Interferometric method for endpointing plasma etch processes

• US 6,400,458 B1
• Filed: 09/30/1999
• Issued: 06/04/2002
• Est. Priority Date: 09/30/1999
• Status: Expired due to Term

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Howald, Arthur M.
• Primary Examiner(s): Font, Frank G.
• Assistant Examiner(s): NATIVIDAD, PHILIP SANA
• Application Number:
  US09/409,840
• Time in Patent Office: 978 Days
• Field of Search: 356/355, 438/16
• US Class Current: 356/496
• CPC Class Codes: B24B 37/013 Devices or means for detecting lapping completion
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• 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

Abstract

A method for monitoring a device fabrication process. The method includes etching into a wafer disposed inside a chamber and detecting the intensity of a portion of a light reflected from a surface of the wafer and further scattered at a scattering inside surface of the chamber.

Claims

1. A method of monitoring a device fabrication process comprising the steps of:

etching into a wafer disposed inside a chamber;

reflecting light off of the wafer;

passing a portion of the reflected light through a roughened surface of a wall of the chamber, the wall being capable of transmitting the light; and

detecting the intensity of the transmitted light.

2. The method of claim 1 wherein the wall is a roughened fused silica window.

3. The method of claim 1 further comprising the step of illuminating the wafer.

4. A method of monitoring a device fabrication process comprising the steps of:

depositing a layer upon a wafer disposed inside a chamber;

reflecting light off of the wafer;

passing a portion of the reflected light through a roughened surface of a wall of the chamber, the wall being capable of transmitting the light; and

detecting the intensity of the transmitted light.

5. The method of claim 4 wherein the wall is a roughened fused silica window.

6. The method of claim 4 further comprising the step of illuminating the wafer.

7. An apparatus for monitoring a wafer fabrication process comprising:

a chamber including a wall capable of transmitting light, the wall having a roughened surface; and

a detecting apparatus operable to detect the intensity of a portion of a light reflected from a surface of the wafer and further scattered at the roughened surface.

8. The apparatus as recited in claim 7 wherein the wall is a roughened fused silica window.

9. The apparatus as recited in claim 7 further comprising an illuminating apparatus operable to illuminate the surface of the wafer.

10. An apparatus for monitoring a wafer fabrication process comprising:

a chamber;

a scattering screen disposed within the chamber; and

a detecting apparatus substantially aimed towards the scattering screen and operable to detect the intensity of a portion of a light reflected from a surface of the wafer and further scattered by the scattering screen.

11. The apparatus as recited in claim 10 wherein said scattering screen is ceramic.