Thin-Film-Edge-Induced Stresses in Substrates

Abstract

ABSTRACTWe have obtained an analytic solution of linear elasticity for the stress distribution under a thin film edge in isotropic substrates of finite thickness and of infinite extent in the other two directions. The following boundary conditions are considered. At the film/substrate interface and the free surfaces at the top and bottom of the substrate, the normal stress component vanishes. Far from the film edge on the side without the film, all stress components are zero. Far from the film edge under the film, the stress distribution is in accordance with that given by the bimetallic strip theory. Two examples of comparison between theory and experiments were given to demonstrate the validity of this solution. The infrared photoelastic stress fringe pattern obtained by a dark-field plane polariscope in a Si substrate under an oxide film edge was successfully reproduced. The calculated and experimental results of Raman-shift of Si under patterned CoSi2 line structures also showed good agreement with each other.