X-ray synchrotron topography investigation of porous silicon formed by patterning in localized areas

X-ray synchrotron topography was used to study the structural features of p orous silicon (PS) layers formed by p(+) (boron)-type silicon anodization w ithin localized areas. Selective anodization was obtained by using a maskin g film (Si3N4) with good chemical inertness to the anodic dissolution or a surface layer of different doping type and level resulting from phosphorus implantation. The overall structural picture of the PS/substrate systems ob tained by the two different masking procedures was built up by combining di fferent topographic methods. The samples were oriented both in Bragg (refle ction) and Lane (transmission) geometry to diffract white or monochromatic radiation with extended (projection topography) or limited (section topogra phy) beam widths. By comparing the effects of the two masking types on the anodization process, the implantation method is unquestionably preferable b ecause of the lower stress at the window edges, the better lateral porosity homogeneity inside the windows, and the flatter interface between porous s ilicon and substrate. (C) 2001 The Electrochemical Society. [DOI: 10.1149/1 1385380] All rights reserved.