Growth of patterned thin epitaxial CoSi 2-films by a titanium oxide mediated epitaxy process

Abstract

A new method for fabricating thin patterned CoSi 2 layers has been studied. The silicide layers were generated by a solid phase epitaxy process, in which Co and Ti were deposited on a thin chemical oxide on Si(100) substrates. Rapid thermal annealing (RTA) of this structure leads to the formation of epitaxial CoSi 2 with a capping layer on top. Two-step annealing in a forming ambient gas produces high quality epitaxial layers with a capping layer which can be easily removed by wet chemicals. A layer structure consisting of 30 nm SiO 2 and 300 nm Si 3N 4, which is patterned using conventional optical lithography and dry etching, induces a stress field into the underlying layers near the patterning edges. This leads to a formation of separated CoSi 2 layers during the silicide formation caused by the anisotropic diffusion of the atoms in the stress field. Such layers show nearly uniform gaps of approximately 100 nm in width.