Optical technique to detect etch process termination

• US 6,501,555 B1
• Filed: 02/01/2001
• Issued: 12/31/2002
• Est. Priority Date: 02/01/2001
• Status: Active Grant

• Current Assignee: Globalfoundries US Incorporated (GlobalFoundries, Inc.)
• Original Assignee: Advanced Micro Devices, Inc.
• Inventors: Singh, Bhanwar, Ghandehari, Kouros, Hui, Angela T.
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): HASAN, MOHAMMED A
• Application Number:
  US09/773,954
• Time in Patent Office: 698 Days
• Field of Search: 356/394, 356/630, 356/631, 356/632, 356/432, 356/434, 356/435, 356/436, 356/440, 356/316, 250/548, 438/700, 438/701, 438/710, 438/14, 438/16, 216/60
• US Class Current: 356/630
• 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

Abstract

The disclosure describes an exemplary method of detecting a process end point during etching in the fabrication of an integrated circuit. This method can include receiving a reference signal indicative of an intensity of a light source, collecting a reflection signal reflected off a surface of an integrated circuit wafer, and comparing the reference signal and the reflection signal to locate absorption bands, the absorption band being indicative of a process end point.

Claims

1. A method of detecting a process end point during etching in the fabrication of an integrated circuit, the method comprising:

receiving a reference signal indicative of an intensity of a light source;

collecting a reflection signal reflected off a surface of an integrated circuit wafer; and

comparing the reference signal and the reflection signal to locate absorption bands, the absorption bands being indicative of a process end point.

2. The method of claim 1, wherein the step of receiving a reference signal indicative of an intensity of a light source comprises collecting a light beam reflected off a mirror at a detector.

3. The method of claim 1, wherein the reference signal does not pass through an etch chamber.

4. The method of claim 1, wherein the surface of the integrated circuit wafer includes an exposed section which indicates a process end point.

5. The method of claim 1, wherein the light source provides light having a wavelength of between 1.0 μ

m and 20.0 μ

m.

6. The method of claim 1, wherein the reflection signal is an indication of chemicals present during the etching process.

7. The method of claim 1, wherein the collected reflection signal is an indication of absorbed light.

8. A method of using scatterometry to detect integrated circuit (IC) process end points in an etch chamber, the method comprising:

providing a reference signal;

reflecting a beam of light off of an integrated circuit surface; and

detecting absorption bands using the reflected beam of light, the absorption bands indicating integrated circuit process end points.

9. A system for fabricating an integrated circuit in which process end points are detected, the system comprising:

an etching chamber configured to etch an integrated circuit wafer;

a light source which projects light in the etching chamber; and

a detector which detects a light beam reflected off a surface of the integrated circuit wafer, the detector comparing the reflected light beam with a reference signal to locate absorption bands, the absorption bands being indicative of a process end point.

10. The system of claim 9, further comprising a mirror which reflects a light beam from the light source to provide a reference signal to the detector.

11. The system of claim 9, wherein the detector detects a new chemical produced in the etching chamber, the new chemical being produced in the formation of an etching end point.

12. The system of claim 9, further comprising polarizers disposed between the light source and the integrated circuit wafer.

13. The system of claim 9, wherein the detector is communicatively coupled to a computing device.