19 이영철(1038~1043).hwp

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1 (JKONI 16(6): , Dec. 2012) 재구성 RF 회로응용을위한다층유전체박막을이용한고 - 가변형커패시터 이영철 *, 이백주 **, 고경현 ** Young-Chul Lee *, Baek-Ju Lee **, and Kyung-Hyun Ko ** 요약 RF BZN/BST/BZN -. - BST - BZN 47% tanδ - - BZN/BST/BZN. quartz 327 x 642 μm2 15 V 800 MHz Q-factor %. Abstract In this work, a high tunable capacitor using a multi-layer dielectric of BZN/BST/BZN is designed and characterized for reconfigurable RF applications. By utilizing a high tunable BST ferroelectric and a low-loss BZN paraelectric thin film, a multi-layer dielectric of BZN/BST/BZN obtained a tunability of 47 % and tanδ of The fabricated tunable capacitor on a quartz wafer using this multi-layer dielectric achieved a Q-factor of 10 and tunability of 60 % at 800 MHz and 15 V. Its size is 327 x 642 μm2. Key words : ferroelectric, paraelectric, tunable capacitor, multi-layer dielectric I. 서론,,., WLAN (wireless local area network), WPAN (wireless ersonal area network) global roaming,. RF (reconfigurable RF) [1]. RF RF - RF SoC (system-on-chip) SoP (system-on-package) * (Department of Electronics, Mokpo National Maritime University) ** (Department of Materials Science and Engineering, Ajou University) 1 (First Author) : (Young-Chul Lee, Tel : , leeyc@mmu.ac.kr) : ( ) : ( : ) :

2 RF - ;,, 1039 RF, RF reconfigurability,,. RF, micro electro mechanical system (MEMS),, (ferroelectric). MEMS [2]. PIN varactor (tunability) [3]. [4-5] (capacitance).,, (thin film) RF CMOS (complementary metal-oxide semiconductor) RF SOC MHz GHz. phase shifter [6], matching network [7], (reconfigurable) [5]. (εr) Ba1-xSrxTiO3 (barium strontium titanate, BST) 1 GHz. Bi2O3-ZnO-Nb2O5 (bismuth zinc niobate, BZN) (tanδ) 5 x 10-4 [8]., BST, BST, BZN BZN/BST/BZN. Ⅱ. 다층박막을이용한커패시터설계및제작 다층박막의제작및유전체특성 BST, BZN, BZN/BST/BZN., 4 inch Si wafer Si/SiO2(3000Å)/TiO2(200Å)/Pt(111) (1500Å) wafer. RF magnetron sputtering system, power BST BZN gun 150W Ar flow rate 20 SCCM O2 flow rate O2/Ar 10% O2, sputter target 13cm. BST BZN 10mTorr sputtering gun power 150W, 500. (post annealing) 600oC 3. BZN/BST/BZN 500oC 600oC 1. 2 sputter gun 3 BZN/BST/BZN., metalinsulator-metal (MIM) 250μm Ag dot shadow mask thermal evaporation 5μm. Agilent 4294A precision impedance analyzer 0.1~10 MHz frequency. [9]. (Tunability, T) (1).

3 MHz DC 30V. ε δ 표 1. BST 와 BZN 가변유전체및다층유전체의특성. Table 1. Characteristics of BST and BZN tunable dielectrics and multi-layer one (1) BZN/BST/BZN 1. si wafer quartz wafer, Ti(100A )/Pt(1,000A ) photo-lithography dry-etching pattern. BZN, BST, BZN 700, 1,500, 700A, photo-lithography,. Au BZN Cr 100A Au 1,000A. Lift-off. 2. CPW, 327 x 642μm2 20 x 10μm2. BST BZN,, 1. 4,000A BST BZN, 1,000Å/2,000/ 1,000Å BZN/BST/BZN BST 78%, BZN 29%. 2-2 다층박막을이용한가변커패시터설계및제작 Cr/Au 100 / 1,000 Å BZN 700 Å BST 1,500 Å BZN 700 Å Ti/Pt 100 / 1,000 Å Quartz ( 500µm ) 그림 2. BZN/BST/BZN 다층유전체박막을이용하여제작한가변커패시터칩. Fig. 2. The fabricated tunable capacitor using a multi-layer dielectric thin film(bzn/bst/bzn). Ⅲ. 가변커패시터의측정결과 (effective capacitance, Ceff) (S11). Probing station vector network analyzer (VNA) (HP8510C) S11 total impedance (Z11), (2) Ceff. 그림 1. 다층유전체박막을이용한가변커패시터의수직구조. Fig. 1. The vertical structure of the tunable capacitor using a multi-layer dielectric thin film. π (2)

4 RF - ;,, 1041 그림 3. 측정된가변커패시터의 S11 특성. Fig. 3. The measured S11 characteristic of the tunable capacitor. 그림 5. 제작된커패시터의인가된 DC 전압에따른가변성 (T) 특성. Fig. 5. The tunability (T) characteristics with different DC bias voltages of the fabricated tunable capacitor. 3 S11 Smith chart, 0 ~ 3GHz 0. Smith chart (self resonance frequency, SRF) 3GHz, 1GHz. 그림 4. 제작된커패시터의인가된 DC 전압에따른유효커패시턴스특성. Fig. 4. The effective capacitance characteristics with different DC bias voltages of the fabricated tunable capacitor. 4 Ceff. ( ),. 5 Ceff. 1 GHz 10, 15, 20 V 45, 58, 64 %., RF 40~50%, 1.3 GHz.. Q-factor.. 6 Q-factor. 0.5GHz Q-factor 20~50 1 GHz., 1,000A ohmic, 1 μm. RFIC Q-factor 10, 10V 500MHz 1GHz Q-factor V, 800 MHz Q-factor %. 800 MHz.

5 그림 6. 제작된커패시터의인가된 DC 전압에따른 Q-factor 특성. Fig. 6. The Q-factor characteristics with different DC bias voltages of the fabricated tunable capacitor. Ⅳ. 결론 RF -. - BST - BZN 47% tanδ - - BZN/BST/BZN, quartz. 327 x 642 μm 2 15 V 800 MHz Q-factor 10 60%. 감사의글 2008 (KRF-2008-D00393). Reference [1] Georg Boeck, Dariusz Pienkowski, Radu Circa, Marius Otte, Benjamin Heyne, Piotr Rykaczewski, Reimund Wittmann, and Ralf Kakerow, "RF Front-End Technology for Reconfigurable Mobile Systems," IEEE Microwave and Optoelectronics Conference 2003, Vol. 2, pp , [2] Guoan Wang, et al., "A High Performance Tunable RF MEMS Switch Using Barium Strontium Titanate (BST) Dielectrics for Reconfigurable Antenna and Phase Arrays" IEEE Antenna and Wireless Propagation Letters, vol.4, pp , [3] Giuseppe Ruvio, et al., "Wideband Reconfogurable Rolled Planar Monopole Antenna" IEEE Trans. on Antenna and Propagation, vol.55, No.6, pp , [4 ] Hai Jiang, et al., "Frequency Tunable Microstrip Patch Antenna Using Ferroelectric Thin Film Varactor", Proceedings of the IEEE 2009 National Aerospace & Electronics Conference (NAECON), pp , [5] Mohsen Sazegar, et al., "Reconfigurable Unit Cell for Reflectarray Antenna Based on Barium-Strontium-Titanate Thick-Film Ceramic", Proceedings of the 39th European Microwave Conference, pp , [6] Judy, D.C. et al. "Reflection-type continuously-tunable phase shifter using PZT thin-film capacitors" Electronics Letters, vol.45, pp , [7] L.-Y. Vicki Chen, et al., "Analog Tunable Matching Network Using Integrated Thin-Film BST Capacitors" IEEE MTT-S International Microwave Symposium Digest, pp , [8] Jiwei Lu, Susanne Stemmer, Low-loss, tunable bismuth zinc niobate films deposited by rf magnetron sputtering Applied Physics Letters, vol. 83, pp , [9] Ma, Zhengxiang, Becker, A. J., Polakos, P., Huggins, H., Pastalan, J., Wu, Hui, Watts, K., Wong, Y. H., Mankiewich, P., RF measurement technique for characterizing thin dielectric films, IEEE Transactions on Electron Devices, vol. 45, issue 8, pp , 1998.

6 RF - ;,, 1043 이영철 ( 李永鐵 ) : ( ) : : ~ : ~ : ~ : ~ : PIER & JEMWA :, System-on-Package (SoP), 이백주 ( 李白朱 ) : : : high-k and capacitor 고경현 ( 高景現 ) : ( ) : KASIT : MIT ~ : MIT Postdoc ~ :