This work describes the formation of submicrometer pore arrays using nanoimprint lithography and photoelectrochemical etching of n-type silicon in a hydrofluoric acid electrolyte. This work highlights more specifically the link between silicon resistivity and pore geometry. A properly chosen silicon resistivity is shown to ensure a stable pore growth and to limit damages in pore walls due to electrical breakdown and photogenerated carrier diffusion. Well ordered pore arrays with a depth up to 20 mu m and a period of 1 mu m, 750 nm, and 500 nm have been fabricated using silicon wafers with resistivities of 0.76, 0.35, and 0.15 Omega cm, respectively. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3514584] All rights reserved.