Effects of trichloroethane during oxide growth on radiation-induced interface traps in Metal/SiO2/Si capacitors

The radiation-induced interface traps in Metal/SiO2/Si capacitors where the oxides are grown in dry O2+1.1.1.-trichloroethane (TCA) have been studied. Among all the samples tested, a peak in the interface trap distribution above midgap (centered at ∼Eν +0.70–0.75 eV) appears immediately after irradiation, and the magnitude of this peak is a function of the amount of TCA during oxide growth. After the termination of the irradiation, this peak will either increase or decrease with time at room temperature for a few hours, followed by a continuous decrease over a long period of time (up to several months) before saturation, and this time-dependent behavior also appears to be a function of the TCA concentration. In the case when this peak decreases with time, a second peak located below midgap (centered at ∼Eν +0.35 eV) will develop, and the rate of growth of the second peak is correlatable to the reduction of the first peak. A closer examination of the data reveals that it is the initial damage level that determines the post-radiation time-dependent behavior, and the apparent dependence on the TCA concentration arises from its effect on the radiation sensitivity of the SiO2/Si interface.