In-situ revealing the degradation mechanisms of Pt film over 1000 °C

Abstract

• The high temperature degradation behaviors of passivated Pt film was studied by in-situ STEM. • The voids formed preferentially at intersections of grain boundaries with Pt-SiN x interface at 1020–1040 °C. • At temperatures above 1040 °C, the voids formed at both the grain boundaries and inside Pt grains. • The growth of voids inside the grains was accelerated by electromigration at high temperature. Degradation of a metallic film under harsh thermal-mechanical-electrical coupling field conditions determines its service temperature and lifetime. In this work, the self-heating degradation behaviors of Pt thin films above 1000 °C were studied in situ by TEM at the nanoscale. The Pt films degraded mainly through void nucleation and growth on the Pt-SiN x interface. Voids preferentially formed at the grain boundary and triple junction intersections with the interface. At temperatures above 1040 °C, the voids nucleated at both the grain boundaries and inside the Pt grains. A stress simulation of the suspended membrane suggests the existence of local tensile stress in the Pt film, which promotes the nucleation of voids at the Pt-SiN x interface. The grain-boundary-dominated mass transportation renders the voids grow preferentially at GBs and triple junctions in a Pt film. Additionally, under the influence of an applied current, the voids that nucleated inside Pt grains grew to a large size and accelerated the degradation of the Pt film.