• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.834-837
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• 2004

BST thin films were etched with inductively coupled $CF_4(C1_2+Ar)$ Plasmas. The maximum etch rate of the BST thin films was 53.6 nm/min for a 10 % $CF_4$ to the $Cl_2/Ar$ gas mixture at RF power of 700 W, DC bias of -150 V, and chamber pressure of 2 Pa. Small addition of $CF_4$ to the $Cl_2/Ar$ mixture increased chemical effect. Consequently, the increased chemical effect caused the increase in the etch rate of the BST thin films. To clarify the etching mechanism, the surface reaction of the BST thin films was investigated by X-ray photoelectron spectroscopy.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 반도체재료
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• pp.8-11
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• 2001

In this study. the recovery of plasma induced damage in the etched PZT thin film with $O_2$ re-annealing have been investigated. The PZT thin films were etched as a function of $Cl_2/Ar$ and additive $CF_4$ into $Cl_{2}(80%)/Ar(20)%$. The etch rates of PZT thin films were $1600\dot{A}/min$ at $Cl_{2}(80%)/Ar(20)%$ gas mixing ratio and $1970\dot{A}/min$ at 30 % additive $CF_4$ into $Cl_{2}(80%)/Ar(20)%$. The etched profile of PZT films was obtained above 70 by SEM. In order to recovery properties of PZT thin films after etching, the etched PZT thin films were re-annealed at various temperatures in $O_2$ atmosphere. From the hysteresis curves, ferroelectrical properties are improved by $O_2$ re-annealing process. The improvement of ferroelectric behavior at annealed sample is consistent with the increase of the (100) and (200) PZT phase revealed by x-ray diffraction (XRD). From XPS analysis, 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 TixOy is recovered by $O_2$ recombination during rapid thermal annealing process. From AFM images, it shows that the surface roughness of re-annealed sample after etching is improved.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 반도체 재료 센서 박막재료 전자세라믹스
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• pp.13-17
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• 2004

The PZT thin films are well-known material that has been widely studied for ferroelectric random access memory (FRAM). We etched the PZT thin films by $CF_4/(Cl_2+Ar)$ plasma and investigated improvement in etching damage by $O_2$ annealing. PZT thin films were etched for 1 min in an ICP using a gas mixture of $Cl_2$(80%)/Ar (20%) with 30% $CF_4$ addition. The etching conditions were fixed at a substrate temperature of $30^{\circ}C$, an rf power of 700 W, a dc-bias voltage of -200 V and a chamber pressure of 2 Pa. To improve the ferroelectric properties of PZT thin films after etching, the samples were annealed for 10 min at various temperatures in $O_2$ atmosphere. After $O_2$ annealing, the remanent polarization, fatigue, and the leakage current were gradually recovered to the characteristics of the as-deposited film, according as the temperature increased.

• 한국세라믹학회지
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• 제40권9호
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• pp.886-890
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• 2003

단결정 LiNbO$_3$를 helicon wave plasma 방법으로 식각시 bias power와 CF$_4$, HBr, SR$_{6}$가 혼합된 gas 유량에 따른 식각 속도와 rms roughness 값의 특성을 관찰하였다. 식각된 깊이는 surface profiler로 관찰하였으며 rms roughness 값은 Atomic Force Microscopy (AFM)으로 측정하였다. Bias power 증가함에 따라 500W에서 가장 높은 식각 속도와 가장 평탄한 표면형상을 얻을 수 있었으며, CF$_4$, HBr, SF$_{6}$ gas 유량을 각각 10～30 sccm으로 증가시킴에 따라 식각 속도는 CF$_4$, HBr, SF$_{6}$ gas 유량이 10 sccm, 30 sccm, 10 sccm에서 가장 높게 나타났으며, rms roughness 값은 CF$_4$, HBr, SF$_{6}$ gas 유량이 30 sccm, 10 sccm, 30 sccm에서 가장 낮은 표면 조도를 나타내었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.375-378
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• 2002

We investigated the reduction of etching damage by additive O$_2$ in etching gas and recovery of etching damage by O$_2$ annealing. The PZT thin films were etched using additive Ar or O$_2$ into Cl$_2$/CF$_4$ gas mixing ratio of 8/2. In order to recover ferroelectric properties of PZT thin films after etching, the etched PZT thin films were annealed at 600 C in O$_2$ atmosphere for 10 min. The remanent polarization is decreased seriously and fatigue is accelerated in the PZT sample etched in Ar/(C1$_2$+CF$_4$) plasma, whereas these characteristics are improved in O$_2$/(Cl$_2$/CF$_4$). From x-ray photoelectron spectroscopy (XPS) analysis, the intensities of Pb-O, Zr-O and Ti-O peaks are changed and the etch byproducts such as metal chloride and metal fluoride are reduced by O$_2$ annealing. From electron probe micro analyzer (EPMA) and auger electron spectroscopy(AES), O$_2$ vacancy is observed after etching. In x-ray diffraction (XRD), the structure damage in the additive O$_2$ into C1$_2$/CF$_4$ is reduced and the improvement of ferroelectric behavioral annealed sample is consistent with the increase of the (100) and (200) PZT peaks.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.275-278
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• 2001

Ferroelectric PZT thin films were fabricated on the RuO$_2$/Pt, Pt bottom electrode with a PZT(53/47) metal alkoxide solutions. All PZT thin films showed a uniform grain structure without the presence of rosette structure. The PZT thin films were etched as a function of Cl$_2$/Ar and additive CF$_4$ into Cl$_2$(80%)/Ar(20%). The etch rates of PZT thin films were 1970 ${\AA}$/min at 30 % additive CF$_4$ into Cl$_2$(80%)/Ar(20%). The remanent polarization and leakage current density in PZT thin film on the RuO$_2$/Pt were 64.2 ${\mu}$C/cm$^2$, 1.4${\times}$10$\^$-6/ respectively.

• Transactions on Electrical and Electronic Materials
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• 제5권6호
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• pp.223-226
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• 2004

The PZT thin films are one of well-known materials that has been widely studied for ferroelectric random access memory (FRAM). We etched the PZT thin films by $CF_{4}/(Cl_{2}+Ar)$ plasma and investigated improvement in etching damage by $O_{2}$ annealing. The maximum etch rate of the PZT thin films was 157 nrn/min and that the selectivity of the PZT thin films to Pt was 3.1 when $CF_{4}(30{\%})$ was added to a $Cl_{2}(80{\%})/Ar(20{\%})$ gas mixing ratio. To improve the ferroelectric properties of PZT thin films after etching, the samples were annealed for 10 min at various temperatures in $O_{2}$ atmosphere. After $O_{2}$ annealing, the remanent polarization of the asdeposited films was $34.6{\mu}/cm^{2}$ and the sample annealed at 650, 550, and $450^{\circ}C$ was 32.8, 22.3, and $18.6{\mu}/cm^{2}$, respectively. PZT thin films with $O_{2}$ annealing at $450^{\circ}C$ retained $77{\%}$ of their original polarization at 106 cycles. Also as the annealing temperature increased, the fatigue properties improved. And the leakage current was decreased gradually and almost recovered to the as-deposited value after the annealing at $450^{\circ}C$.

• 한국진공학회지
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• 제20권6호
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• pp.422-429
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• 2011

식각공정에 주로 사용되는 $Cl_2$/Ar, $CF_4$, $CF_4/O_2$, $CF_4/H_2$, $C_2F_6$, $C_4F_8$, 그리고 $SF_6$ 가스 방전에서 이온, 중성종 및 활성종 밀도의 전자밀도와 온도에 대한 의존성을 수치해석적으로 분석하였다. 이온, 중성종 및 활성종 밀도에 대한 공간평균 유체방정식을 정상상태로 가정하여 상대적으로 측정이 용이한 전자밀도와 온도에 대한 식으로 표현하였고, 이 식을 수치해석적인 방법으로 풀었다. 계산에 사용된 반응계수들은 여러 문헌에서 수집되거나 산란단면적으로부터 계산되었고, 같은 반응에 대해 다른 값을 보일 경우, 계산 결과를 실험 결과와 비교하여 높은 일치도를 보이는 값이 선택되었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(2)
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• pp.229-232
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• 2002

In this paper, etching characteristics of Zr-silicate in Ar/ClrCH4 plasma is studied, and possible plasma damage is investigated by fabricating MIS capacitors. We'could increase the selectivity to near 2 while keeping the etch rate of Zr-silicate to about 70 nm/min. Leakage current and flat band voltage shift of PUZr-silicate/si capacitors are measured before and after plasma etching. Using capacitor patterns with the same area but different circumference lengths, we try to separate etching damage mechanisms and to optimize the process. The leakage current of 1.2$\times$10-3 A/cm2 and smaller capacitance variation of 0.2 nF at -2V are obtained in Ar/Cl2/CF4 plasma at 200 W RF power

• 대한화학회지
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• 제29권6호
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• pp.565-574
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• 1985

MeOH-MeCN 혼합용매계에서 4-치환-2,6-이니트로염화벤젠과 아닐린 치환제 사이의 친핵성 치환반응속도를 전기 전도법에 의해 측정하였다. 기질의 고리에 있는 치환기의 치환기변화에 따른 속도상수의 크기순서는 4-$NO_2{\gg}4-CN {\gg}$4-$CF_3$이었고, 아닐린 고리에 있는 치환기에 의한 속도상수의 크기는 p-O$CH_3 {\gg}p- CH_3{\gg}H {\gg}p-Cl{\gg}m-NO_2$ 순서였다. MeOH함량이 많은 용매에서 속도상수가 MeCN 함량이 많은 용매속에서의 속도상수보다 컸다. MeOH-MeCN 혼합용매계와 친핵체 변화에 대한 속도론적 연구로 볼 때 Cl의 이탈단계가 속도결정단계로 보여졌다. MeOH에 의한 친전자적 촉매작용은 알코올의 수소와 이탈기 염소원자 사이의 전이상태에서 수소결합 형성으로 이루어지고 친핵성 촉매작용은 전이상태에서 알코올의 산소와 아민의 수소사이의 수소결합에 의한 것으로 생각 되었다. 모든 이의 사실로 보아 본 반응은 제 2단계가 속도결정단계인 $S_N$Ar메카니즘으로 진행됨을 알 수 있고 이와 같은 메카니즘은 PES모형으로도 설명할 수 있다.