STRUCTURE OF 3-AMINOPROPYL TRIETHOXY SILANE ON SILICON-OXIDE

3-Aminopropyl triethoxy silane (APTES) was deposited onto silicon oxide surfaces under various conditions of solvent, heat, and time, and then exposed to different curing environments, including air, heat, and ethanol. The macro- and micromolecular structure of APTES was probed on different levels using different techniques. The thickness of APTES layers was measured by ellipsometry, macromolecular structures were identified using microscopic methods (scanning electron microscopy and atomic force microscopy), and chemical form was investigated using angle-resolved X-ray photoelectron spectroscopy and also reflection infrared spectroscopy of APTES on gold and aluminum oxide surfaces. Coverage equivalent to one monolayer was achieved using very mild reaction and curing conditions (reaction in dry toluene for 15 min at room temperature, curing in air, or 15 min in 200°C oven), whereas thick layers were made by increasing reaction and curing times. APTES initially adsorbed to the surface, and curing was necessary to complete covalent binding between APTES and the surface. Deposition of APTES from water gave thin layers, probably electrostatically bound to silicon. © 1991.