Kenneth A Swan

US Patent:

6556876, Apr 29, 2003

Filed:

Oct 12, 2000

Appl. No.:

09/689008

Inventors:

Hank Prosack - Scarborough ME
Patrick H. Ferland - Portland ME
Kenneth Swan - Gorham ME

Assignee:

National Semiconductor Corporation - Santa Clara CA

International Classification:

G05B 1918

US Classification:

700 50, 700 45, 700 52, 706 2

Abstract:

Variation in results of a semiconductor fabrication process is minimized by adjusting process parameters utilizing a fuzzy-controlled learning feedback system. The fuzzy-controlled learning system receives as inputs the results of the fabrication process and then converts these results into a fuzzy set defined by a membership function. An inference engine applies a fuzzy rule base to map an output fuzzy set from the input fuzzy set. The fuzzy output set is then converted to crisp outputs which automatically adjusts parameters of the fabrication process in order to minimize variation.