Methods and apparatus for adjusting beam parallelism in ion implanters

Abstract

Methods and apparatus for implanting ions in a workpiece, such as a semiconductor wafer, include generating an ion beam, measuring parallelism of the ion beam, adjusting the ion beam for a desired parallelism based on the measured parallelism, measuring a beam direction of the adjusted ion beam, orienting a workpiece at an implant angle referenced to the measured beam direction and performing an implant with the workpiece oriented at the implant angle referenced to the measured beam direction. The implant may be performed with a high degree of beam parallelism.

1. A method for implanting ions into a workpiece, comprising the steps of:
 generating an ion beam;  
 adjusting the ion beam for a desired measure of parallelism in a plane;  
 measuring a beam direction of the adjusted ion beam in said plane without implanting any workpiece with the ion beam;  
 tilting a workpiece about an axis perpendicular to said plane at an implant angle referenced to the measured beam direction; and  
 performing an  the implant with the workpiece tilted at the implant angle.  
 
     
     
       2. A method as defined in  claim 1 , wherein the step of adjusting the ion beam comprises adjusting the ion beam for substantially parallel ion trajectories. 
     
     
       3. A method as defined in  claim 2 , wherein the beam direction differs from a reference direction by a beam angle. 
     
     
       4. A method as defined in  claim 1 , wherein the step of tilting a workpiece comprises tilting a semiconductor wafer at the implant angle referenced to the measured beam direction. 
     
     
       5. A method as defined in  claim 1 , wherein the implant angle is zero degrees and the workpiece is tilted normal to the measured beam direction. 
     
     
       6. A method as defined in  claim 1 , further comprising the step of measuring an angle of non-parallelism of the ion beam, wherein the step of adjusting the ion beam is based on the measured angle of non-parallelism. 
     
     
       7. A method as defined in  claim 6 , wherein the beam direction and the angle of non-parallelism of the ion beam are measured with a movable beam profiler and one or more beam detectors. 
     
     
       8. A method for implanting ions into a workpiece, comprising the steps of:
 generating an ion beam;  
 measuring parallelism of the ion beam in a plane;  
 adjusting the ion beam in said plane for a desired parallelism based on the measured parallelism;  
 measuring a beam direction of the adjusted ion beam in said plane without implanting any workpiece with the ion beam;  
 tilting a workpiece about an axis perpendicular to said plane at an implant angle referenced to the measured beam direction; and  
 performing an implant with the workpiece tilted at the implant angle referenced to the measured beam direction.  
 
     
     
       9. A method as defined in  claim 8 , wherein the step of adjusting the ion beam comprises adjusting the ion beam for substantially parallel ion trajectories. 
     
     
       10. A method as defined in  claim 8 , wherein the implant angle is zero degrees and the workpiece is tilted normal to the measured beam direction. 
     
     
       11. A method as defined in  claim 8 , wherein the step of measuring parallelism of the ion beam comprises the step of measuring an angle of non-parallelism of the ion beam and wherein the step of adjusting the ion beam is based on the measured angle of non-parallelism. 
     
     
       12. A method as defined in  claim 11  wherein the angle of non-parallelism and the beam direction are measured with a movable beam profiler and one or more beam detectors. 
     
     
       13. A method as defined in  claim 8  wherein the step of tilting a workpiece comprises tilting a semiconductor wafer. 
     
     
       14. Apparatus for implanting ions into a workpiece, comprising:
 means for generating an ion beam;  
 means for measuring parallelism of the ion beam in a plane;  
 means for adjusting the ion beam in said plane for a desired parallelism based on the measured parallelism;  
 means for measuring a beam direction of the adjusted ion beam in said plane without implanting any workpiece with the ion beam;  
 means for tilting a workpiece about an axis perpendicular to said plane at an implant angle referenced to the measured beam direction; and  
 means for performing an implant with the workpiece tilted at the implant angle referenced to the measured beam direction.  
 
     
     
       15. Apparatus as defined in  claim 14 , wherein said means for adjusting the ion beam comprises means for adjusting the ion beam for substantially parallel trajectories. 
     
     
       16. Apparatus as defined in  claim 14 , wherein the implant angle is zero degrees and the workpiece is tilted normal to the measured beam direction. 
     
     
       17. Apparatus as defined in  claim 14 , wherein said means for measuring parallelism and said means for measuring the beam direction comprises a movable beam profiler and one or more beam detectors. 
     
     
       18. Apparatus as defined in  claim 14 , wherein said means for tilting the workpiece comprises a tilt mechanism for tilting a semiconductor wafer relative to the ion beam. 
     
     
       19. Apparatus for implanting ions into a workpiece, comprising:
 an ion beam generator;  
 an ion optical element for adjusting the ion beam for a desired parallelism in a plane;  
 a measuring system for measuring a beam direction of the adjusted ion beam in said plane without implanting any workpiece with the ion beam; and  
 a tilt mechanism for tilting the workpiece about an axis perpendicular to said plane at an implant angle referenced to the measured beam direction, wherein an implant is performed with the workpiece tilted at the implant angle referenced to the measured beam direction.  
 
     
     
       20. Apparatus as defined in  claim 19 , wherein said ion optical element comprises an angle corrector magnet for adjusting the ion beam for substantially parallel ion trajectories. 
     
     
       21. Apparatus as defined in  claim 18 , wherein said measuring system comprises a movable beam profiler and one or more beam detectors. 
     
     
       22. Apparatus as defined in  claim 18 , wherein said tilt mechanism is configured for tilting a semiconductor wafer. 
     
     
       23. A method as defined in  claim 1 , further comprising the step of scanning the ion beam in said plane. 
     
     
       24. A method as defined in  claim 8 , further comprising the step of scanning the ion beam in said plane. 
     
     
       25. Apparatus as defined in  claim 14 , further comprising means for scanning the ion beam in said plane. 
     
     
       26. Apparatus as defined in  claim 19 , further comprising a scanner for scanning the ion beam in said plane. 
     
     
       27. A method for implanting ions into a workpiece, comprising:
   generating an ion beam;        measuring a beam direction of the ion beam without implanting any workpiece with the ion beam;        tilting a workpiece about an axis that is not parallel to the measured beam direction at an implant angle referenced to the measured beam direction; and        performing an implant with the workpiece tilted at the implant angle.     
     
     
       28. A method as defined in  claim 27 , wherein tilting the workpiece comprises tilting a semiconductor wafer. 
     
     
       29. A method as defined in  claim 27 , wherein tilting the workpiece comprises tilting a semiconductor wafer about an axis that is substantially perpendicular to the measured beam direction. 
     
     
       30. A method as defined in  claim 27 , further comprising scanning the ion beam. 
     
     
       31. A method as defined in  claim 27 , wherein generating an ion beam comprises generating a ribbon ion beam. 
     
     
       32. A method as defined in  claim 27 , further comprising adjusting the ion beam for a desired parallelism. 
     
     
       33. Apparatus for implanting ions into a workpiece, comprising:
   means for generating an ion beam;        means for measuring a beam direction of the ion beam without implanting any workpiece with the ion beam;        means for tilting a workpiece about an axis that is not parallel to the measured beam direction at an implant angle referenced to the measured beam direction, wherein the implant is performed with the workpiece tilted at the implant angle.     
     
     
       34. Apparatus as defined in  claim 33 , wherein said means for tilting the workpiece comprises a tilt mechanism for tilting a semiconductor wafer relative to the ion beam. 
     
     
       35. Apparatus as defined in  claim 33 , where said means for tilting the workpiece comprises a tilt mechanism for tilting a semiconductor wafer about an axis that is substantially perpendicular to the measured beam direction. 
     
     
       36. Apparatus as defined in  claim 33 , further comprising means for scanning the ion beam. 
     
     
       37. Apparatus as defined in  claim 33 , wherein said means for generating comprises means for generating a ribbon ion beam. 
     
     
       38. Apparatus as defined in  claim 33 , further comprising means for adjusting the ion beam for a desired parallelism. 
     
     
       39. Apparatus for implanting ions into a workpiece, comprising:
   an ion beam generator;        a measuring system for measuring a beam direction of the ion beam without implanting any workpiece with the ion beam; and        a tilt mechanism for tilting the workpiece about an axis that is not parallel to the measured beam direction at an implant angle referenced to the measured beam direction, wherein the implant is performed with the workpiece tilted at the implant angle.     
     
     
       40. Apparatus as defined in  claim 39 , wherein said tilt mechanism is configured for tilting a semiconductor wafer. 
     
     
       41. Apparatus as defined in  claim 39 , wherein said tilt mechanism is configured to tilt a semiconductor wafer about an axis that is substantially perpendicular to the measured beam direction. 
     
     
       42. Apparatus as defined in  claim 39 , further comprising a scanner for scanning the ion beam. 
     
     
       43. Apparatus as defined in  claim 39 , where said ion beam generator is configured to generate a ribbon ion beam. 
     
     
       44. Apparatus as defined in  claim 39 , further comprising an ion optical element for adjusting the ion beam for a desired parallelism. 
     
     
       45. A method for implanting ions into a workpiece, comprising the steps of:
   generating an ion beam;        adjusting the ion beam for a desired measure of parallelism;        measuring a beam direction of the adjusted ion beam without implanting any workpiece with the ion beam;        tilting a workpiece about an axis that is not parallel to the measured beam direction at an implant angle referenced to the measured beam direction; and        performing the implant with the workpiece titled at the implant angle.     
     
     
       46. A method as defined in  claim 45 , wherein the step of adjusting the ion beam comprises adjusting the ion beam for substantially parallel ion trajectories. 
     
     
       47. A method as defined in  claim 45 , wherein tilting the workpiece comprises tilting a semiconductor wafer. 
     
     
       48. A method as defined in  claim 45 , wherein tilting the workpiece comprises tilting a semiconductor wafer about an axis that is substantially perpendicular to the measured beam direction. 
     
     
       49. A method for implanting ions into a workpiece, comprising the steps of:
   generating an ion beam;        measuring parallelism of the ion beam;        adjusting the ion beam for a desired parallelism based on the measured parallelism;        measuring a beam direction of the adjusted ion beam without implanting any workpiece with the ion beam;        tilting a workpiece about an axis that is not parallel to the measured beam direction at an implant angle referenced to the measured beam direction; and        performing the implant with the workpiece tilted at the implant angle referenced to the measured beam direction.     
     
     
       50. A method as defined in  claim 49 , wherein the step of adjusting the ion beam comprises adjusting the ion beam for substantially parallel ion trajectories. 
     
     
       51. A method as defined in  claim 49 , wherein tilting the workpiece comprises tilting a semiconductor wafer. 
     
     
       52. A method as defined in  claim 49 , wherein tilting the workpiece comprises tilting a semiconductor wafer about an axis that is substantially perpendicular to the measured beam direction. 
     
     
       53. Apparatus for implanting ions into a workpiece, comprising:
   means for generating an ion beam;        means for measuring parallelism of the ion beam;        means for adjusting the ion beam for a desired parallelism based on the measured parallelism;        means for measuring a beam direction of the adjusted ion beam without implanting any workpiece with the ion beam;        means for tilting a workpiece about an axis that is not parallel to the measured beam direction at an implant angle referenced to the measured beam direction; and        means for performing the implant with the workpiece tilted at the implant angle referenced to the measured beam direction.     
     
     
       54. Apparatus as defined in  claim 53 , wherein said means for adjusting the ion beam comprises means for adjusting the ion beam for substantially parallel ion trajectories. 
     
     
       55. Apparatus as defined in  claim 53 , wherein said means for tilting the workpiece comprises a tilt mechanism for tilting a semiconductor wafer relative to the ion beam. 
     
     
       56. Apparatus as defined in  claim 53 , wherein said means for tilting the workpiece comprises a tilt mechanism for tilting a semiconductor wafer about an axis that is substantially perpendicular to the measured beam direction. 
     
     
       57. Apparatus for implanting ions into a workpiece, comprising:
   an ion beam generator;        an ion optical element for adjusting the ion beam for a desired parallelism;        a measuring system for measuring a beam direction of the adjusted ion beam without implanting any workpiece with the ion beam; and        a tilt mechanism for tilting the workpiece about an axis that is not parallel to the measured beam direction at an implant angle referenced to the measured beam direction, wherein the implant is performed with the workpiece tilted at the implant angle referenced to the measured beam direction.     
     
     
       58. Apparatus as define in  claim 57 , wherein said ion optical element comprises an angle corrector magnet for adjusting the ion beam for substantially parallel ion trajectories. 
     
     
       59. Apparatus as define in  claim 57 , wherein said tilt mechanism is configured for tilting a semiconductor wafer. 
     
     
       60. Apparatus as define in  claim 57 , wherein said tilt mechanism is configured to tilt a semiconductor wafer about an axis that is substantially perpendicular to the measured beam direction.