Adsorption and surface reaction of bis-diethylaminosilane as a Si precursor on an OH-terminated Si (0 0 1) surface

Abstract

The adsorption and the surface reaction of bis-diethylaminosilane (SiH2[N(C2H5)2]2, BDEAS) as a Si precursor on an OH-terminated Si (001) surface were investigated to understand the initial reaction mechanism of the atomic layer deposition (ALD) process using density functional theory. The bond dissociation energies between two atoms in BDEAS increased in the order of SiH, SiN, and the rest of the bonds. Therefore, the relatively weak SiH and SiN bonds were considered for bond breaking during the surface reaction. Optimum locations of BDEAS for the SiH and SiN bond breaking were determined on the surface, and adsorption energies of 0.43 and 0.60eV, respectively, were obtained. The SiH bond dissociation energy of the adsorbed BDEAS on the surface did not decrease, so that a high reaction energy barrier of 1.60eV was required. On the other hand, the SiN bond dissociation energy did decrease, so that a relatively low reaction energy barrier of 0.52eV was required. When the surface reaction energy barrier was higher than the adsorption energy, BDEAS would be desorbed from the surface instead of being reacted. Therefore, the SiN bond breaking would be dominantly involved during the surface reaction, and the result is in good agreement with the experimental data in the literature.