• 대한기계학회논문집A
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• 제30권10호
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• pp.1314-1319
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• 2006

This paper describes the novel fabrication method of the high-aspect-ratio nano structure which is impossible by conventional method using a shadow mask and a Deep X-ray Lithography (DXRL). The shadow mask with $1{\mu}m-sized$ apertures is fabricated on the silicon membrane using a conventional UV-lithography. The size of aperture is reduced to 200nm by accumulated low stress silicon nitride using a LPCVD (low pressure chemical vapor deposition) process. The X-ray mask is fabricated by depositing absorber layer (Au, $3{\mu}m$) on the back side of nano shadow mask. The thickness of an absorber layer must deposit dozens micrometers to obtain contrast more than 100 for a conventional DXRL process. The thickness of $3{\mu}m-absorber$ layer can get sufficient contrast using a central beam stop method, blocking high energy X-rays. The nano circle and nano line, 200nm in diameter in width, respectively, were demonstrated 700nm in height with a negative photoresist of SU-8.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2001년도 춘계학술발표강연 및 논문개요집
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• pp.86-86
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• 2001

• 한국진공학회지
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• 제8권2호
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• pp.102-110
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• 1999

The LIGA X-ray exposure step was modelled into three inequalities, by assuming that the X-ray energy attenuated within a resist is deposited only in the localized range of the resist. From these inequalities, equations for the minimum and maximum exposure times required for a good quality microstructure were obtained. Also, an equation for the thickness of an X-ray mask absorber was obtained from the exposure requirement of threshold dose deposition. The calculation method of the synchrotron radiation power from a synchrotron radiation source was introduced and applied to an X-ray exposure step. A power from a synchrotron radiation source was introduced and applied to an X-ray exposure step/ A power function of photon energy, approximating the attenuation length of the representative LIGA resist, PMMA, and the mean photon energy of the XZ-rays incident upon an X-ray mask absorber were applied to the above mentioned equations. Consequently, the tendencies of the minimum and maximum exposure and with respect to mean photon energy and thick ness of PMMA was obtained. Additionally, the tendencies of the necessary thickness of PMMA and photon energy of the X-ray mask absorber with respect to thickness of PMMA and photon energy of the X-rays incident upon an X-ray mask absorber were examined. The minimum exposure time increases monotonically with increasing mean photon energy for the same total power density and is not a function of the thickness of resist. The minimum exposure time increases with increasing mean photon energy for the same total power density in the case of the general LIGA process, where the thickness of PMMA is thinner than the attenuation length of PMMA. Additionally, the minimum exposure time increases monotonically with increasing thickness of PMMA. The maximally exposable thickness of resist is proportional to the attenuation length of the resist at the mean photon energy with its proportional constant of ln $(Dd_m/D_{dv})$. The necessary thickness of a gold X-ray mask absorber due to absorption edges of gold, increases smoothly with increasing PMMA thickness ratio, and is independent of the total power density itself. The simplicity of the derived equations has made clearly understandable the X-ray exposure phenomenon and the correlation among the exposure times, the attenuation coefficient and the thickness of an X-ray mask absorber, the attenuation coefficient and the thickness of the resist, and the synchrotron radiation power density.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 G
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• pp.3276-3278
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• 1999

LIGA 기술을 제품의 대량생산에 적용하기 위해서는 한번에 넓은 면적을 노광할 수 있는 X-ray 마스크가 요구된다. 기존에 널리 사용되고 있는 SiN 멤브레인 마스크는 내구성이 좋지 않고 면적을 크게하기 어렵다. 따라서 본 연구에서는 이러한 단점을 보완하기 위해 상용 graphite sheet를 이용하여 X-ray 마스크를 제작하였다. 제작된 graphite 마스크와 SiN 마스크를 이용하여 동일한 조건에서 X-ray 노광 실험을 하였고 마스크의 외형변화를 관찰하였다. 그 결과 SiN 마스크는 에너지 2.3GeV, 평균 전류 110mA에서 약 18시간 만에 파괴되었으나 graphite mask는 60시간 경과 후에도 육안상의 변화는 관찰되지 않았다. 또한 graphite 마스크를 이용하여 제작된 미세구조물의 치수측정결과 오차가 $1{\mu}m$ 미만인 정밀한 구조물 제작이 가능함을 확인하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.370-373
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• 2009

X-ray lithography was employed to fabricate ITO-less high resolution sustain electrodes for plasma display panel (PDP). A polyimide film based X-ray mask and Xray sensitive Ag electrode paste were fabricated to check their effect on the patterning of Ag electrodes with less than 30 ${\mu}m$ in width. The X-ray lithographic method was found to be useful for the high resolution sustain electrode patterns due to the high penetration power and low scattering property of X-ray source.

• 대한기계학회논문집A
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• 제26권10호
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• pp.2187-2193
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• 2002

We present a novel method for 3D microfabrication with LIGA process that utilizes a deep X-ray mask in which a micro-actuator is integrated. The integrated micro-actuator oscillates the X-ray absorber, which is formed on the shuttle mass of the micro-actuator, during X-ray exposures to modify the absorbed dose profile in X-ray resist, typically PMMA. 3D PMMA microstructures according to the modulated dose contour are revealed after GG development. An X-ray mask with integrated comb drive actuator is fabricated using deep reactive ion etching, absorber electroplating, and bulk micromachining with silicon-on-insulator (SOI) wafer. 1mm $\times$ 1 mm, 20 $\mu$m thick silicon shuttle mass as a mask blank is supported by four 1 mm long suspension beams and is driven by the comb electrodes. A 10 $\mu$m thick, 50 $\mu$m line and spaced gold absorber pattern is electroplated on the shuttle mass before the release step. The fundamental frequency and amplitude are around 3.6 kHz and 20 $\mu$m, respectively, for a do bias of 100 V and an ac bias of 20 $V_{p-p}$ (peak-peak). Fabricated PMMA microstructure shows 15.4 $\mu$m deep, S-shaped cross section in the case of 1.6 kJ $cm^{-3}$ surface dose and GG development at 35$^{\circ}C$ for 40 minutes.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2000년도 추계 기술심포지움 논문집
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• pp.31-34
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• 2000

• 소성∙가공
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• 제13권3호
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• pp.290-295
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• 2004

Mircolens and microlens V-groove are realized using a novel fabrication technology based on the exposure of a resist, usually PMMA, to deep X-rays and subsequent thermal treatment and inclined deep X-ray lithography, respectively. The fabrication technology is very simple and produces microlenses and microlens V-groove with good surface roughness of several nm. The molecular weight and glass transition temperature of PMMA is reduced when it is irradiated with deep X-rays. The microlenses were produced through the effects of volume change, surface tension, and reflow during thermal treatment of irradiated PMMA. Microlenses were produced with diameters ranging from 30 to $1500\mu\textrm{m}$. The surface X-ray mask is also fabricated to realize microlens arrays on PMMA sheet with a large area. The size of the micro V-groove is fabricated in the range of 12~$60\mu\textrm{m}$.

• 전자공학회지
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• 제22권2호
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• pp.37-50
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• 1995

This paper reviews NTT Laboratories' research and development of x-ray lithography during the last ten years since the application of synchrotron orbital radiation(SOR). First, the historical background of x-ray lithograhpy research, NTT's research programs on synchrotron x-ray lithography(SOR lithography), and the current status of NTT's SOR lithography system are overviewed. Then, the key elements of SOR lithography system are reviewed, including the electron storage ring, the x-ray stepper, and the x-ray mask. Finally the appilcation of SOR lithography technology to device fabrication is reported.

• 한국재료학회지
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• 제8권2호
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• pp.147-153
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• 1998

$WN_x$ 는 리소그라피 마스크의 흡수체나 VLSI 기술에서 금속연결의 확산방지재로써 주목을 받고 있다. RF마르네트론 스퍼터링법으로 여러 증착변수에서 제조한 $WN_x$ 막을 고찰하였다. $SiN_x$ 멤브레인 위에 증착된 박막의 결정구조는 질소아르곤 가스유량비(0-30%), 가스압력(10-43mTorr), RF출력(0150W)및 기판과 타겟사이의 거리 6cm에서 증착한 $WN_x$ 박막은 비정질이였으며 다른 조건에서는 표면이 거친 다결정질이었다. 비정질 박막은 rms가 $3.1\AA$으로 아주 매끈하여 X-선 마스크용 흡착제로써 적합할 것으로 기대된다.