• 마이크로전자및패키징학회지
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• 제16권4호
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• pp.23-28
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• 2009

Si 기판의 캐비티 형성이 불필요한 웨이퍼-레벨 MEMS capping 공정을 연구하였다. 4인치 Si 웨이퍼에 Ni 캡을 전기도금으로 형성하고 Ni 캡 rim을 Si 하부기판의 Cu rim에 에폭시 본딩한 후, SnBi debonding 층을 이용하여 상부기판을 Ni 캡 구조물로부터 debonding 하였다. 진공증착법으로 형성한 SnBi debonding 층은 Bi와 Sn 사이의 심한 증기압 차이에 의해 Bi/Sn의 2층 구조로 이루어져 있었다. SnBi 증착 층을 $150^{\circ}C$에서 15초 이상 유지시에는 Sn과 Bi 사이의 상호 확산에 의해 eutectic 상과 Bi-rich $\beta$상으로 이루어진 SnBi 합금이 형성되었다. $150^{\circ}C$에서 유지시 SnBi의 용융에 의해 Si 기판과 Ni 캡 구조물 사이의 debonding이 가능하였다.

• 마이크로전자및패키징학회지
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• 제15권4호
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• pp.31-39
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• 2008

캐비티 형성이 불필요한 MEMS 캡 본딩을 위해 전기도금법을 이용하여 Cu/Sn rim 구조를 형성하였으며, $25{\sim}400{\mu}m$ 범위의 rim 폭에 따른 본딩특성을 분석하였다. Cu/Sn rim의 폭이 증가함에 따라 rim 패키지 내부의 유효 실장면적비가 감소하는 반면에 파괴하중비가 증가하며, Cu/Sn rim 폭이 150 ${\mu}m$일 때 유효 실장면적비와 파괴하중비를 최적화할 수 있을 것으로 예측되었다. 폭 25 ${\mu}m$ 및 폭 50 ${\mu}m$인 Cu/Sn rim 접합부에서는 모든 계면에서 본딩이 이루어진 반면에, 100 ${\mu}m$ 이상의 폭을 갖는 rim 접합부에서는 Sn 도금표면의 거칠기에 의해 본딩이 이루어지지 않은 기공 부위가 관찰되었다.

• 센서학회지
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• 제29권5호
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• pp.354-359
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• 2020

The high vacuum hermetic sealing technique ensures excellent performance of MEMS resonators. For the high vacuum hermetic sealing, the customization of anodic bonding equipment was conducted for the glass/Si/glass triple-stack anodic bonding process. Figure 1 presents the schematic of the MEMS resonator with triple-stack high-vacuum anodic bonding. The anodic bonding process for vacuum sealing was performed with the chamber pressure lower than 5 × 10^-6 mbar, the piston pressure of 5 kN, and the applied voltage was 1 kV. The process temperature during anodic bonding was 400 ℃. To maintain the vacuum condition of the glass cavity, a getter material, such as a titanium thin film, was deposited. The getter materials was active at the 400 ℃ during the anodic bonding process. To read out the electrical signals from the Si resonator, a vertical feed-through was applied by using through glass via (TGV) which is formed by sandblasting technique of cap glass wafer. The aluminum electrodes was conformally deposited on the via-hole structure of cap glass. The TGV process provides reliable electrical interconnection between Si resonator and aluminum electrodes on the cap glass without leakage or electrical disconnection through the TGV. The fabricated MEMS resonator with proposed vacuum packaging using three-layer anodic bonding process has resonance frequency and quality factor of about 16 kHz and more than 40,000, respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1702-1703
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• 2011

MEMS 소자의 Wafer level Package 관련하여 Deep cavity를 가진 Cap Wafer와 Polymer bonding 중 cavity 단차로 인한 Polymer Patterning 및 접합 불량의 어려움을 극복할 수 있는 새로운 공정 flow를 제안하였다. Cavity를 형성할 때 사용하는 Si deep etching Mask인 기존의 Photoresist를 접합용 감광성 Polymer로 대체하고, cavity 형성 후, 별도의 추가 공정 없이 이 Polymer를 이용해 Wafer bonding을 진행하였다. 이를 통해 cavity 단차에 따른 문제를 해결함과 동시에 공정이 단순하고 제작 비용이 저렴하며, 신뢰성 있는 Wafer level Package를 구현하였다.

• 전기학회논문지
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• 제56권12호
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• pp.2217-2220
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• 2007

In this paper, we propose a new wafer level package (WLP) for the RF MEMS applications. The Film Bulk Acoustic Resonator (FBAR) are fabricated and hermetically packaged in a new wafer level packaging process. With the use of Au-Sn eutectic bonding method, we bonded glass cap and FBAR device wafer which has groove-shaped via formed in the backside. The device wafer includes a electrical bonding pad and groove-shaped via for connecting to the external bonding pad on the device wafer backside and a peripheral pad placed around the perimeter of the device for bonding the glass wafer and device wafer. The glass cap prevents the device from being exposed and ensures excellent mechanical and environmental protection. The frequency characteristics show that the change of bandwidth and frequency shift before and after bonding is less than 0.5 MHz. Two packaged devices, Tx and Rx filters, are attached to a printed circuit board, wire bonded, and encapsulated in plastic to form the duplexer. We have designed and built a low-cost, high performance, duplexer based on the FBARs and presented the results of performance and reliability test.

• 센서학회지
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• 제20권1호
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• pp.58-63
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• 2011

A low loss radio frequency(RF) micro electro mechanical systems(MEMS) switch driven by a low actuation voltage was designed for the development of a new RF MEMS switch. The RF MEMS switch should be encapsulated. The glass cap and fabricated RF MEMS switch were assembled by the Au/Sn eutectic bonding principle for wafer-level packaging. The through-vias on the glass substrate was made by the glass dry etching and Au electroplating process. The packaged RF MEMS switch had an actuation voltage of 12.5 V, an insertion loss below 0.25 dB, a return loss above 16.6 dB, and an isolation value above 41.4 dB at 6 GHz.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.379-380
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• 2008

This paper presents a wafer-level package using a Dry Film Resist(DFR) for RF MEMS devices. Vertical interconnection is made through the hole formed on the glass cap. Bonding using the DFR has not only less effects on the surface roughness but also low process temperature. We used DFR as adhesive polymer and made the vertical interconnection through Au electroplating. Therefore, we developed a wafer-level package that is able to be used in RF MEMS devices and vertical interconnection.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2001년도 추계 기술심포지움
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• pp.129-133
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• 2001

In this paper, hermetic sealing was studied fur wafer level packaging of the MEMS devices. With the flip-chip bonding method, this B-stage epoxy sealing will be profit to MEMS device sealing and further more RF-MEMS device sealing. B-stage epoxy can be cured 2-step and hermetic sealing can be obtained. After defining $500{\mu}{\textrm}{m}$-width seal-lines on the glass cap substrate by screen printing, it was pre-baked at $90^{\circ}C$ for about 30 minutes. It was then aligned and bonded with device substrate followed by post-baked at $175^{\circ}C$ for about 30 minutes. By using this 2-step baking characteristic, the width and the height of the seal-line were maintained during the sealing process. The height of the seal-line was controlled within $\pm0.6${\mu}{\textrm}{m}$ and the strength was measured to about 20MPa by pull test. The leak rate of the epoxy was about $10^7$ cc/sec from the leak test.

• 마이크로전자및패키징학회지
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• 제8권4호
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• pp.11-15
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• 2001

본 연구에서는 RF-MEMS소자의 웨이퍼레벨 패키징에 적용하기 위한 밀봉 실장 방법에 대하여 연구를 하였다. 비전도성 B-stage에폭시를 사용하여 밀봉 실장하는 방법은 플립칩 접합 방법과 함께 MEMS 소자 패키징에 많은 장점을 줄 것이다. 특히 소자의 동작뿐만 아니라 기생성분의 양을 줄여야 하는 RF-MEMS 소자에는 더욱더 많은 장전을 보여준다. 비전도성 B-stage 에폭시는 2차 경화가 가능한 것으로 우수한 밀봉 실장 특성을 보였다. 패키징시 상부기관으로 사용되는 유리기판 위에 500 $\mu\textrm{m}$의 밀봉선을 스크린 프린팅 방식으로 패턴닝을 한 후에 $90^{\circ}C$와 $170^{\circ}C$에서 열처리를 하였다. 2차 경화 후 패턴닝된 모양이 패키징 공정이 끝날 때까지 계속 유지가 되었다. 패턴닝 후 에폭시 놀이가 4인치 웨이퍼에서 $\pm$0.6$\mu\textrm{m}$의 균일성을 얻었으며, 접합강토는 20 MPa을 얻었다. 또한 밀봉실장 특성을 나타내는 leak rate는 $10^{-7}$ cc/sec를 얻었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.858-861
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• 2001

As the application fields of micro parts that are micro endo-scope, PDA, and tele-communication had been extended, there are required the micro machine tools and MEMS in order to machining for those parts. In order to machining of the micro parts, the micro machining center is very effective. The micro machining center had some advantages that are lower cost, higher accuracy, and lower required powers than existing machine tools for machining of micro parts. In this study, in order to analyze the machining characteristics and its application possibility of the developing micro machining center with 60,000rpm rotations, 0.1$\mu\textrm{m}$ resolutions, and 80 50 50mm sliding unit, the machining experiment had been executed. In this experimental machining, 0.1~ 0.5mm endmills are used to machining the micro cap and tele-communication's parts. In the future, experimental results will be adapted to the micro-machining center.