Film thickness control using spectral interferometry

• US 6,413,867 B1
• Filed: 12/23/1999
• Issued: 07/02/2002
• Est. Priority Date: 12/23/1999
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Sarfaty, Moshe, Lymberopoulos, Dimitris P., Davidow, Jed E., Balasubramhanya, Lalitha S.
• Primary Examiner(s): HITESHEW, FELISA CARLA
• Application Number:
  US09/470,828
• Time in Patent Office: 922 Days
• Field of Search: 438/689
• US Class Current: 438/689
• CPC Class Codes: H01L 22/12 for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions electrical measurement of diffusions H01L22/14
• CPC Class Codes: H01L 22/26 Acting in response to an ongoing measurement without interruption of processing, e.g. endpoint detection, in-situ thickness measurement endpoint detection arrangements in CMP apparatus B24B37/013, in discharge apparatus H01J37/32
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A process for controlling a substrate processing operation such as a plasma etch operation. One embodiment of the method of the present invention forms a plasma within a substrate processing chamber to etch a wafer disposed within the chamber. The plasma emission is used by the process as a broadband light source. During the plasma etch process, a plurality of wavelengths of radiation reflected from the surface of the wafer being etched are measured with a spectrometer. These measurements are then compared using pattern recognition techniques to previous measurements taken during a previous plasma etch operation. Certain embodiments of the invention use principal component analysis (PCA) techniques to perform pattern recognition while other embodiment use programmed neural net pattern recognition techniques.

Claims

1. A method for controlling operation of a substrate processing chamber, said method comprising:

transferring a substrate into said substrate processing chamber;

performing a substrate processing operation on said substrate disposed within said substrate processing chamber;

measuring a plurality of wavelengths of radiation reflected from an upper surface of said substrate during said substrate processing operation; and

comparing the measured wavelengths with wavelengths measured during a previous substrate processing operation using a pattern recognition technique and stopping the substrate processing operation in response to a positive comparison.

2. A method for controlling operation of a substrate processing chamber, said method comprising:

transferring a substrate into said substrate processing chamber;

performing a substrate processing operation on said substrate disposed within said substrate processing chamber;

measuring a plurality of wavelengths of radiation reflected from an upper surface of said substrate during said substrate processing operation; and

comparing the measured wavelengths with wavelengths measured during a previous substrate processing operation using a principal component analysis technique.

3. A method for controlling operation of a substrate processing chamber, said method comprising:

transferring a substrate into said substrate processing chamber;

performing a substrate processing operation on said substrate disposed within said substrate processing chamber;

measuring a plurality of wavelengths of radiation reflected from an upper surface of said substrate during said substrate processing operation; and

comparing the measured wavelengths with wavelengths measured during a previous-substrate processing operation using a pattern recognition technique;

wherein said substrate processing operation forms a plasma within said chamber and said radiation reflected from said upper substrate surface is generated from said plasma.

4. The method of claim 3 wherein said substrate processing operation is a plasma etch operation.

5. The process of claim 4 wherein said plasma etch operation is stopped in response to a positive comparison of said measured plurality of wavelengths to said previously measured wavelengths.

6. The method of claim 4 wherein gas flows of said plasma etch operation are altered in response to a positive comparison of said measured plurality of wavelengths to said previously measured wavelengths.

7. The method of claim 3 wherein said substrate processing operation is a plasma enhanced CVD operation.

8. A method for controlling operation of a substrate processing chamber, said method comprising:

transferring a substrate into said substrate processing chamber;

performing a substrate processing operation on said substrate disposed within said substrate processing chamber;

measuring a plurality of wavelengths of radiation reflected from an upper surface of said substrate during said substrate processing operation; and

comparing the measured wavelengths with wavelengths measured during a previous substrate processing operation using a pattern recognition technique and stopping the substrate processing operation in response to a positive comparison;

wherein said radiation reflected from upper substrate surface is generated from a broadband lamp.

9. A method for controlling operation of a substrate processing chamber, said method comprising:

transferring a substrate into said substrate processing chamber;

performing a substrate processing operation on said substrate disposed within said substrate processing chamber;

measuring a plurality of wavelengths of radiation reflected from an upper surface of said substrate during said substrate processing operation; and

comparing the measured wavelengths with wavelengths measured during a previous substrate processing operation using a pattern recognition technique;

wherein said plurality of wavelengths of radiation are measured with a spectrometer.

10. A process for controlling a plasma etch operation, said process comprising:

forming a plasma within a substrate processing chamber to etch a wafer disposed within the chamber;

measuring a plurality of wavelengths of radiation reflected from an upper surface of a wafer being etched with a spectrometer; and

comparing the measured wavelengths with wavelengths measured during a previous plasma etch operation using a pattern recognition technique;

wherein said pattern recognition technique is principal component analysis.

11. A process for controlling a plasma etch operation, said process comprising:

forming a plasma within a substrate processing chamber to etch a wafer disposed within the chamber;

measuring a plurality of wavelengths of radiation reflected from an upper surface of a wafer being etched with a spectrometer; and

comparing the measured wavelengths with wavelengths measured during a previous plasma etch operation using a pattern recognition technique;

wherein said plasma etch operation is stopped in response to a positive comparison of said measured plurality of wavelengths to said previously measured wavelengths.

12. The process of claim 11 wherein said pattern recognition technique is a principal component analysis technique.

13. A process for controlling a plasma etch operation, said process comprising:

forming a plasma within a substrate processing chamber to etch a wafer disposed within the chamber;

measuring a plurality of wavelengths of radiation reflected from an upper surface of a wafer being etched with a spectrometer; and

comparing the measured wavelengths with wavelengths measured during a previous plasma etch operation using a pattern recognition technique;

wherein gas flows of said plasma etch operation are altered in response to a positive comparison of said measured plurality of wavelengths to said previously measured wavelengths.

14. The process of claim 13 wherein said pattern recognition technique is a principal component analysis technique.

15. An apparatus for processing a substrate, said apparatus comprising:

a substrate processing chamber;

a radiation collector operatively coupled to said substrate processing chamber to measure radiation reflected from an upper surface of said substrate during said substrate processing operation, said radiation collector being capable of measuring reflected radiation from a plurality of different radiation wavelengths;

a computer processor that controls the operation of said apparatus; and

a memory coupled to said computer controller, said memory storing a computer program in computer readable format that includes computer instructions to control said apparatus to (1) perform a substrate processing operation on a substrate disposed within said substrate processing chamber, (2) compare measurements from said radiation collector to data representative of a plurality of wavelengths of radiation reflected off the surface of a substrate during a previous substrate processing operation using a pattern recognition technique, and (3) in response to a positive comparison, stop said substrate processing operation.

16. The apparatus of claim 15 wherein said radiation collector is a spectrometer.

17. The apparatus of claim 15 wherein said substrate processing chamber is a plasma etch chamber.