Process endpoint detection in processing chambers

• US 20030136425A1
• Filed: 01/24/2002
• Published: 07/24/2003
• Est. Priority Date: 01/24/2002
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Murugesh, Laxman, Ahr, Gary R.
• Granted Patent: US 6,878,214 B2
• Time in Patent Office: Days
• US Class Current: 134/18
• CPC Class Codes: H01J 37/32862 In situ cleaning of vessels and/or internal parts
• 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
• CPC Class Codes: H01J 37/32972 Spectral analysis
• CPC Class Codes: H01L 21/67253 Process monitoring, e.g. flow or thickness monitoring
• CPC Class Codes: Y10S 438/905 Cleaning of reaction chamber

Abstract

Method and apparatus for determining an endpoint of a cleaning process running in a chamber. In particular, one embodiment of the present invention is a method that includes steps of: (a) directing radiation absorbed by a byproduct of the cleaning process into an exhaust line of the chamber; (b) detecting a measure of absorbance of the radiation by the byproduct; and (c) determining the endpoint when the measure of absorbance falls within a predetermined window.

Claims

1. A method for determining an endpoint of a cleaning process running in a chamber that comprises steps of:

directing radiation absorbed by a byproduct of the cleaning process into an exhaust line of the chamber;

detecting a measure of absorbance of the radiation by the byproduct; and

determining the endpoint when the measure of absorbance falls within a predetermined window.

2. The method of claim 1 wherein the predetermined window corresponds to 100% cleaning of the chamber and less than 100% cleaning of a predetermined portion of the exhaust line.

3. The method of claim 2 wherein the cleaning process is a dark cleaning process and the step of directing comprises directing infrared radiation.

4. The method of claim 3 wherein the step of detecting comprises detecting further radiation emitted by the byproduct after absorbing the radiation.

5. The method of claim 4 wherein the step of detecting further comprises analyzing the further radiation using Fourier Transform Raman spectrometry.

6. The method of claim 5 wherein the step of detecting further comprises generating an output signal representative of the measure.

7. The method of claim 6 wherein the step of determining comprises determining the endpoint when the output signal falls within the predetermined window.

8. The method of claim 6 wherein a second output signal is a predetermined multiple of the output signal.

9. The method of claim 7 wherein the step of determining the endpoint when the output signal falls within the predetermined window comprises determining when the output signal falls below a predetermined level.

10. The method of claim 9 wherein the byproduct is SiF₄.

11. An apparatus for determining an endpoint of a cleaning process running in a chamber that comprises:

a radiation source that transmits radiation absorbed by a byproduct of the cleaning process into an exhaust line of the chamber;

a detector that detects further radiation emitted by the byproduct and a measure of background radiation;

an analyzer that analyzes the further radiation and the measure to determine a measure of absorbance of the radiation by the byproduct; and

controller that generates an endpoint signal when the measure of absorbance reaches a predetermined window.

12. The apparatus of claim 11 wherein the predetermined window corresponds to 100% cleaning of the chamber and less than 100% cleaning of a predetermined portion of the exhaust line.

13. The apparatus of claim 12 wherein the cleaning process is a dark cleaning process and the radiation source comprises a source of infrared radiation.

14. The apparatus of claim 13 wherein the detector comprises a filter that transmits the further radiation and a filter that transmits radiation in a band of wavelengths close to wavelengths of the further radiation.

15. The apparatus of claim 14 wherein the analyzer comprises a Fourier Transform Raman spectrometer.

16. The apparatus of claim 15 wherein the analyzer generates an output signal representative of the measure.

17. The apparatus of claim 16 wherein the controller generates the endpoint signal when the output signal falls within the predetermined window.

18. The apparatus of claim 17 wherein the controller generates the endpoint signal when the output signal falls below a predetermined level.

19. The apparatus of claim 18 wherein byproduct is SiF₄.