Nanometric aperture arrays fabricated by wet and dry etching of silicon for near-field optical storage application

We fabricated nanometric aperture arrays in order to apply to an optical probe in high-density near-field optical storage for increase of data-transmission rate. The aperture arrays were fabricated by forming concave pyramidal grooves on a silicon-on-insulator wafer with electron beam lithography and wet anisotropic etching. Modification of the apex shape of the grooves by re-oxidation and subsequent reactive ion dry etching was able to increase the uniformity of the aperture size remarkably. The light transmission efficiency of the fabricated apertures was measured to be ${\text{∼10}}^{\text{−3}}$ when the aperture size was 100 nm, which was higher than that of a conventional optical fiber probe by several orders of magnitude.