Application of Molecular-Dynamics Simulation to Interface Stabilization in Thin-Film Devices

A molecular-dynamics technique for simulating interface diffusion, which is one of the dominant factors in mechanical failures of thin-film devices, has been developed. This technique was used to find effective methods for suppressing the interface diffusion and for stabilizing interfaces. Barrier-underlayer materials effective for improving the adhesion strength with interconnect films were identified by using this technique. Ruthenium was found to be an effective underlay material for improving the adhesion with Cu interconnects. The crystal orientation of Si substrates effective for reducing atomic diffusion at interfaces between the Si substrates and high-k dielectrics (ZrO2 and HfO2) was determined. The use of Si(111) substrates was found to be effective for suppressing the formation of interfacial layers.