Radiation-Hardened Silicon-Gate CMOS/SOS

High performance, radiation hardened silicon gate CMOS/SOS circuits have been fabricated. Radiation hardness was achieved by using a low temperature (875°C), wetprocess gate oxide, and by minimizing the temperature of subsequent process steps. The need for additional temperature steps was eliminated by in-situ doping of the polysilicon gate material with boron and by using ion-implantation instead of diffusions to form source and drain regions. Radiation effects in simple inverter circuits have been measured. Threshold shifts after 106 rads (Si) of ionizing radiation are ¿0.5 V for n-channel transistors and ¿1. 6 V for p-channel transistors. Irradiation of p-channel transistors in circuit configurations where effective positive gate voltages occur, results in a 4 V shift at 106 rads (Si). Ring oscillator circuits have been fabricated to measure intrinsic circuit performance. With a 15 V power supply, stage delays of 0.5 ns are achieved. These short stage delays verify the suitability of the fabrication process for high speed circuit applications.