Characterization of Cu thin films with structural defects synthesized by low bath temperature electrodeposition.

Abstract

Cu films having high mechanical strength and low electrical resistivity were required in various industrial fields, and nanotwin Cu is one of the strong candidates to satisfy these requirements due to its extraordinary microstructures. The formation mechanism and the effect of deposition parameters on the formation of nanotwin Cu have been intensively investigated. In this research, the effect of bath temperature on the formation of nanotwin Cu in pulse current electrodeposition was studied. Although the variation of bath temperature was small as 30°C (from 40°C to 10°C), the tensile strength was increased as ~56% (479 MPa to 745 MPa) without the significant degradation of elongation and electrical conductivity. In addition, the increase of nanotwin density was observed in the sample deposited at low temperature. The diffusion coefficient of Cu+2 ions, overpotential, and residual Cu film stress were measured to investigate the effect of bath temperature. To solve disadvantage of pulse electro deposition LTHC Cu study is proceeded. At the low temperature and high current density makes non equilibrium grain boundary and several nanometer grains and that boosts tensile strength of deposited film. However, severe self-anneal occurred at LTHC copper, it supposed by diffusion assist structure such as non-equilibrium grain boundary.