In-situ real-time monitoring technique and apparatus for endpoint detection of thin films during chemical/mechanical polishing planarization

• US 7,024,063 B2
• Filed: 01/25/2005
• Issued: 04/04/2006
• Est. Priority Date: 12/28/1992
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Tang, Wallace T. Y.
• Primary Examiner(s): Hassanzadeh, Parviz
• Assistant Examiner(s): MACARTHUR, SYLVIA
• Application Number:
  US11/043,486
• Publication Number:
  US 20050146728A1
• Time in Patent Office: 434 Days
• Field of Search: 156/345.12, 156/345.16, 156/345.13, 216 88- 90, 385/12, 356/381
• US Class Current: 385/12
• CPC Class Codes: B24B 37/013 Devices or means for detecting lapping completion
• CPC Class Codes: B24B 37/042 operating processes therefor
• CPC Class Codes: G01B 11/0683 measurement during deposition or removal of the layer

Abstract

A technique and apparatus is disclosed for the optical monitoring and measurement of a thin film (or small region on a surface) undergoing thickness and other changes while it is rotating. An optical signal is routed from the monitored area through the axis of rotation and decoupled from the monitored rotating area. The signal can then be analyzed to determine an endpoint to the planarization process. The invention utilizes interferometric and spectrophotometric optical measurement techniques for the in situ, real-time endpoint control of chemical-mechanical polishing planarization in the fabrication of semiconductor or various optical devices. The apparatus utilizes a bifurcated fiber optic cable to monitor changes on the surface of the thin film.

Claims

1. A method of chemical mechanical polishing, comprising:

holding a substrate against a polishing surface;

moving the polishing surface relative to the substrate to polish a film on the substrate;

during polishing, illuminating a section of the film with a light beam that is directed through the polishing surface to the film and producing, from the light beam that is directed through the polishing surface, a light beam reflected from the film; and

during polishing, receiving the light beam reflected from the film and determining, based on the light beam reflected from the film, when an end point is reached.

2. The method of claim 1, wherein:

the illuminating step includes generating the light beam directed through the polishing surface to the film from at least one light source, the light beam illuminating at least one section of the film; and

the receiving step includes receiving the light beam reflected from the wafer with at least one device that detects the interferometric change.

3. The method of claim 2, wherein determining when an end point is reached includes:

detecting an interferometric change in the light reflected from the film.

4. The method of claim 3, wherein said interferometric change is detected when said at least one section of the film passes over said at least one device.

5. The method of claim 3, further comprising controlling thickness change in the film in response to the detected interferometric change.

6. The method of claim 3, wherein the light beam directed through the polishing surface to the film comprises at least one wavelength between 200 and 11,000 nanometers, and the interferometric change in the reflected light is analyzed over one or more wavelengths.

7. The method of claim 1, wherein the polishing surface is supported by a platen.

8. The method of claim 1, wherein the light beam directed through the polishing surface passes through a fiber optic cable embedded in the polishing surface.

9. The method of claim 1, wherein more than one section of the film is illuminated.

10. The method of claim 1, wherein polishing the film comprises reducing the thickness of the film or planarizing the film.

11. The method of claim 1, wherein the light beam directed through the polishing surface at the film passes through a fiber optic cable that extends into a platen situated below the polishing surface.

12. A method of claim 1, wherein the film is a metal film.

13. The method of claim 1, wherein the substrate comprises at least one of an insulating material, a conductive material, a semiconductive material, a silicon wafer, a gallium arsenide wafer, or a silicon on insulator.

14. The method of claim 1, wherein the substrate comprises a semiconductor device on a silicon wafer.

15. The method of claim 1, wherein the film comprises at least one of an SiO₂ layer, a spin-on-glass layer, a tungsten layer, an aluminum layer, a silicon layer, or a photoresist layer.

16. The method of claim 1, wherein the film comprises a dielectric layer over a semiconductor substrate.

17. The method of claim 1, wherein the film comprises at least one dielectric layer over at least one metal layer.

18. The method of claim 1, wherein the film comprises a part of a semiconductor device or an integrated circuit.

19. The method of claim 1, wherein the light beam directed through the polishing surface at the film includes at least one wavelength between 200 and 11,000 nanometers.

20. A method of making a planarized substrate comprising:

polishing a film on a substrate with a moving polishing pad;

illuminating at least one section of the film with light transmitted through the moving polishing pad during polishing of said at least one section of the film and producing, from the light transmitted, light reflected from the at least one section of the film; and

detecting interferometric change in the light reflected from the at least one illuminated section of the film.

21. The method of claim 20, wherein:

the light transmitted through the polishing surface passes through a fiber optic cable that runs through a platen that supports the polishing surface.