Method and system for determining the fail patterns of fabricated wafers in automated wafer acceptance test

摘要

A method and system is provided for determining the fail patterns of fabricated wafers in an automated WAT procedure. First, N test items are performed on selected samples from each lot of fabricated wafers, from which a total of N fail percentages are obtained respectively from the N test items. Next, the N fail percentages are formulated as an N-dimensional test-result vector, in which the (i)th element represents the fail percentage of the (i)th test item, for i=1 to N. Subsequently, an N×N conversion matrix is provided to convert the N-dimensional test-result vector into an N-dimensional fail-pattern vector with fail patterns as a basis. In this fail-pattern vector, the (j)th element represents the percentage of the (j)th fail pattern, for j=1 to N. By the method and system, the results from the WAT procedure can be extended to all the fabricated wafers in the lot. It also allows the test engineer group to have a collective overview on the statistics of the test results and perform analysis from the correlation of the test data with the fabrication equipment, fabricated wafers, and lots so that the test data can be more fully utilized than in the prior art.