Electrical characteristics of poly-Si TFT's with smooth surface roughness at oxide/poly-Si interface

We have fabricated a polycrystalline silicon thin film transistor (poly Si TFT) using a novel oxidation method, which improves the surface roughness at the interface between the poly-Si layer and the gate oxide layer. Compared with the poly-Si TFT's fabricated by the conventional oxidation method, the proposed poly-Si TFT exhibits the remarkable enhancement of the electrical parameters, such as the subthreshold swing and the threshold voltage. It is observed that the proposed poly-Si TFT has a higher dielectric strength, and the device characteristics are not degraded significantly after an electrical stress. The improvement of the surface roughness at oxide/poly-Si interface is found to he critical to enhance the device performance.