• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.223-223
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• 1999

PZT(PbZr1-xTixO3) 박막은 고유전율과 같은 remanent polarization을 가져서 고집적 소자의 커패시터 유전율층 또는 비휘발성 메모리 소자의 제조에 이용되고 있으나, fatigue 와 aging 문제로 인하여 새로운 물질의 개발이 필요한데, 그 대표적으로 연구되고 있는 것이 PMN-PT(Pb(Mg1/3Nb2/3)O-PbTiO3) 이다. 본 실험에서는 sol-gel 법에 의하여 제조된 PMN-PT막을 ICP(Inductively coupled plasma)에 의하여 식각하였고 mask층으로는 PR을 사용하였다. 식각 가스로는 Ar, Cl, BCl를 단독 또는 혼합하여 사용하였으며, 식각 특성을 보기 위하여 RF Power, Substrate bias, Operation pressure, Substrate temperature를 변화시켰다. 식각속도는 stylus profiler를 이용하여 측정하였고, 단면 profile은 scanning electron microscopy (SEM)를 이용하여 관찰하였다. 식각 메커니즘을 규명하고자 식각된 박막의 표면을 X-ray photoelectron spectroscopy (XPS)로 관찰하였고, optical emission spectroscopy (OES)로 플라즈마 특성을 규명하고자 하였다. 식각속도는 Ar 또는 Cl2 플라즈마에 BCl3 가스를 혼합하였을 경우 증가되었고, BCl3 가스를 단독으로 사용하여도 높은 식각속도를 나타내었으며, BCl3의 첨가량이 늘어날수록 PR의 식각속도는 감소하여 높은 선택비를 보였다. 90% BCl3/10%Cl2 플라즈마에서 2800$\AA$/min의 식각속도 그리고 1.37:1의 PR 선택비를 얻을 수 있었다. Power나 기판 bias 증가에 따라 식각속도는 증가하였으나 기판 온도변화에는 민감하지 않았다. BCl3 rich에서의 식각속도 증가와 선택비 증가는 B2O3의 형성에 의한 것으로 생각된다.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1022-1024
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• 1995

In this study, $Pb(Zr_xTi_{1-x})O_3$(x=0.65, 0.52, 0.35) thin films were fabricated by Sol-Gel method. A stock solution with excess Pb 10[mol.%] of $Pb(Zr_xTi_{1-x})O_3$ was made and spin-coated on the Pt/$SiO_2$/Si substrate at 4000[rpm] for 30[sec.]. Coated specimens were dried on the hot-plate at $400[^{\circ}C]$ for 10[min.]. Sintering temperature and time were $500{\sim}800[^{\circ}C]$ and $1{\sim}60$[min.]. To investigate crystallization condition, PZT thin films were analyzed with sintering temperature, time and composition by the XRD. The microstructure of thin films were investigated by SEM. The ferroelectric perovskite phases precipitated under the sintering of $700[^{\circ}C]$ for 1 hour. In the PZT(52/48) composition, dielectric constant and dielectric loss were 2133, 2.2[%] at room temperature, respectively.

• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.189-190
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• 2005

Ploycrystalline $Pb(Zr_{0.5},Ti_{0.5))O_3$ and $BaTiO_3$ powder were prepared by sol-gel process. The alumina substrate were sintered at $1400^{\circ}C$ with bottom electrode of Pt for 2 hours. The Pb(Zr0.5,Ti0.5)O3 / BaTiO3 multilayered thick films with laminating times were fabricated on alumina substrate by screening printing method. The obtained thick films were sintered at $800^{\circ}C$ with upper electrode of Ag paste for 1 hour. Structural properties of Pb(Zr0.5,Ti0.5)O3 / BaTiO3 multilayered thick films were investigated. As a result of the Differential Thermal Analysis(DTA) of Pb(Zr0.5,Ti0.5)O3, exothermic peak was observed at around 650 $^{\circ}C$. The X-ray diffraction (XRD) patterns indicated that BaTiO3 and Pb(Zr0.5,Ti0.5)O3 phases and porosities were formed in the interface of Pb(Zr0.5,Ti0.5)O3 / BaTiO3multilayered thick films.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.335-337
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• 1995

In this study, $Pb(Zr_{0.52}Ti_{0.48})O_3$ ceramic thin films were fabricated from an alkoxide-based by Sol-Gel method. $Pb(Zr_{0.52}Ti_{0.48})O_3$ stock solution was made and spin-coated on the $Pt/SiO_2/Si$ substrate at 4000[rpm] for 30[sec]. Coated specimens were dried at 400[$^{\circ}C$] for 10 [min]. The coating process was repeated 4 times and then heat-treated at 500$\sim$800[$^{\circ}C$], 1 hour. The final thickness of the thin films were about 3000[A]. The crystallinity and microstructure of the thin films were investigated for varing the sintering condition. The ferroelectric perovskite' phases precipitated under the sintering of 700[$^{\circ}C$] for 1 hours. In the $Pb(Zr_{0.52}Ti_{0.48})O_3$ thin films sintered at 700[$^{\circ}C$] for 1 hour, dielectric constant and dielectric loss were 2133, 2.2[%] at room temperature, respectively. $Pb(Zr_{0.52}Ti_{0.48})O_3$ thin film capacitors having good dielectric and electrical properties are expected for the application to the dielectric material of DRAM.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1448-1449
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• 2006

Pb(Zr,Ti)$O_3$ is one of the most attractive ferroelectric materials for realizing the FeRAM due to its higher remanant polarization and the ability to withstand higher coercive fields. Generally, the ferroelectric materials were patterned by a plasma etching process for high-density FeRAM. The applicable possibility of CMP process to pattern Pb(Zr,Ti)$O_3$ instead of plasma etching process was investigated in our previous study for improvement of an angled sidewall which prevents the densification of ferroelectric memory and is apt to receive the plasma damage. Our previous study showed that good removal rate with the excellent surface roughness compared to plasma etching process were obtained by CMP process for the patterning of Pb(Zr,Ti)$O_3$. The suitable selectivity to TEOS without any damage to the structural property of Pb(Zr,Ti)$O_3$ was also guaranteed. In this study, the removal mechanism of $Pb_{1.1}(Zr_{0.52}Ti_{0.48})O_3$ coated by sol-gel method was investigated. Surface analysis of polished specimens at the best and worst conditions was carried out by XPS.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.1960-1961
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• 2005

Ploycrystalline $Pb(Zr_{0.5},Ti_{0.5})O_3$ and $BaTiO_3$ powder were prepared by sol-gel process. The alumina substrate were sintered at $1400^{\circ}C$ with bottom electrode of Pt for 2 hours. The Pb(Zr0.5, Ti0.5)O3/BaTiO3 multilayered thick films with laminating times were fabricated on alumina substrate by screening printing method. The obtained thick films were sintered at $800^{\circ}C$ with upper electrode of Ag paste for 1 hour, Structural properties of Pb(Zr0.5,Ti0.5)O3/BaTiO3 multilayered thick films were investigated. As a result of the Differential Thermal Analysis(DTA) of Pb(Zr0.5,Ti0.5)O3, exothermic peak was observed at around $650^{\circ}C$. The X-ray diffraction (XRD) patterns indicated that BaTiO3 and Pb(Zr0.5,Ti0.5)O3 phases and porosities were formed in the interface of Pb(Zr0.5,Ti0.5)O3 / EaTiO3 multilayered thick films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.916-919
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• 2000

A great deal of research has been done in the field of characterization for piezoelectric thin films after the first report on the measurement for the piezoelectric coefficient of thin films in 1990. The main idea of this research is to provide a distinctive solution for the measurement of both the longitudinal and the transverse piezoelectric d-coefficients, d$\sub$33/ and d$\sub$3l/, of ferroelectric thin films and also thick films. In general, to get these two coefficients of thin films, two different measuring systems are required. Here, we propose the improved method for the evaluation of these two coefficients with single equipment and with the relatively convenient procedure. The two-step loading process of applying the both positive and the negative pressure has been designed to acquire the piezoelectric coefficients. These results have beer calibrated for both the longitudinal and the transverse piezoelectric d-coefficients, d$\sub$33/ and d$\sub$31/, of thin films. In the first stage of the experiments, we have obtained d$\sub$33/ of 108pC/N and d$\sub$31/ of 57pC/N for the PZT thin films.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.11
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• pp.831-835
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• 2013

In this study, we fabricated a micro $Pb(Zr,Ti)O_3$ (PZT) film piezoelectric cantilever with a Si proof mass and dual beams through MEMS process. The size of the beam and the integrated Si proof mass were about $4,320{\mu}m{\times}290{\mu}m{\times}12{\mu}m$ and $1,380{\mu}m{\times}880{\mu}m{\times}450{\mu}m$ each. To reduce the air damping and have the larger displacement of dual beams was used for design. After mounting micro PZT film piezoelectric cantilever on shaker, we measured the resonance frequency and a output voltage while making resonant frequency changed. The resonant frequency and the highest average power of the cantilever device were 110.2 Hz and 0.36 ${\mu}W$ each, at 0.8 g acceleration and 23.7 $k{\Omega}$ load resistance, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.9
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• pp.795-800
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• 2003

The dielectric and piezoelectric properties of the xPb(A $l_{0.5}$N $b_{0.5}$) $O_3$-(1-x)Pb(Z $r_{0.52}$ $Ti_{0.48}$) $O_3$ [xPAN-(1-x)PZT] thin films by pulsed laser deposition (PLD) were investigated as a function of PAN contents. The effect of texture on dielectric and piezoelectric properties of the 0.05PAN-0.95PZT thin films having the highest piezoelectric constant( $d_{33}$) was studied more precisely. For 0$\leq$x$\leq$0.15 compositions in xPAN-(1-x)PZT thin films, the well-developed perovskite phase with (111) preferred orientation was obtained at the deposition temperature of 50$0^{\circ}C$. With increasing PAN content, remanent polarization and coercive field decreased. The dielectric constant increased with an increase of PAN content until it reached 1450 at $\chi$= 0.05, and then decreased for higher PAN content. The maximum points of dielectric constant coincides with the maximum points of the piezoelectric constant $d_{33}$.33/.33/././.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.4
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• pp.1-6
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• 2000

Recently, SrBi$_{2}$Ta$_{2}$ $O_{9}$(SBT) and Pb(Zr,Ti) $O_{3}$(PZT) were much attracted as materials of capacitor for ferroelectric random access memory(FRAM) with higher read/ write speed, lower power consumption and nonvolartility. SBT thin film has appeared as the most prominent fatigue free and low operation voltage. To highly integrate FRAM, SBT thin film has to be etched. A lot of papers have been reported over growth of SBT thin film and its characteristics. However, there are few reports about etching SBT thin film owing to difficult of etching ferroelectric materials. SBT thin film was etched in CF$_{4}$Ar plasma using magnetically enhanced inductively coupled plasma (MEICP) system. In order to investigate the chemical reaction on the etched surface of SBT thin films, X-ray Photoelecton spectrosocpy (XPS) and Secondary ion mass spectroscopy(SIMS) was performed.