Heavy ion induced snapback in CMOS devices

Single-event-snapback (SES) susceptibilities of selected CMOS devices to heavy ions were measured using N, Ne, Ar, Cu, and Kr ion beams. Like latchup, snapback was observed macroscopically by detecting the abnormally high bias current condition. However, the snapback susceptibility characteristics differed from those of latchup, and consequently it was possible to measure the snapback responses unambiguously. The responses are expressed in terms of the cross section for varying bias and stopping power of ions. Test data indicate that CMOS devices with rather long channel lengths (on the order of 3 mu m) are free from SES when operated at about 5 V. However, current theories predict that this regenerative breakdown mode of upset may become very important at 5 V or below for devices with extremely short n-channel lengths.<
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