Reliability of High Performance Short Channel Polycrystalline Silicon Thin Film Transistor on the Glass Substrate

Abstract

We have investigated the degradation phenomenon of short channel (L<2μm) poly-Si TFTs annealed by excimer laser on glass substrate. In the typical n-type poly-Si TFT, the threshold voltage is usually increased due to the hot carrier caused by the high drain field after the electrical stress. Whereas, in the high performance n-type short channel TFT, threshold voltage is decreased rather than increased after high drain and gate bias at 15V equally. The decrease of threshold voltage may be attributed to the hole trapping at backside interface between poly-Si active layer and buffer oxide due to self-heating effect. The C-V measurements indicate that the hole trapping to buffer oxide is rather large near the source rather than near the drain. Our experimental results show that the high performance short channel poly-Si TFT employing excimer laser annealing is degraded on backside interface near the source by self-heating effect rather than hot-carrier effect.