Stress-strain curves derived from continuous nano-indentation of W-C-N films

Abstract

In semiconductor metallization processes, diffusion barrier is essential for preventing diffusion between metal (Cu: copper) and Si (silicon). However, the Cu has some problems such as easy reaction, poor adhesion, and diffusion into Si. In this study, we suggest tungsten -carbon -nitride (W-C-N) thin films for diffusion barrier that were made by rf magnetron sputtering. Subsequently, heat treatments execute as high temperature up to 800 °C.The films were analyzed continuous stress - strain test according to depth (from surface to Si substrate) by in-situ nano-indenter. The elastic modulus (Er) and hardness (H) of W-C and W-C-N thin films are changed from 152.08 to 168.31 GPa and from 12.05 to 13.2 GPa, respectively. After annealing at 800 °C, the Er and H values are decreased compared with as-deposited state of W-C and W-C-N films from 105.1 to 131.31 GPa and 2.25 to 11.9 GPa, respectively. From the stress - depth graph, the W-C-N thin film was more stable than that of W-C film after annealing up to 800 °C. From these results, the WC-N thin film is more effective to prevent interdiffusion between Cu and Si.