Fabrication of silica on silicon tips for protein analysis using Atom Probe Tomography

Abstract

This report appraises the custom wet etching technique using Hydrofluoric acid and potassium hydroxide as etchant on silica on silicon chip to prepare Atom Probe Tomography tips. In addition, the report includes how different novel techniques can be used for evaluating the wet etched APT specimen’s potential to be adapted for protein analysis, such as Atom Probe Tomography (APT) and Quartz Crystal Microbalance-Dissipation (QCM-D). Furthermore, it explains the procedure of fabricating Atom probe tips using electropolishing of Nickel and Tungsten wires along with sputter coating of different metals such as Gold and Chromium on the surface for analysis in the Atom Probe Tomography. Subsequently, it presents several images of electropolished tips which were captured using a Scanning Electron Microscope to determine the thickness of the sputtered metal (Au/Cr). It also describes in detail, the usage of K-Layout software for designing an array of circles with different diameters. This design was used as a pattern during the exposure in the Electron Beam Lithography. It also appraises the different instruments used such as electropolishing, sputter coater, cleanroom facility, Electron Beam Lithography, and Scanning Electron Microscope, which was used to fabricate and image the samples fabricated, during the project and its principle for understanding the reason of methodology.