In this work, we shall report the direct observation of the stress field in the silicon substrate induced by an oxide thin film edge using the infrared (IR) photoelastic (PE) method. Our experimental results showed that the earlier analytical solutions cannot give a satisfactory description of the observed IR PE stress fringe patterns. A simple model is developed to treat the stress field under the film edge as a superposition of two contributions. One term is as described by the concentrated force model proposed by Hu which is singular at the thin film edge. The other term is non-singular corresponding to the contribution as described by the bimetallic strip theory. The simulation images of stress fringe patterns are obtained according to this model. Good agreement is found between the simulated and experimental stress fringe patterns. In addition, the effects of film thickness and substrate thickness on the stress distribution in this structure were also investigated.
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