Reaction mechanism and electrical properties of (Ba, Sr)TiO3 films prepared by liquid source chemical vapor deposition

The reaction mechanism in liquid source chemical vapor deposition (CVD) of (Ba, Sr)TiO3 [BST] films has been studied using dipivaloylmethanato (DPM) source materials. Effects of substrate temperature and deposition atmosphere on film characteristics were investigated, such as deposition rate of each source material, step coverage, and electrical properties of the film deposited. The decomposition of DPM source materials for BST film deposition was found to be enhanced in O-2 atmosphere, as compared with that in N-2 atmosphere. Furthermore, the source materials were easier to decompose at higher substrate temperatures. The BST film step coverage became less conformal at higher temperatures and in O-2 atmosphere, implying that more precursors with large sticking probabilities were produced therein. Although O-2 gas was not necessary to form the BST crystalline structure and to improve the step coverage, the addition of O-2 during deposition was found to be necessary to improve the crystallinity and electrical properties of CVD-BST films.