Ridge Type Microfabrication by Maskless Ion Implantation of Si into SiO2 Film

A ridge type pattern can be fabricated by selective chemical etching after maskless ion implantation of Si++ into SiO2 film. The etchant is buffered HF, and maskless ion implantation into SiO2 film is carried out by a 100 kV focused ion beam apparatus with the ion dose from 2×1016 to 3×1018 cm-2. The ridge line width increases with the ion dose. The cross section of the ridge type pattern is a trapezoidal shape at a wide range of ion dose, while it is a triangular shape at a lower ion dose. The minimum line width of 50 nm with height of about 50 nm is obtained for a conventional CVD SiO2 film.