07/01/1993 09:00 AM
Computer Engineering
Undetectable shorts may decrease the long term reliability of a circuit, cause intermittent failures, add noise and delay, or increase test pattern generation costs. This paper describes the undetectable non-feedback shorts that are likely to occur in standard cell implementations of the ISCAS`85 combinational test circuits. For the MCNC implementation of the circuits, all shorts between adjacent wires were extracted and the undetectable ones analyzed. We found that approximately 0.2% are undetectable and that nearly half of these can be easily predicted before the physical layout of the circuit is generated. Since only a small percentage of the shorts are undetectable, and many of the undetectables are easily identifiable, it appears that it is possible to reduce the likelihood, or completely eliminate, the occurrence of a large portion of these shorts by incorporating design for test strategies into routing software.
