An SiO2 Film Deposition Technology Using Tetraethylorthosilicate and Ozone for Interlayer Metal Dielectrics

Abstract

A void‐free interlayer dielectric film formation technology has been developed. This technology utilizes tetraethylorthosilicate [TEOS, ]/ozone atmospheric pressure chemical vapor deposition (APCVD) film gap‐filling, and the TEOS‐based dual frequency plasma enhanced vapor deposition (PECVD) film as an underlayer of APCVD film. This technology enables the formation of void‐free interlayer dielectric films without any pretreatment for the underlayer between aluminum wirings line and space of 600 and 600 nm, respectively. Single‐frequency PECVD films are also applied as an underlayer of APCVD gap‐filling. However, void‐free gap‐filling cannot be achieved, even using the single frequency PECVD underlayer. To clarify the mechanism of the void‐free gap‐filling, the underlayer PECVD film properties are investigated. The film density at the Al wiring pattern's sidewall of the dual‐frequency PECVD films is equal to that at the pattern's bottom, while the density at the pattern's sidewall formed using single‐frequency PECVD films is lower than that at the pattern's bottom. The carbon concentration for the dual‐frequency PECVD films is lower than that for the single‐frequency PECVD films. The and acetaldehyde detected from the dual‐frequency PECVD films due to the oxidation of the ethoxy group, is much more than that from the single‐frequency PECVD films. Based on the experimental results, the mechanism of void‐free gap‐filling of APCVD films is considered to consist of three steps; (i) involving R ions (R, alkyl group) into the PECVD films during film deposition, (ii) Si‒OR bonds formation at the PECVD films' surface, and (iii) oligomers flow at APCVD film deposition. It is considered that the oligomers flow is promoted by the Si‒OR bonds, resulting in the void‐free gap‐filling. The dual‐frequency PECVD films can improve the gap‐filling of APCVD films.