ULTRAMICRO FABRICATIONS ON FE-NI ALLOYS USING ELECTRON-BEAM WRITING AND REACTIVE-ION ETCHING

A novel reactive-ion-etching (RIE) method useful for ferromagnetic mat erial of permalloy (80% Ni-4.5% Mo-Fe) has been developed. This method involves rf plasma of a gas mixture NH3-CO aimed at the formation of volatile transition metal carbonyls. A maximum etching rate of 35 nm/m in and highly anisotropic etching was obtained. The etching selectivit y ratios of permalloy to SiO2 or Si were about 10 or 4, respectively. High-resolution electron-beam writing was followed by the RIE process on the permalloy films. To achieve high-resolution electron-beam writi ng, amorphous carbon film was placed between the resist layer and SiO2 film overlaid on the permalloy film. By this method, nanostructures o f permalloy stripes of 200nm lines and 300nm spaces with clear-cat fea tures were fabricated.