The Effects of Various Gate Oxidation Conditions on Intrinsic and Radiation‐Induced Extrinsic Charged Defects and Neutral Electron Traps

Abstract

The influence of the oxidation temperature, ambient atmosphere, and oxidation rate on intrinsic and Al Kα x‐ray radiation‐induced extrinsic gate oxide defect levels in insulated‐gate field effect transistors (IGFETs) was studied. Using optically assisted electron injection into n‐chahnel polysilicon‐gated IGFETs, neutral electron trap and fixed negative charge defect densities were measured, in addition to the fixed positive charge density. The results indicate that radiation‐induced defect densities in the gate oxide decrease with increasing oxidation temperature in the 800°C to 1000°C range, and are lower for “dry/wet/dry” oxides than for “dry” oxides when the oxidation temperature is below 950°C, but higher when the oxidation temperature is above 950°C. The oxidation rate had no effect on defect levels in dry oxides grown at 1000°C, while at an oxidation temperature of 800°C, the extrinsic defect densities were observed to increase when the oxidation rate was decreased. In all cases, the radiation‐induced fixed positive charge and neutral electron trap defect densities were observed to be dependent upon the gate oxidation conditions in the same fashion. It therefore appears that the same oxidation conditions which might be employed to reduce the sensitivity of gate oxides to radiation‐induced positive charge build‐up will also serve to reduce the sensitivity to neutral electron trap generation.