Testing oriented analysis of CMOS ICs with opens

In a typical approach to VLSI testing, open faults are modeled by the transistor-stuck-open fault model or are not explicitly covered at all. It is shown that functional faults caused by opens, i.e. by regions with missing material, cannot be modeled well by a transistor stuck-open. It is also shown that the majority of opens which occur in CMOS static circuits manifest themselves as timing faults. The analysis of the behavior of a CMOS transistor with a floating gate indicates it acts as a weakly 'on' active load, and therefore an open gate cannot be detected by stuck-fault testing but could be detected by monitoring the static current through the power buses.<
>