ESD and latch-up characteristics of semiconductor device with thin epitaxial substrate

We have evaluated latch-up and ESD characteristics using substrates which have a relatively thin epi layer of 1 /spl mu/m to 5 /spl mu/m. From the measurement results, we found that latch-up immunity does not necessarily increase as the epi layer becomes thinner. The ESD immunities of both the machine model (MM) and the human body model (HBM) have the same tendency that depends on the epi layer thickness and are weakest when the epi layer thickness is 2 /spl mu/m. By examining the latch-up and ESD immunity measurement results, we found that low resistivity substrates greatly affected these results.