SiO2 Films Deposited by APCVD with a TEOS/Ozone Mixture and Its Application to the Gate Dielectric of TFTs

Abstract

Silicon dioxide (SiO2) films were deposited using atmospheric pressure chemical vapor deposition (APCVD) with tetraethyl orthosilicate (TEOS) and ozone (O-3) as reactant gases. These films were used as the gate dielectric of low temperature polycrystalline silicon (LTPS) thin film transistors (TFTs). O-3 gas was chosen instead of oxygen (O-2) gas because the latter is not compatible with the low temperature processing of LTPS TFTs. SiO2 films deposited at low temperatures (< 450 degrees C) have low Si-OH contents and electrical properties desirable for gate insulator materials. Although the LTPS TFTs were fabricated using low cost SiO2 films deposited by APCVD as the gate dielectric, the fabricated devices exhibited a field-effect mobility of 49 cm(2)/V s and a subthreshold swing of 490 mV/dec. The results demonstrate that SiO2 deposited by APCVD with TEOS and O-3 is a promising material for low cost and high quality gate insulators for LTPS TFTs.