Studies on the Surface Reactions of Substituted Disilanes with Silica Surface

Abstract

Both CVD and ALD deposition techniques benefit from a detailed understanding of the reaction mechanisms of the precursor molecules with the surface. In this paper, the reactions of hexakis ethylaminodisilane (AHEAD™), hexamethoxydisilane and hexamethyldisilane were studied on high surface area silica granules at 200-375 °C. Silica was heat treated at 200-820 °C to control the number of surface Si-OH groups. The samples were characterized by FTIR and solid state NMR spectroscopy. After the chemisorption of the precursors with silica, Si-H bonds, not originally present in the molecules, were identified for AHEAD and hexamethoxydisilane, but not for hexamethyldisilane. It is suggested that with AHEAD and hexamethoxydisilane, cleavage of the Si-Si bond takes place during the chemisorption with Si-OH sites. Since no reaction for hexamethyldisilane at the studied temperatures was observed, a prerequisite for the reaction with Si-OH groups seems to be the presence of electronegative O or N atoms in the ligands. In the paper, possible reaction mechanisms with the various surface species are discussed.