Plasma density controller for semiconductor device processing equipment

• US 5,082,517 A
• Filed: 08/23/1990
• Issued: 01/21/1992
• Est. Priority Date: 08/23/1990
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Moslehi, Mehrdad M.
• Primary Examiner(s): Bueker, Richard
• Assistant Examiner(s): Goudreau, George A.
• Application Number:
  US07/571,799
• Time in Patent Office: 516 Days
• Field of Search: 315/111.21, 315/111.51, 315/111.91, 313/231.01, 313/231.31, 156/345, 156/626, 156/643, 118/723, 437/250, 427/39
• US Class Current: 156/345.26
• CPC Class Codes: H01J 37/32266 Means for controlling power transmitted to the plasma
• CPC Class Codes: H01J 37/32357 Generation remote from the workpiece, e.g. down-stream
• CPC Class Codes: Y10S 438/935 Gas flow control

Abstract

A semiconductor fabrication plasma property controller (100) for controlling physical properties of a fabrication process plasma medium (144) under the influence of electromagnetic gas discharge energy from a power source (38) comprises a control volume (130) disposed between the process plasma (144) and the electromagnetic gas discharge energy source (38). A control gas (128) flowing within the control volume prohibits a predetermined portion of the emitted electromagnetic energy from influencing the fabrication process plasma (144). The flow rate and/or pressure of the control gas (128) within control volume 130 is used to adjust the fraction of electromagnetic energy absorbed within process plasma (144) and to prohibit influence of a controlled fraction of the plasma-generating electromagnetic energy on the process gas, plasma stream (144). The control volume (130) absorbs the excess electromagnetic energy emitted by the power source (38).

Claims

1. A plasma density controller for semiconductor device processing equipment for controlling the amount of plasma activation for a process gas as a result of absorbing gas discharge energy from a gas discharge energy source, comprising:

a jacket interposed between the gas discharge energy source and the process gas, said jacket adapted for the presence of a control fluid having the ability to variably control the amount of plasma-generating energy that the process gas receives; and

controls for variably adjusting said control fluid physical parameters to influence the amount of energy the process gas absorbs.

2. The controller of claim 1, wherein said control fluid comprises a control gas, said control gas being capable of controllably generating a plasma as a result of absorbing energy from said energy source.

3. The controller of claim 1, wherein said control fluid comprises a control liquid, said control liquid having the ability to variably control the amount of plasma-generating energy that the process gas receives.

4. The controller of claim 1, wherein said control fluid jacket housing comprises an insulating material.

5. The controller of claim 4, wherein said insulating material is quartz.

6. The controller of claim 4, wherein said insulating material is sapphire.

7. The controller of claim 4, wherein said insulating material is made of a ceramic material.

8. The controller of claim 1, wherein said control fluid comprises a gas capable of generating a plasma in an electromagnetic energy field having a frequency of approximately 2.45 GHz.

9. The controller of claim 1, wherein said control gas comprises a gas capable of producing a plasma through radio-frequency inductively-coupled discharge.

10. The controller of claim 1, wherein said control gas comprises a gas capable of producing a plasma through radio-frequency capacitively-coupled discharge.

11. The controller of claim 1, wherein said plurality of controls further comprises a substance flow controller for variably controlling the fluid flow rate through said control fluid jacket.

12. The controller of claim 1, wherein said plurality of controls further comprises a valve assembly for adjustably controlling pressure within said control fluid jacket.

13. A method for controlling the amount of plasma density that a process gas generates as a result of absorbing energy from an energy source, comprising the steps of:

interposing a variably controllable fluid between the energy source and the process gas; and

variably controlling said control fluid to influence the amount of energy the process gas medium absorbs.

14. The method of claim 13, wherein said variably controllable fluid comprises a control gas.

15. The method of claim 13, wherein said variably controllable fluid comprises a control liquid.

16. The method of claim 13, further comprising the step of variably controlling flow within said control fluid jacket.

17. The method of claim 13, further comprising the step of variably controlling pressure within said control fluid jacket.

18. The method of claim 13, further comprising the step of detecting fabrication plasma physical properties.

19. The method of claim 18, further comprising the step of automatically controlling pressure within said control gas jacket in response to process plasma density or emission intensity measurements.

20. The method of claim 18, further comprising the step of automatically controlling the flow rate through said control fluid jacket in response to process plasma density measurements.

21. A semiconductor fabrication plasma density controller for controlling the process density of a fabrication process plasma under the influence of plasma-generating energy in a process gas flow line, comprising:

a jacket surrounding the process gas flow line;

a control gas flowing within said jacket for producing a control plasma, said control plasma associated to prevent a predetermined aspect of the plasma-generating energy from entering the process flow line; and

a plurality of controls associated with said jacket for variably controlling the extent to which said control plasma prevents the plasma-generating energy from influencing the process plasma.

22. The apparatus of claim 21, wherein said jacket comprises an insulating material.

23. The apparatus of claim 22, wherein said insulating material is quartz.

24. The apparatus of claim 23, wherein said insulating material is sapphire.

25. The apparatus of claim 23, wherein said insulating material is a ceramic material.

26. The apparatus of claim 21, wherein said control gas produces plasma at a microwave frequency of approximately 2.45 GHz.

27. The apparatus of claim 21, wherein said control gas produces plasma in a radio-frequency inductively-coupled gas discharge.

28. The apparatus of claim 21, wherein said control gas produces plasma in a radio-frequency capacitively-coupled gas discharge.

29. The apparatus of claim 21, wherein said plurality of controls further comprises a flow controller for variably controlling the fluid flow rate within said jacket.

30. The apparatus of claim 21, wherein said plurality of controls further comprises a valve for variably controlling pressure within said jacket.

31. The apparatus of claim 21, wherein said plurality of controls further comprises a detector for detecting fabrication process plasma density.

32. The apparatus of claim 21, wherein said plurality of controls further comprises a photodetector for detecting fabrication process plasma emission intensity.

33. The apparatus of claim 30, wherein said plurality of controls further comprises circuitry for automatically varying control fluid flow rate in response to detected fabrication plasma density or emission intensity.

34. A method for remotely controlling semiconductor fabrication plasma density of a fabrication process plasma under the influence of plasma-generating energy in a flow line, comprising the steps of:

disposing a jacket around the flow line;

flowing a control fluid within said jacket to produce a control plasma from said control fluid;

associating said control plasma with the plasma-generating energy to prevent a predetermined aspect of the plasma-generating energy from entering the flow line; and

associating a plurality of controls with said control plasma to thereby variably control the amount of plasma-generating energy entering the process plasma flow line.

35. The method of claim 34, wherein said jacket is formed of an insulating material.

36. The method of claim 34, further comprising the step of automatically varying control plasma density in response to variations in process plasma density or emission intensity.

37. A system for remotely controlling semiconductor fabrication process plasma density, comprising:

a semiconductor device fabrication reactor for fabricating a plurality of semiconductor wafers;

an energy source for emitting plasma-generating gas discharge energy;

a fabrication process gas for producing a fabrication process plasma by absorbing said plasma-generating energy; and

a semiconductor fabrication plasma density controller for controlling the density of said process plasma, said controller comprising;

a control fluid jacket disposed around said fabrication process gas and having a control gas gap;

a control fluid within said control fluid gap associated to absorb a portion of said plasma-generating energy and prevent a portion of said plasma-generating energy from producing said process plasma; and

a plurality of controls for variably controlling properties associated with said control fluid to control the amount of plasma-generating energy said control fluid prevents from being absorbed by said process plasma.

38. The system of claim 37, wherein said plasma energy source comprises a fixed microwave source.

39. The system of claim 37, wherein said microwave source comprises an energy source for emitting electromagnetic energy having a frequency of approximately 2.45 GHz.

40. The system of claim 37, wherein said source comprises a variably controllable microwave source.

41. The system of claim 37, wherein said energy source comprises a radio-frequency induction coil surrounding said control gas jacket and said fabrication process gas.

42. The system of claim 37, wherein said energy source comprises a radio-frequency capacitive coupling electrode surrounding said control gas jacket and said fabrication process gas.

43. The system of claim 37, wherein said control gas jacket comprises an insulating material.

44. The system of claim 37, wherein said insulating material is quartz.

45. The system of claim 37, wherein said insulating material is sapphire.

46. The system of claim 37, wherein said insulating material is ceramic material.

47. The system of claim 37, wherein said plurality of controls comprises a flow controller for variably controlling the fluid flow rate within said control fluid jacket.

48. The system of claim 37, wherein said plurality of controls further comprises a valve assembly for variably controlling gas pressure within said control fluid jacket.

49. The system of claim 37, further comprising circuitry for automatically controlling said control fluid parameters in response to measured variations in process plasma density or emission intensity.

50. The system of claim 49, wherein said circuitry further comprises a feedback control system for continually comparing actual fabrication process plasma density or emission intensity to desired process plasma density setpoints.