A Simple Analysis of Average Mechanical Behavior and Strain Energy Density of Misoriented Grains in a Textured Film

Abstract

Differences in strain energy density between grains of different orientation within a thin film may drive morphological changes such as abnormal grain growth, hillocking, and sunken grains. Models of these morphological changes generally assume that the behavior of each grain is the same as that of a blanket film of corresponding orientation. In order to investigate this assumption as it applies to the behavior of a (100)-oriented grain within a {111}-fiber textured copper film, simple continuum analytical and finite element models are applied to the case of a film on a rigid substrate subjected to temperature changes. The simple models indicate that the behavior of a misoriented grain does not simply duplicate that of a blanket film of the same orientation; the behavior of the surrounding grains must also be considered. The strain energy density difference between the grain and the surrounding film is less than that predicted by blanket film behavior. An elasticity equation is presented which describes the average stress-temperature behavior of widely dispersed misoriented grains within a textured film.