Radiation Hardness and Annealing Tests of a Custom VLSI Device

Several NMOS custom VLSI ("Microplex") circuits have been irradiated with a 500 rad/hr 60Co source. With power off three of four chips tested have survived doses exceeding 1 Mrad. With power on at a 25% duty cycle, all chips tested failed at doses ranging from 10 to 130 krad. Annealing at 200°C was only partially successful in restoring the chips to useful operating conditions.