Electron beam induced carbon deposition used as a negative resist for selective porous silicon formation T. Djenizian, L. Santinacci 1 , H. Hildebrand, P. Schmuki * Department of Materials Science, LKO, University of Erlangen-Nuremberg, Martensstr. 7, D-91058 Erlangen, Germany Received 17 April 2002; accepted for publication 8 August 2002 Abstract The present work describes direct porous silicon patterning based on electron-beam induced carbon deposition used as a mask against pore formation on Si. Under ideal conditions the C-deposits act as a negative resist to suppress completely and selectively the formation of light emitting porous Si at treated locations. Carbon patterns were written at different electron doses on p-type Si(1 00) surfaces. Subsequently by contamination writing in a scanning electron microscope the silicon surface was porosified by galvanostatic experiments in a 20% HF solution. The carbon masks as well as the etched surface were characterized by scanning electron microscopy and Raman spectroscopy. The selectivity of the technique depends on several factors such as the electron dose during masking and the electrochemical pa- rameters. Under conditions typical for porous silicon formation, already a relatively low electron dose is sufficient to achieve the desired mask effect to produce patterned porous silicon structures. Ó 2002 Elsevier Science B.V. All rights reserved. Keywords: Electrochemical methods; Raman scattering spectroscopy; Photoluminescence; Electron bombardment; Amorphous thin films; Porous solids 1. Introduction Nanomaterials have in recent years attracted a great deal of scientific interest. On the one hand interest focuses on possibilities to prepare and study materials with novel properties which are encountered when nanosize dimensions are ap- proached. On the other hand a major thrust for shrinking dimensions originates from the micro- electronic and microsystems fields with a contin- uous demand for a higher degree of smaller devices, system integration and system diversifi- cation. This implies that the classical microelec- tronic materials or newly integrated materials need to be microstructured to obtain a higher function- ality. To achieve sub-lm resolution a wide range of processes have been studied including litho- graphic techniques essentially based on exposure of resists to photons, X-rays and electron-beams (e-beam). More recently, direct patterning of sur- faces has also been investigated using focussed ion beams (FIBs) [1–3] or atomic force microscopy [4,5]. * Corresponding author. Tel.: +49-91-31-852-75-75; fax: +49- 91-31-852-75-82. E-mail address: patrik.schmuki@ww.uni-erlangen.de (P. Schmuki). 1 On leave from, EPF-Lausanne, Department of Material Science, LTP, Switzerland. 0039-6028/02/$ - see front matter Ó 2002 Elsevier Science B.V. All rights reserved. PII:S0039-6028(02)02545-1 Surface Science 524 (2003) 40–48 www.elsevier.com/locate/susc