Claims
- 1. A method for monitoring a process flow of a semiconductor wafer, the method comprising the steps of:calculating a first offset value indicative of the location offset between the nominal location of the wafer and the actual location of the wafer before processing; moving the wafer into a process chamber for processing; processing the wafer; calculating a second offset value indicative of the location offset between the nominal location of the wafer and the actual location of the wafer after processing; comparing said first offset value with said second offset value; determining if a difference between the first and second offset values is greater than a predetermined amount; and activating an alarm if the difference is greater than the predetermined amount.
- 2. The method of claim 1 wherein the steps of calculating first and second offset values comprise the steps of calculating the first offset values between the actual center of the wafer and the nominal center of the wafer.
- 3. The method of claim 1 and further comprising the step of storing the first offset value after calculation said first offset value and before the comparing step.
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims priority from U.S. Provisional Patent Application Ser. No. 60/056,654, filed Aug. 22, 1997.
US Referenced Citations (6)
Provisional Applications (1)
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Number |
Date |
Country |
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60/056654 |
Aug 1997 |
US |