Stability of N-channel polysilicon thin-film transistors with ECR plasma thermal gate oxide

摘要

The effects of electrical stress on n-channel polysilicon thin-film transistors (poly-Si TFTs) with electron cyclotron resonance (ECR) plasma gate oxide have been investigated. The plasma-hydrogenerated low-temperature (/spl les/600/spl deg/C) TFT's exhibited very a small increase of threshold voltage (/spl Delta/V/sub th/>0.3 V) under the stress conditions (V/sub gs/=15 V, V/sub ds/=0 V /spl sim/15 V, and stress time=5/spl times/10/sup 4/ s). The /spl Delta/V/sub t/h 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/sub gs/=V/sub ds/ while for the stress at V/sub gs/>V/sub ds/, degradation of transconductance was the dominant effect seen.