Layer-by-layer in situ stress measurements of metallic multilayers with atomic-layer sensitivity

Abstract

We have developed an ultrahigh sensitive in situ stress-measurement apparatus for thin films using an optical non-contact displacement detector. A change of the gap distance between the detector and the substrate, caused by stress of a deposited film, was detected by a corresponding change of the reflectivity. The sensitivity of the displacement detector was 132 mV/μm and a minimum detectable displacement was 7.6 Å. The apparatus was applied to in situ stress measurements of several multilayers prepared on glass substrate by DC magnetron sputtering. The sensitivity of the detector turned out to be sensitive enough to observe the coherent-to-incoherent transition in the matching planes of Co/Pd, Co/Pt, and Ni/Pt multilayers.