Realistic 55nm IC failure in time (FIT) estimates from automotive field returns

We have demonstrated that the raw failure rate from field data decreases much faster than any realistic statistical reliability model due to the artifact that we are also adding parts into the field as time passes. We have shown with a simple mathematical correction we can get real FIT that behaves as expected from realistic statistical reliability model. This methodology for hard failure rate estimation can also be applied for soft failure rate estimation using “NTF” or “No Trouble Found” field returns that are believed marginal parts. Since the next generation technology may be more sensitive to soft failures than the current generation, it is critical to get both hard and soft failure rate estimates, to allow design for reliability decisions.