Electrochemical deposition of Cu on structured silicon including groves and pores is critical for several applications such as microelectronics, sensors, and energy applications. In the case of Cu filling of porous Si, the silicon skeleton can be either etched to produce free nano-or micro-structured Cu or can be left to form a nano-or micro-composite of Si/Cu. Deposition of metals into n-type porous Si is a relatively straight-forward process, due to the availability of electrons at the conduction band to reduce Cu cations. Cu deposition into p-type porous Si requires illumination, unfortunately, it enhances the growth on pore walls and results in either non-conformal growth or plug-in which lead to voids. In this work, it is shown that illuminating the back side of the wafer combined with insulating the pore walls and pore top leads to conformal growth of Cu from the pore-tip to the pore-top. Two approaches have been tested: wall thinning by chemical etching and SiO2 coating on the pore top. Massive wires have been obtained by completely and conformally filling porous Si without leaving gaps in the case of SiO2-coated samples. The conformal filling of p-type Si was obtained without using additives and without seed layer. (c) 2014 The Electrochemical Society. All rights reserved.