Formation of Macropore and Three-Dimensional Nanorod Array in p-Type Silicon

We carried out a study on the change in pore wall thickness depending on the current density in p-type silicon. We attempted the formation of a uniform macropore or nanorod array with a high aspect ratio in p-type silicon by electrochemical etching through the optimization of the hydrogen fluoride (HF)/organic electrolyte composition and the design of the mask pattern. The electrochemical etching of p-type silicon in the HF : dimethylsulfoxide (DMSO) : deionized (DI) water 1 : 5 : 5 electrolyte can control the velocity of a reaction between an electrolyte and a hole necessary for the electrochemical etching of silicon through the mixing of the protic property of DI water and the aprotic property of DMSO. In this study, we fabricated a p-type silicon nanorod array of three-dimensional structures with an approximately 350 nm diameter from macroporous Si by applying two-step currents (40 mA, 200 s + 38 mA, 1600 s) to a 1.8 cm(2) circular area using an optimized HF : DMSO : DI water 1 : 5 : 5 electrolyte composition. (c) 2010 The Japan Society of Applied Physics