Method and apparatus for monitoring the process state of a semiconductor device fabrication process

• US 6,455,437 B1
• Filed: 04/07/1999
• Issued: 09/24/2002
• Est. Priority Date: 04/07/1999
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Sarfaty, Moshe, Lymberopoulos, Dimitris, Davidow, Jed
• Primary Examiner(s): Utech, Benjamin L.
• Assistant Examiner(s): Tran, Binh X
• Application Number:
  US09/288,041
• Time in Patent Office: 1,266 Days
• Field of Search: 438/710, 438/708, 438/709, 438/714, 438/716, 438/16, 156/345
• US Class Current: 438/710
• CPC Class Codes: H01J 37/32082 Radio frequency generated discharge H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• CPC Class Codes: H01L 21/67069 for drying etching
• CPC Class Codes: H01L 21/67253 Process monitoring, e.g. flow or thickness monitoring
• CPC Class Codes: H01L 21/67265 of substrates stored in a container, a magazine, a carrier, a boat or the like

Abstract

A method and apparatus for monitoring process state using plasma attributes are provided. Electromagnetic emissions generated by a plasma are collected, and a detection signal having at least one frequency component is generated based on the intensity of the collected electromagnetic emissions; or, the RF power delivered to a wafer pedestal is monitored and serves as the detection signal. The magnitude of at least one frequency component of the detection signal then is monitored over time. By monitoring the magnitude of at least one frequency component of the detection signal over time, a characteristic fingerprint of the plasma process is obtained. Features within the characteristic fingerprint provide process state information, process event information and process chamber information. In general, any chemical reaction having an attribute that varies with reaction rate may be similarly monitored.

Claims

1. A method of detecting improper chucking during a plasma process, the plasma being generated by application of an RF power signal, the method comprising:

measuring an attribute of the plasma so as to generate a detection signal;

processing the detection signal to generate a first signal indicative of a frequency component of the detection signal, the frequency component having a frequency less than a frequency of the RF power signal;

monitoring over time variations in the magnitude of the first signal;

generating a characteristic fingerprint for the plasma process based on the monitored first signal;

examining the characteristic fingerprint of the plasma process for at least one feature indicative of improper chucking during the plasma process; and

equating an occurrence of the at least one feature to improper chucking during the plasma process.

2. The method of claim 1, wherein the processing step includes processing the detection signal to generate a plurality of first signals each indicative of a respective frequency component of the detection signal, each of the frequency components having a frequency less than the frequency of the RF power signal;

and

wherein the monitoring step includes monitoring the respective magnitudes of the plurality of first signals.

3. The method of claim 1, wherein the frequency component has a frequency associated with a chemical reaction rate of the plasma process.

4. The method of claim 1, wherein the measuring step comprises generating a detector current.

5. The method of claim 1, wherein the measuring step comprises measuring at least one of a forward and a reflected RF power for a wafer pedestal.

6. The method of claim 1, wherein the measuring step comprises measuring other than a broadband optical electromagnetic emission attribute.

7. The method of claim 1, wherein the measuring step includes:

providing an optical filtering mechanism adapted to pass electromagnetic emissions from a chemical species within the plasma; and

collecting electromagnetic emissions passed by the optical filtering mechanism.

8. The method of claim 7, wherein the optical filtering mechanism comprises an optical filtering mechanism selected from the group consisting of a glass filter and a monochrometer.

9. The method of claim 7, wherein the chemical species comprises a chemical species selected from the group consisting of BCl, Al, AlCl, Ar, Cl and Si.

10. The method of claim 1, wherein the frequency component has a frequency of less than 13 MHz.

11. The method of claim 10, wherein the frequency component has a frequency of less than 50 kHz.

12. The method of claim 11, wherein the frequency component has a frequency in the range 0-300 Hz.

13. A method of detecting a fault within a potentially-faulted chamber, comprising:

measuring an attribute of a plasma during a plasma process within a non-faulted chamber so as to generate a first detection signal, the plasma being generated by application of an RF power signal;

processing the first detection signal to generate a first signal indicative of a frequency component of the first detection signal, the frequency component having a frequency less than a frequency of the RF power signal;

monitoring over time variations in the magnitude of the first signal;

generating a characteristic fingerprint for the plasma process within the non-faulted chamber based on the monitored first signal;

measuring an attribute of a plasma during a plasma process within the potentially-faulted chamber so as to generate a second detection signal;

processing the second detection signal to generate a second signal indicative of a frequency component of the second detection signal, the frequency component having a frequency less than a frequency of the RF power signal;

monitoring over time variations in the magnitude of the second signal;

generating a characteristic fingerprint for the plasma process within the potentially-faulted chamber based on the monitored second signal;

comparing the characteristic fingerprint of the plasma process within the non-faulted chamber to the characteristic fingerprint of the plasma process within the potentially-faulted chamber; and

designating the potentially-faulted chamber as faulted if the characteristic fingerprint of the plasma process within the non-faulted chamber differs from the characteristic fingerprint of the plasma process within the potentially-faulted chamber by more than an amount.

14. The method of claim 13, wherein the non-faulted chamber and the potentially-faulted chamber are the same chamber.

15. The method of claim 13, wherein each processing step includes processing the detection signal to generate a plurality of signals each indicative of a respective frequency component of the detection signal, each of the frequency components having a frequency less than the frequency of the RF power signal;

and

wherein each monitoring step includes monitoring the respective magnitudes of the plurality of signals.

16. The method of claim 13, wherein each frequency component has a frequency associated with a chemical reaction rate of the plasma process.

17. The method of claim 13, wherein each measuring step comprises generating a detector current.

18. The method of claim 13, wherein each measuring step comprises measuring at least one of a forward and a reflected RF power for a wafer pedestal.

19. The method of claim 13, wherein each measuring step comprises measuring other than a broadband optical electromagnetic emission attribute.

20. The method of claim 13, wherein each measuring step includes:

providing an optical filtering mechanism adapted to pass electromagnetic emissions from a chemical species within the plasma; and

collecting electromagnetic emissions passed by the optical filtering mechanism.

21. The method of claim 20, wherein the optical filtering mechanism comprises an optical filtering mechanism selected from the group consisting of a glass filter and a monochrometer.

22. The method of claim 20, wherein the chemical species comprises a chemical species selected from the group consisting of BCl, Al, AlCl, Ar, Cl and Si.

23. The method of claim 13, wherein each frequency component has a frequency of less than 13 MHz.

24. The method of claim 23, wherein each frequency component has a frequency of less than 50 kHz.

25. The method of claim 24, wherein each frequency component has a frequency in the range 0-300 Hz.

26. A method of matching a first chamber to a second chamber, comprising:

measuring an attribute of a plasma during a plasma process within the first chamber so as to generate a first detection signal, the plasma being generated by application of an RF power signal;

processing the first detection signal to generate a first signal indicative of a frequency component of the first detection signal, the frequency component having a frequency less than a frequency of the RF power signal;

monitoring over time variations in the magnitude of the first signal;

generating a characteristic fingerprint for the plasma process within the first chamber based on the monitored first signal;

measuring an attribute of a plasma during a plasma process within the second chamber so as to generate a second detection signal;

processing the second detection signal to generate a second signal indicative of a frequency component of the second detection signal, the frequency component having a frequency less than a frequency of the RF power signal;

monitoring over time variations in the magnitude of the second signal;

generating a characteristic fingerprint for the plasma process within the second chamber based on the monitored second signal;

comparing the characteristic fingerprint of the plasma process within the first chamber to the characteristic fingerprint of the plasma process within the second chamber; and

designating the first and second chambers as matching if the characteristic fingerprint of the plasma process within the first chamber differs from the characteristic fingerprint of the plasma process within the second chamber by less than an amount.

27. The method of claim 26, wherein each processing step includes processing the detection signal to generate a plurality of signals each indicative of a respective frequency component of the detection signal, each of the frequency components having a frequency less than the frequency of the RF power signal;

and

wherein each monitoring step includes monitoring the respective magnitudes of the plurality of signals.

28. The method of claim 26, wherein each frequency component has a frequency associated with a chemical reaction rate of the plasma process.

29. The method of claim 26, wherein each measuring step comprises generating a detector current.

30. The method of claim 26, wherein each measuring step comprises measuring at least one of a forward and a reflected RF power for a wafer pedestal.

31. The method of claim 26, wherein each measuring step comprises measuring other than a broadband optical electromagnetic emission attribute.

32. The method of claim 26, wherein each measuring step includes:

providing an optical filtering mechanism adapted to pass electromagnetic emissions from a chemical species within the plasma; and

collecting electromagnetic emissions passed by the optical filtering mechanism.

33. The method of claim 32, wherein the optical filtering mechanism comprises an optical filtering mechanism selected from the group consisting of a glass filter and a monochrometer.

34. The method of claim 32, wherein the chemical species comprises a chemical species selected from the group consisting of BCl, Al, AlCl, Ar, Cl and Si.

35. The method of claim 26, wherein each frequency component has a frequency of less than 13 MHz.

36. The method of claim 35, wherein each frequency component has a frequency of less than 50 kHz.

37. The method of claim 36, wherein each frequency component has a frequency in the range 0-300 Hz.