A novel technique to examine the optical properties and stress of thin films

This work proposes a three-intensity ellipsometric imaging system with which to measure stress in thin films that are deposited on silicon substrates. This approach goes beyond the limit of the information that the ellipsometer was only able to measure on the flat sample; moreover, it is capable of determining the radius of a curved surface. As a result, film stress based on Stoney equation, in which the change in the radius of the wafer can be obtained, is measurable by the imaging ellipsometer. In our research, the silicon wafer was bent into a one-hundred nanometer film. We discussed the relationship of the film thickness profile and refractive index according to the substrate´s different radius.