Accumulation leakage of SOI back channel transistors with total dose irradiation

Abstract

Summary form only given. The accumulation leakage of separation by implantation of oxygen (SIMOX) and zone melt recrystallization (ZMR) back-channel transistors with respect to total dose irradiation and radiation bias condition is studied. The accumulation phenomenon for a SIMOX wafer with a buried oxide thickness of about 3700 A is observed. The occurrence of leakage in both the accumulation and inversion regions of the back-channel device results in a leakage window from the accumulation leakage threshold (V/sub tx/) to the inversion threshold (V/sub tbg/). The leakage results from (i) field-enhanced emission through energy states located at precipitate boundaries, and (ii) thermionic emission at local Schottky barriers accompanied by Schottky barrier lowering. The zero-volt prerad V/sub tx/ results in excessive leakage for any negative back gate bias and, since V/sub tbg/=+16 V, produces a 16 V leakage window. After irradiation to 50 Krad(SiO/sub 2/) with V/sub tbg/=5 V, the entire leakage window shifts 10 V and further irradiation has little effect. A similar characteristic is observed for a -10 V back bias and suggests a saturation of N/sub ot/ in the buried oxide. Accumulation leakage has also been observed on ZMR devices with V/sub bg/=-10 V. As a result of the very thick (1 mu ) buried oxide, however, the prerad V/sub tx/ is less than -25 V and produces a very large leakage window. In addition, while the accumulation threshold rebounds enhancement after 200 Krad(SiO/sub 2/) total dose. This characteristic enlarges the leakage window and is optimal at high doses. >