Fast macropore growth in n-type silicon

Deep macropores can be grown in classical aqueous HF electrolytes only at slow etching speeds, fast macropores can only be grown to modest depths (150 mu m). The addition of acid acetic to the electrolyte can roughly double the etching speed of the macropores, enabling quick and easy etching of pore depths as deep as 520 mu m, and potentially more, if wafers thicker than 550 mu m would be used. The addition of carboxymethylcellulose sodium salt (CMC) to the electrolyte decreases the roughness of the pore walls significantly. It is successfully shown that electrolytes consisting of HF + acetic acid + CMC can be utilized to produce fast, deep, and smooth macropores simultaneously in n-type silicon, required for a multitude of potential applications. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim