Method and apparatus for in-situ monitoring of ion energy distribution for endpoint detection via capacitance measurement

• US 6,326,794 B1
• Filed: 01/14/1999
• Issued: 12/04/2001
• Est. Priority Date: 01/14/1999
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Singh, Manmohanjit, Nguyen, Son Van, Lundquist, Paul Matthew
• Primary Examiner(s): Metjahic, Safet
• Assistant Examiner(s): KERVEROS, DEMETRIOS C
• Application Number:
  US09/231,043
• Time in Patent Office: 1,055 Days
• Field of Search: 324/686, 324/663, 324/658, 324/668, 324/459, 324/460, 324/678, 324/464
• US Class Current: 324/678
• CPC Class Codes: G01N 27/62 by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
• CPC Class Codes: G01R 19/0061 Measuring currents of particle-beams, currents from electron multipliers, photocurrents, ion currents; Measuring in plasmas
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• CPC Class Codes: H01J 37/32963 End-point detection

Abstract

A method and apparatus that provides in-situ monitoring of both the ion flux and the ion energy distribution of plasma processes to determine the endpoint of the etch process or the integrity and reproducibility of the deposition process where ion bombardment and energy distribution play critical roles in the process. A capacitance sensor is provided for measuring ion flux and ion distribution. At least one capacitance sensor is disposed within a plasma reactor at a first position for detecting ion flux emanating from a plasma within the plasma reactor. The capacitance sensor generates an ion flux measurement signal in response to the detection of the ion flux. Each of the at least one capacitance sensors is coupled to signal lines for routing an ion flux measurement signal outside the plasma reactor. A plurality of capacitance sensors may be formed as one of a plurality of rows of parts to be processed.

Claims

1. A plasma endpoint probe comprising at least one capacitance sensor disposed inside a plasma reactor at a first position for detecting ion flux emanating from a plasma within the plasma reactor that strikes a surface of the capacitance sensor inside the plasma reactor and generating an ion flux measurement signal in response to the detection of the ion flux.

2. The plasma endpoint probe of claim 1 wherein the measurement signal is provided outside the plasma reactor for processing.

3. The plasma endpoint probe of claim 2 wherein each of the at least one capacitance sensor is coupled to signal lines for routing an ion flux measurement signal outside the plasma reactor.

4. The plasma endpoint probe of claim 1 wherein the at least one capacitance sensor comprises two conductors separated by at least one insulation layer.

5. The plasma endpoint probe of claim 4 wherein the insulation layer comprises a dielectric material.

6. The plasma endpoint probe of claim 4 wherein the signal lines are coupled to the two conductors.

7. The plasma endpoint probe of claim 1 wherein the at least one capacitance sensor comprises a plurality of capacitance sensors formed as one of a plurality of rows of parts to be processed.

8. The plasma endpoint probe of claim 1 wherein the at least one capacitance sensor is formed using a substance that is substantially identical to a part being processed minimizing an ion/plasma electrical potential disruption in the plasma reactor.

9. The plasma endpoint probe of claim 1 wherein the at least one capacitance sensor is disposed in a pallet, the pallet providing support to a device being subjected to the plasma.

10. The plasma endpoint probe of claim 1 wherein the ion flux measurement signal represents a number of ions impinging a capacitance sensor.

11. The plasma endpoint probe of claim 10 wherein at least one capacitance sensor comprises a plurality of capacitance sensors diffused within the electrode.

12. The plasma endpoint probe of claim 11 wherein the plurality of capacitance sensors measure the ion distribution from the plasma.

13. The plasma endpoint probe of claim 1 wherein the at least one capacitance sensor comprises a shape of a part to be processed to prevent a disturbance of the plasma by minimizing an ion flux and an ion energy distribution in a plasma environment.

14. The plasma endpoint probe of claim 1 wherein the at least one capacitance sensor has an electric potential applied thereto for tuning the capacitance sensor to a predetermined energy range.

15. The plasma endpoint probe of claim 14 wherein the electric potential is scanned to determine an energy distribution of the ions.

16. A method for probing a plasma reactor to determine an ion flux and ion energy distribution for a plasma process, comprising:

providing at least one capacitance sensor inside a plasma reactor at a first position;

detecting ion flux emanating from a plasma within the plasma reactor that strikes a surface of the capacitance sensor inside the plasma reactor; and

generating an ion flux measurement signal from the capacitance sensor in response to the detection of the ion flux.

17. The method of claim 16 wherein the at least one capacitance sensor comprises two conductors separated by at least one insulation layer.

18. The method of claim 17 wherein the insulation layer comprises a dielectric material.

19. The method of claim 17 wherein the signal lines are coupled to the two conductors.

20. The method of claim 16 wherein providing at least one capacitance sensor comprises providing a plurality of capacitance sensors formed as one of a plurality of rows of parts to be processed.

21. The method of claim 16 wherein the at least one capacitance sensor is disposed in a pallet, the pallet providing support to a device being subjected to the plasma.

22. The method of claim 16 wherein the ion flux measurement signal represents a number of ions impinging a capacitance sensor.

23. The method of claim 22 wherein at least one capacitance sensor comprises a plurality of capacitance sensors diffused within the electrode.

24. The method of claim 23 further comprising measuring the ion distribution from the plasma using the plurality of capacitance sensors.

25. The method of claim 16 further comprising preventing the disturbance of the plasma by forming the at least one capacitance sensor in a shape of a part to be processed to minimize an ion flux and an ion energy distribution in a plasma environment.

26. The method of claim 16 further comprising tuning the capacitance sensor to a predetermined energy range by applying an electric potential to the at least one capacitance sensor.

27. The method of claim 26 further comprising scanning the electric potential to determine an energy distribution of the ions.

28. The method of claim 16 further comprising forming the at least one capacitance sensor using a substance that is substantially identical to a part being processed minimizing an ion/plasma electrical potential disruption in the plasma reactor.