Room-temperature Chemical Vapor Deposition of Aluminum and Aluminum Oxides on Alkanethiolate Self-Assembled Monolayers

Abstract

We have investigated the reaction of trimethylaluminum (TMA) with −CH3, −OH, and −COOH terminated self-assembled monolayers (SAMs) adsorbed on Au, using time-of-flight secondary ion mass spectrometry and X-ray photoelectron spectroscopy. TMA is a well-known atomic layer deposition precursor that is employed commercially to deposit compound semiconductors, alumina, and nitrides. We demonstrate that TMA can be employed to deposit both alumina and aluminum on SAMs at room temperature. TMA reacts with −OH and −COOH terminated SAMs to form a surface-bound dimethyl aluminum complex but does not react with −CH3 terminal groups. If deposition is performed in a nitrogen-purged glovebox, an alumina film is grown on −CH3, −OH and −COOH terminated SAMs. The alumina film can be removed from −CH3 terminated SAMs by rinsing with organic solvents. However if the base pressure of the deposition chamber is below 10-8 Torr, a metallic Al overlayer is selectively deposited on −OH and −COOH terminated SAMs, and no reaction is observed on −CH3 terminated SAMs. Using these reactions, we demonstrate that alumina and aluminum can be selectively deposited on patterned SAMs. The possible reaction pathways involved in the film growth on these different surfaces are discussed.