An improved optical cantilever technique using image processing for measuring in situ stress in thin films

The purpose of this paper is demonstrating an in situ technique for measuring stress during the growth of thin films. This technique, based on the beam bending method, uses the reflection of a laser beam to follow up the change in the radius of curvature of the sample. This geometrical variation is monitored by image processing which presents a great versatility of use. The reproducibility of the technique is ca 8%. First results obtained for chromium thin films deposited by magnetron sputtering are presented. A correlation between stress evolution and microstructure is then proposed.