Physical fault injection: a suitable method for the evaluation of functional test efficiency

The last generation of 32-bit microprocessors seems `to ring the knell´ of functional test methods. Indeed, those based on fault hypothesis cannot cope with the technological reality; the other ones (ad hoc tests, systematic test, . . .) are overwhelmed by the very large number of cases (instructions) to be analyzed. The authors present a pragmatic approach that attempts to resolve this critical problem: physical faults are injected by means of a microcutting laser equipment on a set of good circuits in order to evaluate the efficiency of different test sequences. This approach is illustrated by an actual experiment performed on more than an hundred of 68000 microprocessors