Wafer inspection system for distinguishing pits and particles

Patent 6118525 Issued on September 12, 2000. Estimated Expiration Date:

October 27, 2017. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

3749496

3904293

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Inventors

Assignee

ADE Optical Systems Corporation

Application

No. 958230 filed on 10/27/1997

US Classes:

356/237.2, Surface condition356/364BY POLARIZED LIGHT EXAMINATION

Examiners

Primary: Kim, Robert H.

Attorney, Agent or Firm

Fish & Richardson P.C.

Foreign Patent References

398781 EP. 11/13/1990
42 27 593A DE. 02/13/1993
61-240663 JP. 10/13/1986
2-216035 JP. 08/13/1990
3-128445 JP. 05/13/1991
5-18889 JP. 01/13/1993
5-118994 JP. 05/13/1993
5-142156 JP. 06/13/1993
5-288536 JP. 11/13/1993
6-174655 JP. 06/13/1994
06229939A JP. 08/13/1994
6-242015 JP. 09/13/1994
07146245A JP. 06/13/1995
07146245 JP. 06/13/1995
7-81958 JP. 09/13/1995
07270326 JP. 10/13/1995
7-318504 JP. 12/13/1995
09145630A JP. 06/13/1997
2661913 JP. 06/13/1997
09210918A JP. 08/13/1997
2747921 JP. 02/13/1998
10-221268 JP. 08/13/1998
10-282009 JP. 10/13/1998
10-510359 JP. 10/13/1998
096987 TW. 03/13/1988
2 321 964A GB. 08/13/1988
94/12867 WO. 06/13/1994
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WO 96/28721 WO. 09/13/1996
WO 96/27786 WO. 09/13/1996
WO 97/12226 WO. 04/13/1997
WO 97/46865 WO. 12/13/1997

International Class

G01N 021/00

Abstract

A surface inspection system and method is provided which detects defects such as particles or pits on the surface of a workpiece, such as a silicon wafer, and also distinguishes between pit defects and particle defects. The surface inspection system comprises an inspection station for receiving a workpiece and a scanner positioned and arranged to scan a surface of the workpiece at the inspection station. The scanner includes a light source arranged to project a beam of P-polarized light and a scanner positioned to scan the P-polarized light beam across the surface of the workpiece. The system further provides for detecting differences in the angular distribution of the light scattered from the workpiece and for distinguishing particle defects from pit defects based upon these differences.

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