Investigation of silicon nitride for spacer via plasma-enhanced atomic layer deposition using a (tert-butylamino)dimethylsilane precursor

Abstract

Silicon nitride (SiNx) has attracted considerable attention as a spacer in advanced semiconductor devices, owing to its superior barrier performance. However, the fabrication of SiNx films remains challenging, because of the corrosive byproducts generated when using chlorine precursors and impurities associated with the redeposition species of precursor ligands. The selection of precursor and optimization of the process parameters influence the film growth and improve the film properties. In this study, the (tert-butylamino)dimethylsilane (TBADMS) precursor and N2 plasma were introduced for the first time by plasma-enhanced atomic layer deposition (PEALD) to deposit SiNx films. We attempted to improve the film properties by adjusting the substrate temperature and investigated different growth mechanisms. The film deposited at 300 °C exhibited the most superior film properties, with an N/Si ratio close to ideal Si3N4, high film density, smooth surface, and low wet etch rate. The proposed growth mechanism demonstrates the influence of the initial surfaces and residual redeposition species removal within the film. Additionally, dielectric characterization indicates that films deposited at a higher temperature exhibit enhanced dielectric constant and reduced hysteresis (k = 7.2, ΔV = 0.6 V) in comparison to those (k = 4.9, ΔV = 1.2 V) deposited at lower temperature.