• 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.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 하계종합학술대회 논문집(2)
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• pp.359-362
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• 2004

Electron beam on high energy acceleration, which travels deeply and sharply through photoresist, became to be used in e-beam lithography apparatus for nano-patterning in due to its high resolution. An advanced electron beam lithography simulation tool is currently undergoing development for nano-patterning. This paper will demonstrate such simulation efforts with experiments at 200 keV e-beam lithography processes on PMMA, ZEP520 of which photoresist parameters and characteristics will be explained with simulation results. Neureuther parameters was extracted from the contrast curve of the resist

• 대한전자공학회논문지SD
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• 제39권1호
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• pp.18-24
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• 2002

본 논문에서는 서로 다른 dose를 갖는 이중 노광 방법을 사용한 전자빔 묘화 방법을 이용하여 0.2 ㎛의 wide-head T-게이트를 갖는 PHEMT를 제작하였다. 0.2 ㎛의 게이트 길이와 1.3 ㎛의 게이트 머리의 크기를 갖는 wide-head T-게이트를 형성하기 위하여 PMMA/P(MMA-MAA)/PMMA의 3층 레지스트 구조를 사용하였다. 0.2 ㎛의 게이트 길이와 80 ㎛의 단위 게이트 폭 및 4개의 게이트 핑거를 갖는 PHEMT의 DC 특성으로 323 ㎃/㎜의 드레인 전류 밀도 및 232 mS/㎜의 최대 전달 컨덕턴스를 얻었다. 또한 동일한 소자의 RF 특성으로 40 ㎓에서 2.91 ㏈의 S/sub 21/ 이득과 11.42 ㏈의 MAG를 얻었으며, 전 이득 차단 주파수와 최대 공진 주파수는 각각 63 ㎓와 150 ㎓였다.

• 한국진공학회지
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• 제15권6호
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• pp.637-641
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• 2006

본 논문에서는 100 nm 게이트 길이를 갖는 InGaAs/InAlAs/GaAs MHEMT(metamorphic high electron mobility transistors)m의 DC와 RF 특성을 분석 하였다. 이중 노광 방법으로 ZEP520/P(MMA-MAA)/PMMA 3층 구조의 레지스터와 게이트 길이 100 nm인 게이트를 제작하였다. 게이트의 단위 폭이 $70\;{\mu}m$인 2개의 게이트와 길이가 100 nm로 제작된 MHEMT를 DC 및 RF특성을 조사하였다. 최대 드레인 전류 밀도는 465 mA/mm, 상호전달 컨덕턴스는 844 mS/mm이, RF 측정으로부터 전류 이득 차단 주파수는 192 GHz와 최대 진동주파수 310 GHz인 특성을 보였다.

• 한국산학기술학회논문지
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• 제15권4호
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• pp.1838-1843
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• 2014

나노 임프린트 리소그래피는 수십 나노미터에서 수십 마이크론에 이르는 패턴을 간단하고 저비용으로 대면적 기판에 제작할 수 있어 차세대 패터닝 기술로 주목 받고 있다. 특히, 발광소자, 태양전지, 디스플레이 등의 분야에서는 저반사 나노패턴, 광결정 패턴 등 기능성 패턴을 제작하고 이를 적용하는 연구가 활발히 진행 중에 있다. NIL공정을 통해 성공적으로 패턴을 전사시키기 위해서는 적절한 공정조건의 선택이 필요하다. 이에 본 연구에서는 열 나노임프린트를 이용하여 모스아이 패턴을 전사할 때, 충전과정 및 잔류층 형성을 수치 해석하여 폴리머 레지스트의 점탄성 거동을 살펴 보았고, 레지스트 초기 코팅 두께의 변화 및 가압력의 변화가 충전과정 및 잔류층에 미치는 영향을 조사하였다. 해석결과 본 논문에서 고려된 PMMA의 경우, 4MPa 이상의 압력에서 100초 내로 충전공정이 완료되는 것으로 나타났다.

• 한국정밀공학회지
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• 제25권4호
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• pp.134-139
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• 2008

A spirally arrayed nano-pattern is designed as a model pattern for the next generation optical storage media. The pattern consists off types of embossed rectangular dot, which are 50nm, 100nm, 150nm and 200nm in length and 50nm in width. The height of the dot is designed to be 50nm. The pitch of the spiral track of the pattern is 100nm. A ER(Electron resist) master for this pattern is fabricated by e-beam lithography process. The ER is first spin-coated to be 50nm thick on a Si wafer and then the model pattern is written on the coated ER layer by e-beam. After developing this pattern written wafer in the solution, a ER pattern master is fabricated. The most conventional e-beam machine can write patterns in orthogonal way, so we made our own pattern generator which can write the pattern in circular or spiral way. This program generates the patterns to be compatible with the e-beam machine from Raith(Raith 150). To fabricate 50nm pattern master precisely, a series of experiments were done including the design compensation for the pattern size, optimization of the dose, acceleration voltage, aperture size and developing. Through these experiments, we conclude that the higher accelerating voltages and smaller aperture size are better for mastering the nano pattern which is in order of 50nm. With the optimized e-beam lithography process, a spiral arrayed 50nm pattern master adopting PMMA resist was fabricated to have dimensional accuracy over 95% compared to the designed. Using this pattern master, a metal pattern stamp will be fabricated by Ni electro plating for injection molding of the patterned plastic substrate.

• 한국재료학회지
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• 제16권4호
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• pp.225-230
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• 2006

Nanoimprint lithography (NIL) is a novel method of fabricating nanometer scale patterns. It is a simple process with low cost, high throughput and resolution. NIL creates patterns by mechanical deformation of an imprint resist and physical contact process. The imprint resist is typically a monomer or polymer formulation that is cured by heat or UV light during the imprinting process. Stiction between the resist and the stamp is resulted from this physical contact process. Stiction issue is more important in the stamps including narrow pattern size and wide area. Therefore, the antistiction layer coating is very effective to prevent this problem and ensure successful NIL. In this paper, an antistiction layer was deposited and characterized by PECVD (plasma enhanced chemical vapor deposition) method for metal stamps. Deposition rates of an antistiction layer on Si and Ni substrates were in proportion to deposited time and 3.4 nm/min and 2.5 nm/min, respectively. A 50 nm thick antistiction layer showed 90% relative transmittance at 365 nm wavelength. Contact angle result showed good hydrophobicity over 105 degree. $CF_2$ and $CF_3$ peaks were founded in ATR-FTIR analysis. The thicknesses and the contact angle of a 50 nm thick antistiction film were slightly changed during chemical resistance test using acetone and sulfuric acid. To evaluate the deposited antistiction layer, a 50 nm thick film was coated on a stainless steel stamp made by wet etching process. A PMMA substrate was successfully imprinting without pattern degradations by the stainless steel stamp with an antistiction layer. The test result shows that antistiction layer coating is very effective for NIL.

• 대한전자공학회논문지SD
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• 제41권9호
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• pp.19-24
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• 2004

우리는 3층 구조의 레지스터와 이중 노광 방법을 이용하여 유전체 지지대를 사용하지 않은 새로운 방법으로 게이트 길이가 70 nm인 T-게이트를 갖는 InGaAs/InAlAs/GaAs metamorphic HEMT 제작 하였다. 게이트 길이가 70 nm이고 게이트 단위폭이 70 ㎛인 2개의 게이트를 가지고 있는 MHEMT는 최대 포화 전류밀도가 최대 포화 전류밀도가 228.6 mA/mm, 상호전달 컨덕턴스는 645 mS/mm, 전류이득차단주파수가 255 GHz인 특성을 보였다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.71-71
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• 2003

Hot embossing has been widely accepted as an alternative to photolithography in generating patterns on polymeric substrates. The optimization of embossing process should be accomplished based on polymer substrate materials. In this paper, the effect of polymer substrates on nano scale hot embossing process was studied. Silicon molds with nano size patterns were fabricated by e-beam direct writing. Molds were coated with self-assembled monolayer (SAM) of (1, 1, 2.2H -perfluorooctyl)-trichlorosilane to reduce the stiction between mold and substrates. For an embossing, pressure of 55, 75 bur, embossing time of 5 min and temperature of above transition temperature were peformed. Polymethylmethacrylates (PMMA) with different molecular weights of 450,000 and 950,000, MR-I 8010 polymer (Micro Resist Technology) and polyaliphatic imide copolymer were applied for hot embossing process development in nano size. These polymers were spun coated on the Si wafer with the thickness between 150 and 200 nm. The nano size patterns obtained after hot embossing were observed and compared based on the polymer properties by scanning electron microscopy (SEM). The imprinting uniformity dependent on the Pattern density and size was investigated. Four polymers have been evaluated for the nanoimprint By optimizing the process parameters, the four polymers lead to uniform imprint and good pattern profiles. A reduction in the friction for smooth surfaces during demoulding is possible by polymer selection.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.629-629
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• 2013

Graphene is a carbon based material and it has intriguing features, such as phenomenally strong, thin, flexible, transparent and conductive, those make it attractive for a broad range of applications.Unfortunately, graphene is extremely sensitive to contamination. When we fabricate graphene devices, electrical properties of graphene are altered [1], and the charge carrier mobility drops accordingly by orders of magnitude. This significant impact on electron mobility occurs because any surrounding medium could act as a dominant source of extrinsic scattering, which effectively reduces the mean free path of carriers [2,3]. The dominant contaminant is generated through fabrication stage by polymethyl methacrylate (PMMA) [4], or photo resist (PR). Surface contamination by these residues has long been a critical problem in probing graphene's intrinsic properties. If we clearly solve this problem, we can get highly performed graphene devices. Here, we will report on graphene cleaning process by Induced Coupled Plasma (ICP). We demonstrated how much decomposition of residue impact on improving electrical properties of graphene.