Microstructure and In-plane Resistivity of Cu/Ni Multilayers

The Cu/Ni multilayers were deposited using ion beam sputtering at room temperature and 250℃ respectively. The microstructures of the multilayers including interfacial roughness, grain size and growth direction have been investigated by transmission electron microscopy and X-ray diffraction. The microstructure depends strongly on the substrate temperature and modulation wavelength, bigger grain size and larger interfacial roughness were obtained when the multilayers were deposited at 250℃, and the multilayers ceased to grow epitaxially due to the increasing defects in the multilayers. The resistivity of the multilayers is very sensitive to the microstructure due to the size-effect. In order to study the influence of the microstructure to the resistivity, the in-plane resistivity of Cu/Ni multilayers was measured using four-point probe. The resistivity increases with higher substrate temperature, and it decreases when the modulation wavelength becomes short. The interfacial roughness and grain size have co-contribution to the resistivity. The interface scattering is the main factor that has effect on the resistivity of Cu/Ni multilayers.