We have investigated the thermal oxidation of epitaxial CoSi2 on Si(111). The epitaxial layers were grown by molecular beam allotaxy with thicknesses ranging from 30 to 40 nm. Similar to the well established technology for local oxidation of silicon (LOCOS), the silicide layer was capped by 20 nm SiO2 followed by 200 nm Si3N4. The nitride was patterned by optical lithography and dry etching. Wet thermal oxidation was used in a temperature range from 850 to 1000 degrees C. On the unprotected regions SiO2 formed on top of the silicide. During this process Co atoms diffused from the SiO2/CoSi2 interface through the silicide layer to the CoSi2/Si interface to form CoSi2, leading to a shift of the silicide layer into the Si substrate. Near the edges of the nitride mask the silicide layer thinned and finally separated. Two metallic layers electrically separated by Si and SiO2 with a small gap of about 300-500 nm were produced this way. We have observed a strong temperature dependence of the separation process in the investigated temperature range of 850 degrees C and 1000 degrees C. We attribute this behavior to the distinctly different activation energies of the Co diffusion and the silicide oxidation. We will show that the lateral uniformity of the separation process is related to the crystal symmetry of the Si(111) wafer.