Influence of the Redeposition effect for Focused Ion Beam 3D Micromachining in Silicon

Fu, Yongqi; Bryan, Ngoi Kok Ann; Shing, Ong Nan; Hung, N.P.

doi:10.1007/s001700070005

Cited by 42 publications

(15 citation statements)

References 7 publications

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“…A milling at higher current of 9.3 nA seems to produce an uneven diameter and a larger size of pore as compared to the one milled at a low milling current of 2.1 nA. This happens due to the larger beam current corresponding to the large beam spot size [28]. Figure 3c shows the cross-sectional image of the conical-shape micropore milled also at 2.1 nA.…”

Section: Resultsmentioning

confidence: 94%

Fabrication of Si Micropore and Graphene Nanohole Structures by Focused Ion Beam

Ibrahim

Hashim

2020

Sensors

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A biosensor formed by a combination of silicon (Si) micropore and graphene nanohole technology is expected to act as a promising device structure to interrogate single molecule biopolymers, such as deoxyribonucleic acid (DNA). This paper reports a novel technique of using a focused ion beam (FIB) as a tool for direct fabrication of both conical-shaped micropore in Si3N4/Si and a nanohole in graphene to act as a fluidic channel and sensing membrane, respectively. The thinning of thick Si substrate down to 50 µm has been performed prior to a multi-step milling of the conical-shaped micropore with final pore size of 3 µm. A transfer of graphene onto the fabricated conical-shaped micropore with little or no defect was successfully achieved using a newly developed all-dry transfer method. A circular shape graphene nanohole with diameter of about 30 nm was successfully obtained at beam exposure time of 0.1 s. This study opens a breakthrough in fabricating an integrated graphene nanohole and conical-shaped Si micropore structure for biosensor applications.

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Section: Resultsmentioning

confidence: 94%

Fabrication of Si Micropore and Graphene Nanohole Structures by Focused Ion Beam

Ibrahim

Hashim

2020

Sensors

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“…11 (a) SEM micrograph of FIB sputtered paraboloid on silicon, and (b) cross-sectional view along the depth axis as plotted with the ideal parabolic curve (area offset = 3-5%) 74 change of sputtering yield at the periphery is found to be insignificant. [74][75][76] A parabolic micromold cavity (Fig. 11) is fabricated on silicon substrate using Micrion direct modification (DMOD) Description Language (MDDL).…”

Section: Three Dimensional Microcavitymentioning

confidence: 99%

A review of focused ion beam sputtering

Ali

Hung

2010

Int. J. Precis. Eng. Manuf.

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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.

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“…This removed volume serves as the optical cavity for the sensor, and therefore the sidewalls in the cavity need to be strictly parallel with each other to ensure sufficient reflected signals can be coupled back into the fibre core for detection. Unfortunately, it is known that an amorphous layer can be formed on FIB machined sidewalls due to the redeposition effect [29]. In order to minimize the redeposition and increase the machining efficiency, the ion beam scanning commenced 2 μm away from the edge of the top surface as it is shown in figure 2(a), forming one open edge, from which machining debris can easily escape.…”

Section: Fabrication Of the Optical Cavitymentioning

confidence: 99%

Fabrication of a side aligned optical fibre interferometer by focused ion beam machining

Sun¹,

Li²,

Maier³

et al. 2013

J. Micromech. Microeng.

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Focused ion beam (FIB) machining is a promising technique for the fabrication of micro-optical components with high quality surface finishes. In this work, a prototype of a side aligned optical fibre interferometer was successfully fabricated by the three-dimensional deterministic FIB machining technique. A highly accurate 45• reflective mirror with surface roughness (Ra) of 10 nm has been successfully fabricated at the centre of the fibre to direct the core guided light to the side of the fibre. A surface topography simulation method was developed to simulate the ion beam polishing process. According to the simulation result, a 0.5• offset on the ion beam polishing direction is necessary to maintain the machining accuracy. In the fabrication process, it was also found that for structures requiring a high aspect ratio the existence of an open edge can mitigate against the material redeposition on the sidewalls and therefore increase the overall material removal rate. The fibre has been tested optically and the interference signals have been successfully observed, demonstrating the alignment accuracy of the fabrication method.

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Influence of the Redeposition effect for Focused Ion Beam 3D Micromachining in Silicon

Cited by 42 publications

References 7 publications

Fabrication of Si Micropore and Graphene Nanohole Structures by Focused Ion Beam

Fabrication of Si Micropore and Graphene Nanohole Structures by Focused Ion Beam

A review of focused ion beam sputtering

Fabrication of a side aligned optical fibre interferometer by focused ion beam machining

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