High growth rate and high wet etch resistance silicon nitride grown by low temperature plasma enhanced atomic layer deposition with a novel silylamine precursor

Abstract

Trisilylamine (TSA), an exemplary chlorine and carbon-free commercial silylamine precursor, is well-known to induce improvements in the process and properties of silicon nitride (SiN_x) thin films grown using atomic layer deposition (ALD). Herein, we report a TSA homolog, tris(disilanyl)amine (TDSA), as a novel chlorine and carbon-free precursor for the deposition of highly etch resistant SiN_x thin films having a high growth rate at a low temperature (<300 °C) using plasma enhanced ALD (PEALD) with hollow cathode plasma (HCP). These improvements in PEALD SiN_x using TDSA may be attributed to higher surface reactivity of the molecule enabled by weaker Si–N bonds, higher molecular polarity and the existence of reactive Si–Si bonds in the molecule. The performance of PEALD SiN_x grown by TDSA has been compared with that of TSA, aminosilanes and chlorosilanes, and explained with the structure–property relationship of the molecule. TDSA grows SiN_x film faster than TSA. Furthermore, the TDSA precursor produces SiN_x films that have lower wet etch rate (WER) when compared to other silylamine precursors like TSA, or other types of silane precursors such as aminosilanes and chlorosilanes. We believe that the result, that TDSA-grown SiN_x films exhibit lower WER than TSA-grown SiN_x films, can be attributed to the abundance of Si in SiN_x films, which thereby offers high resistance to a wet etch.