Improvement of the properties and electrical performance on TiCl_4-based TiN film using sequential flow chemical vapor deposition process

摘要

Sequential flow chemical vapor deposition (SFCVD), utilizing TiCl_4/NH_3 as reactants and immediate NH_3 treatment after film deposition, is applied to produce TiN barrier films in the contact process. Secondary ion mass spectroscopy results indicate that the SFCVD TiN film can effectively block the diffusion of WF_6 into the underlying Ti layer during W deposition. NH_3 treatment immediately after film deposition causes SFCVD TiN films to be less contaminated with carbon than TiN films that are formed by metallic organic compounds chemical vapor deposition (MOCVD) and to contain less chlorine residue than conventional TiCl_4/NH_3 CVD TiN layers even at a low reaction temperature. According to the resistance measurement of Kelvin contacts, the SFCVD process yields a lower resistance and a more uniform distribution than the MOCVD or CVD process. Transmission electron microscopic observations demonstrate that WF_6 can diffuse through the MOCVD TiN to react with the underlying Ti layer, causing a rupture at the Ti/TiN interface and poor W adhesion. The SFCVD TiN can serve as a sufficient diffusion barrier against WF_6 penetration during W CVD deposition.