On the capability of delay tests to detect bridges and opens

Recent empirical and simulation studies show that adding at-speed testing to the test suite helps in detecting defective ICs missed by slow-speed and I/sub DDQ/ testing. At-speed testing attempts to detect ICs with defects, like bridges and opens, which cause faulty dynamic logic behavior. Path delay tests and transition tests are two popular tests used during at-speed testing. We show that these tests often fail to detect many bridges and opens which cause faulty dynamic behavior. Computing at speed tests is therefore fundamentally different from computing delay tests for parametric testing and new techniques need to be developed.