Damage and contamination free fabrication of thin Si wires with highly controlled feature size

For the precise control of the electrical conductivity in Si ultrafine structures by single ion implantation (SII), silicon wires with well-defined patterns have been successfully fabricated without introducing damages and contaminations by combining a focused Si ion beam irradiation with the anisotropic etching of Si crystal in a hydrazine-water solution. A silicon ion beam irradiation enhanced the etching rate of the thermally grown SiO ₂ overlayer on SIMOX (separation by implanted oxygen) Si in HF-water solution. The top-Si was subsequently etched by the hydrazine-water solution with the patterned SiO ₂ film as a mask. It was confirmed by the four point probe measurement that our technique had no influence on the electrical properties of the Si wires.