THE INTERACTION OF DIMETHYLETHYLAMINEALANE AND AMMONIA ON CLEAN AND OXIDIZED AL(111) - ATOMIC LAYER GROWTH OF ALUMINUM NITRIDE

The adsorption of dimethylethylaminealane (Me(2)EtN . AlH3 or DMEAA) o n clean and oxidized Al(111), its subsequent thermal decomposition, an d reaction with ammonia (NH3) to form aluminum nitride (AlN) was studi ed using temperature-programmed desorption (TPD), Auger electron spect roscopy (AES), and reactive scattering. DMEAA physisorbs on clean Al(1 11) 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 substrat e 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 m olecularly in a self-limiting manner at 300 K. Consecutive DMEAA and N H3 exposure cycles result in atomic layer growth of AIN at temperature s 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 contam ination in the AlN films. During film growth at 600 K, each DMEAA expo sure results in the deposition of a new aluminum layer and a subsequen t NH3 dose converts this layer to AlN.