Epitaxial CoSi₂-nanostructures: An approach to Si nanoelectronics

CoSi₂-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 SiO₂ and Si₃N₄, 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 CoSi₂/Si-heterostructure. Rapid thermal oxidation (RTO) leads to the separation of the CoSi₂ 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 CoSi₂-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.