Reaction Mechanism of Atomic Layer Deposition of Al on the Si (100) Surface: A Density Functional Theory Study

Abstract

Using H2 and Al (CH3)3(TMA) as precursor, we investigated the atomic layer deposition mechanism of the metal Al on Si (100) surface by density functional theory. The reaction process comprises two half-reaction depositions: TMA "half-reaction" includes I and II on the H blunt reaction surface; H2 "half-reaction" includes the subsequent reaction Ⅲ and Ⅳ. In the TMA half reaction process, trimethyl aluminum first molecularly adsorbed in the active site of H*-Si9H12-H* to form a stable complex in the form of chemical adsorption state. Potential curves show that at 298 K, adsorption energy is -2.26kJ/mol, with respect to the chemical adsorption state, the activation barrier energy is 124.72kJ/mol, and finally the whole exothermic reaction energy is 41.4kJ/mol. After H2 half reaction, the bond length between Al-Si can be considered equal; two Al-C bonds become relatively stable molecular structure. The adsorption energy is -0.10kJ/mol at 298 K, and the activation barrier energy 189.15kJ/mol. The results show that two half-reaction process mechanism is similar, TMA endothermic reaction needs more energy to be carried out under heating conditions ; endothermic and exothermic reaction energy is basic balance, the activation energy is large, so the reaction is the best using ionized gas to be carried out.