비전도성 에폭시를 사용한 RF-MEMS 소자의 웨이퍼 레벨 밀봉 실장 특성

박윤권,이덕중,박흥우,송인상,김정우,송기무,이윤희,김철주,주병권 한국마이크로전자및패키징학회 2001 마이크로전자 및 패키징학회지 Vol.8 No.4

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. In this paper, hermetic sealing technology was studied for wafer level packaging of the RF-MEMS devices. With the flip-chip bonding method. this non-conductive B-stage epoxy sealing will be profit to the MEMS device sealing. It will be particularly profit to the RF-MEMS device sealing. B-stage epoxy can be cured by 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 could be maintained during the sealing process. The height of the seal-line was controlled within $\pm$0.6 $\mu\textrm{m}$ in the 4 inches wafer and the bonding strength was measured to about 20MPa by pull test. The leak rate, that is sealing characteristic of the B-stage epoxy, was about $10^{-7}$ cc/sec from the leak test.

In-line RF-MEMS series switches for reconfigurable antenna applications

Jung, Chang Won,Lee, Byungje,De Flaviis, Franco Wiley Subscription Services, Inc., A Wiley Company 2007 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS Vol.49 No.12

<P>The air bridged RF-MEMS capacitive series switches in single pole single throw transmission lines for reconfigurable antenna applications are presented. The RF characteristics of capacitive series switches are analyzed, measured, and compared with microstripline and coplanar-waveguide, which are generally used for transmission lines of MEMS reconfigurable circuits. RF-MEMS series switches are fabricated in both transmission lines on a glass substrate (ϵ<SUB>r</SUB> = 7.4 and tan δ = 0.001). The reconfigurable beam steering spiral antenna (f<SUB>o</SUB> = 11 GHz), which is monolithic integrated with RF-MEMS capacitive series switches on the same glass substrate, is also presented as an example of the use of in-line capacitive series switches. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 3130–3134, 2007; Published online in Wiley Inter-Science (www.interscience.wiley.com). DOI 10.1002/mop.22971</P>

HEMS 기술을 이용한 180° 하이브리드 결합기가 집적된 단일 평형 혼합기의 설계 및 제작에 관한 연구

김성찬,임병옥,백태종,고백석,안단,김순구,신동훈,이진구,Kim Sung-Chan,Lim Byeong-Ok,Baek Tae-Jong,Ko Baek-Seok,An Dan,Kim Soon-Koo,Shin Dong-Hoon,Rhee Jin-Koo 한국전자파학회 2005 한국전자파학회논문지 Vol.16 No.7

본 논문에서는 표면 MEMS 기술을 이용하여 제작된 $180^{\circ}$ 하이브리드 결합기가 집적된 60 GHz 대역의 단일평형 혼합기를 설계$\cdot$제작하였다. 혼합기에 사용된 $180^{\circ}$ 하이브리드 결합기는 substrate에 의한 dielectric loss를 최소화하기 위하여 polyimide dielectric을 지지대로 사용하여 신호선이 공기 중에 떠 있는 형태의 마이크로스트립 라인을 이용하여 설계하였으며, 이때 지지대의 높이는 $10{\mu}m$이고 면적은 $20{\mu}m{\times}20{\mu}m$을 사용하였다. 제작된 혼합기 의 측정 결과, LO 주파수가 58 GHz에서 LO power가 7.2 dBm 57 GHz에서 RF power가 -15 dBm 일 때, 15.5 dB의 변환 손실과 -40 dB의 RF-LO isolation 특성을 얻었다. 본 논문에서 제안된 혼합기는 RF MEMS 수동 소자를 MMIC와 집적화 함으로써 칩 성능의 감소 없이 크기를 줄일 수 있다는 장점을 가지고 있다. In this paper, we have developed a new type of single balanced mixer with the RF MEMS $180^{\circ}$ hybrid coupler using surface micromachining technology. The $180^{\circ}$ hybrid coupler in this mixer is composed of the dielectric-supported air gapped microstriplines(DAMLs) which have signal line with $10{\mu}m$ height to reduce substrate dielectric loss and dielectric posts with size of $20{\mu}m{\times}20{\mu}m$ to elevate the signal line on air with stability At LO power of 7.2 dBm, the conversion loss was 15.5 dB f3r RF frequency or 57 GHz and RF power of -15 dBm. Also, we obtained the good RF to LO isolation of -40 dB at LO frequency of 58 GHz and LO power of 7.2 dBm. The main advantage of this type of mixer is that we are able to reduce the size of the chips due to integrating the MEMS passive components.

Low Actuation Voltage Capacitive Shunt RF-MEMS Switch Using a Corrugated Bridge with HRS MEMS Package

Yo-Tak Song,Hai-Young Lee,Masayoshi Esashi 한국전자파학회JEES 2006 Journal of Electromagnetic Engineering and Science Vol.6 No.2

This paper presents the theory, design, fabrication and characterization of the novel low actuation voltage capacitive shunt RF-MEMS switch using a corrugated membrane with HRS MEMS packaging. Analytical analyses and experimental results have been carried out to derive algebraic expressions for the mechanical actuation mechanics of corrugated membrane for a low residual stress. It is shown that the residual stress of both types of corrugated and flat membranes can be modeled with the help of a mechanics theory. The residual stress in corrugated membranes is calculated using a geometrical model and is confirmed by finite element method(FEM) analysis and experimental results. The corrugated electrostatic actuated bridge is suspended over a concave structure of CPW, with sputtered nickel(Ni) as the structural material for the bridge and gold for CPW line, fabricated on high-resistivity silicon(HRS) substrate. The corrugated switch on concave structure requires lower actuation voltage than the flat switch on planar structure in various thickness bridges. The residual stress is very low by corrugating both ends of the bridge on concave structure. The residual stress of the bridge material and structure is critical to lower the actuation voltage. The Self-alignment HRS MEMS package of the RF-MEMS switch with a 15 Ωㆍ㎝ lightly-doped Si chip carrier also shows no parasitic leakage resonances and is verified as an effective packaging solution for the low cost and high performance coplanar MMICs.

수직형 Feed-through 갖는 RF-MEMS 소자의 웨이퍼 레벨 패키징

박윤권,이덕중,박흥우,김훈,이윤희,김철주,주병권,Park, Yun-Kwon,Lee, Duck-Jung,Park, Heung-Woo,kim, Hoon,Lee, Yun-Hi,Kim, Chul-Ju,Ju, Byeong-Kwon 한국전기전자재료학회 2002 전기전자재료학회논문지 Vol.15 No.10

Wafer level packaging is gain mote momentum as a low cost, high performance solution for RF-MEMS devices. In this work, the flip-chip method was used for the wafer level packaging of RF-MEMS devices on the quartz substrate with low losses. For analyzing the EM (electromagnetic) characteristic of proposed packaging structure, we got the 3D structure simulation using FEM (finite element method). The electric field distribution of CPW and hole feed-through at 3 GHz were concentrated on the hole and the CPW. The reflection loss of the package was totally below 23 dB and the insertion loss that presents the signal transmission characteristic is above 0.06 dB. The 4-inch Pyrex glass was used as a package substrate and it was punched with air-blast with 250${\mu}{\textrm}{m}$ diameter holes. We made the vortical feed-throughs to reduce the electric path length and parasitic parameters. The vias were filled with plating gold. The package substrate was bonded with the silicon substrate with the B-stage epoxy. The loss of the overall package structure was tested with a network analyzer and was within 0.05 dB. This structure can be used for wafer level packaging of not only the RF-MEMS devices but also the MEMS devices.

Analysis on Selection of Beam Material for Novel Step Structured RF-MEMS Switch used for Satellite Communication Applications

K. Girija Sravani,Koushik Guha,K. Srinivasa Rao 한국전기전자재료학회 2018 Transactions on Electrical and Electronic Material Vol.19 No.6

This paper mainly reports a proper selection of beam material for the step structured based RF MEMS switch. Generally,the performance of the device purely depends upon beam material used for the RF switch. There is a wide range of materialsavailable for the beam layer which may change the performance of RF switch with their distinct material properties. Thoughvarious material selection methods are implemented earlier, among those methodologies Ashby’s material approach requiresminimum execution steps for the beam selection based on various geometrical and performance indices. There are mainlythree key performance indices like actuation voltage, S-parameters and residual stress by heat, are used to obtain the desiredperformance. The material selection in this work says that SU-8, PTFE followed by aluminum and gold are the more suitablematerials for beam material selection for Step structured RF-MEMS switch. Due to fabrication complexity, SU-8 andPTFE are not considered for the beam layer. After the investigation, the above given two material (i.e.) Gold and Aluminumare preferable for the beam, owing to its high cost gold is not much preferable material for the beam. Therefore, Aluminumis good for the beam layer.

Ultra Thin 실리콘 웨이퍼를 이용한 RF-MEMS 소자의 웨이퍼 레벨 패키징

김용국,박윤권,김재경,주병권 한국전기전자재료학회 2003 전기전자재료학회논문지 Vol.16 No.12

In this paper, we report a novel RF-MEMS packaging technology with lightweight, small size, and short electric path length. To achieve this goal, we used the ultra thin silicon substrate as a packaging substrate. The via holes lot vortical feed-through were fabricated on the thin silicon wafer by wet chemical processing. Then, via holes were filled and micro-bumps were fabricated by electroplating. The packaged RF device has a reflection loss under 22 〔㏈〕 and a insertion loss of -0.04∼-0.08 〔㏈〕. These measurements show that we could package the RF device without loss and interference by using the vertical feed-through. Specially, with the ultra thin silicon wafer we can realize of a device package that has low-cost, lightweight and small size. Also, we can extend a 3-D packaging structure by stacking assembled thin packages.

Analysis on Selection of Bridge Material for High Power RF-MEMS Shunt Capacitive Switches

Mahesh Angira,Deepankar Deshmukh 한국전기전자재료학회 2020 Transactions on Electrical and Electronic Material Vol.21 No.4

This paper focuses on the material selection for high power based shunt capacitive RF-MEMS switches. Multi Attribute Decision Making (MADM) based material selection techniques such as TOPSIS and VIKOR have been used for this purpose. The materials are selected in such a way that RF-MEMS capacitive switch should have high pull-in voltage, low insertion loss, high thermal conductivity, high melting point and low thermal coeffi cient of expansion. For this purpose, the material indices are as follows: high value of Young’s modulus, high electrical conductivity, high melting point, high thermal conductivity and low thermal coeffi cient. From both the methods, W and Ir are at rank 1 and rank 2 respectively. Thus, W is the best material for high power based capacitive RF-MEMS switches.

Investigation on Switching Structure Material Selection for RF-MEMS Shunt Capacitive Switches Using Ashby, TOPSIS and VIKOR

Deepankar Deshmukh,Mahesh Angira 한국전기전자재료학회 2019 Transactions on Electrical and Electronic Material Vol.20 No.3

This paper utilizes three material selection methodologies to select the most promising material for switching structure of RF-MEMS shunt capacitive switches. The material should be selected such that RF-MEMS capacitive switches should have low pull-in voltage, low RF loss, high thermal conductivity and maximum displacement of the beam. For this purpose, the concerned material indices are as follows: low value of Young’s modulus, low electrical resistivity, high thermal conductivity and high fracture strength. Following Ashby, TOPSIS and VIKOR method were used to select the best material. The results obtained from these methods show good correlation. The end results suggest that gold and copper are the most suitable materials for RF-MEMS switches.

Investigation on Switching Structure Material Selection for RF-MEMS Shunt Capacitive Switches Using Ashby, TOPSIS and VIKOR

Deepankar Deshmukh,Mahesh Angira 한국전기전자재료학회 2019 Transactions on Electrical and Electronic Material Vol.20 No.2

This paper utilizes three material selection methodologies to select the most promising material for switching structure of RF-MEMS shunt capacitive switches. The material should be selected such that RF-MEMS capacitive switches should have low pull-in voltage, low RF loss, high thermal conductivity and maximum displacement of the beam. For this purpose, the concerned material indices are as follows: low value of Young’s modulus, low electrical resistivity, high thermal conductivity and high fracture strength. Following Ashby, TOPSIS and VIKOR method were used to select the best material. The results obtained from these methods show good correlation. The end results suggest that gold and copper are the most suitable materials for RF-MEMS switches.