Nanometer patterning of epitaxial CoSi2/Si(100) by local oxidation

Nanometer patterning of single crystalline CoSi2 layers on Si(100) by local oxidation was studied. Epitaxial CoSi2 layers with thicknesses around 20 n m were grown on Si(100) by molecular beam allotaxy. A nitride layer was dep osited on the surface of the silicide and subsequently patterned along the (110) direction by optical lithography and dry etching. Rapid thermal oxida tion was then performed at a temperature of 950 degrees C in dry O-2 ambien t. During oxidation SiO2 forms on the unprotected regions of the CoSi2 laye r. 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 th e protected part. Using this patterning method highly uniform gaps with a w idth of 70 nm between the two silicide layers have been obtained. It was sh own that the separation gap is not only dependent on the oxidation paramete rs, 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. (C) 1999 Elsevier Science Ltd. All rights reserved.