• 한국세라믹학회지
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• 제43권1호
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• pp.42-47
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• 2006

In this paper, we prepared high-quality ZnO thin films for application of FBAR (Film Bulk Acoustic Resonator) by using pulse DC magnetron sputtering. To prevent the formation of low dielectric layers between metal and piezoelectric layer, Ru film of 30 nm thickness was used as a buffer layer. In addition we investigated the influence of annealing condition with various temperatures. As the annealing temperature increased, the crystalline orientation with the preference of (002) c-axis and resistance properties improved. The single resonator which was fabricated at $500^{\circ}C$ exhibited the resonance frequency and the return loss 0.99 GHz and 15 dB, respectively. This work demonstrates potential feasibility for the use of thin film Ru buffer layers and the optimization of annealing condition.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 C
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• pp.509-510
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• 2000

Piezoelectric ZnO thin films were deposited on slide glass by Facing Targets Sputtering(FTS). The Facing Targets Sputtering system can deposit thin film in plasma-free situation and change the deposition condition in wide range. The characteristics of zinc oxide thin films on power, working pressure, and substrate temperature were investigated by XRD (x-ray diffractometer), alpha-step (Tencor) and SEM (Scanning Electron Microscopy) analyses. In the results, we suggest that FTS system is very suitable to preparing high quality ZnO thin films with good c-axis orientation.

• 한국전기전자재료학회논문지
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• 제18권2호
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• pp.164-168
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• 2005

Piezoelectric ZnO thin films were for the first time formed on SiO$_2$/Si(100) substrate using 2-step deposition, atomic layer deposition(ALD) and RF magnetron sputtering deposition, for film bulk acoustic resonator(FBAR) applications. The ZnO buffer layer by ALD was deposited using alternating diethyl zinc(DEZn)/$H_2O$ exposures and ultrahigh purity argon gas for purging. The ZnO films by 2-step deposition revealed stronger c-axis-preferred orientation and smoother surface than those by the conventional RF sputtering method. The solidly mounted resonator(SMR)-typed FBAR fabricated by using 2-step deposition method revealed higher quality factor of 580 and lower return loss of -17.35dB. Therefore the 2-step deposition method in this study could be applied to the FBAR device fabrication.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2007년도 추계 종합학술대회 논문집
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• pp.804-806
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• 2007

ZnO박막을 c-축 방향으로 실리콘(Si 100)기판 위에 rf 마그네트론 스퍼터링 법으로 증착 하였고, 증착변수가 박막의 결정학적, 전기적 특성에 미치는 영향을 연구하였다. 기판온도 $200^{\circ}C$, rf전력이 150W, 산소:아르곤 가스의 비율이 50%:50%, 그리고 증착압력이 10mTorr의 조건에서 증착된 박막이 강한 c-축 성장과 우수한 결정성을 나타내었다. 증착변수의 변화에 의한 ZnO 박막의 전기비저항은 크게 영향을 받고 있었는데, 산소비율이 증가할수록, 기판온도가 감소할수록, 비저항이 증가하였다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제5권1호
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• pp.17-23
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• 2005

This paper describes the simulation of a micromachined dome-shaped-diaphragm acoustic transducer built on a $1.5{\mu}m$ thick silicon nitride diaphragm ($2,000{\mu}m$ in radius, with a circular clamped boundary on a silicon substrate) with electrodes and piezoelectric ZnO film in a silicon substrate. Finite element analysis with ANSYS 5.6 has been performed to analyze the static and dynamic behaviors of the transducer under both pressure and voltage loadings.

• 한국재료학회지
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• 제4권7호
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• pp.783-791
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• 1994

rf 마그네트론 스퍼터링법을 이용하여 7059 유리기판 위에 ZnO압전박막을 증착하고, 공정변수인 rf 인가전력, 반응기 압력, $O_{2}$/Ar의 조성비등이 증착되는 박막의 결정성 및 전기적 특성에 미치는 영향을 고찰하였다. 증착된 ZnO박막은 문헌에 보고된 증착속도보다 높은 값(200-1000$\AA$/min)을 가졌으며, XRD(002)피크의 rocking curve 표준편차가 SAW 필터로의 응용이 가능한 $6^{\circ}$미만의 값을 가졌다. $O_{2}$Ar 유입비가 25%이상의 경우에는 매우 높은 저항치를 가짐을 알 수 있었다. ZnO박막의 두께와 파장의 비, $\frac{h}{\lambda}$=0.25인 조건에서 필터를 제조하였다. 측정한 주파수 응답특성과 이론치에 의해 계산한 주파수응답특성은 비교적 잘 일치함을 알 수 있었다. 이때 중심주파수는 39.08MHz였으며, 상속도는 \ulcorner 2501m/sec, 삽입손실은 약 29dB였다.

• 한국전기전자재료학회논문지
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• 제27권5호
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• pp.297-302
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• 2014

$La_{0.5}Sr_{0.5}CoO_3$ (LSCO) electrode thin films with a resistivity of ~ 1,600 ${\mu}{\Omega}cm$ were grown on c-$Al_2O_3$ (0001) substrate. $ZnSnO_3$ (ZTO) thin films with different thicknesses were directly grown on LSCO/c-$Al_2O_3$ (0001) substrates at a substrate temperature that ranged from 550 to $750^{\circ}C$ using Pulsed Laser Deposition (PLD). The secondary phase $Zn_2SnO_4$ occurred during the growth of ZTO films and it became more significant with further increasing substrate temperature. Polarization-electric-field (P-E) hysteresis characteristics, with a remnant polarization and coercive field of 0.05 ${\mu}C/cm^2$ and 48 kV/cm, respectively, were obtained in the ZTO film grown at $700^{\circ}C$ in 200 mTorr.

• 센서학회지
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• 제17권6호
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• pp.418-424
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• 2008

The PZT based piezoelectric thick films prepared by screen printing method have been mainly used as a functional material for MEMS applications due to their compatibility of MEMS process. However the screen printed thick films generally reveal poor electrical and mechanical properties because of their porous microstructure. To improve microstructure we mixed attrition milled powder with ball milled powder of 0.01Pb$(Mg_{1/2}W_{1/2})O_3$-0.41Pb$(Ni_{1/3}Nb_{2/3})O_3$-$0.35PbTiO_3$-$0.23PbZrO_3$+0.1 wt% ${Y_2}{O_3}$+1.5 wt% ZnO composition. By mixing 25 % of attrition milled powder and 75 % of ball milled powder, the broadest particle size distribution was obtained, leading to a dense thick film with crack-free microstructure and improved dielectric properties. The X-ray diffraction analysis revealed that the film was in wellcrystallized perovskite phase. The remanent polarization was increased from $13.7{\mu}C/cm^2$ to $23.3{\mu}C/cm^2$ at the addition of 25 % attrition milled powder.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권7호
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• pp.308-314
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• 2005

The 2 GHz film bulk acoustic wave resonator(FBAR), one of the most necessary device of the next generation mobile communication system, consisted of solidly mounted resonator(SMR) structure using Brags reflector, was researched in this paper The FBAR applied SiO$_{2}$ and W had large difference of the acoustic impedance to reflector Al to electrode and ZnO to piezoelectric layer. Specially, the FBAR applied the two-step deposition method to improve the c-axis orientation and increase reproducibility of the fabrication device had good performance. The electrical properties of plasma such as impedance, resistance, reactance, $V_{pp},\;I{pp}$, VSWR and phase difference of voltage and current, was analyzed and measured by RF sensor with the variable experiment process factors such as gas ratio, RF power and base vacuum level about concerning the thickness, c-axis orientation, adhesion and roughness. The FBAR device about the optimum condition resulted reflection loss(S$_{11}$) of -17 dB, resonance frequency of 1.93 GHz, electric-mechanical coefficient(k$_{eff}$) of 2.38 $\%$ and Qualify factor of 580. It was seen better qualify than the common dielectric filter at present and expected on business to the filter device of 2 GHz bandwidth with the MMIC technology.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 춘계학술대회 논문집
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• pp.22-25
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• 1995

In this paper, the physical characteristics of piezoelectric transducer which generates acoustic weve at microwave frequency were theoretically analized. We found that increasing electrode thickness is showed large distorthion on bandwidth. ZnO thin film were desposited by RF magnetron sputtering method. considering the sputtering parameters. Thickness of the desposited ZnO was 3.9 $\mu\textrm{m}$. In this experiment, we get that resistivity is 12.196${\times}$109 [cm$\Omega$], that resonance frequency is 827.47MHz Measuring insertion loss, we ascertained to possibility of transducer application for microwave frequency.