Semiconductor wafer inspection system

• US 20040152250A1
• Filed: 07/29/2003
• Published: 08/05/2004
• Est. Priority Date: 02/03/2003
• Status: Active Grant

• Current Assignee: Qcept Investments, LLC
• Original Assignee: Qcept Technologies, Inc.
• Inventors: Steele, M. Brandon, Hawthorne, Jeffrey Alan
• Granted Patent: US 6,957,154 B2
• Time in Patent Office: Days
• US Class Current: 438/200
• CPC Class Codes: G01N 2033/0095 Semiconductive materials
• CPC Class Codes: G01N 27/002 by investigating the work function voltage

Abstract

A method and system for identifying a defect or contamination on a surface of a material. The method and system involves providing a material, such as a semiconductor wafer, using a non-vibrating contact potential difference sensor to scan the wafer, generate contact potential difference data and processing that data to identify a pattern characteristic of the defect or contamination.

Claims

1. A method of identifying a defect on a surface of a semiconductor wafer, comprising:

providing a semiconductor wafer;

providing a non-vibrating contact potential difference sensor;

scanning the semiconductor wafer relative to the non-vibrating contact potential difference sensor;

generating contact potential difference data from the non-vibrating sensor; and

processing the non-vibrating contact potential difference sensor data to automatically detect a pattern that represents a defects.

2. The method as defined in claim 1 further including the steps of:

displaying the contact potential difference data on a display to generate a characteristic wafer image; and

comparing the characteristic wafer image with stand images to identify the category of defect present on the surface of the semiconductor wafer.

3. The method as defined in claim 1 wherein the step of processing the sensor data includes assembling of the sensor data into an image that is displayed to the user for evaluation by the user.

4. The method as defined in claim 1 wherein the step of processing the sensor data includes automatically processing the sensor data to identify the category of defect detected.

5. The method as defined in claim 1 wherein the standard images are selected from the group of a metal contaminated wafer image, an alcohol contaminated wafer image, a vacuum pick up damaged wafer image, a latex contaminated wafer image, a human fingerprint contaminated wafer image, a mechanically damaged wafer image.

6. The method as defined in claim 1 wherein the scanning step includes moving the semiconductor wafer.

7. The method as defined in claim 6 wherein the step of moving the semiconductor wafer comprises spinning the wafer.

8. The method as defined in claim 1 wherein the semiconductor wafer includes at least one additional layer disposed on a base silicon wafer.

9. The method as defined in claim 1 wherein the category of defect comprises a mechanical defect.

10. The method as defined in claim 1 wherein the category of defect comprises a chemical defect.

11. The method as defined in claim 1 wherein the category of defect comprises an electronic defect.

12. The method as defined in claim 1 wherein the step of scanning comprises the sensor being displaced relative to a fixed form of the wafer.

13. The method as defined in claim 1 wherein the step of scanning includes moving both the wafer and the sensor.

14. The method as defined in claim 1 wherein the step of comparing comprises performing a pattern recognition methodology.

15. The method as defined in claim 1 further including the step of processing the wafer with a treatment for ameliorating the category of defect identified.

16. The method as defined in claim 1 further including the step of performing a supplementary analysis.

17. The method as defined in claim 16 wherein the step of performing a supplementary analysis includes analyzing chemical contaminants.

18. The method as defined in claim 17 wherein the step of analyzing chemical contaminants includes at least one of x-ray photoelectron spectroscopy, Auger spectroscopy and Rutherford backscattering.

19. The method as defined in claim 1 further including the step of applying a computerized decisional methodology to reject selected ones of the semiconductor wafers having an unwanted category of defect.

20. A system for identifying a category of defect on a surface of a semiconductor wafer, comprising:

a non-vibrating contact potential difference sensor;

a device for moving the sensor relative to the semiconductor wafer;

a computer for receiving and analyzing wafer data generated by the sensor; and

processing the non-vibrating contact potential difference sensor data to automatically detect a pattern that represents a defects.

21. The method as defined in claim 20 further including a data base of images of standard defects, the computer including computer software which can analyze the wafer data and compare with the images of standard defects to generate identification information about the type of defect present on the surface of the wafer.

22. The system as defined in claim 20 further including a transport device to move selected ones of the semiconductor wafers to a secondary processing system having a category of defect which can be remedied.

23. The system as defined in claim 22 wherein the transport device comprises a wafer handler.

24. The system as defined in claim 20 further including a plurality of the sensors with one of the sensors disposed immediately downstream from each of a plurality of cleaning systems, thereby enabling monitoring of the semiconductor wafer after processed at each of the cleaning systems.

25. The system as defined in claim 20 that includes a mechanism for automatically determining the cleanliness of wafers and modifying cleaning parameters to improve the cleaning process.