Devlopement of a Radiation Hard N-Channel Power MOSFET

Radiation-hard N-channel power MOSFETs have been manufactured using a "reverse sequence" silicon gate process in which drive-ins and anneals are completed before gate oxidation to minimise subsequent high temperature treatments. Results with initial runs in which a number of process steps were varied confirm that gate threshold shift is affected not only by gate oxidation conditions, but by subsequent steps such as flowglass densification and aluminium deposition. It has become apparent that degradation of transconductance with ionizing radiation is another process-dependent factor of major significance in power MOSFETs.