Growth mode of copper films electrodeposited on silicon from sulfate and pyrophosphate solutions

The electrodeposition of thin copper films on silicon substrates from coppe r pyrophosphate and copper sulfate solutions, without the addition of addit ives or hydrofluoric acid, is presented. The copper films obtained from the se two solutions have different characteristics. Cyclic voltammetry was per formed in order to investigate the silicon/electrolyte interface. This prov ides an explanation why the copper pyrophosphate solution is more favorable for electrodepositing copper on a semiconductor substrate. The copper film s obtained with the pyrophosphate solution, having thicknesses ranging from 20 to 280 nm, were characterized in detail. They are homogeneous, exhibit a metallic luster, and show good adhesion. The topography was examined by a tomic force microscopy, providing the root-mean-square roughness and the av erage grain size on the surface. The grain size values are compared with th e average value of the scattering coherence length determined by X-ray diff raction. The kinetic roughening of the copper deposits was investigated by dynamic scaling behavior and compared to previous studies. (C) 1999 The Ele ctrochemical Society. S0013-4651(98)08-028-8. All rights reserved.