Real-Time in Situ Imaging of the Delamination of thin Ta Films on Si(100) Substrates Via a Synchrotron Radiation Technique

Abstract

ABSTRACTThe thermal stress-induced delamination of 500nm polycrystalline Ta coatings on Si(100) substrates was studied via a recently developed real-time in situ imaging technique. This method used white beam synchrotron (on SSRL station 2-2) Laue transmission diffraction topography coupled with simultaneous direct radiography to record the thermomechanical failure modes of the Ta films as a function of temperature. The observations were made using a novel experimental apparatus, consisting of a 600°C hot stage and a portable CCD x-ray imaging/storage system with ~20m m resolution. The system is capable of recording 30 images/sec; hence, at moderate strain rates not only was the morphology of failure evident, but detailed study of the dynamics of delamination was also possible. The mode of failure and the adhesion strength are correlated with the physiochemical nature of the coating-substrate interface, and also with the degree of in-plane/out-of-plane texture of the Ta films. These observations should be capable of extension to the study of a variety of adhesion and cyclic failure issues in thin coatings.