Effect of Temperature on the Surface Morphology and Texture of Electrodeposited Polycrystalline Copper Thin Films

Abstract

We made a quantitative comparison of the surface morphology and texture of polycrystalline copper thin films electrodeposited at fixed potential from an organic additive-free acid sulfate bath as a function of temperature and current density. The deposition conditions were (i) room temperature and 0.25 M Cu2 + , (ii) zero Celsius and 0.25 M Cu2 + , and (iii) room temperature and a Cu2 + concentration selected to give the same current density as (ii). Atomic Force Microscopy (AFM) and scanning electron microscopy (SEM) images showed qualitative differences between samples deposited under the different growth conditions. However, quantitative analysis of the AFM data also revealed similarities in how the surface morphology evolved. X-ray diffraction (XRD) results indicate that under all the conditions studied, the ratio of the Cu {220} to the Cu {111} peak height increases as the film thickness increases, and that this increase is much greater at room temperature than at zero Celsius. Temperature-dependent nucleation rates provide a plausible explanation for the texture differences between films deposited at room temperature and zero Celsius.