• Journal of the Semiconductor & Display Technology
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• v.2 no.1
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• pp.11-14
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• 2003

The high Q(quality factor) suspended spiral inductors were fabricated on the silicon substrate by 3D surface micromachined process. The integration of 2.4GHz VCO has been performed by fabricating suspended spiral inductor of the top of CMOS VCO circuit. The phase noise of VCO integrated MEMS inductor is 93.5 dBc/Hz at 100kHz of offset frequency.

• ETRI Journal
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• v.38 no.5
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• pp.988-995
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• 2016

In this paper, we present a new specific and customized interface tool with parameter identification of Modified Butterworth-Van Dyke models for ladder bulk acoustic wave filters. The aforementioned tool is easy to use and flexible because it allows simulations and reengineering to be conducted in an application. A modular design approach is applied to simplify the extension of the proposed tool for different topologies. The proposed tool was validated using measurements from an aluminum-nitride based ladder BAW filter dedicated to the frequency ranges of the Universal Mobile Telecommunications Service and standards and Wideband Code Division Multiple Access.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.5 s.335
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• pp.1-8
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• 2005

A RC parallel gate model is used to consider gate distributed effect that affects RF MOSFET performance, and extraction formula based on $Y_{11}$-parameters are used to extract model parameters directly from measured S-parameters. Better agreement between measured and modeled S-parameters in the frequency range beyond 10 GHz is achieved by using the RC parallel model than conventional Rg one, demonstrating the accuracy of the RC model and extraction technique. Using these extraction methods, gate voltage dependent curves of RC gate model parameters are newly extracted, and these parameter data will greatly contribute to developing a RF nonlinear gate model.

• Journal of Sensor Science and Technology
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• v.11 no.3
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• pp.163-170
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• 2002

This paper proposes a $10\;{\mu}m$ thick oxide air-bridge structure which can be used as a substrate for RF circuits. The structure was fabricated by anodic reaction, complex oxidation and micromachining technology using TMAH etching. High quality films were obtained by combining low temperature thermal oxidation ($500^{\circ}C$, 1 hr at $H_2O/O_2$) and rapid thermal oxidation (RTO) process ($1050^{\circ}C$, 2 min). This structure is mechanically stable because of thick oxide layer up to $10\;{\mu}m$ and is expected to solve the problem of high dielectric loss of silicon substrate in RF region. The properties of the transmission line formed on the oxidized porous silicon (OPS) air-bridge were investigated and compared with those of the transmission line formed on the OPS layers. The insertion loss of coplanar waveguide (CPW) on OPS air-bridge was (about 2dB) lower than that of CPW on OPS layers. Also, the return loss of CPW on OPS air-bridge was less than about -20 dB at measured frequency region for 2.2 mm. Therefore, this technology is very promising for extending the use of CMOS circuitry to higher RF frequencies.

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.385-390
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• 2004

In this paper, we designed a 4-bit optical true time-delay(TTD) for phased array antennas(PAAs), which is composed of a wavelength-fixed optical source, 2 ${\times}$ 2 optical MEMS switches, and fiber-optic delay lines. A 4-bit TTD with a unit time delay difference of 6 ps for 10-GHz PAAs has been implemented. Measurement results on time delay show an error of -0.4 ps at maximum, corresponding to a radiation angle error of less than 1.63$^{\circ}$. Thus, the TTD implemented in this research performs in excellent agreement with theory. Each TTD line, composed of MEMS switches and fiber-optic delay lines, connected to the corresponding antenna element has insertion loss in between 1.36 ㏈ and 2.40 ㏈ depending upon the setup of the switches. On the other hand, the insertion loss difference between TTD lines was 0.32 ㏈ at maximum for a fixed radiation angle. The TTD structure proposed in this paper might be more reliable and economical than those previously proposed using tunable wavelength sources if proper power equalization either with gain control of RF amplifiers or variable attenuators is achieved.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2003.12a
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• pp.82-85
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• 2003

MEMS(Micro Electro Mechanical Systems) 응용 분야에 있어서 RF나 Optic등에 응용되는 금속 구조물이나 배선을 위한 도금, 두꺼운 구조물의 식각등을 위해서 수십 um두께의 감광막이 필요하다. 특히 이러한 감광막은 도금을 위한 전단계에서 몰드 형성에 이용되는데 그 이유는 제작이 용이할 뿐만 아니라 다양한 두께 형성이 가능하고 금속과의 선택적 제거가 쉬운 장점이 있다. 감광막 몰드가 갖추어야 할 조건으로는 수직에 가까운 측면 기울기, 두께, 도금액에 대찬 저항성을 들 수 있으며 그 중에서 측면 기울기 개선에 관한 연구가 많이 진행되고 있다. 본 논문에서는 감광막의 형상에 영향을 주는 요인을 찾아내고 수식모델링을 통해 측면 기울기를 예측하고자 한다.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1414-1415
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• 2006

Air-gap type film bulk acoustic wave resonator device using ZnO for piezoelectric layer and sacrifice layer, deposited by RF magnetron sputter with various conditions, fabricated in this study. Also, membrane$(SiO_2)$ and top and bottom electrode(both Al) of piezoelectric layer deposited by RF magnetron sputter. Using micro electro mechanical systems(MEMS) technique, sacrifice layer removed and then air-gap formed. The results of each process checked by XRD, AFM, SEM to obtain good quality device.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.631-634
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• 2009

Recent advances in wireless communication, electronics, MEMS device, sensor and battery technology have made it possible to manufacture low-cost, low-power, multi-function tiny sensor nodes. A large number of tiny sensor nodes form sensor network through wireless communication. Sensor networks represent a significant improvement over traditional sensors, research on Zigbee wireless image transmission has been a topic in industrial and scientific fields. In this paper, we design a Zigbee wireless image sensor node and multimedia monitoring server system. It consists of embedded processor, memory, CMOS image sensor, image acquisition and processing unit, Zigbee RF module, power supply unit and remote monitoring server system. In the future, we will further improve our Zigbee wireless image sensor node and monitoring server system. Besides, energy-efficient Zigbee wireless image transmission protocol and interworking with mobile network will be our work focus.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1708-1711
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• 2007

This paper presents high cycle fatigue properties of an Al-3%Ti thin film, used in a RF (radio-frequency) MEMS switch for a mobile phone and also describes new test method for obtaining static and dynamic characteristics of thin film and reliability evaluation method on MEMS device with thin film developed by authors. Durability should be ensured for such devices under cycling load. Therefore, with the proposed specimen and test procedure, tensile and fatigue tests were performed to obtain mechanical and fatigue properties. The specimen was made with dimensions of $1000{\mu}m$ long, $1.0{\mu}m$ thickness, and 3 kinds of width, 50, 100 and $150{\mu}m$. High cycle fatigue tests for each width were also performed, from which the fatigue strength coefficient and the fatigue strength exponent were found to be 193MPa and .0.02319 for $50{\mu}m$, 181MPa and -0.02001 for $100{\mu}m$, and 164MPa and -0.01322 for $150{\mu}m$, respectively. We found that the narrower specimen is, the longer fatigue life of Al-3%Ti is and the wider specimen is, the more susceptible to stress level fatigue life of Al-3%Ti was.

• Journal of Sensor Science and Technology
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• v.15 no.6
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• pp.386-390
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• 2006

This paper describes the ohmic contact formation of polycrystalline 3C-SiC films deposited on thermally grown Si wafers. In this work, a TiW (titanium tungsten) film as a contact material was deposited by RF magnetron sputter and annealed with the vacuum process. The specific contact resistance (${\rho}_{c}$) of the TiW contact was measured by using the C-TLM (circular transmission line method). The contact phase and interfacial reaction between TiW and 3C-SiC at high-temperature as also analyzed by XRD (X-ray diffraction) and SEM (scanning electron microscope). All of the samples didn't show cracks of the TiW film and any interfacial reaction after annealing. Especially, when the sample was annealed at $800^{\circ}$ for 30 min., the lowest contact resistivity of $2.90{\times}10{\Omega}cm^{2}$ was obtained due to the improved interfacial adhesion. Therefore, the good ohmic contact of polycrystalline 3C-SiC films using the TiW film is very suitable for high-temperature MEMS applications.