In Situ Reflective High-Energy Electron Diffraction Analysis During the Initial Stage of a Trimethylaluminum/Water ALD Process

the process, especially of the initial stage of the deposition. In this paper the first results obtained from in situ reflective highenergy electron diffraction (RHEED) measurements during the ALD of $Al_2O_3$ on Si(001), using $Al(CH_3)_3$ and $H_2O$ as precursors, are presented. The goal of this work is to show the feasibility of using a surface-sensitive analysis technique to study the surface chemistry during ALD. The results show the expected decrease in reflected intensity on deposition of aluminum atoms and a recovery of intensity, attributed to removal of methyl groups from the surface, on exposure to $H_2O$. Growth initiation by TMA exposure, and subsequent growth inhibition are observed. A discrete time model of ALD is used to analyze the measured decay in reflected intensity.