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KSCN이 함유된 용액에서 레이저유도 에칭된 구리 마이크로 구조물의 특성
오광환(Kwang H. Oh),조석인(S. I. Cho),정성호(S. H. Jeong) 한국레이저가공학회 2007 한국레이저가공학회 학술대회 논문집 Vol.2007 No.-
A fabrication technique of copper microgrooves with triangular cross-sectional profile using the laser-assisted etching is introduced. To simplify the complex setup of a conventional objective lens-based laser micromachining, a novel optical fiber-based laser-assisted etching system is proposed to manufacture metallic microgrooves. In the new laser micromachining system, the optical fiber plays a key role as a light waveguide and machining tool. The mixture of H₂SO₄ and H₂O₂ included 0.1% KSCN is chosen as the optimal etchant for manufacturing copper microgroove without background etching in the non-irradiated area. The fabrication of copper microgroove with 100~300㎛ in depth and 100~150㎛ in width is achieved with the proposed machining technique. The grooves fabricated at the optimal process condition have smooth surface and clear edge. The angle of triangular groove is measured to be in the range of 30~50 degree and the aspect ratio of grooves is about 1~2. The overall etching characteristics are investigated with respect to process parameters in this paper.
레이저유도 에칭을 이용한 고세장비 마이크로채널 가공 및 응용
오광환(Kwang H. Oh),이민규(M. K. Lee),김수근(S. G. Kim),임현택(H. T. Lim),정성호(S. H. Jeong) 한국정밀공학회 2006 한국정밀공학회 학술발표대회 논문집 Vol.2006 No.5월
High-aspect-ratio(max. 12.5) microchannels with excellent surface quality and good shape uniformity have been realized utilizing laser-induced etching technique. Etch width and depth variations depend largely upon process variables such as laser power and etchant concentration. Etchant concentration in association with viscosity also influence on the cross-sectional profile of the channels. The optimum process conditions for the fabrication of high-aspect-ratio microchannels applicable to micro thermal devices are demonstrated.
레이저 에칭 가공이 마이크로 홈의 벽면 조도에 미치는 영향
오광환(Kwang H. Oh),정성호(S. H. Jeong) 한국레이저가공학회 2008 한국레이저가공학회 학술대회 논문집 Vol.2008 No.-
A novel laser etching technique utilizing an optical fiber as the machining tool is introduced. Here, depending upon whether a pulsed or a continuous wave (CW) laser is employed as the irradiation source, it was found that the etch depth and surface morphology of the grooves varied significantly. It was then demonstrated that deep microgrooves with smooth sidewalls can be obtained using a hybrid pulse-and-CW scanning process. Subsequent thermal and chemical analyses of the microgrooves revealed that sidewall roughness is mainly attributed to surface melting.
오광환(Oh, Kwang H.),정혜정(Jeong, Hyejeong),지은옥(Chi, Eun-Ok),김지찬(Kim, Ji Chan),부성재(Boo, Seongjae) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.06
Aluminum-induced crystallization (AIC) of amorphous silicon (a-Si) is studied with the structure of a glass/Al/SiO₂/a-Si, in which the SiO₂ layer has micron-sized laser holes in the stack. An oxide layer between aluminum and a-Si thin films plays a significant role in the metal-induced crystallization (MIC) process determining the properties such as grain size and preferential orientation. In our case, the crystallization of a-Si is carried out only through the key hole because the SiO₂ layer is substantially thick enough to prevent a-Si from contacting aluminum. The crystal growth is successfully realized toward the only vertical direction, resulting a crystalline silicon grain with a size of 3{sim}4{mu}m under the hole. Lateral growth seems to be not occurred. For the AIC experiment, the glass/Al/SiO₂/a-Si stacks were prepared where an Al layer was deposited on glass substrate by DC sputter, SiO₂ and a-Si films by PECVD method, respectively. Prior to the a-Si deposition, a 30{times}30 micron-sized hole array with a diameter of 1{sim}2{mu}m was fabricated utilizing the femtosecond laser pulses to induce the AIC process through the key holes and the prepared workpieces were annealed in a thermal chamber for 2 hours. After heat treatment, the surface morphology, grain size, and crystal orientation of the polycrystalline silicon (pc-Si) film were evaluated by scanning electron microscope, transmission electron microscope, and energy dispersive spectrometer. In conclusion, we observed that the vertical crystal growth was occurred in the case of the crystallization of a-Si with aluminum by the MIC process in a small area. The pc-Si grain grew under the key hole up to a size of 3{sim}4{mu}m with the workpiece.
간격제어가 가능한 레이저유도 에칭기술을 이용한 금속채널의 제조
임현덕(H. D. Im),오광환(Kwang H. Oh),정성호(S. H. Jeong) 한국레이저가공학회 2007 한국레이저가공학회 학술대회 논문집 Vol.2007 No.-
A new laser-assisted etching technique with gap control between a fiber tip and a workpiece is introduced. The gap control system consisting of a laser diode and a position sensitive detector controls the gap to make uniform shape and size microchannels. By using the etching technique, microchannels with triangular cross-section are fabricated, and the shape and size of microchannels are analyzed to evaluate the gap control system. The gap control system correctly worked according to the analysis, and hence it is expected that the proposed etching technique can be applied to the fabrication of micro devices based on microchannels.
정혜정(Jeong, Hyejeong),오광환(Oh, Kwang H.),이종호(Lee, Jong Ho),부성재(Boo, Seongjae) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.06
We studied the fabrication of polycrystalline silicon (pc-Si) films as seed layers for application of pc-Si thin film solar cells, in which amorphous silicon (a-Si) films in a structure of glass/Al/Al₂O₃/a-Si are crystallized by the aluminum-induced layer exchange (ALILE) process. The properties of pc-Si films formed by the ALILE process are strongly determined by the oxide layer as well as the various process parameters like annealing temperature, time, etc. In this study, the effects of the oxide film thickness on the crystallization of a-Si in the ALILE process, where the thickness of Al₂O₃ layer was varied from 4 to 50 nm. For preparation of the experimental film structure, aluminum (~300 nm thickness) and a-Si (~300 nm thickness) layers were deposited using DC sputtering and PECVD method, respectively, and Al₂O₃ layer with the various thicknesses by RF sputtering. The crystallization of a-Si was then carried out by the thermal annealing process using a furnace with the in-situ microscope. The characteristics of the produced pc-Si films were analyzed by optical microscope (OM), scanning electron microscope (SEM), Raman spectrometer, and X-ray diffractometer (XRD). As results, the crystallinity was exponentially decayed with the increase of Al₂O₃ thickness and the grain size showed the similar tendency. The maximum pc-Si grain size fabricated by ALILE process was about 45{mu}m at the Al₂O₃ layer thickness of 4 nm. The preferential crystal orientation was <111> and more dominant with the thinner Al₂O₃ layer. In summary, we obtained a pc-Si film not only with {sim}45{mu}m grain size but also with the crystallinity of about 75% at 4 nm Al₂O₃ layer thickness by ALILE process with the structure of a glass/Al/Al₂O₃/a-Si.