Investigation of reaction mechanisms in the chemical vapor deposition of al from DMEAA

We propose a novel reaction scheme for the chemical vapor deposition (CVD) of Al films on substrates from dimethylethylamine alane (DMEAA), supported by the prediction of the Al deposition rate as a function of process temperature. The scheme is based on gas phase oligomerizations of alane which form a substantial amount of intermediates. Combined with reversible surface dehydrogenation steps, the global deposition reaction is composed of a set of 12 chemical reactions. This new scheme entails four intermediates and includes side reactions that play an important role in the formation of Al thin films. The chemistry mechanism is incorporated in a 2D Computational Fluid Dynamics (CFD) model of the CVD reactor setup used for the experimental investigation. The simulation predictions of the Al deposition rate are in good agreement with corresponding experimental measurements. The success of this novel reaction pathway lies in its ability to capture the abrupt decrease of the deposition rate at temperatures above 200 °C, which is attributed to the gas phase consumption of alane along with its increased desorption rate from the film surface.