Microporous silicon has been formed by anodization of p-type silicon. The pores with diameter less than 2 nm were filled with copper by using supercritical carbon dioxide fluid. The copper-filled layers were investigated with the field emission scanning electron microscopy, X-ray diffractometry, and energy-dispersive X-ray spectroscopy. Structural characterizations indicated that copper was continuously deposited into porous silicon down to a depth of about 0.5 mu m. Electrical measurement confirmed this result. Copper-deposited layers exhibited much improved current density-potential curves. (C) 2014 Elsevier B.V. All rights reserved.