Copper deposition onto a porous silicon (PS) layer by immersion plating from organic solutions was studied using methanol (MeOH) and acetonitrile (MeCN). Copper metal was deposited at the open circuit potential onto the surface of PS From MeOH solution containing copper ions while no metal deposition was detected from MeCN solution, although both solutions contain a comparable amount of residual water. The difference in the deposition behavior is related to the difference in the rest potential of PS that is mainly attributed to the solution chemistry of copper ions in these solutions. Fourier transform infrared spectroscopy revealed that the reduction of metal ions was accompanied by the simultaneous oxidation of PS. The absence of the two peaks related to Si(0) and SiO2 in X-ray photoelectron spectroscopy measurements indicates the complete coverage of the PS surface with Cu metal from MeOH solution. Current-potential curves were measured to investigate the electrochemical behavior of the solutions. The effect of an air-oxidized PS surface on the deposition behavior was also studied. (C) 2001 Elsevier Science Ltd. All rights reserved.