A Block Partitioning Method for Region Exhaustive Test to Reduce the Number of Test Patterns and Improve Gate Exhaustive Fault Coverage

In gate-exhaustive test that covers cell-internal defects in a circuit, there exists a proportional relationship between the number of gates and the number of gate-exhaustive faults. Thus, the numbers of gate-exhaustive faults and test patterns increase when the number of gates increases. Region-exhaustive fault model has been proposed to reduce the number of gate-exhaustive faults. In region-exhaustive test, a block which is constituted from some gates is recognized as region. A circuit is partitioned into several block such that the number of region-exhaustive faults become smaller than that of gate-exhaustive faults. However, in region-exhaustive test, the number of test patterns is large compared with gate-exhaustive test and the fault coverage is low. Moreover, the gate-exhaustive fault coverage has not been evaluated with test patterns generated for region-exhaustive faults. In this paper, we propose a block partitioning method which consider untestable faults in gate-exhaustive test and the number of inputs for a region in order to reduce the number of test patterns and to maintain the gate-exhaustive fault coverage.