Simultaneous Overall and Local Stress Analysis of Thin Metal Films by Light Scattering and Beam Deflection Measurements

Abstract

AbstractWe have developed an optical instrument for real-time overall stress as well as local stress relaxation measurements. The physical principle of the instrument is based on the fact that when a sample is exposed to heating the overall film stress bends the substrate and hillocks, the evidence of the local stress relaxation, form on the surface. Early hillock formation can be observed in real-time with integrated scattering technique, but the overall stress can be readily observed by laser beam deflection. Our instrument integrates laser beam deflection and light scattering techniques to achieve simultaneous overall stress and local stress relaxation measurements. A stress study is presented for an aluminium thin film on a silicon substrate.