Influence of Gas Desorption from SiOF Film Prepared by High-Density-Plasma Chemical Vapor Deposition upon TiN/Ti Film

Abstract

The influence of gas desorption from fluorine-doped silicon oxide (SiOF) film prepared by high-density-plasma chemical vapor deposition (CVD) upon TiN/Ti film is investigated. In this investigation, two types of SiOF films, containing 14% and 6% fluorine atoms, are compared with regard to gas desorption and diffusion of fluorine, hydrogen and oxygen atoms into TiN/Ti film on SiOF film, as-deposited on TiN/Ti/SiOF film and after 400°C annealing. In addition, W film was prepared on TiN/Ti/SiOF film in order to examine the practical effect of gas desorption upon adhesion between Ti film and SiOF film. Thermal desorption mass spectroscopy (TDS) and secondary-ion mass spectroscopy (SIMS) spectral studies clarified the following. (1) SiOF film containing 14% fluorine atoms has a high hydrogen-fluoride content due to moisture absorption after exposure to air, while that containing 6% fluorine atoms does not. (2) During deposition of TiN/Ti film at 200°C, many fluorine and hydrogen atoms diffuse from SiOF film containing 14% fluorine atoms and are trapped within the Ti film or the Ti/SiOF interface. (3) During 400°C annealing, more fluorine atoms diffuse from SiOF film containing 14% fluorine atoms and are also trapped within the Ti film. (4) Fluorine atoms trapped within the Ti film degrade the adhesion between Ti film and SiOF film.