Impact of aminosilane and silanol precursor structure on atomic layer deposition process

Abstract

Atomic layer deposition (ALD) and rapid atomic layer deposition (RALD) have emerged as useful techniques for depositing highly conformal and uniform thin films for advanced semiconductor devices. The performance of the ALD or RALD process depends on the design of precursor molecules. In this work, the aminosilane precursor molecules (bis(tertbutylamino)silane (BTBAS), bis(diethylamino)silane (BDEAS), and tris(dimethylamino)silane (TDMAS)) in ALD and two silanol precursors (tris(tert-butoxy)silanol (TBS) and tetra(tert-butoxy)silane [(tBuO)4Si]) in RALD were investigated using first-principles based on density functional theory. The energy diagrams of the growth process on the hydroxylated SiO2(001) surface were calculated for each precursor. Furthermore, the rate-determining step was confirmed, and the precursors were compared in terms of thermochemical energies and activation barriers. BTBAS showed the lowest energy barrier in the rate-determining step among all precursors, which suggested that the rapid rate of RALD might be due to the addition of trimethylaluminum catalyst. Moreover, during the decomposition process of ALD and RALD, the bond length at the transition state demonstrated a correlation with the reaction activation energies, which provided a new perspective for studying these processes. This work helps clarify the reaction processes, facilitating the design and preparation of more efficient precursors.