The interaction of dimethylethylaminealane and ammonia on clean and oxidized Al(111): atomic layer growth of aluminum nitride

Abstract

The adsorption of dimethylethylaminealane (Me 2EtN·AlH 3 or DMEAA) on clean and oxidized Al(111), its subsequent thermal decomposition, and reaction with ammonia (NH 3) to form aluminum nitride (AIN) was studied using temperature-programmed desorption (TPD), Auger electron spectroscopy (AES), and reactive scattering. DMEAA physisorbs on clean Al(111) at 130 K in ultra-high vacuum and molecular desorption is observed at 190 K. The reactive sticking probability of DMEAA at T<300 K is very low, especially at low surface defect density. At higher substrate temperatures ( T>300 K), the reactive sticking probability of DMEAA is high and elementally pure Al film growth is observed. On oxidized Al(111) at surface temperatures above 400 K, the reactive probability of DMEAA is lower than on the Al(111) surface and, in contrast to the clean Al(111) surface, on the oxidized Al(111) surface DMEAA adsorbs molecularly in a self-limiting manner at 300 K. Consecutive DMEAA and NH 3 exposure cycles result in atomic layer growthof AIN at temperatures as low as 300 K but these films have a high carbon content owing to accumulation of amine groups on the surface. Increasing the substrate temperature from 300 to 600 K results in greatly reduced carbon contamination in the AIN films. During film growth at 600 K, each DMEAA exposure results in the deposition of a new aluminum layer and a subsequent NH 3 dose converts this layer to AIN.