The Effects of Pressure, Temperature, and Time on the Annealing of lonizing Radiation Induced Insulator Damage in N-channel IGFET's

Abstract

The effects of annealing pressure, temperature, and time (p,T,t) on residual levels of n-channel insulated gate field effect transistor (IGFET) process induced insulator radiation damage has been examined, and the behavior over the range p =1-5 atm H2, T = 300°-450°C, and times up to 14 hr at 300°C have been defined for polysilicon gated devices. It has been found that higher temperatures, higher pressures, and longer times all lead to decreased residual neutral trap and positive charge densities levels, but that neutral traps are more difficult to remove. Removal of positive charge does not appear to depend on initial damage level while residual neutral trap level is sensitive to the initial damage level. It has been found also that with the specific damage technique employed, which involves electron beam (E-beam) metal evaporation, positive trap levels saturate at about 5 × 105 rads Si, while apparent negative charge and neutral traps appear to increase slowly with exposure of the gate insulator to this ionizing radiation. Adequate removal of all charged and neutral centers can be achieved in 50 atm of forming gas at 400°C for 30 min for doses as great as 5 × 107 rads SiO2. If damage levels are not too high, 25 atm treatments are useful for the same temperature and time. © 1983, The Electrochemical Society, Inc. All rights reserved.