• 한국전기전자재료학회논문지
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• 제15권4호
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• pp.319-324
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• 2002

In this study, the reduce of plasma etching damage in PZT thin film with addictive gas and re-annealing after etching have been investigated. The PZT thin films were etched as a function of $Cl_2/CF_4$ with addition of Ar and $O_2$ with inductively coupled plasma. The etch rates of PZT thin films were 1450 ${\AA}/min$ at 30% additive Ar and 1100 ${\AA}/min$ at 10% auditive $O_2$ into $Cl_2/CF_4$ gas mixing ratio of 8/2. In order to reduce plasma damage of PZT thin films after etching, the etched PZT thin films were re-annealed at various temperatures at $O_2$ atmosphere. From the hysteresis curries, the ferroelectric properties are improved by $O_2$ re-annealing process. The improvement of ferroelectric behavior at annealed PZT films is consistent wish the increase of the (100) and (200) PZT peaks revealed by x-ray diffraction (XRD). From x ray photoelectron spectroscopy (XPS) analysis, the intensity of Pb-O, Zr-O and Ti-O peak are increased and the chemical residue peak is reduced by $O_2$ re-annealing. The ferroelectric behavior consistent with the dielectric nature of $Ti_xO_y$ is recovered by $O_2$ recombination during rapid thermal annealing process.

• 한국전기전자재료학회논문지
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• 제11권3호
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• pp.229-236
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• 1998

Ferroelectric $Sr_xBi_yTa_2O_{9+\alpha}$/(0.7$\leqSr\leq1.0,\; 2.0\leqBi\leq2.6)$ solutions were prepared by MOD (Metalorganic Deposition) process. These solutions were made into thin films with thickness ranging from 1500~2000${\AA}$ by spin coating. The phase transformation of the SBT thin films by variation of annealing temperature and annealing time were observed using high temperature XRD and SEM. The crystallization and grain growth of SBT thin film were accomplished at $800^{\circ}C$ for 30 minutes after deposition of Pt top electrode by sputtering to prevent electrical breakdown. Ferroelectric properties of the SBT thin films were measured in the range of $\pm$3V\; and\; \pm5V$. The specimen with composition ratio of Sr/Bi/Ta (0.8/2.4/2.0) has the excellent ferroelectric properties ; $2P_r = 10.5,\; 13.2\muC/cm^2 \;at\; \pm3V\; and\; \pm5V$ respectively. Observing the post annealed Pt/SBT/Pt interface by SEM, it was found that Pt electrode sputtered on to the SBT thin film penetrated into the hollow on the SBT thin film, thus decreasing the effective insulation thickness. The effective insulation thickness recovered by post annealing, and this was confirmed by leakage current density measurement.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.1829-1831
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• 2005

Ferroelectric $Bi_{3.25}Nd_{0.75}Ti_3O_{12}$(BNdT) thin films were proposed for capacitor of FeRAM. The BNdT thin films were grown on Pt/Ti $SiO_2/P-Si(100)$ substrates by the RF magnetron sputtering deposition. The dielectric properties of the BNdT were investigated by varying post-annealing temperatures. Increasing post-annealing temperature, the (117) peak was increased. An increase of rod type grains of BNdT films with increasing post-annealing temperature was observed by the Field Emission Scanning Electron Microscopy(FE-SEM). The dielectric constant and dielectric loss of the BNdT thin films with post-annealing temperature of $700^{\circ}C$ were 418 and 0.37, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 센서 박막재료 반도체재료 기술교육
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• pp.107-110
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• 2002

The optical memory devices of BST thin films to composite $(Ba_{0.7}\;Sr_{0.3})TiO_{3}$ using sol-gel method were fabricated by changing of the depositing layer number on $Pt/Ti/SiO_{2}/Si$ substrate. The structural properties of optical memory devices to be ferroelectric was investigated by fractal analysis and 3-dimension image processing. The thickness of BST thin films at each coating numbers 3, 4 and 5 times was $2500[\AA]$, $3500[\AA]$ and $3800[\AA]$. BST thin films exhibited the most pronounced grain growth. The surface morphology image was roughness with coating numbers. The thin films increasing with coating numbers shows a more textured and complex configuration.

• 한국세라믹학회지
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• 제42권3호
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• pp.150-154
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• 2005

Ferroelectric $Bi_{3.35}Sm_{0.65}Ti_{3}O_{12}(BSmT)$ thin films were synthesized by sol-gel process. In this experiments, $Bi(TMHD)_{3},\;Sm_{5}(O^{i}Pr)_{13},\;Ti(O^{i}Pr)_4$ were used as precursors, which were dissolved in 2-methoxyethanol. The BSmT thin films were deposited on the Pt/TiO/SiO/Si substrates by spin-coating. Thereafter, the thin films with the thickness of 240 nm were annealed from 600 to $720^{\circ}C$ in oxygen atmosphere for 1 h, and post-annealed in oxygen atmosphere for 1 h after deposition of Pt electrode to enhance the electrical properties. To investigate the effects of Sm-substitution in the BTO thin films, the BTO and BSmT thin films were prepared, respectively. The remanent polarization and coercive voltage of the BSmT thin films annealed at $720^{\circ}C$ were $19.48{\mu}C/cm^2$ and 3.40 V, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.236-237
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• 2005

The structural properties of $(Bi,Ce)_4Ti_3O_{12}(BCT)$ thin films with post-annealing temperature were investigated. $(Bi,Ce)_4Ti_3O_{12}(BCT)$ thin films were deposited by RF sputtering method on Pt/Ti/$SiO_2$/Si substrates with optimum deposition condition. The $(Bi,Ce)_4Ti_3O_{12}(BCT)$ thin films was post-annealed at 600$^{\circ}C$, 650$^{\circ}C$, 700$^{\circ}C$, 750$^{\circ}C$, 800$^{\circ}C$ in furnace,respectively. Increasing the post-annealing temperature, the grain size, density and peak intensity of (117) and c-axis orientation were increased. The $(Bi,Ce)_4Ti_3O_{12}(BCT)$ thin films that annealed at 750$^{\circ}C$ exhibited well crystallized phase and had no vacancy and grain was uniform. but there are some secondary phases observed. At this time, the average thickness of $(Bi,Ce)_4Ti_3O_{12}(BCT)$ thin films was 2000 ${\AA}$.

• E2M - 전기 전자와 첨단 소재
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• 제9권8호
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• pp.836-850
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• 1996

In this study, we have analyzed structural analysis and measured ferroelectric characteristics of PZT thin films prepared by sol gel process with different sintering conditions and different Zr/Ti mot%. When the Zr mot% of PZT thin film was increased, it was found that the remanent. polarization and coercive field were decreased and increased, respectively. Also, the maxium dielectric constant of PZT(50/50) thin film was 786.8. We got double hysteresis(anti-fcrroelectric) curve from PbZrO$_{3}$ thin film. As heating rate goes up, pyrochlore phase of PZT thin film was decreased and dielectric and ferroelectric characteristics were improved. As a result of variation of sintering temperature and time 500.deg. C-800.deg. C and 5 sec.-8 hours, respectively, we got optimal sintering temperature and time. The optimium sintering temperature and time of conventional furnace method and rapid thermal processing method were 650.deg. C-700.deg. C for 30-60 minutes and 700.deg. C/20 seconds-2 minutes, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.660-663
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• 2001

The devices of BST thin films to composite (Ba$\_$0.7/ Sr$\_$0.3/)TiO$_3$using sol-gel method were fabricated by changing of the depositing layer number on Pt/Ti/SiO$_2$/Si substrate. The thin film capacitor to be ferroelectric devices was investigated by structural and electrical properties. The thickness of BST thin films at each coating numbers 3, 4 and 5 times was 2500[${\AA}$], 3500[${\AA}$], 3800[${\AA}$]. The dielectric factor of thin film when the coating numbers were 3, 4 and 5 times was 190, 400 and 460 on frequency 1[MHz]. The dielectric loss of BST thin film was linearly increased by increasing of the specimen area.

• 한국세라믹학회지
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• 제35권10호
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• pp.1040-1048
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• 1998

Ferroelectric properties of{{{{ { { { {SrBi }_{2 }Ta }_{2-x }Nb }_{x }O }_{9 } }} (SBIN) thin films were affected by the amount of Bi content in SBTN. The addition of Bi into the SBTN films could be accomplished by heat treating SBTN/Bi2O3/SBTN het-erostructures fabricated by r.f. magnetron sputtering method. The variation of Bi content was controlled by changing the thickness of the sandwiched Bi2O3 in SBTN/Bi2O3/SBTN heterostructure from 50 to 400$\AA$. As changing the thickness of the sandwiched Bi2O3 in Bi2O3 films was increased from 0 to 100$\AA$ the grain grew faster and the ferroelectric pro-perties were improved. On the other hand when the thickness of Bi2O3 films was thicker than 150$\AA$ the fer-roelectric properties were deteriorated Especially for SBTN thin films inserted by 400$\AA$ Bi2O3 layer a Bi2Phase appeared as a second phase resulting in poor ferroelectric properties. The maximum remanent po-larization (2Pr) and coercive field(Ec) were obtained for the SBTN/Bi2O3/(100$\AA$)/SBTN thin films. In this case 2Pr and Ec were 14.75 $\mu$C/cm2 and 53.4kV/cm at an applied voltage of 3V respectively.

• 한국전기전자재료학회논문지
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• 제14권9호
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• pp.695-699
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• 2001

Cerium dioxide (CeO$_2$) was used as the intermediate layer between the ferroelectric thin film and Si substrate in a metal-ferroelectric-semiconductor field effect transistor (MFSFET), to improve the interface property by preventing the interdiffusion of the ferroelectric material and the Si substrate. In this study, CeO$_2$ thin films were etched with a CF$_4$/Ar gas combination in inductively coupled plasma (ICP). The maximum etch rate of CeO$_2$ thin films was 270$\AA$/min under CF$_4$/(CF$_4$+Ar) of 0.2, 600 W/-200V, 15 mTorr, and $25^{\circ}C$. The selectivities of CeO$_2$ to PR and SBT were 0.21, 0.25, respectively. The surface reaction in the etching of CeO$_2$ thin films was investigated with x-ray photoelectron spectroscopy (XPS). There is a chemical reaction between Ce and F. Compounds such as Ce-F$_{x}$ remains on the surface of CeO$_2$ thin films. Those products can be removed by Ar ion bombardment. The results of secondary ion mass spectrometry (SIMS) were consistent with those of XPS. Scanning electron microscopy (SEM) was used to examine etched profiles of CeO$_2$ thin films. The etch profile of over-etched CeO$_2$ films with the 0.5${\mu}{\textrm}{m}$ line was approximately 65$^{\circ}$.>.