Mechanism of Stress-Induced Leakage Due to Plasma Charging and Effect of Oxide Thickness

Plasma charging causes gate oxide degradation and breakdown. In this paper a mechanisin is presented for P+ poly gates where the plasma charging during processing causes a stress induced Ieakage behavior (SILC) under accelerated life testing. The mechanism appears under positive gate bias for P+ poly-gated devices, and does not show under any bias conditions for N + poly-gated devices. The degradation exhibited a strong dependence on oxide thickness and temperature. The mechanism is explained in terms of enhanced degradation for the P+ poly-gated devices during processing and subsequent trap assisted-tunneling under accelerated life test.