• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.404-404
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• 2016

태양전지 제작 시 표면에 피라미드 구조를 형성하면 입사되는 광의 흡수를 높여 광 생성 전류의 향상에 기여한다. 일반적인 KOH를 이용한 습식 표면조직화 공정은 평균 10%의 반사율을 보였으며, 유도 결합 플라즈마를 이용한 RIE 공정은 평균 5.4%의 더 낮은 반사율을 보였다. 그러나 RIE 공정을 이용한 표면조직화는 낮은 반사율과 서브 마이크론 크기의 표면 구조를 만들 수 있지만 플라즈마 조사에 의한 표면 손상이 많이 발생하게 된다. 이러한 표면 손상은 태양전지 제작 시 표면에서 높은 재결합 영역으로 작용하게 되어 포화 전류(saturation currents, $J_0$)를 증가시키고 캐리어 수명(carrier lifetime, ${\tau}$)을 낮추는 결함 요소로 작용한다. 이러한 플라즈마에 의한 표면 손상을 제거하기 위해 HF, HNO3, DI-water를 이용하여 DRE(Damage Remove Etching) 공정을 진행하였다. DRE 공정은 HF : DI-water 솔루션과 HNO3 : HF : DI-water 솔루션의 두 가지 공정을 이용하여 공정 시간을 가변하며 진행하였다. 포화전류($J_0$), 캐리어 수명(${\tau}$), 벌크 캐리어 수명(Bulk ${\tau}$)을 비교를 하기위해 KOH, RIE, RIE + DRE 공정을 진행한 세 가지 샘플로 실험을 진행하였다. DRE 공정을 적용할 경우 공정 시간이 지날수록 반사도가 높아지는 경향을 보였지만, 두 번째의 최적화된 솔루션 공정에서 $2.36E-13A/cm^2$, $42{\mu}s$의 $J_0$, Bulk ${\tau}$값과 가장 높은 $26.4{\mu}s$의 ${\tau}$를 얻을 수 있었다. 이러한 결과는 오제 재결합(auger recombination)이 가장 많이 발생하는 지역인 표면과 불균일한 도핑 영역에서 DRE 공정을 통해 나아진 표면 특성과 균일한 도핑 프로파일을 형성하게 되어 재결합 영역과 $J_0$가 감소 된 것으로 판단된다. 높아진 반사도의 경우 $SiN_x$를 이용한 반사방지막을 통해 표면 반사율을 1% 이내로 내릴 수 있어 보완이 가능하였다. 본 연구에서는 RIE 공정 중 플라즈마에 의해 발생하는 표면 손상 제거를 통하여 캐리어 라이프 타임의 향상된 조건을 찾기 위한 연구를 진행하였으며, 기존 RIE 공정에 비해 반사도의 상승은 있지만 플라즈마로 인한 표면 손상을 제거하여 오제 재결합에 의한 발생하는 $J_0$를 낮출 수 있었고 높은 ${\tau}$값인 $26.4{\mu}s$의 결과를 얻어 추후 태양전지 제작에 향상된 효율을 기대할 수 있을 것으로 기대된다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.368-370
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• 2007

AAO(Anodic Aluminum Oxidation) method has been known that it is practically useful for the fabrication of nano-structures and makes it possible to fabricate the highly ordered nano masters on large surface and even on the 2.5 or 3D surface at low cost comparing to the expensive e-beam lithography or the conventional silicon processing. In this study, by using the multi-step anodizing and etching processes, highly ordered nano patterned master with concave shapes was fabricated. By varying the processing parameters, such as initial matter and chemical conditions; electrical and thermal conditions; time scheduling; and so on, the size and the pitch of the nano pattern can be controlled. Consequently, various alumina/aluminum nano structures can be easily available in any size and shape by optimized anodic oxidation in various aqueous acids. The resulting good filled uniform nano molded structure through hot embossing molding process shows the validity of the fabricated nano pattern masters.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1265-1267
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• 1995

In the fiber-photodiode(PD) coupling module using v-groove, the paraxial approximation is no longer valid because the beam enters obliquely the PD substrate with the angle of $20^{\circ}$ after being reflected from the $55^{\circ}$ mirror formed by anisotropically etching of the (100) silicon wafer. In this paper, we study the beam profile incident on the PD active area and fiber-PD coupling efficiency for this case.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.207-208
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• 2002

In the present study, the friction and wear properties of boundary lubricated textured surfaces were investigated. The capability of textured surfaces to feed lubricant into the interface of a sliding contact and to isolate wear partices was studied and related to the properties of the textured surfaces. Well-defined surface textures were produced by lithography and anisotropic etching of silicon wafers. Different widths and distributions of parallel groves were manufactured and subsequently the wafers were PVD coated with thin wear resistant TiN or DLC coatings, retaining the substrate texture. The surfaces were evaluated in reciprocating sliding against a ball bearing steel ball under starved or boundary lubricated conditions.

• 전자공학회논문지D
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• 제35D권9호
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• pp.48-53
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• 1998

실리콘 벌크 마이크로머시닝과 표면 마이크로머시닝기술을 혼합하여 새로운 구조의 정전렌즈를 제작하였다. 표면 마이크로머시닝을 위한 구조층과 희생층으로는 폴리실리콘을 사용하였으며 구조층을 열산화막으로 보호하여 실리콘 습식 식각시 손상되지 않도록 하였다. 이전의 마이크로컬럼에 사용되던 정전렌즈에 비하여 이 구조가 갖는 장점은 1) 양극 접합의 수를 줄일 수 있어 구멍간 정렬, 렌즈의 생산성, 신뢰도, 손상 면에서 우수하고, 2) 마이크로컬럼의 집적화를 통한 arrayed lithography에도 유리하다는 것이다.

• 한국결정성장학회지
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• 제17권4호
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• pp.160-164
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• 2007

Carbon nanofibers were deposited on silicon oxide substrate by thermal chemical vapor deposition method. For the enhancement of the characteristics of carbon nanofibers, the source gases ($C_2H_2,\;H_2$) flows were intentionally manipulated as the cyclic on/off modulation of $C_2H_2$ flow. By the cyclic modulation process during the initial deposition stage, the formation density of carbon nanofibers on the substrate could be much more enhanced. The diameter of as-grown carbon nanofibers was also reduced by the cyclic modulation process. The cause for the variation in the characteristics of carbon nanofibers by the cyclic modulation process was discussed in association with the hydrogen gas etching ability.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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• pp.200-203
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• 2001

Micromolding methods such as micro-injection molding and micro-compression molding are most suitable for mass production of plastic micro-optics with low cost. In this study, plastic micro-optical components, such as refractive microlenses and diffractive optical elements(DOEs) with various grating patterns, were fabricated using micro-compression molding process. The mold inserts were made by ultrapricision mechanical machining and silicon etching. A micro compression molding system was designed and developed. Polymer powders were used as molded materials. Various defects found during molding were analyzed and the process was optimized experimentally by controlling the governing process parameters such as histories of mold temperature and compression pressure. Mim lenses of hemispherical shape with $250{\mu}m$ diameter were fabricated. The blazed and 4 stepped DOEs with $24{\mu}m$ pitch and $5{\mu}m$ depth were also fabricated. Optical and geometrical properties of plastic molded parts were tested by interferometric technique.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.381-385
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• 2003

This paper presents the fabrication possibility of the micro actuator which uses a micro-thermal bubble, generated by a micro-heater under pulse heating. The micro-actuator is consist of three plate. The lower plate includes the channel and chamber are fabricated on high processability silicon wafer by the DRIE(Deep Reactive ion Etching) process. The middle plate includes the chamber and diaphragm, and the upper plate is the micro-heater. The micro-heater designed non-uniform width and results in periodic generation of stable single bubbles in D.I water. The single bubble appears precisely on the narrow part of the micro-heater and control is recorded.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 춘계학술대회 논문집 디스플레이 광소자 분야
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• pp.187-190
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• 2000

We fabricated general photo diode, surface etched photo diode and floating gate MOSFET by CMOS process. In a design stage, we expect that surface etched photo diode will be improved as to photo sensitivity. However, because the surface of silicon was damaged in etching process, the surface etched diode had a high dark current as well as low photo current level. Finally, we examined the current-voltage properties for the floating gate MOSFET on n-well and confirmed that the device can be act as an efficient photo-sensor. The floating gate MOSFET was operated in parasitic bipolar transistor mode.

• 한국결정성장학회지
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• 제21권3호
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• pp.119-123
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• 2011

Carbon nanotilaments (CNFs) could be synthesized on nickel catalyst layer-deposited silicon oxide substrate using $C_2H_2$ and$H_2$ as source gases under thermal chemical vapor deposition system. By the incorporation of $SF_6$ as a cyclic modulation manner, the geometries of carbon coils-related materials, such as nano-sized coil and wave-like nano-sized coil could be observed on the substrate. The characteristics (formation density and morphology) of as-grown CNFs with or without $SF_6$ incorporation were investigated. Diameter size reduction for the individual CNFs-related shape and the enhancement of the formation density of CNFs-related material could be achieved by the incorporation of $SF_6$ as a cyclic modulation manner. The cause for these results was discussed in association with the slightly increased etching ability by $SF_6$ addition and the sulfur role in SF 6 for the geometry change.