Submicrometer patterning of cobaltdisilicide layers by local oxidation

Abstract

We investigated the diffusion and reaction processes occurring during local silicide oxidation. We patterned epitaxial CoSi 2-layers also by local oxidation. This novel method for patterning of silicide layers allows the realization of deep submicrometer spacings between silicide layers. Epitaxial CoSi 2-silicide layers were grown by a special molecular beam epitaxy method on Si(100) and Si(111) with thicknesses of 40 nm. The SiO 2/Si 3N 4 oxidation mask was patterned photolithographically with line widths of ∼ 1 μm. During thermal oxidation SiO 2 forms on the unprotected regions of the silicide layer. The silicide is pushed into the substrate in these regions. By this process the silicide layer thins near the edges of the oxidation mask and at a critical oxide thickness the oxidized part of the silicide layer separates from the protected part. Using this patterning method we fabricated metallic CoSi 2 layers separated by distances as small as ∼ 200 nm on Si(100) and Si(111). Spacings below 100 nm should be feasible.