IP Library › Granted Patent US 11,227,741
Granted Patent B2
US 11,227,741 · App. 16/398,487 · Granted Jan 18, 2022

Scanning ion beam etch

Inventors: Sarpangala Hariharakeshava Hegde (Fremont, CA); Vincent Lee (Fremont, CA)
Assignee: PLASMA-THERM NES LLC
H01J37/1474H01J37/243H01J37/32715H01L21/3065H01J2237/20207H01J2237/20214H01J2237/20228H01J2237/3323H01J2237/3341
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Quick Facts
Patent No.
US 11,227,741
App. No.
16/398,487
Granted
Jan 18, 2022
Kind
B2
Abstract

The present disclosure provides a method to adjust asymmetric velocity of a scan in a scanning ion beam etch process to correct asymmetry of etching between the inboard side and the outboard side of device structures on a wafer, while maintaining the overall uniformity of etch across the full wafer.

Claims (78)

1. A method of correcting asymmetry during a wafer etching process, the method comprising:

producing a plasma from a plasma source, the plasma source comprising a plasma chamber and the ion extraction grid system, the ion extraction grid system configured to produce an ion beam from the plasma, the ion beam having a central axis;

supporting a wafer on a stage;

scanning the wafer relative to the ion beam along a scan path, wherein a scan velocity of the wafer is varied as the wafer travels along the scan path, wherein the scan velocity decreases as an area of the wafer exposed to the ion beam decreases; and

modifying applied beam flux as a function of a position of the wafer.

2. The method of claim 1 , further comprising rotating the stage about the central axis during at least a portion of the etching process.

3. The method of claim 1 , further comprising tilting the stage with respect to the ion beam during at least a portion of the etching process.

4. The method of claim 1 , further comprising cooling the wafer during at least a portion of the etching process.

5. The method of claim 1 , wherein the scan path is linear.

6. The method of claim 1 , wherein the scan path is non-linear.

7. The method of claim 1 , wherein a center of the scan path coincides with a center of the ion beam.

8. The method of claim 1 , wherein a center of the scan path does not coincide with a center of the ion beam.

9. The method of claim 1 , wherein modifying the applied beam flux as a function of a position of the wafer comprises adjusting ion beam current.

10. The method of claim 1 , wherein modifying the applied beam flux as a function of a position of the wafer comprises inserting a plurality of physical blocks along the scan path to create an aperture and adjusting the aperture position to narrow the applied ion beam.

11. The method of claim 1 , wherein modifying the applied beam flux as a function of a position of the wafer comprises adjusting an amount of time the wafer is exposed to the ion beam.

12. The method of claim 1 , wherein the scan velocity decreases as a distance between the wafer and the ion beam increases during the scan.

13. The method of claim 1 , wherein the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam and a scan back path from the second end of the ion beam to the first end of the ion beam, wherein the scan out path is the same as the scan back path.

14. The method of claim 1 , wherein the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam and a scan back path from the second end of the ion beam to the first end of the ion beam, wherein the scan out path is different from the scan back path.

15. The method of claim 1 , wherein the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam and a scan back path from the second end of the ion beam to the first end of the ion beam, wherein an endpoint of the scan out path is different from an endpoint of the scan back path.

16. The method of claim 1 , wherein the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam according to a scan out velocity function and a scan back path from the second end of the ion beam to the first end of the ion beam according to a scan back velocity function, wherein the scan out velocity function is different from the scan back velocity function.

17. The method of claim 1 , wherein the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam according to a scan out velocity function and a scan back path from the second end of the ion beam to the first end of the ion beam according to a scan back velocity function, wherein one of the scan out velocity function and the scan back velocity function varies as a function of time.

18. The method of claim 1 , wherein the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam according to a scan out velocity function and a scan back path from the second end of the ion beam to the first end of the ion beam according to a scan back velocity function, wherein both the scan out velocity function and the scan back velocity function vary as a function of time.

19. The method of claim 1 , wherein the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam according to a scan out velocity function and a scan back path from the second end of the ion beam to the first end of the ion beam according to a scan back velocity function, wherein at least one of the scan out velocity function and the scan back velocity function vary within one scan path.

20. The method of claim 1 , wherein the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam according to a scan out velocity function and a scan back path from the second end of the ion beam to the first end of the ion beam according to a scan back velocity function, wherein at least one of the scan out velocity function and the scan back velocity function vary each scan path.

21. The method of claim 1 , wherein the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam according to a scan out velocity function and a scan back path from the second end of the ion beam to the first end of the ion beam according to a scan back velocity function, wherein both the scan out velocity function and the scan back velocity function vary each scan path.

22. The method of claim 1 , wherein the scan velocity of the wafer is slowed as a center of the wafer travels along the far side of the scan path.

23. The method of claim 22 , wherein the scan velocity is asymmetric with respect to the central axis of the ion beam.

24. A method of correcting asymmetry during a wafer etching process, the method comprising:

producing a plasma from a plasma source, the plasma source comprising a plasma chamber and the ion extraction grid system, the ion extraction grid system configured to produce an ion beam from the plasma, the ion beam having a central axis;

supporting a wafer on a stage including at least one of rotating the stage about the central axis and tilting the stage with respect to the ion beam during at least a portion of the etching process;

scanning the wafer relative to the ion beam along a scan path in accordance with a scan velocity function, wherein a scan velocity of the wafer is varied as the wafer travels along the scan path, wherein the scan velocity decreases as an area of the wafer exposed to the ion beam decreases; and

modifying applied beam flux as a function of a position of the wafer by varying the scan velocity function as the wafer travels along the scan path.

25. The method of claim 24 , wherein the scan velocity decreases as a distance between the wafer and the ion beam increases during the scan.

26. The method of claim 24 , further comprising:

rotating the stage about the central axis during at least a portion of the etching process; and

tilting the stage with respect to the ion beam during at least a portion of the etching process.

27. The method of claim 26 , wherein modifying the applied beam flux as a function of a position of the wafer comprises inserting a plurality of physical blocks along the scan path to create an aperture and adjusting the aperture position to narrow the applied ion beam.

28. The method of claim 26 , wherein the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam according to a scan out velocity function and a scan back path from the second end of the ion beam to the first end of the ion beam according to a scan back velocity function, wherein both the scan out velocity function and the scan back velocity function vary as a function of time.

29. The method of claim 26 , wherein the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam according to a scan out velocity function and a scan back path from the second end of the ion beam to the first end of the ion beam according to a scan back velocity function, wherein at least one of the scan out velocity function and the scan back velocity function vary within one scan path.

30. The method of claim 26 , wherein the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam according to a scan out velocity function and a scan back path from the second end of the ion beam to the first end of the ion beam according to a scan back velocity function, wherein at least one of the scan out velocity function and the scan back velocity function vary each scan path.

31. The method of claim 26 , wherein the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam according to a scan out velocity function and a scan back path from the second end of the ion beam to the first end of the ion beam according to a scan back velocity function, wherein both the scan out velocity function and the scan back velocity function vary each scan path.

32. The method of claim 26 , wherein the scan velocity of the wafer is slowed as a center of the wafer travels along the far side of the scan path.

33. The method of claim 32 , wherein the scan velocity is asymmetric with respect to the central axis of the ion beam.

34. A method of correcting asymmetry during a wafer etching process, the method comprising:

producing a plasma from a plasma source, the plasma source comprising a plasma chamber and the ion extraction grid system, the ion extraction grid system configured to produce an ion beam from the plasma, the ion beam having a central axis;

supporting a wafer on a stage;

scanning the wafer relative to the ion beam along a scan path, the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam according to a scan out velocity function and a scan back path from the second end of the ion beam to the first end of the ion beam according to a scan back velocity function, wherein one of the scan out velocity function and the scan back velocity function varies as a function of time, wherein a scan velocity of the wafer is varied as the wafer travels along the scan path, wherein the scan velocity decreases as an area of the wafer exposed to the ion beam decreases; and

modifying applied beam flux as a function of a position of the wafer.

35. The method of claim 34 , further comprising rotating the stage about the central axis during at least a portion of the etching process.

36. The method of claim 35 , further comprising tilting the stage with respect to the ion beam during at least a portion of the etching process.

37. The method of claim 36 , wherein modifying the applied beam flux as a function of a position of the wafer comprises inserting a plurality of physical blocks along the scan path to create an aperture and adjusting the aperture position to narrow the applied ion beam.

38. A method of correcting asymmetry during a wafer deposition process, the method comprising:

producing a plasma from a plasma source, the plasma source comprising a plasma chamber and the ion extraction grid system, the ion extraction grid system configured to produce an ion beam from the plasma, the ion beam having a central axis;

supporting a wafer on a stage;

scanning the wafer relative to the ion beam along a scan path, wherein a scan velocity of the wafer is varied as the wafer travels along the scan path, wherein the scan velocity decreases as an area of the wafer exposed to the ion beam decreases; and

modifying applied beam flux as a function of a position of the wafer.

39. The method of claim 38 , further comprising rotating the stage about the central axis during at least a portion of the deposition process.

40. The method of claim 38 , further comprising tilting the stage with respect to the ion beam during at least a portion of the deposition process.

41. The method of claim 38 , further comprising cooling the wafer during at least a portion of the deposition process.

42. The method of claim 38 , wherein the scan path is linear.

43. The method of claim 38 , wherein the scan path is non-linear.

44. The method of claim 38 , wherein a center of the scan path coincides with a center of the ion beam.

45. The method of claim 38 , wherein a center of the scan path does not coincide with a center of the ion beam.

46. The method of claim 38 , wherein modifying the applied beam flux as a function of a position of the wafer comprises adjusting ion beam current.

47. The method of claim 38 , wherein modifying the applied beam flux as a function of a position of the wafer comprises inserting a plurality of physical blocks along the scan path to create an aperture and adjusting the aperture position to narrow the applied ion beam.

48. The method of claim 38 , wherein modifying the applied beam flux as a function of a position of the wafer comprises adjusting an amount of time the wafer is exposed to the ion beam.

49. The method of claim 38 , wherein the scan velocity decreases as a distance between the wafer and the ion beam increases during the scan.

50. The method of claim 38 , wherein the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam and a scan back path from the second end of the ion beam to the first end of the ion beam, wherein the scan out path is the same as the scan back path.

51. The method of claim 38 , wherein the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam and a scan back path from the second end of the ion beam to the first end of the ion beam, wherein the scan out path is different from the scan back path.

52. The method of claim 38 , wherein the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam and a scan back path from the second end of the ion beam to the first end of the ion beam, wherein an endpoint of the scan out path is different from an endpoint of the scan back path.

53. The method of claim 38 , wherein the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam according to a scan out velocity function and a scan back path from the second end of the ion beam to the first end of the ion beam according to a scan back velocity function, wherein the scan out velocity function is different from the scan back velocity function.

54. The method of claim 38 , wherein the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam according to a scan out velocity function and a scan back path from the second end of the ion beam to the first end of the ion beam according to a scan back velocity function, wherein one of the scan out velocity function and the scan back velocity function varies as a function of time.

55. The method of claim 38 , wherein the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam according to a scan out velocity function and a scan back path from the second end of the ion beam to the first end of the ion beam according to a scan back velocity function, wherein both the scan out velocity function and the scan back velocity function vary as a function of time.

56. The method of claim 38 , wherein the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam according to a scan out velocity function and a scan back path from the second end of the ion beam to the first end of the ion beam according to a scan back velocity function, wherein at least one of the scan out velocity function and the scan back velocity function vary within one scan path.

57. The method of claim 38 , wherein the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam according to a scan out velocity function and a scan back path from the second end of the ion beam to the first end of the ion beam according to a scan back velocity function, wherein at least one of the scan out velocity function and the scan back velocity function vary each scan path.

58. The method of claim 38 , wherein the scan path comprising a scan out path from the first end of the ion beam to the second end of the ion beam according to a scan out velocity function and a scan back path from the second end of the ion beam to the first end of the ion beam according to a scan back velocity function, wherein both the scan out velocity function and the scan back velocity function vary each scan path.

59. The method of claim 38 , wherein the scan velocity of the wafer is slowed as a center of the wafer travels along the far side of the scan path.

60. The method of claim 59 , wherein the scan velocity is asymmetric with respect to the central axis of the ion beam.

Assignments (2)
SECURITY INTEREST Recorded Jun 28, 2022
From: RAJE TECHNOLOGY GROUP, LLC; PLASMA-THERM, LLC; REV-TECH MANUFACTURING SOLUTIONS, LLC; HINE AUTOMATION, LLC; DRYTEK, LLC; PLASMA-THERM NES, LLC; LOGIX TECHNOLOGY HOLDINGS, LLC; PLASMA THERM IC-DISC, INC.
To: VALLEY NATIONAL BANK
Reel/Frame 060447/0766 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Jun 11, 2019
From: HEGDE, SARPANGALA H.; LEE, VINCENT
To: PLASMA-THERM NES LLC
Reel/Frame 049434/0189 →
Cited By (1)
US 12,671,062