Neutron-Induced Latch-Up Immunity in Metal Gate CMOS Integrated Circuits

Neutron-induced latch-up immunity has been studied in metal gate CMOS integrated circuits as a function of neutron fluence by measuring both the current gain products (beta product) of parasitic NPN and PNP transistors, and the flash x-ray latch-up thresholds prior to and following irradiation and subsequent stabilization anneal. Correlations between the actual latch-up thresholds and the measured beta products are established for the three part types investigated. These correlations indicate that the measurement of beta products on judiciously chosen parasitic transistors is a viable technique for estimating latch-up susceptibility when the observed margin is substantial.