Nanometer patterning of epitaxial CoSi 2/Si(100) by local oxidation

Abstract

Nanometer patterning of single crystalline CoSi 2 layers on Si(100) by local oxidation was studied. Epitaxial CoSi 2 layers with thicknesses around 20 nm were grown on Si(100) by molecular beam allotaxy. A nitride layer was deposited on the surface of the silicide and subsequently patterned along the 〈110〉 direction by optical lithography and dry etching. Rapid thermal oxidation was then performed at a temperature of 950°C in dry O 2 ambient. During oxidation SiO 2 forms on the unprotected regions of the CoSi 2 layer. The silicide in this region is pushed into the substrate. Near the edges of the nitride mask the silicide layer thins and finally separates from the protected part. Using this patterning method highly uniform gaps with a width of 70 nm between the two silicide layers have been obtained. It was shown that the separation gap is not only dependent on the oxidation parameters, but also on the thickness and the width of the nitride mask due to the stress effects. Possible applications of this new technique are discussed.