Effects of NH3-plasma nitridation on the electrical characterizations of low-k hydrogen silsesquioxane with copper interconnects

Abstract

The interaction between topper interconnects and low-k hydrogen silsesquioxane! (HSQ) film was investigated using a Cu/HSQ/Si metal insulation semiconductor capacitor and NH3 plasma post-treatment. Owing to serious diffusion of copper atoms in HSQ film, degradations of the dielectric properties are significant with the increase of thermal stress, The leakage current behavior in high field conduction is well explained by the Poole-Frenkel (P-F) mechanism. By applying NH3-plasma treatment to the HSQ film, however, the leakage current is decreased and P-F conduction can be significantly suppressed. In addition, the phenomenon of serious Cu penetration is not observed by means of electrical characteristic measurements and secondary ion mass spectroscopy (SIMS) analysis even in the absence of diffusion barrier layers. This indicates the copper diffusion in low-k HSQ film can be effectively blocked by NH3 plasma post-treatment.