Chemical vapor deposition plasma reactor having plural ion shower grids

• US 20050211170A1
• Filed: 06/22/2004
• Published: 09/29/2005
• Est. Priority Date: 03/26/2004
• Status: Active Grant

• 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
• Granted Patent: US 7,695,590 B2
• Time in Patent Office: Days
• US Class Current: 118/723.R
• CPC Class Codes: C23C 14/358 Inductive energy
• 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 a set of plural parallel ion shower grids that divide the chamber into an upper ion generation region and a lower reactor region, each of the ion shower grids having plural orifices in mutual registration from grid to grid, each orifice being oriented in a non-parallel direction relative to a surface plane of the respective ion shower grid. A workpiece support in the process region faces the lowermost one of the ion shower grids. A reactive species source furnishes into the ion generation region a chemical vapor deposition precursor species. The reactor further includes a vacuum pump coupled to the reactor region, a plasma source power applicator for generating a plasma in the ion generation region and a grid potential source coupled to the set of ion shower grids. The orifices through at least some of the ion shower grids have an aspect ratio sufficient to limit ion trajectories in the reactor region to a narrow angular range about the non-parallel direction, and a resistance to gas flow sufficient to support a pressure drop between the ion generation and reactor regions of about at least a factor of 4. The grid potential source can be capable of applying different voltages to different ones of the grids.

Claims

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

a reactor chamber;

a set of plural parallel ion shower grids that divide said chamber into an upper ion generation region and a lower reactor region, each of said ion shower grids having plural orifices in mutual registration from grid to grid, each orifice being oriented in a non-parallel direction relative to a surface plane of the respective ion shower grid;

a workpiece support in said process region facing the lowermost one of said ion shower grids;

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

a vacuum pump coupled to said reactor region;

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

a grid potential source coupled to said set of ion shower grids, the orifices through at least some of said ion shower grids having;

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

(b) a resistance to gas flow sufficient to support a pressure drop between said ion generation and reactor regions of about at least a factor of 4.

2. The reactor of claim 1 wherein said grid potential source comprises a set of independently controllable grid potential sources coupled to respective ones of said set of ion shower grids.

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

4. The reactor of claim 2 wherein said set of grid potential sources comprise sources of successively greater attractive potentials for ions.

5. The reactor of claim 4 wherein selected ones of said set of grid potential sources comprise sources of repulsive potentials for ions.

6. The reactor of claim 2 wherein said set of grid potential sources comprises a single voltage source coupled to a voltage divider having plural voltage output terminals coupled to respective ones of said set of ion shower grids.

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

8. The reactor of claim 7 wherein said temperature controller comprises internal fluid flow passages thermally coupled to said ion shower grid and a pump for pumping a coolant through said internal fluid flow passages.

9. The reactor of claim 1 further comprising a neutralization source for furnishing electrons into the vicinity of said workpiece support.

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

11. The reactor of claim 9 wherein said neutralization source comprises an electron gun oriented toward said workpiece support.

12. The reactor of claim 9 wherein said neutralization source comprises a source for furnishing an electron-donor gas into said process region and near said workpiece.

13. The reactor of claim 12 wherein said electron-donor gas comprises Zenon.

14. The reactor of claim 1 wherein said plasma source power applicator comprises a capacitively coupled plasma source power applicator.

15. The reactor of claim 14 wherein said capacitively coupled plasma source power applicator comprises an RF generator coupled between a ceiling of said reactor and one of (a) the uppermost one of said grids, (b) a side wall of said ion generation region of said reactor.

16. The reactor of claim 14 further comprising a bias potential source coupled to said workpiece.

17. The reactor of claim 16 wherein said bias potential source is a source of an RF voltage.

18. The reactor of claim 1 wherein said plasma source power applicator comprises an RF power generator, and each of said grid potential sources 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.

19. The reactor of claim 18 wherein each of said grid potential sources 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.

20. The reactor of claim 1 wherein said plasma source power applicator comprises an inductively coupled plasma source power applicator.

21. The reactor of claim 20 further comprising a bias potential source coupled to said workpiece support.

22. The reactor of claim 21 wherein said bias potential source comprises an RF power generator.

23. The reactor of claim 20 wherein said plasma source power applicator comprises an RF power generator and a coil antenna coupled to said RF power generator, and each of said grid potential sources comprise at least one of:

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

24. The reactor of claim 23 wherein each of said grid potential sources 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.

25. The reactor of claim 1 wherein said plasma source power applicator comprises a microwave power source coupled to said ion generation region.

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

27. The reactor of claim 26 wherein said bias potential source comprises an RF voltage source.

28. The reactor of claim 25 wherein each of said grid potential sources comprises at least one of:

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

29. The reactor of claim 28 wherein said each of said grid potential sources 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.

30. The reactor of claim 1 wherein said plasma source power applicator comprises an external reentrant conduit coupled across said ion generation region and an RF power applicator for coupling RF plasma source power into the external reentrant conduit.

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

32. The reactor of claim 31 wherein said bias potential source comprises an RF voltage source.

33. The reactor of claim 30 wherein each of said grid potential sources 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.

34. The reactor of claim 33 wherein each of said grid potential sources 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.

35. 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.

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

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

38. 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.

39. 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.

40. 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.

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

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

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

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

45. The reactor of claim 6 wherein said voltage divider further has an output terminal coupled to said workpiece support pedestal.

46. The reactor of claim 45 wherein said voltage divider couples from said single potential source a high ion-repulsive potential to the grid nearest the ion generation region, and successively smaller ion-repulsive potentials to successive ones of the remaining grids and a reference potential to said wafer support pedestal.

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

48. The reactor of claim 45 wherein said voltage divider couples from said single potential source a reference potential to the grid nearest said ion generation region, and successively greater ion-attractive voltages to successive ones of the other grids and a highest ion-attractive potential to the wafer support pedestal.

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

50. The reactor of claim 48 wherein said plasma source power applicator comprises a torroidal plasma source.

51. The reactor of claim 1 wherein said plural grids are joined at their peripheries to a side wall of said reactor whereby to limit gas flow between said ion generation and process regions to orifices in said grids.

52. 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.