Inverted method for fabricating a nano-aperture device with subwavelength structures

An inverted method for fabricating a plasmonic nanoaperture device by using focused ion beam (FIB) milling and focused electron beam (FEB) induced deposition is proposed here. The device structure presented consists of a periodic annulus grating pattern along the interface of a quartz substrate and sputtered aluminum layers and a cylindrical high-index filled nanoaperture through the aluminum film in the center of the grating. FIB milling was used to process the annulus pattern on the quartz substrate. A dielectric nanopost (or inverted nanoaperture) was fabricated by FEB-induced deposition using tetraethyl orthosilicate as a precursor. The device geometry was characterized by atomic force microscopy and scanning electron microscopy. The structural processability of the device was proven with adequate accuracy and the properties of the materials also met the conditions of the device model in terms of functionality.