• Transactions on Electrical and Electronic Materials
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• v.11 no.4
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• pp.190-193
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• 2010

This report covers an effective fabrication method of graphene nanoribbon for top-gated field effect transistors (FETs) utilizing electron beam lithography with a bi-layer resists (XR-1541/poly methtyl methacrylate) process. To improve the variation of the gating properties of FETs, the residues of an e beam resist on the graphene channel are successfully taken off through the combination of reactive ion etching and a lift-off process for the XR-1541 bi-layer. In order to identify the presence of graphene structures, atomic force microscopy measurement and Raman spectrum analysis are performed. We believe that the lift-off process with bi-layer resists could be a good solution to increase gate dielectric properties toward the high quality of graphene FETs.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1262-1264
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• 1993

An amorphous $Se_{75}Ge_{25}$ thin film as inorganic resist for the focused ion beam lithography(FIBL) is investigated. This film offers an attractive potential alternative to polymer resists because of a number of advantages, such as the possibility of preparing physically uniform films of thickness as small as 200A and obtaining both positive and negative resist action in the same material, compatibility with dry processing, the sensitivity on optical, e-beam and ion beam exposure, the high-temperature stability, etc. In previous paper, the defocused ion beam-induced characteristics in a-$Se_{75}Ge_{25}$ film has been propose. Practically it is neccesary to know the relation with resist and source ions. For the purpose, the ion stopping power, the ion projected range and ion transmission coefficiency are studied. In this paper, the theoretically calculated values of parameters are presented and compared with theory.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.5
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• pp.129-133
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• 2007

Focused Ion Beam(FIB) systems is a useful tool for the fabrication of micro-nano scale structures. In this study, the effects of FIB etching on the Au microstructure are systematically investigated. As the fabrication parameters, ion dose, dwell time and beam overlap ratio are studied. First, the increases of Ga ion dose makes the milling yield higher and the sidewall of milling profile steeper. Dwell time is found to have little effects on the milling profile due to the relatively large milling area of $1\times1{\mu}m^2$ used in this study. However, beam overlap significantly affects not only milling rate but also milling profile. As the beam overlap ratio changes from positive to negative, the development of regular cross-stripe patterns at the bottom with low milling rate is observed.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.8 s.197
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• pp.108-115
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• 2007

3D nano-scale manufacturing is an important aspect of advanced manufacturing technology. A key element in ability to view, fabricate, and in some cases operate micro-devices is the availability of tightly focused particle beams, particularly of photons, electrons, and ions. The use of ions is the only way to fabricate directly micro-/ nano-scale structures. It has been utilized as a direct-write method for lithography, implantation, and milling of functional devices. The simulation of ion beam induced physical and chemical phenomena based on sound mathematical models associated with simulation methods is presented for 3D micro-/nanofabrication. The results obtained from experimental investigation and characteristics of ion beam induced direct fabrication will be discussed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.427-428
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• 2008

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.1
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• pp.200-205
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• 1995

The 1st and 2nd-order grating structure for long wavelength DFB(Distributed FeedBack) laser diodes are successfully fabricated on InP substrates by using electron beam lithography and reactive ion etch techniques, and also characterized non-destructively by diffraction analysis without removal of photo-resis layer. A new composite layer made by lifted-off Cr layer on thin SiO2 film is developed and used as an etch mask, because PMMA, the e-beamresist, is unsuitable for reactive ion etch of InP. In addition, it is experimentally confiremed that diffraction analysis makes it possible to predict the grating parameters, and the analysis can be used as a non-destructive on-line test to prevent incomplete gratings from being successively processed.

• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.853-856
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• 2005

Inductively coupled plasma reactive ion etching of magnetic tunnel junction (MTJ) stack, which is one of the key elements in magnetic random access memory, was studied. The MTJ stacks were patterned in nanometer size by electron(e)-beam lithography, and TiN thin films were employed as a hard mask. The etch process of TiN hard mask was examined using Ar, $Cl_2/Ar$, and $SF_6/Ar$. The TiN hard mask patterned by e-beam lithography was first etched and then the etching of MTJ stack was performed. The MTJ stacks were etched using Ar, $Cl_2/Ar$, and $BCl_3/Ar$ gases by varying gas concentration and pressure.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2092-2094
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• 2000

As a next generation lithography (NGL) technology for VLSI semiconductor fabrication, electron beam, ion beam, X-ray and extreme ultraviolet(EUV) are considered as possible candidates. Among these methods, EUV lithography(EUVL) is thought to be the most probable because it is easily realized by improving current optical lithography technology. In order to set EUV radiation which can be applied to EUVL, it is essential to generate very high density and high temperature plasma stably. The method using a pulse power laser and a high voltage pulse discharge is commonly used to accomplish such a high density and high temperature plasma. In this paper we review the recent trends of the EUV generation technique by high density and high temperature plasma.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.05a
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• pp.113-115
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• 1994

We considered the ion and photo-induced properties as a function of wavelength by exposing the light over the band gap of a-Ag/a-$Se_{75}$$Ge_{25}$ and the low-energy defocused $Ga^{+}$ ion beam on Ag/a-$Se_{75}$$Ge_{25}$ thin film. This film acts as a negative resist for photo or ion beam lithography. We observed that the absorbance coefficient decreased with increasing the photo-exposing time and exposing the ion beam. The bandgap shifts toward longer wavelength called a "darkening effect" are observed in the films exposed to both photons and ions. We suggest that a primary step in the Ag layer and a secondary step is in a-$Se_{75}$$Ge_{25}$ film layer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.976-979
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• 2002

A focusing grating coupler (FGC) was not fabricated by the 'Continuous Path Control' writing strategy but by an electron-beam lithography system of more general exposure mode, which matches not only the address grid with the grating period but also an integer multiple of the address grid resolution (5 nm), To more simplify the fabrication, we are able to reduce a process step without large decrease of pattern quality by excluding a conducting material or layer such as metal (Al, Cr, Au), which are deposited on top or bottom of an e-beam resist to prevent charge build-up during e-beam exposure. A grating pitch period and an aperture feature size of the FGC designed and fabricated by e-beam lithography and reactive ion etching were ranged over 384.3 nm to 448.2 nm, and $0.5{\times}0.5mm^2$ area, respectively, This fabrication method presented will reduce processing time and improve the grating quality by means of a consideration of the address grid resolpution, grating direction, pitch size and shapes when exposing. Here our investigations concentrate on the design and efficient fabrication results of the FGC for coupling from slab waveguide to a spot in free space.