Noncontact and Full-Field Measurement of Residual and Thermal Stress in Film/Substrate Structures

Dong Yang,Xumeng Zhang,Jianguo Zhu

doi:10.3390/surfaces4010011

Abstract

Residual stress and thermal stress of a film/substrate system are determined based on the curvature measurement with a 3D digital image correlation method (DIC) and calculation of the thin-film stresses by the extension of Stoney’s formula. A Ni film electroplated on a H62Cu plate is used to verify the proposed method. The full fields of nonuniform thin-film stresses are obtained in a room temperature to high-temperature environment of 200 °C, which can be potentially extended to higher temperatures. These results provide a fundamental approach to understanding thin-film stresses and a feasible measurement method for high temperature.

Highlights

IntroductionThin films are widely used in a large number of technologies ranging from micro/optoelectronic devices, MEMS/NEMS (thermal sensors and actuators), optical components (lenses, mirrors, filters, etc.) to protective and functional coatings intended to impart thermal, mechanical, tribological, environmental, electrical, magnetic, or biological functions [1]
Thin films are widely used in a large number of technologies ranging from micro/optoelectronic devices, MEMS/NEMS, optical components to protective and functional coatings intended to impart thermal, mechanical, tribological, environmental, electrical, magnetic, or biological functions [1]
The 3D digital image correlation (DIC) method is a full-field, real-time, noncontact optical technique which is insensitive to vibration and able to provide the full-field curvatures of specimens [20]

Summary

Introduction

Thin films are widely used in a large number of technologies ranging from micro/optoelectronic devices, MEMS/NEMS (thermal sensors and actuators), optical components (lenses, mirrors, filters, etc.) to protective and functional coatings intended to impart thermal, mechanical, tribological, environmental, electrical, magnetic, or biological functions [1]. A method currently and widely used to estimate the stresses in thin films is based on the measurement of the substrate curvature. Stoney derived a relationship between the film stress and the amount of substrate bend in the early 1900s [8]. Because it is nondestructive and can be used in real-time, it has been widely used for quantifying stress in thin films [9,10,11]. Nonuniform residual stress and thermal stress of the thin film at high temperature are obtained by the extension of Stoney’s formula.

Theoretical Equation

Experiment

Residual Stress

Thermal Stress

Conclusions