Stability of N-Channel Polysilicon Thin-Film Transistors with ECR Plasma Thermal Gate Oxide

Abstract

The effects of electrical stress on n-channel polysilicon thin-film transistors (poly-Si TFT's) with electron cyclotron resonance (ECR) plasma gate oxide have been investigated, The plasma-hydrogenerated low-temperature (less than or equal to 600 degrees C) TFT's exhibited very a small increase of threshold voltage (Delta V-th < 0.3 V) under the stress conditions (V-gs = 15 V, V-ds = 0 V similar to 15 V, and stress time = 5 x 10(4) s), The Delta V-th was larger for the stress in the linear region than in the saturation region. It was found that the device degradation for the. stress in the saturation region was caused by the hot-carriers, Increase of OFF current was maximum for the stress at V-gs = V-ds while for the stress at V-gs < V-ds, degradation of transconductance was the dominant effect seen.