate, the actual wafer carrier rotation rate, and the actual wafer carrier oscillation rate and distance to keep the actual wafer carrier pressure, the actual polishing surface rotation rate, the actual wafer carrier rotation rate, and the actual wafer carrier oscillation rate and distance within the established ranges. 
     
     
       13. The apparatus in accordance with  claim 3 , further comprising a plurality of wafer carriers. 
     
     
       14. The apparatus in accordance with  claim 13 , wherein said computer means, said oscillation measurement means and said means for oscillating said wafer carriers are configured to control the oscillation rate and distance of each of said wafer carriers on said polishing surface independent of the oscillation rate and distance of the other wafer carriers. 
     
     
       15. The apparatus in accordance with  claim 13 , wherein at least one of said plurality of wafer carriers has a pressure, a rotation rate or an oscillation rate which is different from a pressure, rotation rate or oscillation rate of at least one other of said plurality of wafer carriers. 
     
     
       16. A computer controlled apparatus for polishing a surface of a thin wafer material, comprising: 
       
         a rotating polishing surface;  
       
       
         surface rotation sensing means for measuring the rotation rate of said polishing surface;  
       
       
         a plurality of wafer carriers, wherein each of said wafer carriers is configured for securing a thin wafer of material to a surface thereof;  
       
       
         air cylinder means for pressing the wafers secured to each of said wafer carriers against said polishing surface;  
       
       
         pressure sensing means for measuring a pressure applied by each of said wafer carriers to said polishing surface;  
       
       
         wafer carrier rotation means for rotating each of said wafer carriers while said wafers are being pressed against said polishing surface;  
       
       
         wafer carrier rotation sensing means for measuring the rotation rate of each of said wafer carriers;  
       
       
         means for establishing ranges of polishing table rotation rate, and wafer carrier pressure and rotation rate for each of said wafer carriers; and  
       
       
         computer means responsive to said pressure sensing means, said surface rotation sensing means and said wafer carrier rotation sensing means for substantially continuously maintaining the polishing surface rotation rate, and the wafer carrier pressure and rotation rate for each of said wafer carriers within the ranges established by the means for establishing. 
       
     
     
       17. The apparatus in accordance with  claim 16 , wherein said means for establishing ranges comprises a data input module. 
     
     
       18. The apparatus in accordance with  claim 17 , wherein said data input module further comprises an operator input interface. 
     
     
       19. The apparatus in accordance with  claim 16 , wherein said computer means is configured to maintain the polishing surface rotation rate and the wafer carrier pressures and rotation rates for each of said wafer carriers within the established ranges by comparing an actual polishing surface rotation rate and actual wafer carrier pressures and rotation rates for each of said wafer carriers with the established ranges, and adjusting the actual polishing surface rotation rate and the actual wafer carrier pressures and rotation rates for each of said wafer carriers to keep the actual polishing surface rotation rate and the actual wafer carrier pressures and rotation rates for each of said wafer carriers within the established ranges. 
     
     
       20. The apparatus in accordance with  claim 16 , further comprising: 
       
         a load station for loading and securing the wafer to the surface of the wafer carrier prior to polishing the wafer, and an unload station for subsequently unloading the wafer from the wafer carrier after the wafer has been polished;  
       
       
         a polishing station, which includes the rotating polishing surface, for polishing the surface of the workpiece; and  
       
       
         an airflow system for keeping particles that may exist in said polishing station from entering said load and unload station, so that said load and unload station is maintained at a cleaner clean room environment class than said polishing station. 
       
     
     
       21. The apparatus in accordance with  claim 16 , wherein said polishing surface comprises at least one polishing surface. 
     
     
       22. The apparatus in accordance with  claim 16 , further comprising: 
       
         oscillating means for oscillating each of said wafer carriers on said polishing surface;  
       
       
         oscillation measurement means for measuring the distance and rate of each of said wafer carriers oscillation; and  
       
       
         said computer means further comprising means responsive to said oscillation measurement means for maintaining the oscillation of each of said wafer carriers within predetermined ranges. 
       
     
     
       23. The apparatus in accordance with  claim 16 , wherein said computer means, said pressure sensing means and said air cylinder means are configured to control the pressure applied by each of said wafer carriers against said polishing surface independent of the pressure applied by the other wafer carriers. 
     
     
       24. The apparatus in accordance with  claim 16 , wherein said computer means, said wafer carrier rotation sensing means and said wafer carrier rotation means are configured to control the rotation rate of each of said wafer carriers independent of the rotation rate of the other wafer carriers. 
     
     
       25. The apparatus in accordance with  claim 16 , wherein at least one of said plurality of wafer carriers has a pressure or a rotation rate which is different from a pressure or rotation rate of at least one other of said plurality of wafer carriers. 
     
     
       26. The apparatus in accordance with  claim 22 , wherein said computer means is configured to maintain the polishing surface rotation rate, and the wafer carrier pressures, rotation rates, and oscillation rates and distances for each of said wafer carriers within the established ranges by comparing an actual polishing surface rotation rate, and actual wafer carrier pressures, rotation rates, oscillation rates and distances for each of said wafer carriers with the established ranges and adjusting the actual polishing surface rotation rate, and the actual wafer carrier pressures, rotation rates, and oscillation rates and distances for each of said wafer carriers to keep the actual polishing surface rotation rate, and the actual wafer carrier pressures, rotation rates, oscillation rates and distances for each of said wafer carriers within the established ranges. 
     
     
       27. The apparatus in accordance with  claim 22 , wherein said computer means, said oscillation measurement means and said oscillating means are configured to control the oscillation rate and distance of each of said wafer carriers on said polishing surface independent of the oscillation rate and distance of the other wafer carriers. 
     
     
       28. The apparatus in accordance with  claim 22 , wherein at least one of said plurality of wafer carriers has a pressure, a rotation rate or an oscillation rate which is different from a pressure, rotation rate or oscillation rate of at least one other of said plurality of wafer carriers. 
     
     
       29. The apparatus for processing a thin wafer of material, comprising: 
       
         storage means for storing a plurality of input variables associated with a plurality of processes, wherein a first process of said plurality of processes is configured to control an operation at a first station and a second process of said plurality of processes is configured to control an operation at a second station;  
       
       
         computer means for controlling said plurality of processes and for executing and for resetting said first process and for executing said second process, based upon at least some of said input variables;  
       
       
         coupling means for coupling said storage means to said computer means; and  
       
       
         condition indicating means coupled to said computer means for indicating to said computer means when a condition in said first process is met;  
       
       
         wherein said computer means is responsive to an indication of a condition by said condition indicating means so as to reset said first process while continuing to execute said second process. 
       
     
     
       30. The apparatus as recited in  claim 29 , wherein said condition is an error condition. 
     
     
       31. The apparatus as recited in  claim 29 , wherein said condition is a ready condition, such that said computer means optimizes the efficiency of said apparatus by resetting and running said first process when said first process is ready while continuing to execute said second process. 
     
     
       32. The apparatus as recited in  claim 29 , wherein said plurality of processes comprises at least one of the following routines: 
         start - up; input; load; unload; polish; and cleaning workpieces.   
     
     
       33. The apparatus as recited in  claim 29 , wherein said first process is commenced in accordance with the current status of said second process. 
     
     
       34. The apparatus as recited in  claim 29 , wherein said first process is associated with operations carried out at said first station and said second process is associated with operations carried out at a second station. 
     
     
       35. An apparatus for processing a thin wafer of material, comprising: 
       
         first and second stations for performing operations on said wafer; and  
       
       
         computer means for carrying out a plurality of processes;  
       
       
         wherein said computer means is coupled to said first and said second stations to control operations of said first and said second stations and to detect conditions associated with said first and said second stations, and wherein said computer means starts a new process in response to the detecting of a condition while conducting a second process. 
       
     
     
       36. The apparatus as recited in  claim 35 , wherein said condition occurs in said second station and said new process controls the operation of said second station. 
     
     
       37. The apparatus as recited in  claim 35 , wherein said condition occurs in said second station, and wherein said new process controls operation of said first station. 
     
     
       38. A control system for controlling a wafer processing system including at least a first station and a second station, comprising: 
       
         a memory for storing data associated with a plurality of processes; and  
       
       
         a processor coupled to said memory;  
       
       
         wherein said processor is configured for executing a first process and a second process of said plurality of processes, said first process being configured to control an operation of said first station, said first process having a condition; and  
       
       
         wherein said processor is further configured to reset said first process when said condition in said first process is met while continuing to execute said second process. 
       
     
     
       39. The apparatus as recited in  claim 38 , wherein said condition is an error condition. 
     
     
       40. The control system as recited in  claim 38 , wherein said condition is a ready condition, such that said computer means optimizes the efficiency of said apparatus by resetting and running said first process when said first process is ready while continuing to execute said second process. 
     
     
       41. The apparatus as recited in  claim 38 , wherein said plurality of processes comprises at least one of the following routines: 
         start - up; input; load; unload; polish; and cleaning workpieces.   
     
     
       42. The apparatus as recited in  claim 38 , wherein said first process is commenced in accordance with the current status of said second process. 
     
     
       43. A method for polishing a surface of a thin wafer of material, the steps comprising: 
       ( a )  providing a rotating polishing surface, a wafer carrier for securing a thin wafer of material to a surface thereof, and a computer for controlling the operation of said polishing surface and said wafer carrier;    
       ( b )  establishing ranges of polishing surface rotation rate, wafer carrier rotation rate and wafer polishing pressure;    
       ( c )  rotating said polishing surface at a rotation rate within the range established in step  ( b ) , and monitoring and adjusting the rotation rate of said polishing surface so that the rotation rate is maintained within the established range;    
       ( d )  rotating said wafer carrier at a rotation rate within the range established in step  ( b ) , and monitoring and adjusting the rotation rate of said wafer carrier so that the rotation rate of said wafer carrier is maintained within the established range; and    
       ( e )  using said wafer carrier, pressing said wafer against said polishing surface with a pressure that is within the wafer polishing pressure range established in step  ( b ) , and monitoring and adjusting the pressure applied to said wafer against said polishing surface so that the pressure is maintained within the established wafer polishing pressure range.   
     
     
       44. The method as recited in  claim 43 , further comprising the steps of: 
       ( f )  establishing ranges of oscillation distance and rate for said wafer carrier on said polishing surface; and    
       ( g )  oscillating said wafer carrier a distance and at a rate within the ranges established in step  ( b ) , and monitoring and adjusting the oscillation distance and rate of said wafer carrier so that they are maintained within the established ranges.   
     
     
       45. A method for polishing a respective surface of each of a plurality of thin wafers, comprising the steps of: 
       ( a )  providing a rotating polishing surface, a plurality of wafer carriers, wherein each of said wafer carriers is configured to secure one of said wafers to a surface thereof, and a computer for controlling the operation of said polishing surface and said plurality of wafer carriers;    
       ( b )  establishing ranges of polishing surface rotation rate, and wafer polishing pressure and wafer carrier rotation rate for each one of said plurality of wafer carriers, wherein said wafer polishing pressure ranges and said wafer carrier rotation rate ranges may differ for each one of said wafer carriers;    
       ( c )  rotating said polishing surface at a rotation rate within the range established in step  ( b )  and monitoring and adjusting the rotation rate of said polishing surface so that the rotation rate is maintained within the established range;    
       ( d )  rotating each one of said plurality of wafer carriers at a rotation rate within the ranges established in step  ( b ) , and monitoring and adjusting the rotation rate of each one of said plurality of wafer carriers so that the rotation rate of each one of said plurality of wafer carriers is maintained within the established ranges; and    
       ( e )  using each one of said plurality of wafer carriers, pressing each one of said plurality of wafers secured to each one of said plurality of wafer carriers against said polishing surface with a pressure that is within the wafer polishing pressure ranges established in step  ( b )  for each one of said plurality of wafer carriers, and monitoring and adjusting the pressures applied to each one of said wafers against said polishing surface so that the pressures are maintained within the established wafer polishing pressure ranges.   
     
     
       46. The method as recited in  claim 45 , further comprising the steps of: 
       ( f )  establishing ranges of oscillation distance and rate for each one of said wafer carriers on said polishing surface, wherein said oscillation distance and rate ranges may differ for each one of said wafer carriers; and    
       ( g )  oscillating each one of said wafer carriers a distance and at a rate within the ranges established in step  ( b ) , and monitoring and adjusting the oscillation distance and rate of each one of said wafer carriers so that they are maintained within the established ranges.   
     
     
       47. A method for processing a thin wafer of material, comprising the steps of: 
       ( a )  providing a wafer processing system comprising a first station and a second station for performing operations on a wafer, and a control system including a memory and a processor, said control system configured for executing a plurality of processes so as to control said wafer processing system;    
       ( b )  executing a first process of said plurality of processes, said first process configured for controlling an operation at said first station;    
       ( c )  executing, a second process of said plurality of processes, said second process configured for controlling an operation at said second station, wherein said second process executes at least partly simultaneously with said first process;    
       ( d )  during the execution of said first process, monitoring said first process for an occurrence of a condition; and    
       ( e )  upon the occurrence of said condition in said first process, resetting said first process while continuing to execute said second process.   
     
     
       48. Computer controlled apparatus for polishing a surface of a thin wafer of material, comprising: 
       
         a moving polishing surface;  
       
       
         means for measuring the rate of movement of said polishing surface;  
       
       
         a wafer carrier for securing a thin wafer of material to a surface thereof;  
       
       
         air cylinder means for pressing a wafer secured to said wafer carrier against said polishing surface;  
       
       
         pressure sensing means for measuring the pressure applied by said wafer carrier to said polishing surface;  
       
       
         means for rotating said wafer carrier while said wafer of material is being pressed against said polishing surface;  
       
       
         means for measuring the rotation rate of said carrier;  
       
       
         means for establishing ranges of wafer carrier pressure, polishing surface movement rate and wafer carrier rotation rate; and  
       
       
         computer means responsive to said pressure sensing means, said means for sensing the polishing surface movement rate and said means for sensing wafer carrier rotation rate for substantially continuously maintaining the pressure, the polishing surface movement rate and the wafer carrier rotation rate within the ranges established by the means for establishing. 
       
     
     
       49. The apparatus in accordance with  claim 48 , wherein said means for establishing ranges comprises a data input module. 
     
     
       50. The apparatus in accordance with  claim 48 , wherein said data input module further comprises an operator input interface. 
     
     
       51. The apparatus in accordance with  claim 48 , wherein said computer means is configured to maintain the wafer carrier pressure, the polishing surface movement rate and the wafer carrier rotation rate within the established ranges by comparing an actual wafer carrier pressure, an actual polishing surface movement rate and an actual wafer carrier rotation rate with the established ranges, and adjusting the actual wafer carrier pressure, the actual polishing surface movement rate and the actual wafer carrier rotation rate to keep the actual wafer carrier pressure, the actual polishing surface movement rate and the actual wafer carrier rotation rate within the established ranges. 
     
     
       52. The apparatus in accordance with  claim 48 , further comprising: 
       
         a load station for loading and securing the wafer to the surface of the wafer carrier prior to polishing the wafer, and an unload station for subsequently unloading the wafer from the wafer carrier after the wafer has been polished;  
       
       
         a polishing sation, which includes the rotating polishing surface, for polishing the surface of the workpiece; and  
       
       
         an airflow system for keeping particles that may exist in said polishing station from entering said load and unload station, so that said load and unload station is maintained at a cleaner clean room environment class. 
       
     
     
       53. The apparatus in accordance with  claim 48 , wherein said polishing surface comprises at least one polishing surface. 
     
     
       54. The apparatus in accordance with  claim 48 , further comprising a plurality of wafer carriers. 
     
     
       55. The apparatus in accordance with  claim 48 , wherein said computer means, said pressure sensing means and said air cylinder means are configured to control the pressure applied by each of said wafer carriers against said polishing surface independent of the pressure applied by the other wafer carriers. 
     
     
       56. The apparatus in accordance with  claim 54 , wherein said computer means, said means for measuring the rotation rate of said wafer carriers and said means for rotating said wafer carriers are configured to control the rotation rate of each of said wafer carriers independent of the rotation rate of the other wafer carriers. 
     
     
       57. The apparatus in accordance with  claim 54 , wherein at least one of said plurality of wafer carriers has a pressure or a rotation rate which is different from a pressure or rotation rate of at least one other of said plurality of wafer carriers. 
     
     
       58. The apparatus in accordance with  claim 48 , further comprising: 
       
         means for oscillating said wafer carrier on said polishing surface;  
       
       
         oscillation measurement means for measuring the distance and rate of such wafer carrier oscillation; and  
       
       
         said computer means comprises means responsive to said oscillation measurement means for maintaining said wafer carrier oscillation within predetermined ranges. 
       
     
     
       59. The apparatus in accordance with  claim 58 , wherein said computer means is configured to maintain the wafer carrier pressure, the polishing surface movement rate, the wafer carrier rotation rate, and the wafer carrier oscillation rate and distance within the established ranges by comparing an actual wafer carrier pressure, an actual polishing surface movement rate, an actual wafer carrier rotation rate, and an actual wafer carrier oscillation rate and distance with the established ranges, and adjusting the actual wafer carrier pressure, the actual polishing surface movement rate, the actual wafer carrier rotation rate, and the actual wafer carrier oscillation rate and distance to keep the actual wafer carrier pressure, the actual polishing surface movement rate, the actual wafer carrier rotation rate, and the actual wafer carrier oscillation rate and distance within the established ranges. 
     
     
       60. The apparatus in accordance with  claim 58 , further comprising a plurality of wafer carriers. 
     
     
       61. The apparatus in accordance with  claim 60 , wherein said computer means, said oscillation measurement means and said means for oscillating said wafer carriers are configured to control the oscillation rate and distance of each of said wafer carriers on said polishing surface independent of the oscillation rate and distance of the other wafer carriers. 
     
     
       62. The apparatus in accordance with  claim 61 , wherein at least one carrier has a pressure a rotation rate or an oscillation rate which is different from a pressure, rotation rate or oscillation rate of at least one other carrier.