Testing for Intermittent Resistive Faults in CMOS Integrated Systems

The required dependability of integrated CMOS systems has to be continuously increased because nowadays many applications are safety-critical. Having a good knowledge of potential realistic faults plays an important role in this case. The most difficult and expensive category of faults that can occur are the no-faults found (NFF). We have investigated the influence of intermittent resistive faults (IRF), an NFF resulting from e.g. cracks in ball-grid array-to-board interconnections and on-chip interconnections. Previous circuit simulations from us have indicated the potential effect of IRFs on the behavior of analogue as well as simple digital CMOS circuits. In this paper, a hardware IRF generator is presented to accelerate the IRF fault injection process. As a case study, a digital CMOS UART is selected and experimental results for software and hardware-based fault injections are provided. The experimental results demonstrate that the IRF fault injection can be accelerated by 7 orders of magnitude.