Method for measuring plasma properties in semiconductor processing

• US 4,859,277 A
• Filed: 05/03/1988
• Issued: 08/22/1989
• Est. Priority Date: 05/03/1988
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Economou, Demetre J., Barna, Gabriel G.
• Primary Examiner(s): Powell, William A.
• Application Number:
  US07/189,572
• Time in Patent Office: 476 Days
• Field of Search: 156/626, 156/643, 156/646, 156/345, 204/192.33, 204/192.13, 204/298, 356/437, 427/8, 427/38, 427/39, 118/50.1, 118/620, 118/712, 118/728
• US Class Current: 438/7
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge

Abstract

An apparatus and method for measuring the concentration profile of an active species across the surface of a semiconductor slice in a plasma reactor is disclosed that permits uniformity of etch and deposition across the surface of the semiconductor slice.

Claims

1. A method for determining the concentration profile of the active gas species in a plasma reactor so as to allow the adjustment thereof, comprising the steps of:

measuring the intensity of the emission of light from the plasma; and

adjusting the concentration gradient of the active species dependent upon the measured intensity of the light emission of the plasma.

2. The method according to claim 1, wherein the surface of a semiconductor slice is being altered by etched/deposition, the measurement of the intensity of the emission of light from the plasma is of a cylinder of light from the plasma parallel to the surface of the semiconductor slice.

3. The method according to claim 2, wherein the measurement of the intensity of the emission of the light from the plasma is done with an optical train.

4. The method according to claim 3, wherein the optical train is translated in a horizontal plane to profile the emission line of light across the surface of the semiconductor slice.

5. The method according to claim 2, wherein the plasma is observed through one or more diaphragms, an optical filter, and a focus lens that directs the light into an optical fiber input of a monochrometer.

6. The method according to claim 1, including the step of introducing a gas in addition to the active gas species into the plasma reactor to serve as an actinometer.

7. The method according to claim 6, wherein light emission of the two gases are measured using a beam-splitter and two photodiodes and two optical filter corresponding to the optical emission lines of the two gases.

8. The method according to claim 6, wherein the introduced gas in addition to the active gas species is argon.

9. The method according to claim 8, wherein the actinometer is introduced in an amount of up to 6% mole fraction.

10. The method according to claim 1, wherein a small amount of inert gas is introduced into the plasma and the intensity of the light of the plasma and the intensity of the light of the inert gas are compared.

11. A method for determining and controlling the concentration profile of the active gas species in a plasma reactor comprising the steps of:

introducing an actinometry gas into the plasma in the reactor;

measuring the intensity of light emitted by the gas species as compared with the intensity of light emitted by the actinometry gas; and

adjusting the concentration gradient of the active species gas dependent upon the comparison of the species gas and the actinometry gas.

12. The method according to claim 11, wherein the surface of a semiconductor slice is being altered by etch/deposition, and the measurement of the intensity of the emission of light from the plasma is of a cylinder of light from the plasma parallel to the surface of the semiconductor slice.

13. The method according to claim 12, wherein the measurement of the intensity of the emission of the light from the plasma is done with an optical train.

14. The method according to claim 13, wherein the measurement of the optical train is translated in a horizontal plane to profile the emission line of light across the surface of the semiconductor slice.

15. The method according to claim 12, wherein the plasma is observed through one or more diaphragms, an optical filter, and a focus lens that directs the light into an optical fiber input of a monochrometer.

16. The method according to claim 11, including the step of introducing argon in addition to the active gas species into the plasma reactor to serve as an actinometer.

17. The method according to claim 16, wherein light emission of the two gases are measured using a beam-splitter and two photodiodes and two optical filter corresponding to the optical emission lines of the two gases.

18. The method according to claim 11, wherein the actinometer gas is introduced in an amount of up to 6% mole fraction.

19. A method for uniformly etching or deposition across the surface of a semiconductor slice in a plasma reactor utilizing one of more specie gases comprising the steps of;

measuring the uniformity of the concentration profile of the active species gas across the surface of the semiconductor gas; and

adjusting the concentration of the active species gas dependent upon the measurement profile.

20. The method according to claim 19, wherein the surface of a semiconductor slice is being etched, the measurement of the intensity of the emission of light from the plasma is of a cylinder of light from the plasma parallel to the surface of the semiconductor slice.

21. The method according to claim 20, wherein the measurement of the intensity of the emission of the light from the plasma is done with an optical train.

22. The method according to claim 21, wherein the optical train is translated in a horizontal plane to profile the emission line of light across the surface of the semiconductor slice.

23. The method according to claim 20, wherein the plasma is observed through one or more diaphragms, an optical filter, and a focus lens that directs the light into an optical fiber input of a monochrometer.

24. The method according to claim 19, including the step of introducing a gas in addition to the active gas species into the plasma reactor to serve as an actinometer.

25. The method according to claim 24, wherein light emission of the two gases are measured using a beam-splitter and two photodiodes and two optical filter corresponding to the optical emission lines of the two gases.

26. The method according to claim 24, wherein the introduced gas in addition to the active gas species is argon.

27. The method according to claim 24, wherein the actinometer is introduced in an amount of up to 6% mole fraction.

28. The method according to claim 19, wherein a small amount of inert gas is introduced into the plasma and the intensity of the light of the plasma and the intensity of the light of the inert gas are compared.

29. An apparatus for determining the concentration profile of an active species across the surface of a semiconductor slice in a plasma reactor, comprising an optical system for observing the plasma emission within the plasma reactor, a monochrometer for measuring the intensity of at least one specific emission line from the plasma profiled across the surface of the semiconductor slice, and means for adjusting the concentration profile across the surface of the semiconductor slice to provide uniform etch/deposition on the surface of the semiconductor slice.

30. The apparatus according to claim 29, wherein the optical system includes one or more diaphragms, at least one filter, and a lens, for directing the plasma emission from the plasma reactor to the monochrometer.

31. The apparatus according to claim 29, wherein an actinometer gas is introduced into the reactor, and including a beamsplitter, two photodiodes and at least two filters to measure the emission lines from the active species and the actinometer gas forming the plasma in the reactor.

32. A method for determining the three dimensional concentration profile of the active gas species in a plasma reactor so as to allow the adjustment thereof, comprising the steps of:

measuring the intensity of the emission of light from the plasma; and

adjusting the concentration gradient of tee active species dependent upon the measured intensity of the light emission of the plasma.