Fast prototyping of high-aspect ratio, high-resolution X-ray masks by gas-assisted focused ion beam

Malek, Chantal Khan; Hartley, Frank T.; Neogi, J.

doi:10.1007/s00542-002-0215-5

Cited by 13 publications

(8 citation statements)

References 19 publications

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“…are the few of many innovative applications of FIB. [40][41][42] SIMS technique, TEM sample preparation, high aspect ratio microstructures, and several other micro/nano structures fabrication are discussed in the following subsections. The overall sizes of these components are in the range from submicrometer to few hundreds of micrometers.…”

Section: Application Of Fib Sputteringmentioning

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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Section: Application Of Fib Sputteringmentioning

confidence: 99%

A review of focused ion beam sputtering

Ali

Hung

2010

Int. J. Precis. Eng. Manuf.

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“…It required large computer memory and processing time. In the case of higher aspect ratio microcavity, the redeposition at the bottom and sidewall distorted the geometry (Friedrich and Vasile 1996;Malek et al 2003;Nassar et al 1998). …”

Section: Dwell Time Control Techniquementioning

confidence: 99%

“…But this tool also has been applied to fabricate nonelectronic components for microelectromechanical systems (MEMS) such as microgear, microneedle, microchannel, micromilling tool, etc. (Steve and Robert 2001;Ali and Ong 2006;Friedrich and Vasile 1996;Malek et al 2003). Moreover, the capability of FIB sputtering has been realized to produce microcavity such as parabolic trough, microgear cavity, etc.…”

Section: Introductionmentioning

confidence: 99%

Geometrical integrity of micromold cavity sputtered by FIB using multilayer slicing approach

Ali

Loo

2006

Microsyst Technol

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This paper discusses the investigation of geometrical integrity of micromold cavity produced by focused ion beam (FIB) sputtering slice by slice. Parabolic shaped micromold cavity was chosen as an example. Preliminary experiments were carried out to characterize the machine and select the optimum process parameters such as beam current, pixel spacing, aperture size, and dwell time. The geometrical integrity of the sputtered micromold cavity was analyzed based on three selected criteria such as aspect ratio, cross-sectional area, and area offset. The theoretical and sputtered profiles were compared. The investigation showed that the measured aspect ratio was almost equal to the theoretical aspect ratio for low aspect ratio microcavity. For high aspect ratio cavity, the measured aspect ratio was higher than the theoretical aspect ratio by 5-8%. The area offset was found to be 5-10% of the theoretical area. The variation in theoretical and sputtered cross-sectional area was 2-4%. The characterization showed that the geometrical integrity of micromold cavity sputtered by FIB using slicing approach was high.

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“…Similarly to EDM, the Focused Ion Beam (FIB) technique scans an ion beam, with spot sizes ranging from 10 to 500 nm, over a specimen, etching the material [5]. Additionally to etching, this technique can be used to build new structures by localized deposition using the ion beam-induced decomposition of an organo-metallic gas [6]. Examples of the use of a FIB system are the milling of angled cuts into the suspension ligaments of MEMS accelerometers, and the milling of large depthto-width aspect ratios tracks to make photonic band gap lattices in As40S60 [5,7].…”

Section: Introductionmentioning

confidence: 99%