科研之友
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摘要
Degradation of a metallic film under harsh thermal-mechanical-electrical coupling field conditions deter-mines its service temperature and lifetime.In this work,the self-heating degradation behaviors of Pt thin films above 1000 ℃ were studied in situ by TEM at the nanoscale.The Pt films degraded mainly through void nucleation and growth on the Pt-SiNx interface.Voids preferentially formed at the grain boundary and triple junction intersections with the interface.At temperatures above 1040 ℃,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-SiNx interface.The grain-boundary-dominated mass transportation renders the voids grow preferen-tially 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.
