Epitaxial CoSi 2-nanostructures: an approach to Si nanoelectronics

Abstract

CoSi 2-nanostructures were fabricated using a self-assembly process involving local oxidation of silicides (LOCOSI). The nanostructures are generated along the edge of a mask consisting of SiO 2 and Si 3N 4, deposited by plasma enhanced chemical vapor deposition (PECVD) and patterned with conventional optical lithography. The mask induces a stress field near its edges into the underlying CoSi 2/Si-heterostructure. Rapid thermal oxidation (RTO) leads to the separation of the CoSi 2 layer in this region due to the concomitant anisotropic diffusion of the cobalt atoms in the stress field. Using this method, uniform gaps and narrow wires were produced from 20–30 nm-thick single-crystalline, epitaxial CoSi 2-layers grown by molecular beam allotaxy (MBA) on conventional Si(100) and silicon-on-insulator (SOI) substrates. These structures with dimensions down to 40 nm can be used as building blocks for nanoscale metal-oxide-semiconductor field effect transistor (MOSFET) devices. We produced 70 nm gate-length Schottky barrier MOSFETs (SBMOSFETs) on SOI using the silicide nanostructures. These devices can be driven as both p-channel and n-channel MOSFETs without complementary substrate doping and show good I– V characteristics.