A review of focused ion beam sputtering

Abstract

NOMENCLATURE η = atomic density α = coefficient of energy transfer φ = ion flux η = atomic density of the target σ = standard deviation δ = pixel spacing (nm) (distance between two adjacent beam centres) φ (x,y) = ion flux at point (x, y) ε b = bonding energy per atom pair ∆Z ij = sputtering depth at each point (x i , y i ), a = peak-to-valley height of the variable cumulative intensity profile A = aperture size (nm) B = beam function d = ion dose f x,y = energy density function of Gaussian beam in two dimensions I = total ion beam current J(x,y) = beam current intensity at any point x,y J 0 = peak current intensity (at the centre of the beam) K 1 , K 2 = material factor for different crystalline structure, and other properties respectively M = material function m i , m t = atomic mass of the incident (sputtering) ion, and target material respectively MRR = material removal rate R = function representing the sputtered surface profile r = FIB radius (nm) R a , R max = average and maximum (peak-to-valley height) surface roughness respectively S(θ) = angle dependant sputtering yield T C = critical dwell time or sputtering time T d = dwell time t x,y = dwell time in second of the ion beam at point (x i , y j ) U 0 = atomic binding energy V = acceleration voltage Y(E) = normal sputtering yield z = sputtered depth Z i , Z t = nuclear charge of the incident ion and target atom respectively This paper reviews the applications of focused ion beam (FIB) sputtering for micro/nano fabrication. Basic principles of FIB were briefly discussed, and then empirical and fundamental models for sputtering yield, material removal rate, and surface roughness were presented and compared. The empirical models were more useful for application compared to fundamental models. Fabrication of various micro and nano structures was discussed. Trimmed atomic force microscope (AFM) tips were tested in measurement and imaging of high aspect ratio nanopillars where higher accuracy and clarity were observed. Micromilling tool fabricated using FIB sputtering was used to machine microchannels. Slicing and dwell time control approaches on FIB sputtering were presented for the fabrication of three dimensional microcavities. The first approach is preferred for practical applications.The maximum aspect ratio of 13:1 of the microstructures was achieved. The minimum size of the nanopore was in the range of 2-10 µm. Cavities of microgear of 70 µm outside diameter were sputtered with submicrometer accuracy and 2-5 nm average surface roughness. The microcavities were then filled with polymer in a subsequent micromodling process. The replicated microcomponents were inspected with scanning electron microscope where faithful duplication of accuracy and surface texture of the cavity was observed.

Calcium orthophosphate deposits: Preparation, properties and biomedical applications

“…As the ions leave the source, they are neutralized by electrons from the second external filament and form neutral atoms. A pressure gradient between the ion source and a sample chamber is generated by placing a gas inlet at the source and shooting through a tube in into the sample chamber [275].…”

Nanoscale hybrid manufacturing process by nano particle deposition system (NPDS) and focused ion beam (FIB)

“…NPDS is an additive process for thin film deposition [6], and FIB has various functions such as imaging, etching, implanting, and deposition [7][8][9][10][11], but in this research, FIB was used as a subtractive process for nanoscale etching. As a sample nanoscale 3D structure, Sn (metal) and Al 2 O 3 (ceramic) were deposited as a nanoscale multi-layer structure on silicon wafer using NPDS, and profile cutting was carried out using FIB.…”

Development of in-process visualization system for laser-assisted three-dimensional microfabrication using photocatalyst nanoparticles

“…Various microfabrication techniques [1][2][3][4][5][6] have been proposed; however, a technique that can be used to efficiently fabricate 3-D structures via a simple procedure has not been reported thus far. Because 3-D metal structures have not only mechanical functions but also electromagnetic functions, it is desirable to develop such a technique.…”