• Journal of the Korean Society for Precision Engineering
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• v.28 no.2
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• pp.245-250
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• 2011

A high-resolution shadow mask, a nanostencil, is widely used for high resolution lithography. This high-resolution shadowmask is often fabricated by a combination of MEMS processes and focused ion beam (FIB) milling. In this study, FIB milling on 500-nm-thin SiN membrane was tested and characterized. 500 nm thick and $2{\times}2$ mm large membranes were made on a silicon wafer by micro-fabrication processes of LPCVD, photolithography, ICP etching and bulk silicon etching. A subsequent FIB milling enabled local membrane thinning and aperture making into the thinned silicon nitride membrane. Due to the high resolution of the FIB milling process, nanoscale apertures down to 60 nm could be made into the membrane. The nanostencil could be used for nanoscale patterning by local deposition through the apertures.

• Electrical & Electronic Materials
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• v.7 no.5
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• pp.389-396
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• 1994

The bilayer film of Ag/a-S $e_{75.G}$ $e_{25}$ and the monolayer film of a-S $e_{75.G}$ $e_{25}$ act as a negative-type and a positive-type resist in focused ion beam lithography, respectively. Using a model which takes into account the ion stopping power, the ion projected range, the ion concentration implanted into resists and the ion transmission coefficient, etc., the ion resist parameters are calculated for a broad range of ion energies and implanted doses. Ion sources of A $r^{+}$, S $i^{++}$ and G $a^{+}$ are used to expose resists. As the calculated results, the energy loss per unit distance by Ga'$^{+}$ ion is about 10$^{3}$[keV/.mu.M] and nearly constant for all energy range. Especially, the projected range and struggling for 80[keV] G $a^{+}$ ion energy are 0.0425[.mu.m] and 0.020[.mu.m], , respectively and the resist thickness of a-S $e_{75}$ G $e_{25}$ to minimize the ion penetration rate into a substrate is 0.118[.mu.m].u.m]..u.m].

• Journal of the Korean Society for Precision Engineering
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• v.23 no.3 s.180
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• pp.56-60
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• 2006

A high-resolution shadow mask, or called a nanostencil was fabricated for high resolution lithography. This high-resolution shadowmask was fabricated by a combination or MEMS processes and focused ion beam (FIB) milling. 500 nm thick and $2{\times}2mm$ large membranes wore made on a silicon wafer by micro-fabrication processes of LPCVD, photolithography, ICP etching and bulk silicon etching. A subsequent FIB milling enabled local membrane thinning and aperture making into the thinned silicon nitride membrane. Due to the high resolution of the FIB milling process, nanoscale apertures down to 70 nm could be made into the membrane. By local deposition through the apertures of nanostencil, nanoscale patterns down to 70 nm could be achieved.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.871-874
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• 2004

Fabrication of a high-resolution shadow mask, or called nanostencil, is presented. This high-resolution shadowmask is fabricated by a combination of MEMS processes and focused ion beam (FIB) milling. 500 nm thick and 2x2 mm large membranes are made on a silicon wafer by micro-fabrication processes of LPCVD, photolithography, ICP etching and bulk silicon etching. Subsequent FIB milling enabled local membrane thinning and aperture making into the thinned silicon nitride membrane. Due to high resolution of FIB milling process, nanoscale apertures down to 70 nm could be made into the membrane.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1246-1249
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• 1994

Thin amorphous film of $a-Se_{75}Ge_{25}$ acts as a positive resist in ion beam lithography. Previously, we reported the optical characteristics of amorphous $Se_{75}Ge_{25}$ thin film by the low-energy ion beam exposure and presented analytically calculated values such as ion range, ion concentration and ion transmission coefficient, etc. As the calculated results of analytical calculation, the energy loss per unit distance by $Ga^+$ ion is about $10^3[keV/{\mu}m]$ and nearly constant for all energy range. Especially, the projected range and struggling for 80 [KeV] $Ga^+$ ion energy are 0.0425[${\mu}m$] and 0.020[${\mu}m$], respectively. Hear, we present the results of Monte-Carlo computer simulation of Ga ion scattering, exposure and development in $a-Se_{75}Ge_{25}$ resist film for focused ion beam(FIB) lithography. Monte-Carlo method is based on the simulation of individual particles through their successive collisions with resist atoms. By the summation of the scattering events occurring in a large number N(N>10000) of simulated trajectories within the resist, the distribution for the range parameters is obtained. Also, the deposited energy density and the development pattern by a Gaussian or a rectangular ion beam exposure can be obtained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.11a
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• pp.134-136
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• 1993

Microelectronic fabrication technology .is based on the use of lithsgraphy to create small linewidths and patterns that make up ULSI. In previous papers, we discussed the theoretically calculated values such as ion range, ion concentration,ion transmission coefficient and the defocused ion beam-induced characteristics in a-Se$_{75}$Ge$_{25}$. In this paper, the typical Monte Carlo (MC) simulation results and p개cedures for the focused ion beam lithography were presented. The interaction and scattering of ions with the resist depend on the beam energy, impact parameter arid resist parameters. For ion exposure simulations, the quantity of interest is the spatial distribution of energy deposited by ions in the resist due to interaction phenomena with resist ions.s.s.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.05a
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• pp.30-33
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• 1992

This thesis was investigated on ion-induced characteristics in a-$Se_{75}Ge_{25}$ positive and negative resists for focused-ion-beam microlithogaphy. The exposed a-$Se_{75}Ge_{25}$ inorganic thin film shows an increase in optical absorption after exposure to~$10_{16}$ dose of Ga+. The observed shift in the absorption edge toward longer wavelengths is consistent with that in films exposed to band-gap photons(~$10^{21}$photons/cm2). This result may be related with microstructural rearrangements with in the short range of SeGe network. Due to changes in the short range order, the chemical bonding may be affected, which results in increased chemical dissolution in ion-induced film. Also, this resist exhibits good thermal stability because of its high Tg(~$220^{\circ}C$). When focused ion beams are used for direct exposure of resist over a substrate, unwanted implantation of the substrate may be an issue. A possible way to avoid this is to match the thickness of the resist to the range of ions in the resist. Thin aspect is currently under investigation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.224-227
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• 1995

The micro-patterning by a Bow energy FIB whish has been conventionally utilized far mask-repairing was investigated. Amorphous Se$\_$75/Gee$\_$25/ resist irradiated by 9[keV]-defocused Ga$\^$+/ ion beam(∼10$\^$15/[ions/$\textrm{cm}^2$]) resulted in increasing the optical absorption, which was also observed also in the film exposed by an optical dose of 4.5${\times}$10$\^$20/[photons/$\textrm{cm}^2$]. The ∼0.3[eV] edge shift for ion-irradiated film was about twice to that obtained for photo-exposed. These large shift could be estimated as due to an increase in disorder from the decrease in the sloop of the Urbach tail. For Ga$\^$+/ FIB irradiation with a relatively low energy, 30[keV] and above the amount of dose of 1.4${\times}$10$\^$16/[ions/$\textrm{cm}^2$], the irradiated region in a-Se$\_$75/Ge$\_$25/ resist was perfectly etched in acid solution for 10[sec], which is relatively a short development time. A contrast was about 2.5. In spite of the relatively low incident energy,∼0.225[$\mu\textrm{m}$] pattern was clearly obtained by the irradiation of a dose 6.5${\times}$10$\^$16/[ions/$\textrm{cm}^2$] and a scan diameter 0.2[$\mu\textrm{m}$], from which excellent results were expected fur incident energies above 50[keV] which was conventionally used in FIBL.