Patent ID: 11934094
Assignee: INTERNATIONAL BUSINESS MACHINES CORPORATION
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. A method for confirming mask integrity of a first wafer, the method comprising:
measuring an initial state of a set of SRAM bits on the first wafer before testing the first wafer;
identifying a first set of SRAM bits of the set of SRAM bits, wherein the first set of SRAM bits comprise a consistent initial state greater than a first threshold percentage of times;
measuring physical dimensions of features corresponding to each of the first set of SRAM bits on a second wafer selected during manufacturing prior to completion;
identifying a set of signature SRAM bits of the first set of SRAM bits, wherein the set of signature SRAM bits comprise physical dimensions of features which correlate to the initial state of each correlated SRAM bit on the first wafer;
performing a Die to Database (D2DB) inspection of the second wafer by comparing a pattern on the second wafer to an initial design pattern of the mask; and
confirming the mask integrity of a third wafer by measuring an initial state of a corresponding set of signature SRAM bits on the third wafer.