• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2005년도 추계 학술대회
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• pp.124-128
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• 2005

To produce a highly sensitive uncooled microbolometer, the development of a high-performance thermometric material is essential. In this work, amorphous vanadium-tungsten oxide was developed as a thermometric material at a low temperature of $300^{\circ}C$, and the microbolometer, coupled with the material, was designed and fabricated using surface micromachining technology. The vanadium-tungsten oxide showed good properties for application to the microbolometer, Such as a high temperature coefficient of resistance of over -4.0 $\%$/K and good compatibility with the surface micromachining and integrated circuit fabrication process due to its low fabrication temperature. As a result, the uncooled microbolometer could be fabricated with high detectivity over $1.0\;{\times}\;10^9\;cmHz^{1/2}/W$ at a bias current of $7.5\;{\mu}A$ and a chopper frequency of 10-20 Hz

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 추계학술대회 논문집
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• pp.247-248
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• 2009

• 반도체디스플레이기술학회지
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• 제5권3호
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• pp.5-10
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• 2006

This paper investigates cutting qualities after laser dicing and predicts the problems that can be generated by laser dicing. And through 3 point bending test, die strength is measured and the die strength after laser dicing is compared with the die strength after mechanical sawing. Laser dicing is chiefly considered as an alternative to overcome the defects of mechanical sawing such as chipping on the surface and crack on the back side. Laser micromachining is based on the thermal ablation and evaporation mechanism. As a result of laser dicing experiments, debris on the surface of wafer is observed. To eliminate the debris and protect the surface, an experiment is done using a water soluble coating material and ultrasonic. The consequence is that most of debris is removed. But there are some residues around the cutting line. Unlike mechanical sawing, chipping on the surface and crack on the back side is not observed. The cross section of cutting line by laser dicing is rough as compared with that by mechanical sawing. But micro crack can not be seen. Micro crack reduces die strength. To measure this, 3 point bending test is done. The die strength after laser dicing decreases to a half of the die strength after mechanical sawing. This means that die cracking during package assembly can occur.

• 한국레이저가공학회지
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• 제12권1호
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• pp.7-13
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• 2009

Engineering ceramics as sapphire are widely used in industry owing to their superior mechanical and corrosion properties. However, micromachining of sapphire is a considerable challenge due to its transparency. Recently, direct ablation of sapphire has been demonstrated with a visible laser pulse at sufficiently high laser intensity. In this work, the theoretical model for pulsed laser ablation of sapphire is suggested and numerical analysis is carried out using the model. Sapphire ablation begins with plasma generation by the laser interaction with surface defects, impurities and contaminations in the initial stage of machining. Subsequent absorption of the visible laser beam can be explained by three mechanisms: metalization of sapphire surface due to the EUV radiation from the hot plasma, increments of surface roughness and temperature-dependent absorption coefficient. Comparison of the computation results with experimental observation indicates that the proposed model of sapphire is reasonable.

• 한국정밀공학회지
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• 제29권10호
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• pp.1089-1095
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• 2012

Laser beam machining (LBM) using nanosecond pulsed laser is widely known to be rapid and non-wear process for micromachining. However, the quality itself cannot meet the precision standard due to the recast layer and heat affected zone. In this paper, a fabrication method for machining micro features in stainless steel using a hybrid process of LBM using nanosecond pulsed laser and electrochemical etching (ECE) is reported. ECE uses non-contacting method for precise surface machining and selectively removes the recast layer and heat affected zone produced by laser beam in an effective way. Compared to the single LBM process, the hybrid process of LBM and ECE enhanced the quality of the micro features.

• 한국레이저가공학회지
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• 제16권2호
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• pp.1-6
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• 2013

Picosecond lasers are a very effective tool for micromachining metals, especially when high accuracy, high surface roughness and no heat affected zone are required. However, low productivity has been a limit to broadening the spectrum of their industrial applications. Recently it was reported that in the micromachining of copper with a 1064nm picosecond laser, there exist the optimal pulse energy and repetition rate to achieve the maximum volume ablation rate. In this paper, we used a 515nm picosecond laser, which is more efficient for micromachining copper in terms of laser energy absorption, to obtain its optimal pulse energy and repetition rate. Theoretical analysis based on the experimental data on copper ablation showed that using a 515nm picosecond laser instead of a 1064nm picosecond laser is more favorable in that the calculated threshold fluence is 75% lower and optical penetration depth is 50% deeper.

• 대한전자공학회논문지SD
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• 제44권12호
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• pp.7-11
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• 2007

본 논문에서는 MMIC 응용을 위한 dielectric-supported air-gapped microstrip line (DAML) 구조를 이용하여 dual-mode stepped impedance 링 공진기를 설계 제작하였다. 링 공진기는 표면 마이크로머시닝 기술을 이용하여 만들어졌다. DAML ring resonator는 다층구조로써 공기중에 위치한 신호선과 MMIC 응용에 적합하도록 CPW가 한 평면에 구성되 있으며 DAML-CPW 트랜지션이 자유로운게 특징이다. DAML 링 공진기는 $10{\mu}m$ 높이로 GaAs 기판 으로부터 띄어져 있다. 대역통과 여파기는 dual-mode 공진을 하며 stepped impedance 이용한 구조이다. 측정결과로 중심주파수 97 GHz에선 감쇠특성은 15 dB, 삽입손실은 2.65 dB를 보였으며, 상대 대역폭은 12 %를 나타냈다. 이같은 구조의 대역통과 여파기는 MMIC 와의 직접화에 유리하다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.157-158
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• 2012

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1991-1993
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• 1996

This paper describes a standardized micromachinung project (SMP) performed at Seoul National University (SNU). The SNU SMP uses a 3-mask, 2-polysilicon surface micromaching process. The entire process is performed at SNU Inter-University Semiconductor Research Institute(ISRC). In this first SNU SMP attemp, 16 $1cm^2$ cells containing different designs were fabricated.

• 대한기계학회논문집B
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• 제37권12호
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• pp.1159-1165
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• 2013

파우더 블라스팅은 미세 유리가공법으로서 가공속도가 빠르고 저비용의 장점이 있지만 유리를 취성파괴 시키기 때문에 표면거칠기가 좋지않다. 블라스팅된 표면에 저압의 워터젯을 분사하여 표면에서의 연마 슬러리의 흐름을 통해 표면거칠기를 저감할 수 있다. 본 연구에서는 소다라임 유리에 블라스팅으로 마이크로 채널을 가공한 후 워터젯을 연속 적용하고, 마이크로 채널의 표면거칠기 및 단면 형상의 변화의 과정을 관찰하였다. 워터젯의 적용결과, 초기단계에서는 블라스팅에 의한 미세 요철이 제거되었고, 이후 표면하부의 크랙이 제거되어 평균 표면거칠기 50 nm 근방의 매끈한 표면을 얻을 수 있었다. 표면거칠기 저감에 동반하여 채널단면의 확장 과정도 함께 관측하였다. 마지막으로 제안한 방법에 의해 미세유체칩의 가공 결과를 제시하였다.