• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 춘계종합학술대회
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• pp.376-380
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• 2005

The paper presents some methods to improve characteristics of film bulk acoustic resonator (FBAR) devices. The FBAR devices were fabricated on Bragg reflectors. Thermal treatments were done by sintering and/or annealing processes. The measurement showed a considerable improvement of return loss (S$_{11}$) and quality factor (Q$_{s/p}$). These thermal techniques seem very promising for enhancing FBAR resonance performance.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 추계종합학술대회
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• pp.311-315
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• 2005

In this paper, we emphasize the advantage of thermal annealing treatments for improvement characteristics of film bulk acoustic resonator (FBAR) devices. The FBAR devices were fabricated on multi-layer thin films, namely, Bragg reflectors. Sintering and/or annealing processes were applied in our experiments. The measurements confirm once again a considerable improvement of return loss $(S_{11})$ and quality factor $(Q_{s/p})$. these thermal treatment techniques are really promising for enhancing performance of FBAR resonators in industry fabrication of RF devices.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2002년도 추계학술발표강연 및 논문개요집
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• pp.92-92
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• 2002

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2000년도 추계총회,초청강연,특별강연,연구발표회
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• pp.193.2-193
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• 2000

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 춘계학술발표강연 및 논문개요집
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• pp.56-56
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• 2003

최근 정보통신 분야의 급격한 발달로 인하여 무선통신에 사용되는 주파수 영역 또한 계속 높아짐에 따라 대역통과 필터 소자의 삽입 손실, 소비 전력, 크기, MMIC화에 대한 많은 연구가 진행되고 있다 압전 현상을 이용한 박막형 공진기가 이러한 요구를 충족시키고, 현재의 SAW filter를 대체할 소자로 떠오르고 있다. 본 실험에서는 단결정 미세 구조를 만들 수 있고, 압전 효과 또한 우수하며, Surface Micromachining보다 비교적 제조 공정이 간단하고 선택적 에칭이 가능한 Bulk Micromachining을 이용하여 Si$_3$N$_4$ Membrane을 이용한 중심주파수 5.2GHz인 두께 진동모드 Film Bulk Acoustic Wave Resonator(FBAR)를 제작하고 공진기의 고주파 특성을 평가하였다. Membrane구조 형성을 위해 Backside면인 Si$_3$N$_4$, Si은 RIE(Reactive Ion Etching)와 선택적 에칭용액인 KOH로 각각 에칭하여 Membrane을 갖는 구조로 중심주파수 5.2GHz인 두께 진동모드 FBAR를 설계 및 제조하였다. 체적 탄성파 공진 현상은 r.f Magnetron Sputtering법으로 증착한 AIN 압전박막과 Mo전극으로부터 발생 가능하였다. 본 연구에서는 0.9$\mu\textrm{m}$-Si$_3$N$_4$ Membrane을 이용해 FBAR를 제작/평가하고, RIE을 통해 Membrane을 제거해 가면서 공진기의 특성 즉, Quality factor와 유효전기기계결합계수(K$_{eff}$) 및 S parameter특성을 비교 측정해 보았다. 측정해본 결과 Membrane Free일때가 훨씬더 공진 특성이 우수함을 볼 수 있다

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.41-42
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• 2005

The characteristics of ZnO films are reported depending on different deposition conditions for film bulk acoustic resonators (FBARs). The ZnO films have been deposited on Al films evaporated on p-type (100) silicon substrate by pulsed laser deposition (PLD) technique using a Nd:YAG laser. These films exhibit an electrical resistivity higher than $10^7$ $\Omega$m. X-ray diffraction measurements have shown that ZnO films are highly c-axis oriented with full width at half maximum (FWHM) below $0.5^{\circ}$. These results show the possibility of FBAR devices using by PLD.

• 전기학회논문지
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• 제56권5호
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• pp.915-920
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• 2007

AIN-based film bulk acoustic resonator (FBAR) devices which adopt a membrane-type configuration such as Mo/AIN/bottom-metal/Si are fabricated by employing a novel process. The proposed resonator structure does not require any supporting layer above the substrate, which leads to the reduction in energy loss of the resonators. For all the FBAR devices, the frequency response characteristics are measured and the device parameters, such as return loss and input impedance, are extracted from the frequency responses, and analyzed in terms of the various metals such as Al. Cu, Mo, W used in the bottom-electrode. The mass-loading effect caused by the used bottom-electrode metals is found to be the main reason for the difference revealed in the measured characteristics of the fabricated FBAH devices. The results obtained in this study also show that the degree of match in lattice constant and thermal expansion coefficient hetween piezoelectric layers and electrode metals is crucial to determine the device performance of FEAR.

• 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.

• 한국세라믹학회지
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• 제40권4호
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• pp.393-397
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• 2003

To investigate the effect of AIN c-axis orientation on the resonance performance of film bulk acoustic wave resonators, solidly mounted resonators with crybtallographically different AIN piezoelectric films were prepared by changing only the bottom electrode surface conditions. As increasing the degree of c-axis texturing, the effective electromechanical coupling coefficient ($\kappa$$\_$eff/)$^2$ in resonators increased gradually. The least 4 degree of full width at half maximum in an AIN(002) rocking curve, which corresponds to $\kappa$$^2$$\_$eff/ of above 5%, was measured to be necessary for band pass filter applications in wireless communication system. The longitudinal acoustic wave velocity of AIN films varied with the degree of c-axis texturing. The velocity of highly c-axis textured AIN film was extracted to be about 10200 n/s by mathematical analysis using Matlab.

• 한국전기전자재료학회논문지
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• 제20권2호
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• pp.152-155
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• 2007

In this study, we fabricated FBAR(film bulk acoustic resonator) by using $Li_{2}CO_{3}:ZnO$ as a function of annealing temperature and concentrated on effect of frequency characteristic of FBAR. The results show that the annealing affects resistivity and crystallity. The optimum properties were observed for film annealed at $500^{\circ}C$. The resistivity was $1.5{\times}10^{11}\;{\Omega}{\cdot}cm$ and the roughness was 21.10 nm. And the return loss is improved from -24.9 at $300^{\circ}C$ to -29.8 at $500^{\circ}C$ without the resonant frequency change. We finally confirmed the improvement on the frequency characteristics of FBAR device by annealing process at the optimized condition.