Neutron reflectivity investigation of bis-amino silane films

Abstract

Neutron reflectivity is used to elucidate the morphology of silane films deposited on silicon wafers, and the response of these films to vapors of swelling solvents. Bis-silyl functional silanes studied here have six hydrolyzable groups and are believed to be more crosslinked than tri- and tetra-functional analogs. The enhanced crosslinking leads to better barrier properties in anti-corrosion applications. In this study, solvent swelling is used to assess the degree of condensation and the crosslink density in bis-[trimethoxysilylpropyl]amine (bis-amino) films. Nitrobenzene swells the films but does not react chemically with the films. The results show that bis-amino silane films are highly condensed, with a nitrobenzene-depleted layer near the silicon substrate. D₂O both swells (at 25°C and 80°C) and chemically alters the films (at 80°C). The reflectivity data upon exposure to D₂O vapors at 80°C are consistent with exchange of the amino proton (¹H) with deuterium (D). A hydrophilic layer is postulated at both the air and substrate interfaces.

Keywords:

• SILANE
• NEUTRON REFLECTIVITY
• DEGRADATION
• SWELLING