Fabrication of subwavelength-size aperture for a near-field optical probe using various microfabrication procedures

Abstract

We successfully fabricated subwavelength-size silicon oxide apertures on a cantilever array as a near-field optical probe. Various semiconductor processes were utilized for subwavelength-size aperture fabrication. The anisotropic etching of the Si substrate by alkaline solutions followed by anisotropic crystal orientation dependent oxidation, anisotropic plasma etching, and isotropic oxide etching was carried out. 2, 3, and 4 μm size dot arrays were initially photolithographically patterned on a Si(100) wafer. After fabrication of a V-groove shape by anisotropic etching, oxide growth at 1000 °C was performed to have an oxide etch mask. The oxide layer on the Si(111) plane has been utilized as an etch mask for plasma dry etching and water-diluted HF wet etching for subwavelength-size aperture fabrication. A Au thin layer was deposited on the fabricated oxide aperture on the cantilever array. After this procedure, the initial opening, 300 nm of the oxide aperture was reduced down to ∼95 nm.