Thermal decomposition pathways of chlorinated trisilanes

Abstract

Chlorinated trisilanes are important precursors for low-temperature deposition of silicon nitride thin films. However, the thermal decomposition may hinder their application. In this work, the chemical pathways for thermal decomposition of chlorinated trisilanes (Si3H8-xClx, where x = 0, 1, 2, and 8) were explored using density functional theory (DFT) calculations. Three major decomposition paths are considered, by which byproducts of H2-zClz, SiH4-zClz, and SiH2-zClz can be formed. Among considered routes, formation of SiH4-zClz with SiX3-SiX (monosilane with silylsilylene) (X is H or Cl atom), or SiH2-zClz with Si2H6-yCly (silylene with disilane) are similarly preferred in terms of calculated energetics, including activation energy. Hence, the two paths might be the most probable decomposition route of (chloro)trisilane. SiX3-SiH- and SiH2-involving reactions display significantly lower mean reverse activation energy (1–2 kcal/mol) than reactions with other products (10–13 kcal/mol), which is much smaller than the energy required to separate the reaction complex (14–15 kcal/mol), so they may not lead to decomposition. Current results are corroborated by comparison to experimental values from literature. © 2022, The Author(s), under exclusive licence to Springer Nature B.V.