End point detection with imaging matching in semiconductor processing

• US 6,930,782 B1
• Filed: 03/28/2003
• Issued: 08/16/2005
• Est. Priority Date: 03/28/2003
• Status: Expired due to Fees

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Yi, Jingang, Xu, Cangshan
• Primary Examiner(s): Toatley, Jr., Gregory J.
• Assistant Examiner(s): Lyons, Michael A.
• Application Number:
  US10/401,446
• Time in Patent Office: 872 Days
• Field of Search: 356/504, 356/491, 356/492, 356/496, 356/499, 356/503
• US Class Current: 356/504
• CPC Class Codes: B24B 21/04 for grinding plane surfaces
• CPC Class Codes: B24B 37/013 Devices or means for detecting lapping completion
• CPC Class Codes: B24B 37/04 designed for working plane surfaces
• CPC Class Codes: B24B 49/12 involving optical means
• CPC Class Codes: G01N 21/95607 using a comparative method
• CPC Class Codes: G06T 2207/30148 Semiconductor; IC; Wafer
• CPC Class Codes: G06T 7/001 using an image reference approach
• CPC Class Codes: G06T 7/70 Determining position or orientation of objects or cameras camera calibration G06T7/80

Abstract

An end point detection system may compare a production image developed during processing of production semiconductor wafer with a reference image. The reference image is representative of a desired state of processing of the production semiconductor wafer. The reference image is determined by processing a reference semiconductor wafer. The reference semiconductor wafer may be part of a wafer group of similar wafers that includes the production semiconductor wafer. The end point detection system may dynamically develop the production image during processing of the production semiconductor wafer. Indication may be provided by the end point detection system when the reference image and the production image are substantially similar.

Claims

1. A method of detection of a desired state of processing of a semiconductor wafer, the method comprising:

forming a process snapshot with captured spectral data representative of light intensity in a plurality of wavelengths;

sequentially collecting process snapshots while processing a production semiconductor wafer;

processing a plurality of process snapshots to form a production image;

comparing all of the wavelengths of the production image to a reference image having a plurality of wavelengths; and

signaling when the light intensity of the wavelengths of the production image and a light intensity of the wavelengths of the reference image are within a determined level of similarity.

2. The method of claim 1, wherein processing comprises representing spectral data and other process related data with the production image.

3. The method of claim 1, wherein processing comprises dynamically re-scaling the production image to compensate for variation in processing of the semiconductor wafer by adjustment of the number of wavelengths included in the production image.

4. The method of claim 1, wherein spectral data is captured utilizing optical interferometry.

5. The method of claim 1, wherein comparing comprises performing image matching techniques to determine substantial similarity between the production image and the reference image.

6. The method of claim 1, wherein signaling comprises enabling termination of the processing of the production semiconductor wafer.

7. The method of claim 1, wherein processing a plurality of process snapshots comprises forming the production image from a plurality of variable gradients that are at least one of color gradients or grayscale gradients or combinations thereof, wherein at least a portion of the variable gradients are representative of spectral data from each of the process snapshots.

8. The method of claim 1, wherein comparing all of the wavelengths of the production image comprises size adjusting the reference image based on the number of snapshots used to form the production image.

9. A method of detection of a desired state of processing of a semiconductor, the method comprising:

processing a reference semiconductor to a desired state;

capturing process related data indicative of the desired state in the form of a two-dimensional reference image;

representing light intensity in each of a plurality of wavelengths in the two-dimensional reference image, wherein the level of the light intensity in each of the wavelengths is resented with corresponding color from a predefined range of colors;

processing a production semiconductor after the reference semiconductor;

capturing process related data indicative of the current state of the production semiconductor in the form of a two-dimensional production image;

representing light intensity in each of a plural of wavelengths in the two-dimensional production image, wherein the level of light intensity in each of the wavelength is represented with corresponding color from the predefined range of colors; and

signaling when the color present in the two-dimensional production image and the color present in the two-dimensional reference image are substantially similar.

10. The method of claim 9, wherein processing comprises chemical mechanical planarization of the reference semiconductor and the production semiconductor.

11. The method of claim 9, wherein capturing process related data indicative of the desired state in the form of a two-dimensional production image comprises:

sequentially collecting process snapshots to develop the two-dimensional production image; and

eliminating an oldest process snapshot in favor of a newest process snapshot to keep a production snapshot window from exceeding the size of a reference snapshot window.

12. The method of claim 9, wherein capturing process related data indicative of the desired state in the form of a two-dimensional production image comprises adjusting the size of the reference image as a function of the size of the production image.

13. The method of claim 9, wherein capturing process related data indicative of the desired state in the form of a two-dimensional production image comprises re-scaling the production image by dynamic adjustment of the quantity of process snapshots used to develop the production image.

14. The method of claim 9, wherein capturing process related data indicative of the desired state in the form of a two-dimensional production image comprises selecting a range of process snapshots for the production image that are other than a range of process snapshots used to form the reference image.

15. The method of claim 9, wherein capturing process related data indicative of the desired state in the form of a two-dimensional production image comprises adjusting the number of wavelengths represented in the reference image and the production image.

16. The method of claim 9, wherein capturing process related data comprises capturing spectral data, a roller motor current and a semiconductor wafer temperature in each of a plurality of process snapshots.

17. An endpoint detection system for detection of a desired state of processing, the endpoint detection system comprising:

a memory device;

instructions stored in the memory device to dynamically develop a two-dimensional production image that displays variations in the magnitude of process related data with corresponding colors from a predefined range of colors as a function of ongoing processing of a production semiconductor wafer;

instructions stored in the memory device to compare the two-dimensional production image to a two-dimensional reference image that also displays variation in the magnitude of the process related data with corresponding colors from the predetermined range of colors, wherein the two-dimensional reference image is representative of a desired state of processing of the two-dimensional production image; and

instructions stored in the memory device to generate a signal when the colors present in the two-dimensional production image and the colors present in the two-dimensional reference image are substantially similar.

18. The endpoint detection system of claim 17, wherein the instructions stored in the memory device to dynamically develop the two-dimensional production image comprise instructions to capture a process snapshot that includes spectral data indicative of the intensity of light in a plurality of wavelengths that is reflected off a surface of the production semiconductor wafer.

19. The endpoint detection system of claim 17, wherein the instructions stored in the memory device to dynamically develop the two-dimensional production image comprise instructions to represent spectral data from a plurality of wavelengths and other process related data in the two-dimensional production image.

20. The endpoint detection system of claim 17, wherein the instructions to dynamically develop a two-dimensional production image comprise instructions stored in the memory device to add a new process snapshot and removing an oldest process snapshot to enable a movable production snapshot window.

21. The endpoint detection system of claim 17, wherein the instructions to dynamically develop a two-dimensional production image comprise instructions stored in the memory device to re-scale the production image by adjustment of the processing time represented in the production image.

22. An endpoint detection system for detection of a desired state of processing, the endpoint detection system comprising:

a computer,

a first signal provided to the computer, wherein the first signal is representative of the desired state of processing of a reference semiconductor wafer with data indicative of the intensity of light in each of a plurality of wavelengths,

wherein the computer is operable to develop a reference image as a function of the first signal, the reference image is developed to display the intensity of light in each of the wavelengths with a corresponding color from a predetermined range of colors; and

a second signal dynamically provided to the computer during processing of a production semiconductor wafer, wherein the second signal is representative of the state of processing of the production semiconductor wafer with data indicative of the intensity of light in each of a plurality of wavelengths,

wherein the computer is operable to develop a production image as a function of the second signal, the production image is developed to display the intensity of light in each of the wavelengths with a corresponding color from the predetermined range of colors,

wherein the computer is operable to compare the reference image and the production image and provide a third signal when the reference image and the production image are substantially similar.

23. The endpoint detection system of claim 22, wherein the first and second signals are spectral data representative of the intensity of light reflected off the surface of a semiconductor wafer.

24. The endpoint detection system of claim 22, wherein the computer comprises a data acquisition module, a memory module and a processor.

25. The endpoint detection system of claim 22, wherein the reference image and the production image are developed from a plurality of process snapshots that are captured as a function of the respective first and second signals during processing of the reference semiconductor wafer and the production semiconductor wafer, respectively.

26. A method of detection of a desired state of processing of a semiconductor wafer, the method comprising:

simultaneously capturing the intensity of a plurality of wavelengths of light energy in each of a plurality of sequentially collected snapshot images;

developing a production image that represents the intensity of the light energy in the wavelengths of the snapshot images with at least one of color gradients or gray scale gradients or combinations thereof; and

comparing the at least one of color gradients or gray scale gradients or combination thereof that are included in the production image with at least one of color gradients or gray scale gradients, or combinations thereof that are included in a reference image.

27. The method of claim 26, wherein comparing the at least one of color gradients or gray scale gradients comprises image matching the production image and the reference image to be substantially similar above a determined threshold.

28. The method of claim 26, wherein developing a production image comprises representing other process related variable data with at least one of color gradients or gray scale gradients in the production image.

29. The method of claim 28, wherein representing other process related data comprises plotting at least one of a roller motor current or a semiconductor wafer temperature.

30. The method of claim 26, wherein comparing the at least one of color gradients or gray scale gradients comprises adjusting the size of the reference image as a function of the number of process snapshots used to plot the production image.

31. The method of claim 26, wherein developing a production image comprises re-scaling the production image by dynamic adjustment of the quantity of process snapshots used to develop the production image.

32. The method of claim 26, wherein developing a production image comprises selecting a range of process snapshots for the production image that are other than a age of process snapshots used to form a reference image.