Verification of FEM analysis of load-deflection methods for measuring mechanical properties of thin films

Abstract

It is shown that in contrast to the analytical models, which have to assume a shape function, the finite-element method (FEM) model yields the shape function, and this shape function is in good agreement with experiment. Through an extensive FEM analysis of load-deflection methods, it is confirmed that while the functional form of the analytical result is correct, three constants in the model must be corrected by as much as 30%. Experimental measurements of the deformed membrane shape have been made, and they match the FEM results, verifying the accuracy of the FEM models. Experimental values extracted from load-deflection analysis for the biaxial modulus and the residual stress of thin films of Dupont PI2525 and Hitachi PIQ13 are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>