Reproducible Large-Area Microfabrication of Sub-100 nm Apertures on Hollow Tips

Abstract

We report on a silicon‐based microfabrication process to generate apertures with dimensions of less than 100 nm at the apex of hollow silicon dioxide tips. The fabrication process is self‐adjusting and leads to highly reproducible aperture dimensions. It relies substantially on the inhomogeneous thickness distribution and modified etch rate of a silicon dioxide layer thermally grown on structured (001) oriented silicon wafers at relatively low temperatures of about 900–950°C. Process parameters are presented to obtain single or double aperture tips. Once the apertures are fabricated, a further reduction of aperture size below 80 nm is achieved by thin film deposition of, e.g., metal layers or other materials. The possibility of fabricating apertures reliably and reproducibly on large areas, e.g., complete silicon wafers, is emphasized. © 2000 The Electrochemical Society. All rights reserved.

Wafer-scale fabrication of nanoapertures using corner lithography

“…The pit typically forms following the anisotropic etch characteristics of crystalline silicon in hydroxide-based solutions [64,65]. Even though submicron apertures were achieved, they improved the technique in 2000 to sub-200 nm resolution by the effect of oxidation retardation at the concave corner of the etch pit [66]. The effect is essentially identical to the previously mentioned oxidation-based sharpening technique.…”

Fabrication of subwavelength surface structures combining self-assembled masking layer with plasma etching techniques

“…Other self-adjusting techniques have been developed recently, based on growth of silicon dioxide layer of nonuniform thickness on already structured silicon substrate. 6,7 Growth is slightly retarded at surface features of large curvature which allows to perforate the silicon dioxide film by either wet or dry etching techniques forming orifices of 90 nm dimension. 8,9 In this article, we report a method for producing structures without any need of high-resolution lithography.…”

3D Nanofabrication of fluidic components by corner lithography

“…submicron apertures were achieved, they improved the technique in 2000 to sub-200 nm resolution by the effect of oxidation retardation at the concave corner of the etch pit (Mihalcea et al, 2000). The effect is essentially identical to the previously mentioned oxidation-based sharpening technique.…”

“…It is at this point important to compare our approach with the wafer scale techniques presented before Mihalcea et al (2000) created a silicon oxide pyramidal structure in an anisotropic etch pit in a silicon mold. The combination of the oxidation retardation in the apex and an HF thinning step (when the pyramid is still in the mold) leads to a reduced thickness of the silicon oxide near the apex of a silicon oxide pyramidal structure.…”

“…The pit typically forms following the anisotropic etch characteristics of crystalline silicon in hydroxide-based solutions (Oosterbroek et al, 2000;Berenschot et al, 2009). Even though (Mihalcea et al, 2000) (reprinted with permission, copyright The Electrochemical Society 2000). Right: convex side etch forming a sharp single aperture (Minh et al, 1999) (reprinted with permission, copyright American Institute of Physics 1999).…”