Chemical vapor deposition plasma reactor having an ion shower grid

• US 20050211171A1
• Filed: 06/22/2004
• Published: 09/29/2005
• Est. Priority Date: 03/26/2004
• Status: Abandoned Application

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Tanaka, Tsutomu, Ramaswamy, Kartik, Hanawa, Hiroji, Collins, Kenneth S., Nguyen, Andrew, Al-Bayati, Amir
• Application Number:
  US10/873,474
• Publication Number:
  US 20050211171A1
• Time in Patent Office: Days
• US Class Current: 118/723.R
• CPC Class Codes: C23C 16/045 Coating cavities or hollow spaces, e.g. interior of tubes; Infiltration of porous substrates
• CPC Class Codes: C23C 16/507 using external electrodes, e.g. in tunnel type reactors
• CPC Class Codes: H01J 37/32357 Generation remote from the workpiece, e.g. down-stream
• CPC Class Codes: H01J 37/32449 Gas control, e.g. control of the gas flow

Abstract

A plasma reactor for processing a semiconductor workpiece includes a reactor chamber and an ion shower grid dividing the chamber into an upper ion generation region and a lower process region, the ion shower grid having plural orifices oriented in a non-parallel direction relative to a surface plane of the grid. A workpiece support in the process region has a workpiece support surface in facing relationship to the ion shower grid. The reactor further includes a reactive species source for introducing into the ion generation region a chemical vapor deposition precursor species, a vacuum pump coupled to the process region, a plasma source power applicator for generating a plasma in the ion generation region and a grid potential source coupled to the ion shower grid. The orifices through the grid have an aspect ratio sufficient to limit ion trajectories in the process region to a narrow angular range about the non-parallel direction and a resistance to gas flow sufficient to support a pressure drop of at least a factor of about 4 across the grid.

Claims

1. A plasma reactor for processing a semiconductor workpiece, comprising:

a reactor chamber;

an ion shower grid dividing said chamber into an upper ion generation region and a lower process region, said ion shower grid having plural orifices oriented in a non-parallel direction relative to a surface plane of said grid;

a workpiece support in said process region having a workpiece support surface in facing relationship to said ion shower grid;

a reactive species source for introducing into said ion generation region a chemical vapor deposition precursor species;

a vacuum pump coupled to said process region;

a plasma source power applicator for generating a plasma in said ion generation region; and

a grid potential source coupled to said ion shower grid, the orifices through said grid having;

(a) an aspect ratio sufficient to limit ion trajectories in said process region to a narrow angular range about said non-parallel direction,

(b) a resistance to gas flow sufficient to support a pressure drop of at least a factor of about 4 across said grid.

2. The reactor of claim 1 wherein said vacuum pump has a capacity sufficient to maintain an ion-neutral mean collision distance in said process region in excess of a multiple of a distance between said workpiece and said ion shower grid.

3. The reactor of claim 1 wherein said plasma source power applicator and said grid potential source are comprised together in a single potential source connected between said ion shower grid and an internal surface of said ion generation region of said reactor.

4. The reactor of claim 1 wherein said grid potential source is at least one of:

(a) a pulsed D.C. potential source, (b) an RF potential source, (c) a D.C. potential source, (d) a pulsed RF potential source.

5. The reactor of claim 4 wherein said grid potential source is a combination of at least two of:

(a) a pulsed D.C. potential source, (b) an RF potential source, (c) a D.C. potential source, (d) a pulsed RF potential source.

6. The reactor of claim 1 further comprising a temperature controller thermally coupled to said ion shower grid.

7. The reactor of claim 6 wherein said temperature controller comprises a pump and internal fluid flow passages connected to an input of said pump and to an output of said pump and thermally coupled to said ion shower grid.

8. The reactor of claim 1 further comprising a neutralization source for furnishing electrons to the vicinity of said workpiece.

9. The reactor of claim 8 wherein said neutralization source of electrons comprises a magnetic field source under said workpiece having sufficient magnetic flux to trap electrons near said workpiece surface.

10. The reactor of claim 8 wherein said neutralization source comprises an electron gun directed toward said workpiece surface.

11. The reactor of claim 8 wherein said neutralization source comprises a source of an electron-donor gas coupled to said process region.

12. The reactor of claim 8 wherein said neutralization source comprises an external plasma source.

13. The reactor of claim 1 wherein:

said plasma source power applicator comprises a capacitively coupled plasma source power applicator; and

said grid potential source is coupled between an internal chamber surface of said ion generation region and said ion shower grid.

14. The reactor of claim 13 wherein said capacitively coupled plasma source power applicator comprises an RF generator coupled between a ceiling of said reactor and one of (a) said grid, (b) a side wall of said reactor.

15. The reactor of claim 13 wherein said plasma source power applicator comprises an RF power generator and said grid potential source comprises at least one of:

(a) a pulsed D.C. voltage source, (b) an RF voltage source, (c) a D.C. voltage source, (d) a pulsed RF voltage source.

16. The reactor of claim 15 wherein said grid potential source comprises at least two of (a) a pulsed D.C. voltage source, (b) an RF voltage source, (c) a D.C. voltage source, (d) a pulsed RF voltage source.

17. The reactor of claim 15 further comprising a bias voltage source coupled to said workpiece support.

18. The reactor of claim 17 wherein said bias voltage source comprises one of:

(a) D.C. voltage source, (b) an RF voltage source, (c) a pulsed D.C. voltage source, (d) a pulsed RF voltage source.

19. The reactor of claim 1 wherein said plasma source power applicator comprises an inductively coupled plasma source power applicator and said grid potential source is coupled between said ion shower grid and an internal chamber surface of said ion generation region.

20. The reactor of claim 19 wherein said plasma source power applicator comprises an RF power source and said grid potential source comprises at least one of:

(a) a pulsed D.C. voltage source, (b) an RF voltage source, (c) a D.C. voltage source (d) a pulsed RF voltage source.

21. The reactor of claim 20 wherein said grid potential source comprises at least two of (a) a pulsed D.C. voltage source, (b) an RF voltage source, (c) a D.C. voltage source, (d) a pulsed RF voltage source.

22. The reactor of claim 20 further comprising a bias voltage source coupled to said workpiece.

23. The reactor of claim 22 wherein said bias voltage source comprises one of:

(a) a D.C. voltage source, (b) an RF voltage source, (c) a pulsed D.C. source, (d) a pulsed RF voltage source.

24. The reactor of claim 1 wherein said plasma source power applicator comprises a microwave power source, and said grid potential source is coupled between said ion shower grid and an internal chamber surface of said ion generation region.

25. The reactor of claim 24 wherein said grid potential source comprises at least one of:

(a) a pulsed D.C. voltage source, (b) an RF voltage source, (c) a D.C. voltage source (d) a pulsed RF voltage source.

26. The reactor of claim 25 wherein said grid potential source comprises at least two of (a) a pulsed D.C. voltage source, (b) an RF voltage source, (c) a D.C. voltage source, (d) a pulsed RF voltage source.

27. The reactor of claim 25 further comprising a bias voltage source coupled to said workpiece support.

28. The reactor of claim 27 wherein said bias voltage source comprises at least one of:

(a) a D.C. voltage source, (b) an RF voltage source, (C) a pulsed D.C. voltage source, (d) a pulsed RF voltage source.

29. The reactor of claim 1 wherein said plasma source power applicator comprises an external reentrant conduit coupled across said ion generation region and a power applicator coupled to said external reentrant conduit, and said grid potential source is coupled between said ion shower grid and an internal reactor surface of said ion generation region.

30. The reactor of claim 29 further comprising a bias voltage source coupled to said workpiece support.

31. The reactor of claim 30 wherein said bias voltage source comprises at least one of:

(a) a pulsed D.C. voltage source, (b) an RF voltage source, (c) a D.C. voltage source, (d) a pulsed RF voltage source.

32. The reactor of claim 29 wherein said grid potential source comprises at least one of:

(a) a pulsed D.C. voltage source, (b) an RF voltage source, (c) a D.C. voltage source, (d) a pulsed RF voltage source.

33. The reactor of claim 32 wherein said grid potential source comprises a source of a mixture of at least two of (a) a pulsed D.C. voltage, (b) an RF voltage, (c) a D.C. voltage, (d) a pulsed RF voltage source.

34. The reactor of claim 1 wherein said reactive species source comprises:

a semiconductor sputtering target in said ion generation region;

a sputter source coupled to said target for sputtering atoms from said target into said ion generation region for ionization by plasma source power coupled from said plasma source power applicator.

35. The reactor of claim 34 wherein said sputter source comprises a sputter voltage source coupled to said sputtering target.

36. The reactor of claim 35 wherein said sputter source comprises an external plasma source coupled to said ion generation region.

37. The reactor of claim 1 further comprising an external plasma source furnishing ions or radicals to at least one of said ion generation and process regions.

38. The reactor of claim 1 further comprising an electrical connection between said wafer support and said ion shower grid for holding said ion shower grid and said wafer support at the same electrical potential.

39. The reactor of claim 1 wherein said workpiece support is translatable in the plane of said workpiece for scanning an ion beam from said grid across said workpiece.

40. The reactor of claim 39 wherein said workpiece support has a larger diameter than said grid.

41. The reactor of claim 1 wherein said workpiece support is tiltable for tilting said workpiece relative to said grid.

42. The reactor of claim 1 further comprising thermal control apparatus coupled to said wafer support pedestal for heating or cooling the workpiece.

43. The reactor of claim 42 wherein said wafer support pedestal comprises an electrostatic chuck.

44. The reactor of claim 3 further comprising a voltage divider coupled to said single potential source, said internal surface of said ion generation region, said grid and said workpiece support.

45. The reactor of claim 44 wherein said voltage divider couples from said single potential source a high ion-repulsive potential to said internal ion generation region surface, an intermediate ion-repulsive potential to said grid and a reference potential to said workpiece support pedestal.

46. The reactor of claim 45 wherein said reference potential is ground.

47. The reactor of claim 44 wherein said voltage divider couples from said single potential source a reference potential to said internal ion generation region surface, an intermediate ion attractive potential to said grid and a high ion attractive potential to said workpiece support pedestal.

48. The reactor of claim 47 wherein said reference potential is ground.

49. The reactor of claim 47 wherein said plasma source power applicator comprises a torroidal plasma source.

50. The reactor of claim 1 wherein said grid is joined at its periphery to a side wall of said reactor whereby gas flow between said ion generation and process regions is restricted to orifices in said grid.

51. The reactor of claim 1 wherein said reactive species source comprises a gas injection orifice opening into said ion generation region and a process gas supply coupled to said gas injection orifice for furnishing a process gas containing said chemical vapor deposition precursor species.