Analysis of the performance of a micromechanical test structure to measure stress in thick electroplated metal films

Abstract

Previously reported suspended microrotating test structures designed to measure the stress in thick layers of electroplated Permalloy (NiFe alloy) have been analysed using finite element modelling and compared with experimental measurements. These results have been used to optimise a stress sensor test structure and design a new mask, with an array of test structures specifically designed to wafer map the stress of thick nickel and Permalloy films. This is the first time these structures have been employed for determining spatial variation in film stress and the results of this characterisation are reported for nickel.