• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.140-141
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• 2007

To fabricate the metal-ferroelectric-insulator-semiconductor (MFIS) structure for the ferroelectric random access memory (FRAM) application, we prepared the ferroelectric $Sr_{0.9}Bi_{2.1}Ta_2O_9$ (SBT) and the insulator LaZrOx (LZO) thin films on the silicon substrate using a sol-gel method. In this study, we will investigate the feasibility of the SBT/LZO/Si structure as one of the promising gate configuration for the 1-transistor (1-T) type FRAM, by measurements of the electrical properties and the physical properties.

• 한국세라믹학회지
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• 제41권1호
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• pp.13-18
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• 2004

$La_{0.5}Sr_{0.5}CoO_3$ (LSCO) electrodes were prepared on ferroelectric $Sr_{0.9}Bi_{2.1}Ta_2O_9$(SBT) thin films by spin coating method using photosensitive sol-gel solution. Self-patterning technique of photosensitive sol-gel solution has advantages such as simple manufacturing process compared to photoresist/dry etching process. Lanthanum(III) 2-methoxyethoxide, Stronitium diethoxide. Cobalu(II)2-methoxyethoxide were used as starting materials for LSCO electrode. UV irradiation on LSCO thin films lead to decrease solubility by M-O-M bond formation and the solubility difference allows us to obtain self-patternine. There was little composition change of the LSCO thin films between before leaching and after leaching in 2-methoxyethanol. The lowest resistivity of LSCO thin films deposited on $SiO_2$/Si substrate was $1.1{\times}10^{-2}{\Omega}cm$ when the thin film was ennealed at $740^{\circ}C$. The values of Pr/Ps and 2Pr of LSCO/SBT/Pt capacitor on the applied voltage of 5V were 0.51, 8.89 ${\mu}C/cm^2$, respectively.

• The Korean Journal of Ceramics
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• 제6권3호
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• pp.219-223
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• 2000

The ferroelectric SBT films were deposited on Pt/Ti/SiO$_2$/Si substrates by liquid injection metalorganic chemical vapor deposition (MOCVD) with single-mixture solution of Sr[Ta(OEt)$_5$(dmae)]$_2$and Bi(C$_6$ 6/H$_5$)$_3$. The Sr/Ta and Bi/Ta ratio in SBT films depended on deposition temperature and mol ratio of precursor in the single-mixture solution. At the substrate temperature of 40$0^{\circ}C$, Sr/Ta and Bi/Ta ratio were close to 0.4 and 1 at precursor mol ratio of 0.5~1.0, respectively. As-deposited film was amorphous. However, after annealing at 75$0^{\circ}C$ for 30 min in oxygen atmosphere, the diffraction patterns indicated polycrystalline SBT phase. The remanent polarization (Pr) and coercive field (Ec) of SBT film annealed at 75$0^{\circ}C$ were 4.7$\mu$C/$\textrm{cm}^2$ and 115.7kV/cm at an applied voltage of 5V, respectively. The SBT films annealed at 75$0^{\circ}C$ showed practically no polarization fatigue up to 10$^10$ switching cycles.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 센서 박막재료 반도체 세라믹
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• pp.116-119
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• 2003

Self-patterning of thin films using photosensitive sol solution has advantages such as simple manufacturing process compared to photoresist/dry etching process. In this study, ferroelectric $Sr_{0.9}Bi_{2.1}Ta_2O_9$(SBT) and $La_{0.5}Sr_{0.5}CoO_3$(LSCO)thin films have been prepared by spin coating method using photosensitive sol solution. $Sr(OC_2H5)_2$, $Bi(TMHD)_3$ and $Ta(OC_2H)_5)_5$ were used as starting materials for SBT solution and $La(OCH_2CH_2OCH_3)_3$, $Sr(OC_2H_5)_2$, $CO(OCH_2CH_2OCH_3)_2$ were used for LSCO solution. Solubility difference by UV irradiation on LSCO thin film allows to obtain a fine patterning due to M-O-M bond formation. The lowest resistivity($4{\times}10^{-3}{\Omega}cm$) of LSCO thin films was obtained by annealing at $740^{\circ}C$.

• 한국재료학회지
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• 제10권12호
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• pp.807-811
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• 2000

MFISFET (Metal-ferroelectric-nsulator-semiconductor-field effect transistor)에의 적용을 위해 CeO$_2$와 SrBi$_2$Ta$_2$O$_{9}$ 박막을 각각 r.f. sputtering 및 pulsed laser ablation법으로 제조하였다. CeO$_2$ 박막은 증착시 스퍼터링개스비 (Ar:O$_2$)에 따른 특성을 고찰하였다. Si(100) 기판 위에 $700^{\circ}C$에서 증착된 CeO$_2$ 박막들은 (200)방향으로 우선방향성을 가지고 성장하였고 $O_2$ 개스량이 증가함에 따라 박막의 우선방향성, 결정립도 및 표면거칠기는 감소하였다. C-V특성에서는 Ar:O$_2$가 1 : 1인 조건에서 제조된 박막이 가장 양호한 특성을 보였다. 제조된 박막들의 누설전류값은 100kV/cm의 전계에서 $10^{-7}$ ~$10^{-8}$ A의 차수를 보였다. CeO$_2$/Si 기판위에 성장된 SBT는 다결정질상의 치밀한 구조를 가지고 성장을 하였다 80$0^{\circ}C$에서 열처리된 SBT박막으로 구성된 MFIS구조의 C-V 특성에서 memory window 폭은 0.9V를 보였으며 5V에서 4$\times$$10^{-7}$ A/$\textrm{cm}^2$의 누설전류밀도를 보였다.

• 마이크로전자및패키징학회지
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• 제6권2호
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• pp.51-61
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• 1999

R.f. magnetron sputtering법에 의해 $SrBi_2Ta_2O_9$ 박막을 $Pt/SiO_2$/Si p-tyPp (100) 기판 위에 제조하였다. 제조된 박막을 $800^{\circ}C$에서 열처리한 후 증착 조건에 따라 미세구조와 전기적 특성을 측정하였다. $800^{\circ}C$에서 열처리된 박막은 (006), (111), (200) 및 이차상인 BiPt 피크가 XRD 분석 결과 나타났으며, 가스 압력의 감소와 기판 온도의 증가에 따라 결정입자는 성장하였다. 50mtorr, $100^{\circ}C$에서 증착 후 $800^{\circ}C$에서 열처리한 박막의 두께는 200nm이었다. 이 박막의 잔류분극과 항전계 값은 각각 20.07 $\mu$C/$\textrm {cm}^2$, 79kV/cm이었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 반도체재료
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• pp.67-70
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• 2001

$SrBi_2Ta_2O_9$ thin films were etched at high-density $Cl_2/CF_4/Ar$ in inductively coupled plasma system. The chemical reactions on the etched surface were studied with x-ray photoelectron spectroscopy and secondary ion mass spectrometry. The etching of SBT thin films in $Cl_2/CF_4/Ar$ were chemically assisted reactive ion etching. The maximum etch rate was 1060 Am /min in $Cl_2$(20)/CF_4(20)/Ar(80). The small addition of $Cl_2$ into $CF_4$(20)/Ar(80) plasma will decrease the fluorine radicals and the increase CI radical. The etch profile of SBT thin films in $Cl_2/CF_4/Ar$ plasma is steeper than in $CF_4$/Ar plasma.Ā저會Ā저ﶖ⨀⡌ឫഀĀ᐀會Ā᐀㡆ﶖ⨀쁌ឫഀĀ᐀會Ā᐀遆ﶖ⨀郞ග堂瀀ꀏ會Āﶖ⨀〲岒ऀĀ᐀會Ā᐀䁇ﶖ⨀젲岒Ā㰀會Ā㰀顇ﶖ⨀끩Ā㈀會Ā㈀ﶖ⨀䡪Ā᐀會Ā᐀䡈ﶖ⨀Ā᐀會Ā᐀ꁈﶖ⨀硫Ā저會Ā저ﶖ⨀샟ගကĀ저會Ā저偉ﶖ⨀栰岒ఀĀ저會Ā저ꡉﶖ⨀1岒Ā저會Ā저Jﶖ⨀惝ග؀Ā؀會Ā؀塊ﶖ⨀ග㼀Ā切會Ā切끊ﶖ⨀⣟ගఀĀ搀會Ā搀ࡋﶖ⨀큭킢Ā저會Ā저

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.319-322
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• 2003

To match the charge induced by the insulators $CeO_2$ with the remanent polarization of ferro electric SBT thin films, areas of Pt/SBT/Pt (MFM) and those of $Pt/CeO_2/Si$ (MIS) capacitors were ind ependently designed. The area $S_M$ of MIS capacitors to the area $S_F$ of MFM capacitors were varied from 1 to 10, 15, and 20. Top electrode Pt and SBT layers were etched with for various area ratios of $S_M\;/\;S_F$. Bottom electrode Pt and $CeO_2$ layers were respectively deposited by do and rf sputtering in-situ process. SBT thin film were prepared by the metal orgnic decomposition (MOD) technique. $Pt(100nm)/SBT(350nm)/Pt(300nm)/CeO_2(40nm)/p-Si$ (MFMIS) gate structures have been fabricated with the various $S_M\;/\;S_F$ ratios using inductively coupled plasma reactive ion etching (ICP-RIE). The leakage current density of MFMIS gate structures were improved to $6.32{\times}10^{-7}\;A/cm^2$ at the applied gate voltage of 10 V. It is shown that in the memory window increase with the area ratio $S_M\;/\;S_F$ of the MFMIS structures and a larger memory window of 3 V can be obtained for a voltage sweep of ${\pm}9\;V$ for MFMIS structures with an area ratio $S_M\;/\;S_F\;=\;6$ than that of 0.9 V of MFS at the same applied voltage. The maximum memory windows of MFMIS structures were 2.28 V, 3.35 V, and 3.7 V with the are a ratios 1, 2, and 6 at the applied gate voltage of 11 V, respectively. It is concluded that ferroelectric gate capacitors of MFMIS are good candidates for nondestructive readout-nonvolatile memories.

• 한국전기전자재료학회논문지
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• 제15권5호
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• pp.388-392
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• 2002

In this work, the etching of $CeO_2$ thin films has been performed in an inductively coupled $Ar/CF_4/Cl_2$ plasma. The highest etch rate of the $CeO_2$ thin film ws 250 ${\AA}/min$ and the selectivity of CeO$_2$to SBT was 0.4 at a 10% additive $Cl_2$ into Ar/($Ar+CF_4$)gas mixing ratio of 0.8. From result of X-ray photoelectron spectroscopy (XPS) analysis, there are Ce-Cl and Ce-F bonding by chemical reaction between Cl, F and Ce. During the etching of $CeO_2$ thin films in $Ar/CF_4/Cl_2$ plama, Ce-Cl and Ce-F bond is formed, and these prodcuts can be removed by the physical bombardment of Ar ions. The 10% additive $Cl_2$ into the Ar/($Ar+CF_4$)gas mixing ratio of 0.8 could enhance the reaction between Cl, F and Ce.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.897-900
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• 2000

Annealing dependencies of the fatigue properties of SrBi$_2$Ta$_2$$O_{9}$ thin films were observed as function of substrate temperature(400-50$0^{\circ}C$) by the rf magnetron sputtering method. With increasing annealing temperature from $600^{\circ}C$ to 85$0^{\circ}C$, flourite phase was crystalized to $650^{\circ}C$ and Bi-layered perovskite phase was crystalized above $700^{\circ}C$. The fatigue characteristics of SBT thin films deposited on Pt/TiO$_2$/SiO$_2$/Si substrate did not change up to 101o switching cycles.s.