Ultra-thin silicon-oxide films by sputter-deposition and their application to high-quality poly-Si TFTS

Abstract

This paper describes ultra-thin high-quality silicon oxide (SiO 2) films deposited at low temperature by sputtering from a SiO 2 target in an oxygen–argon mixture. SiO 2 films up to a thickness of 6.5 nm are successfully formed on polycrystalline silicon (poly-Si) films which have a surface roughness of several nanometers. The SiO 2 films show electrical properties with a sufficiently high breakdown voltage and low leakage current which are comparable with the electrical properties of the thermally grown SiO 2 film on single-crystalline Si at high temperature. Moreover, both n- and p-channel polycrystalline silicon thin film transistors (poly-Si TFTs) with ultra-thin sputtered SiO 2 films show excellent characteristics.