• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1408-1411
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• 2009

This paper describes organic acid-based wet chemical etching behaviors of amorphous Ga-doped zinc oxide (GZO) thin film sputter-deposited at low temperature (room temperature). Wet etch parameters such as etching time, temperature, and etchant concentration are investigated for formic and citric acid etchants, and their effects on the etch rate, etch residue and the feature of edge line are compared.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.497-500
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• 1999

This paper reports on the fabrication and characteristics of recessed gate GaN MESFETs fabricated using a photoelectrochemical wet etching method. The unique etching process utilizes photo-resistive mask and KOH based etchant. GaN MESFETs with successfully recessed gate structure was characterized in terms of dc and RF performance. The fabricated GaN MESFET exhibits a current saturation at $V_{DS}$ = 4 V and a pinch-off at $V_{GS}$ =-3V The peak drain current of the device is about 230mA/mm at 300 K and the value is remained almost same for 500K operation. The $f_{T}$ and $f_{max}$ from the device are 6.357Hz and 10.25 GHz, respectively.y.y.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.9
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• pp.705-710
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• 1998

Intrinsic gettering is usually to improve wafer quality, which is an important factor for reliable ULSI devices. In order to generate oxygen precipitation in lightly and heavily boron doped silicon wafers with or without high $^75 As^+$ ion implantation, the 2-step annealing method was adopted. After annealing, the were cleaved and etched with th Wright etchant. The morphology of cross section on samples was inspected by FESEM(field emission scanning electron microscopy). The morphology of unimplanted samples was rater rough than that of the implanted. Oxygen precipitation density observed by an optical microscope in lightly boron doped samples was about 3$\times10^6/cm^3$. However, in heavily boron doped samples, the density of oxygen precipitation was largest at $600^{\circ}C$ in 1st annealing, and decreased abruptly until $800^{\circ}C$, But it increased slightly at $1000^{\circ}C$ and was independent with the implantation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.677-680
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• 1999

Rapid developing automation technology enhances the need of sensors. Among many materials, silicon has the advantages of electrical and mechanical property, Single-crystalline silicon has different piezoresistivity on 야fferent directions and a current leakage at elevated temperature, but poly-crystalline silicon has the possibility of controling resistivity using dopping ions, and operation at high temperature, which is grown on insulating layers. Each wafer has slightly different thicknesses that make difficult to obtain the precisely same thickness of a diaphragm. This paper deals with the fabrication process to make poly-crystalline silicon based pressure sensors which includes diaphragm thickness and wet-etching techniques for each layer. Diaphragms of the same thickness can be fabricated consisting of deposited layers by silicon bulk etching. HF etches silicon nitride, HNO$_3$+HF does poly -crystalline silicon at room temperature very fast. Whereas ethylenediamice based etchant is used to etch silicon at 11$0^{\circ}C$ slowly.

• Proceedings of the KIEE Conference
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• 1998.07g
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• pp.2550-2552
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• 1998

The stiction phenomena poses a design constraint in surface micromachining by reducing the releasable size of the microstructure. This problem occurs during the fabrication process of surface micromachined microstructures during the wet etch of sacrificial layers. For the prevention of the sticking problem, the microsctructure is released by sublimation after the substitution of the sacrificial layer etchant with a sublimation material heated above its melting temperature. In the sublimation drying method, the sublimation materials such as p-dichlorobenzene, t-butyl alcohol, and cyclohexane are used. In this paper, a method for designing a sublimation drying system is developed, and its performance is experimentally evaluated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.557-560
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• 2000

Combination of SDB(Si-wafer Direct Bonding) and electrochemical etch-stop in TMAH anisotropic etchant can be used to create a variety of MEMS(Micro Electro Mechanical System). Especially, fabrication of SDB SOI structures using electrochemical etch-stop is accurate method to fabrication of 3D(three-dimensional) microstructures. This paper describes on the fabrication of SDB SOI structures with sealed cavity for MEMS applications and thickness control of active layer on the SDB SOI structure by electrochemical etch-stop. The flatness of fabricated SDB SOI structure is very uniform and can be improved by addition of TMAH to IPA and pyrazine.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.248-250
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• 1996

VTR 자기헤드의 핵심소재로 사용되는 ferrite는 VTR 의 주기능인 영상의 기록 및 재생역할에 가장 중요한 소재이다. 이러한 종류의 head는 지금까지 mask wet chemical etching과 mechanical Process 에 의해 제작 되어왔다. 그러나 기록용량의 중가로 자기장치의 recording density를 높일것이 요구됨에 따라 자기헤드의 gap width를 줄일 필요가 있게 되었다. 본 연구는 mask와 photoresist를 사용하지 않고 ferrite를 직접 미세가공 하는 laser-induced wet etching을 이용하여 자기헤드의 기록용량을 높이고자 하였다. $Ar^+$ laser ( 파장 514 nm )를 빔 확장기와 렌즈를 사용 하여 직경 $1.8{\mu}m$ 로 집속하고, $100{\sim}500\;mW$의 출력 변화를 주어 실험을 하였다. 인산 수용액 (45, 65, 85 %)을 etchant로 사용하여 $5{\sim}30{\mu}m/sec$의 주사속도로 etching 하여, 미세선폭과 high aspect ratio를 갖는 groove를 얻을 수 있었다.

• Applied Microscopy
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• v.44 no.4
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• pp.133-137
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• 2014

We suggest a facile transmission electron microscopy (TEM) specimen preparation method for the direct (polymer-free) transfer of layer-area graphene from Cu substrates to a TEM grid. The standard (polymer-based) method and direct transfer method were by TEM, high-resolution TEM, and energy dispersive X-ray spectroscopy (EDS). The folds and crystalline particles were formed in a graphene specimen by the standard method, while the graphene specimen by the direct method with a new etchant solution exhibited clean and full coverage of the graphene surface, which reduced several wet chemical steps and accompanying mechanical stresses and avoided formation of the oxide metal.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.548-549
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• 2007

과거 PCB 제조의 주된 화제는 다양한 산업분야의 발전을 위해 한정된 시간 안에 좀 더 많은 PCB를 양산하는 기술 개발에 집중되어 있었지만, 현재는 비정상적인 공정 상태를 파악함으로써 제조 공정 환경에서의 오류를 줄여 전체 수률을 높이는 방법에 시선을 돌리고 있다. PCB 에칭의 경우 에칭 용액의 상태를 실시간으로 모니터링 하는 것이 중요하다. 본 논문에서는 기존 애칭용액의 상태를 판단할 때 사용되는 ORP 센서 대신, RGB 센서를 이용하여 실시간으로 용액의 상태를 모니터링 할 수 있는 시스템을 개발 하였다. 개발된 시스템을 이용하여 기존 ORP 시스템과의 비교 분석을 및 RGB 센서률 이용한 모니터링 방법이 ORP 센서를 이용한 방법 보다 좀 더 쉽고 정확하게 에칭 액의 상태를 모니터링할 수 있다는 것을 확인 하였다.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1183-1185
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• 1993

The plasma polymerized thin film of MMA+Sty was prepared using a capacitively coupled gas-flow-type reactor. This thin films were also delincated by the electron-beam apparatus with an acceleration voltage 30KV, and the pattern in the resist was developed with the gas-flow-type reactor using an argon as an etchant. The effect of discharge power on groth rate and etching rate of the thin film were studied. The molacular structure of the resist was investigated by ESCA and FT-IR.