Observation of new oscillatory phenomena during the electrochemical anodization of silicon

This paper reports the observation of large undamped voltage oscillations d uring the anodic polarization of silicon in electrolyte containing a combin ation of acids. One of them stimulates oxide growth and the other its chemi cal dissolution (in the present case, (0.01-0.1 M H3PO4) + (0.001-0.01 M HF ). This temporal patterning of the anodization process is shown to be due t o the formation of a thin (50-90 nm) oxide layer at the sample surface and its subsequent lifting-off. The mechanism of oxide detachment is thought to be an isotropic growth of micropores at the oxide/silicon interface trigge red on by changes of electrochemical conditions there. (C) 1999 The Electro chemical Society. S1099-0062(98)12-023-0. All rights reserved.