Proton and Heavy-Ion Radiation Damage Studies in MOS Transistors

This paper discusses extensive radiation damage measurements that were made on unprotected, radiation-soft, p-channel MOS transistors irradiated with beams of either energetic protons or heavy ions. These studies provide important data and valuable insights into the radiation responses of this least complex type of MOS transistor to the different ions employed. For the heavy-ion irradiations under positive gate bias, charge recombination in the oxide was so pronounced that the threshold voltage shifts per unit dose were only a few percent of those measured for the proton exposures. The data also indicate that the heavier ions do considerable radiation damage in both the oxide and the channel that is markedly different than that observed for Co-60 or energetic proton irradiations. These differences in addition to being of fundamental importance raise the question of the suitability of employing heavy ions in certain kinds of device testing.