Evaluation of Internal Stress in Reactively Sputter-Deposited ZrN Thin Films

Publisher Website
Google Scholar
Abstract
The influence of preparation conditions (nitrogen flow ratio, total pressure and applied substrate bias) on the internal stress of ZrN films deposited on a Si substrate was investigated by means of the substrate deflection method. The film microstructure was also examined by high-resolution field emission scanning electron microscope (FE-SEM). Films deposited at relatively low pressure have a dense microstructure and a compressive stress of from 1.7 to 4.2 GPa dependent on the nitrogen flow ratio, while films deposited at high pressure have an open structure and the stress decreases to 0.3 GPa. The latter films are densified by applying a negative substrate bias, leading to high compressive stress of up to 6.5 GPa. It has been found that the stress is closely connected with the film microstructure, and oxygen impurities in the films have a relaxation effect on the compressive stress.