Atomic-Ratio effect of transition layer for linear mobility in poly-Si TFTs

Abstract

AbstractPoly-Si TFTs with high field effect mobility are fabricated by using PECVD SiO2layer deposited with a new method: two-step (graded) oxide deposition. To adjust stoichiometry of the poly-Si/oxide interface and the bulk oxide layer, the double layer oxide films were deposited. The oxide films near the interface were deposited with high N2O/SiH4gas ratio to obtain the stoichiometric layer for good matching between poly-Si and SiO2. The remaining bulk oxide films were deposited with low N2O/SiH4gas ratio. The composition of the bulk oxide film was measured by using ESCA and the interface layer was analized with ESR. The poly-Si TFT with the double layer gate oxide resulted to the better performance than conventional TFT wth single layer gate oxde.