Process endpoint detection in processing chambers

• US 6,878,214 B2
• Filed: 01/24/2002
• Issued: 04/12/2005
• Est. Priority Date: 01/24/2002
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Ahr, Gary R., Murugesh, Laxman
• Primary Examiner(s): Markoff, Alexander
• Application Number:
  US10/057,037
• Publication Number:
  US 20030136425A1
• Time in Patent Office: 1,174 Days
• Field of Search: 438/905, 134/18, 134/21, 134/22.1, 134/22.18
• 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 having wavelengths overlapping an absorption band of a byproduct of the cleaning process into an exhaust line of the chamber;

receiving radiation from the exhaust line;

filtering the radiation received from the exhaust line through a first filter that transmits radiation at said absorption band of said byproduct;

filtering the radiation received from the exhaust line through a second filter that transmits radiation in a band of wavelengths different from said absorption band of said byproduct;

determining a measure of absorbance of the radiation by the byproduct by subtracting the radiation filtered through the second filter from the radiation filtered through the first filter;

amplifying said measure of absorbance to provide a voltage signal; and

determining the endpoint when the voltage signal reaches a predetermined voltage level.

2. The method of claim 1 wherein the cleaning process is a dark cleaning process and the step of directing comprises directing infrared radiation.

3. The method of claim 1 wherein the step of determining a measure of absorbance further comprises detecting radiation emitted by the byproduct after absorbing the radiation directed in the step of directing radiation.

4. The method of claim 1 wherein the step of determining a measure of absorbance further comprises analyzing the radiation respectively transmitted through the first and second filters using Fourier Transform Raman spectrometry.

5. The method of claim 1 wherein the step of determining a measure of absorbance further comprises generating an output signal representative of the measure of absorbance.

6. The method of claim 1 wherein the step of determining the endpoint when the voltage signal reaches the predetermined voltage level comprises determining when the voltage signal falls below a predetermined level.

7. The method of claim 1 wherein the byproduct is SiF₄.

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

a radiation source that transmits radiation having wavelengths overlapping an absorption band of a byproduct of the cleaning process into an exhaust line of the chamber;

a first filter positioned to receive radiation from the exhaust line, wherein the first filter transmits radiation at said absorption band of said byproduct;

a second filter positioned to receive radiation from the exhaust line, wherein the second filter transmits radiation in a band of wavelengths different from said absorption band of said byproduct;

a detector that outputs a signal representing the radiation transmitted through the first filter minus the radiation transmitted through the second filter;

a controller, connected to receive the signal outputted by the detector, that generates an endpoint signal when the signal outputted by the detector reaches a predetermined voltage level.

9. The apparatus of claim 8 wherein the cleaning process is a dark cleaning process and the radiation source comprises a source of infrared radiation.

10. The apparatus of claim 8 wherein the controller generates the endpoint signal when the output signal falls below a predetermined level.

11. The apparatus of claim 8 wherein the byproduct is SiF₄.