In situ transmission electron microscopy study of dislocations in a polycrystalline Cu thin film constrained by a substrate

Dislocation plasticity in a thin Cu film on a SiNx/SiOx coated silicon wafer was observed by transmission electron microscopy (TEM) during thermal cycling of a cross-sectional specimen. While the in situ TEM study revealed jerky dislocation motion at low homologous temperatures, continuous dislocation glide occurred at elevated temperatures. Furthermore, dislocations were pulled into the Cu/SiNx interface, where dislocation contrast disappeared. It is assumed from these preliminary observations that the limited mobility of dislocations at low homologous temperatures rather than interfacial dislocation segments may be responsible for the high yield stress of the Cu film. (C) 2000 American Institute of Physics. [S0003-6951(00)01634-X].