• 한국재료학회지
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• 제14권10호
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• pp.688-695
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• 2004

The capacitor contact barrier(CCB) layers have been introduced in the FeRAM integration to prevent the Pt/Al reaction during the back-end processes. Therefore, the interdiffusion and intermetallic formation in $Pt(1500{\AA})/Al(3000{\AA})$ film stacks were investigated over the annealing temperature range of $100\sim500^{\circ}C$. The interdiffusion in Pt/Al interface started at $300^{\circ}C$ and the stack was completlely intermixed after annealing over $400^{\circ}C$ in nitrogen ambient for 1 hour. Both XRD and SBM analyses revealed that the Pt/Al interdiffusion formed a single phase of $RtAl_2$ intermetallic compound. On the other hand, in the presence of TiN($1000{\AA}$) barrier layer at the Pt/Al interface, the intermetallic formation was completely suppressed even after the annealing at $500^{\circ}C$. These were in good agreement with the predicted effect of the TiN diffusion barrier layer. But the conventional TiN CCB layer could not perfectly block the Pt/Al reaction during the back-end processes of the FeRAM integration with the maximum annealing temperature of $420^{\circ}C$. The difference in the TiN barrier properties could be explained by the voids generated on the Pt electrode surface during the integration. The voids were acted as the starting point of the Pt/Al reaction in real FeRAM structure.

• 한국재료학회지
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• 제15권6호
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• pp.375-381
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• 2005

High temperature oxidation behavior of thermal barrier coating (TBC) system (IN738 substrate + NiCoCrAlY or NiAl bond coat with or without Pt + yttria stabilized zirconia) prepared by air plasma spray (APS) process has been studied in order to understand the effect of Pt addition to bond coat on the stability of TBC system. Specimens were oxidized in thermal cycling and isothermal oxidation test at $1100^{\circ}C$. The Pt addition in TBC system with NiCoCrAlY bond coat showed a longer life time compared to that without addition of Pt. Pt addition to TBC system is believed to help the formation of more stable thermally grown oxide, $Al_2O_3$, at the TBC/bond coat interface, leading to a longer lifetime of TBC system.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.187-187
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• 2010

In this study, we investigated the effect of electrodes on resistance switching of TaOx film. Pt, Ni, TiN, Ti and Al metal electrodes having the different oxidation degree were deposited on TaOx/Pt stack. Unipolar resistance switching behavior in Pt or Ni/TaOx/Pt MIM stacks was investigated, but bipolar resistance switching behavior in TiN, Ti or Al /TaOx/Pt MIM stacks was shown. We investigated that the voltage dependence of capacitance was decreased with higher oxidation degree of metal electrodes. Through the C-V results, we expected that linearity ($\alpha$) and quadratic ($\beta$) coefficient was reduced with an increase of interface layer between top electrode and Tantalum oxide. Transmission Electron Microscope (TEM) images depicted the thickness of interface layer formed with different oxidation degree of top electrode. Unipolar resistance switching behavior shown in lower oxidation degree of top electrode was expected to be generated by the formation of the conducting path in TaOx film. But redox reaction in interface between top electrode and Tantalum oxide may play an important role on bipolar resistance switching behavior exhibited in higher oxidation degree of top electrode. We expected that the resistance switching characteristics were determined by oxidation degree of metal electrodes.

• 대한화학회지
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• 제40권4호
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• pp.264-272
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• 1996

ASED-MO(Atom Superposition and Electoron Delocalization-Molecular Orbtal)이론을 이용하여 Pt(lll)과 ${\upsilon}-Al_2O_3$(III) 표면 모델에 대한 계면간 결합 세기에 관해 연구하였다. $Al^{3+}$의 환원 정도가는 알루미나 뭉치(cluster)에 대한 산소와 알루미늄의 비에 따라 달라진다. $Al^{3+}$의 환원 정도가 크면 클수록 Pt 원소들에 대해 강한 결합 에너지를 가진다. 산소로 덮인 ${\gamma}-Al_{20}_3$(III) 표면과 Pt 계면간 결합이 매우 약하지만 백금의 산화 조건에서의 결합은 매우 강하다. 백금 표면에서 부분적으로 빈 O-2p 띠(band)와 $Al^{3+}$ dangling surface orbital로 전하가 이동하는 전하이동(charge transfer) 메카니즘에 의해 백금과 알루미나 계면간 결합은 가능하다.

• 한국진공학회지
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• 제12권4호
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• pp.218-227
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• 2003

AlGaAs/GaAs HBT 에미터 오믹 접촉을 위해 n형 InGaAs에 대한 Pd/Si/Ti/Pt 및 Pd/Si/Pd/Ti/Au 오믹 접촉 특성을 조사하였다. Pd/Si/Ti/Pt 오믹 접촉의 경우, 증착 상태에서는 접촉 비저항을 측정할 수 없을 정도의 비오믹 특성을 보였으며, $375^{\circ}C$에서 10초 동안 열처리한 경우 $5\times10^{-3}\Omega\textrm{cm}^2$의 높은 접촉 비저항을 나타내었다. 그러나 열처리 조건을 $425^{\circ}C$, 10초로 변화시킬 경우 $2\times10^{-6}\Omega\textrm{cm}^2$의 낮은 접촉 비저항을 나타내었다. Pd/Si/Pd/Ti/Au 오믹 접촉의 경우, $450^{\circ}C$까지의 열처리 동안에 전반적으로 우수한 오믹 특성을 나타내어 $400^{\circ}C$, 20초의 급속 열처리 조건에서 최저 $3.9\times10^{-7}\Omega\textrm{cm}^2$의 접촉 비저항을 나타내었다. 두 오믹 접촉 모두 오믹 재료와 InGaAs의 평활한 계면을 유지하면서 우수한 오믹 특성을 나타내어, 화합물 반도체 소자의 오믹 접촉으로 충분히 응용 가능하였다. Pd/Si/Ti/Pt 및 Pd/Si/Pd/Ti/Au를 AlGaAs/GaAs HBT의 에미터 오믹 접촉으로 사용하여 제작된 HBT 소자의 고주파 특성을 측정한 결과, 차단 주파수가 각각 63.9 ㎓ 및 74.4 ㎓로, 또한 최대공진 주파수가 각각 50.1 ㎓ 및 52.5 ㎓로 우수한 작동특성을 보였다.

• 한국재료학회지
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• 제13권7호
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• pp.465-472
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• 2003

Pd/Ge/Ti/Pt and Pd/Ge/Pd/Ti/Au ohmic contacts to n-type InGaAs were investigated for applications to AlGaAs/GaAs HBT emitter ohmic contacts. In the Pd/Ge/Ti/Pt ohmic contact minimum specific contact resistivity of $3.7${\times}$10^{-6}$ $\Omega$$\textrm{cm}^2$ was achieved by rapid thermal annealing at $^400{\circ}C$/10 sec. In the Pd/Ge/Ti/Au ohmic contact, minimum specific contact resistivity of $1.1${\times}$10^{-6}$ $\Omega$$\textrm{cm}^2$ was achieved by annealing at 40$0^{\circ}C$/10 sec but the ohmic performance was degraded with increasing annealing temperature due to the reaction between the ohmic contact materials and the InGaAs substrate. However, non-spiking planar interface and relatively good ohmic contact (high-$10^{-6}$ /$\Omega$$\textrm{cm}^2$) were maintained after annealing at $450^{\circ}C$/10 sec. Therefore, these thermally stable ohmic contact systems are promising candidates for compound semiconductor devices. RF performance of the AlGaAs/GaAs HBT was also examined by employing the Pd/Ge/Ti/Pt and Pd/Ge/Pd/Ti/Au systems as emitter ohmic contacts. Cutoff frequencies were 63.5 ㎓ and 65.0 ㎓, respectively, and maximum oscillation frequencies were 50.5 ㎓ and 51.3 ㎓, respectively, indicating very successful high frequency operations.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2003년도 춘계학술발표회 초록집
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• pp.53-53
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• 2003

Plasma polymerized organic thin films were deposited on Si(100) glass and metal substrates using thiophene and ethylcyclohexane precursors by PECVD method. In order to compare electrochemical properties of the as-grown thin films, the effects of the RF plasma power in the range of 30~100 W. AFM showed that the polymer films with smooth surface and sharp interface could be grown under various deposition conditions. Impedance analyzer was utilized for the determination of I-V curve for leakage current density and C-V for dielectric constants, respectively. To obtain C-V curve, we used a MIM structure of metal(Al)-insulator(plasma polymerized thin film)-metal(Pt) structure. Al as the electrode was evaporated on the thiophene films that grew on Pt coated silicon substrates, and the dielectric constants of the as-grown films were then calculated from C- V data measured at 1MHz. From the electrical property measurements such as I-V and C-V characteristics, the minimum dielectric constant and the best leakage current of thiophene thin films were obtained to be about 3.22 and $1{\;}{\times}10^{-11}{\;}A/cm^2$. However, in case of ethylcyclohexane thin films, the minimum dielectric constant and the best leakage current were obtained to be about 3.11 and $5{\;}{\times}10^{-12}{\;}A/cm^2$.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 II
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• pp.1045-1048
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• 2003

In this paper, we studied plasma damage of MIS capacitor with $Al_2$O$_3$ dielectric film. Using capacitor pattern with the same area but different perimeters, we tried to separate etching damage mechanism and to optimize the dry etching process. After etching both metal and dielectric layer by the same condition, leakage current and C-V measurements were carried out for Pt/A1$_2$O$_3$/Si structures. The flatband voltage shift was appeared in the C-V plot, and it was caused by the variation of the fixed interface charge and the interface trapped charge. From I-V measurement, it was found the leakage current along the periphery could not be ignored. Finally, we established the process condition of RF power 300W, 100mTorr, Ar/Cl$_2$ gas 60sccm as an optimal etching condition.

• 한국자기학회지
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• 제11권2호
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• pp.72-77
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• 2001

DC 마그네트론 방식으로 제조한 PtMn계 상부층형(top) 스핀밸브 박막을 반강자성층인 PtM의 fcc (111) 구조에서 fat (111)구조 천이를 위하여 27$0^{\circ}C$에서 3 kOe의 외부자장을 가해주면서 일차적인 열처리를 한 후, 이차적으로 무자장 열처리를 하여 상온에서 자기적 특성을 조사하였다. Si/A1$_2$O$_3$ (500$\AA$)/Ta(50$\AA$)NiFe(40$\AA$)/CoFe(17$\AA$)/Cu(28$\AA$)/CoFe (30$\AA$)PtMn(200$\AA$)Ta(50$\AA$) top 스핀밸브 시료에서 자기저항비를 조사한 결과 열처리 온도가 높아질수록 자기저항비가 완만히 감소하나 325 $^{\circ}C$ 이상에서 급격히 감소하여 1 %까지 감소하는 것을 확인하였으며, 이것은 열처리 온도가 높아질수록 반강자성층과 피고정층사이의 교환 결합력이 약해지는 것에 기인하는 것으로 판단하였다. 열처리 온도 증가에 따른 교환 바이어스 자장은 325 $^{\circ}C$ 이상에서 급격히 감소하였고, 고정층과 자유층사이의 상호 결합 세기(interlayer coupling field, $H_{int}$)는 $325^{\circ}C$ 이상에서 크게 증가하였는데, 이것은 열처리 온도가 증가함에 다라 Mn의 상호 확산(inter-diffusion)dl 증가하여 계면에서의 거칠기(roughness)가 커지기 때문이라고 생각하였다. 이와 같은 결과에서 PtMn 스핀밸브의 급격한 자기적 특성변화가 일어나는 열처리 온도가 PtMn계 스핀밸브 박막의 블로킹 온도(blocking temperature, $T_b$)와 잘 일치함을 호가인할 수 있었다.

• 전자공학회논문지A
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• 제31A권12호
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• pp.56-63
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• 1994

The effects of sulfur treatments on the barrier heithts of Schottky contacts and the interface-state density of metal-insulator-semiconductor (MIS) capacitors on InP have been investigated. Schottky contacts were formed by the evaporation of Al, Au, and Pt on n-InP substrate before and after (NH$_{4}$)$_{2}$S$_{x}$ treatments, respectively. The barrier height of InP Schottky contacts was measured by their current-voltage (I-V) and capacitance-voltage (C_V) characteristics. We observed that the barrier heights of Schottky contacks on bare InP were 0.35~0.45 eV nearly independent of the metal work function, which is known to be due to the surface Fermi level pinning. In the case of sulfur-treated Au/InP ar Pt/InP Schottky diodes, However, the barrier heights were not only increased above 0.7 eV but also highly dependent on the metal work function. We have also investigated effects of (NH$_{4}$)$_{2}$S$_{x}$ treatments on the distribution of interface states in Si$_{3}$N$_{4}$InP MIS diodes where Si$_{3}$N$_{4}$ was provided by plasma enhanced chemical vapor deposition (PECVD). The typical value of interface-state density extracted feom 1 MHz C-V curve of sulfur-treated SiN$_{x}$/InP MIS diodes was found to be the order of 5${\times}10^{10}cm^{2}eV^{1}$. This value is much lower than that of MiS diodes made on bare InP surface. It is certain, therefore, that the (NH$_{4}$)$_{2}$S$_{x}$ treatment is a very powerful tool to enhance the barrier heights of Au/n-InP and Pt/n-InP Schottky contacts and to reduce the density of interface states in SiN$_{x}$/InP MIS diode.