A Reliability Assessment of Bipolar PROMS

Design factors affecting the reliability of Schottky T2L PROMs are discussed with special attention to the high voltage programming circuitry and fuse design. Key process controls during nichrome deposition, fuse delineation (masking) and subsequent processing environments have been developed as a result of device failure analysis. Approaches to functional and AC testing before actual progranming are detailed with respect to the use of additional test "bit" and "word" lines and device design layout. One pulse programming of extra test fuses in each device is used as a special manufacturing screen to remove would be failures. "User" liabilities involved in programming, testing and Hi-Rel processing are explored with emphasis on long term reliability.