SiO2 films deposited at low temperature by using APCVD with TEOS/O-3 for TFT applications

Abstract

A silicon-dioxide (SiO2) film was deposited using tetra ethyl orthosilicate (TEOS) along with oxygen (O-2) or ozone (O-3) as a reaction gas in an atmospheric pressure chemical vapor deposition (APCVD) system instead of using a hazardous gas like SiH4. h was impossible to grow the film below 500 degrees C by using O-2 as a reaction gas. The films deposited at 400 degrees C using O-3 as a reaction gas showed the best deposition rate and electrical and optical properties good enough to make them applicable for many semiconductor devices, especially poly-silicon (poly-Si) thin-film transistors (TFTs). The annealing of the films at 700 degrees C. was found to reduce the interface defect density, making the film more useful as a passivation layer. Conventional APCVD requires high-temperature processing whereas in the current study, we developed a low-temperature process. The interface trap density was substantially decreased in the silicon surface coated with the silicon dioxide film after annealing in an air ambient.