Position-selective and material-selective silicon etching to form measurement structures for semiconductor fabrication

Abstract

A method for position-selective and material-selective etching of silicon, and examination structures formed using the method, are presented. A semiconductor topography is exposed to an electron beam in the presence of xenon difluoride (XeF ) gas. The beam is scanned over a portion of the semiconductor topography, and silicon portions of the topography contacted by the electron beam and the XeF gas are etched. Non-silicon portions, such as dielectrics, metals, and/or metal silicides, are not believed to be etched. Shorter exposure times may be used to remove polycrystalline silicon portions of a topography, while leaving monocrystalline silicon portions intact. Removal of silicon and non-silicon portions of the topography by other means may be used to expose silicon portions of the topography. The electron beam controlled etching recited herein may be used alone or combined with such removal by other means to form examination structures for use in evaluation of semiconductor manufacturing techniques.