Fabrication of structures of metal/semiconductor compound by x-ray/euv projection lithography

Abstract

A lithography method for fabricating structures of etch-resistant metal-semiconductor compound on a substrate with sub-micrometer scale resolutions is described. Superposed layers of metal and semiconductor capable of reacting with each other to form etch-resistant metal/semiconductor compound are deposited on the substrate. Radiation from a X-ray/EUV source propagates through a patterned X-ray transparent/EUV reflective mask and is projected on the superposed metal and semiconductor layers. The X-ray transparent mask includes X-ray absorbing patterns imparted to the X-ray radiation while the EUV reflective mask includes EUV absorbing patterns also imparted to the EUV radiation. The energy of X-ray/EUV photons is absorbed locally by the metal and semiconductor layers. Absorption of this energy induces a reaction between the two layers responsible for the formation of etch-resistant metal/semiconductor compound with structures corresponding to the patterns imparted to the radiation by the X-ray/EUV mask. The metal layer is subsequently etched using selective plasma or wet etching, leaving the structures of etch-resistant metal/semiconductor compound intact. The semiconductor layer may also be etched using selective plasma or wet etching, also leaving the structures of etch-resistant metal/semiconductor compound intact. The underlying layers of the substrate may also be partially or completely etched away using selective plasma or wet etching. Again, the structures of etch resistant metal/semiconductor compound protects the substrate against etching whereby these structures form corresponding patterns in the underlying layers of the substrate.