The effect of plasma power on the properties of low-temperature silicon nitride deposited by RPALD for a gate spacer

Abstract

We investigated the effects of NH3 plasma power on characteristics of low-temperature silicon nitride thin films for application of a gate spacer. SiNx thin film was deposited on a Si(100) substrate by remote plasma atomic layer deposition (RPALD) using trisilylamine (TSA) as a Si precursor and NH3 gas as a reactant. NH3 remote plasma was analyzed with optical emission spectroscopy (OES) and it largely consisted of NH and H. As the plasma power increased, more NH and H radicals were generated and a proportion of NH radicals in the plasma increased, which resulted in the slight increase of the high-N content and low-H content in SiNx thin film. The low-H content with nearly stoichiometric SiNx thin films improve etch rate properties. The densities of RPALD SiNx thin film were 2.7 g cm(-3) and almost the same regardless of plasma power. RPALD SiNx thin films showed a low leakage current density of 10(-7)A cm(-2) at 2 MV cm(-1) and a breakdown voltage of approximately 8 MV cm(-1).