Chemical Resistance Of Porous Silicon: Photolithographic Applications

Low-temperature passivation is employed in this study to improve the chemical resistance of porous silicon to both weak-alkali and HF solutions, enabling complex and multi-mask patterning of porous silicon. Passivation is achieved by annealing the film in N-2 atmosphere at temperatures ranging from 560 degrees C-800 degrees C. The resistance of the passivated porous silicon to both KOH and HF solutions was examined by immersing the sample into these solutions and working out the optical thickness change. It is shown that higher passivation temperatures result in improved chemical resistance. Infrared spectroscopy show that exposing the films to HF can remove the passivation layer, enabling repeated anodisation; the restoration of the hydrogen bond on the porous silicon surface after HF immersion makes repeated passivation and processing possible. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim