Morphology, Texture and Twinning Structure of Cu Films Prepared by Low-Temperature Electroplating

Abstract

Surface morphology, crystallographic texture and microstructure of Cu films deposited at temperature below ambient under direct-current (DC) and pulsed-current (PC) modes are investigated. By lowering the electroplating temperature from 20°C to 0°C, the DC-plated films show reduced surface roughness and strong (111)-oriented texture, while the PC-plated ones increased roughness and no crystallographic preferred orientation. A narrower and slightly downshift in distribution of twin lamella width is observed for the Cu films electroplated at lower temperature under PC mode. The dependence of hardness on twin lamella width is found to obey the Hall-Petch relation. The variations of crystallographic texture and twinning structure of electroplated Cu films are ascribed to temperature-dependent electrochemical nucleation and growth kinetics and relaxation of deposition-induced stress.