Adhesion Characteristics between Chemical Vapor Deposited Cu and TiN Films: Aspects of Process Integration

Abstract

This paper examines the properties of Cu films deposited on different TiN substrates. The TiN substrates were prepared using TiCl4/NH3 chemistry based chemical vapor deposited (CVD) TiN process by varying the preparation methods and temperatures. Properties examined include morphology and crystallinity as well as adhesion characteristics of the Cu films on the TiN substrates. It was found that the Cu film properties were strongly affected by the overall stress in the multi-layer structure and the amount of residual chlorine (Cl) in the TiN film. When the stress conditions of the Cu and TiN films are the same, good adhesion occurred. Higher Cl concentrations caused adhesion enhancement of the Cu film; however, surface morphology was degraded. Angle resolved X-ray photoelectron spectroscopy (XPS) results and depth analysis implied that fast Cu diffusion occurred in the near-interface region. It is suggested that Cl enhances the diffusion of Cu, resulting in the formation of a diffusion interface that improves adhesion.