• Korean Journal of Materials Research
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• v.29 no.8
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• pp.463-468
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• 2019

The electrical and interfacial properties of $HfO_2/Al_2O_3$ and $Al_2O_3/HfO_2$ dielectrics on AlN/p-Ge interface prepared by thermal atomic layer deposition are investigated by capacitance-voltage(C-V) and current-voltage(I-V) measurements. In the C-V measurements, humps related to mid-gap states are observed when the ac frequency is below 100 kHz, revealing lower mid-gap states for the $HfO_2/Al_2O_3$ sample. Higher frequency dispersion in the inversion region is observed for the $Al_2O_3/HfO_2$ sample, indicating the presence of slow interface states A higher interface trap density calculated from the high-low frequency method is observed for the $Al_2O_3/HfO_2$ sample. The parallel conductance method, applied to the accumulation region, shows border traps at 0.3~0.32 eV for the $Al_2O_3/HfO_2$ sample, which are not observed for the $Al_2O_3/HfO_2$ sample. I-V measurements show a reduction of leakage current of about three orders of magnitude for the $HfO_2/Al_2O_3$ sample. Using the Fowler-Nordheim emission, the barrier height is calculated and found to be about 1.08 eV for the $HfO_2/Al_2O_3$ sample. Based on these results, it is suggested that $HfO_2/Al_2O_3$ is a better dielectric stack than $Al_2O_3/HfO_2$ on AlN/p-Ge interface.

• Journal of the Korean Ceramic Society
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• v.24 no.1
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• pp.33-40
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• 1987

The investigation includes phase equilibria of Al2O3-HfO2 Cr2O3-ZrO2, Cr2O3-HfO2, Al2O3-Cr2O3-ZrO2, Al2O3-Cr2O3-HfO2, Al2O3-ZrO2-HfO2, Cr2O3-ZrO2-HfO2, Al2O3-Cr2O3-ZrO2-HfO2. In the systems the solubility near the end members has been studied at 1500$^{\circ}C$ and 1600$^{\circ}C$, respectively. Selective Compositions were investigated in the area of the guarternary system where the phae relation was examined.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.304.2-304.2
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• 2016

Hafnium oxide-aluminum oxide (HfO2-Al2O3) dielectric films have been fabricated by Pulsed Laser Deposition (PLD), and their properties are studied in comparison with HfO2 films. As a gate dielectric of the TFT, in spite of its high dielectric constant, HfO2 has a small energy band gap and microcrystalline structure with rough surface characteristics. When fabricated by the device, it has the drawback of generating a high leakage current. In this study, the HfAlO films was obtained by Pulsed Laser Deposition with HfO2-Al2O3 target(chemical composition of (HfO2)86wt%(Al2O3)14wt%). The characteristics of the thin Film have been investigated by x-ray diffraction (XRD), atomic force microscopy (AFM) and spectroscopic ellipsometer (SE) analyses. The X-ray diffraction studies confirmed that the HfAlO has amorphous structure. The RMS value can be compared to the surface roughness via AFM analysis, it showed HfAlO thin Film has more lower properties than HfO2. The energy band gap (Eg) deduced by spectroscopic ellipsometer was increased. HfAlO films was expected to improved the interface quality between channel and gate insulator. Apply to an oxide thin Film Transistors, HfAlO may help improve the properties of device.

• Transactions on Electrical and Electronic Materials
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• v.15 no.3
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• pp.164-169
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• 2014

We investigated the etching characteristics of $HfAlO_3$ thin films in $O_2/Cl_2/Ar$ and $O_2/BCl_3/Ar$ gas, using a high-density plasma (HDP) system. The etch rates of the $HfAlO_3$ thin film obtained were 30.1 nm/min and 36 nm/min in the $O_2/Cl_2/Ar$ (3:4:16 sccm) and $O_2/BCl_3/Ar$ (3:4:16 sccm) gas mixtures, respectively. At the same time, the etch rate was measured as a function of the etching parameter, namely as the process pressure. The chemical states on the surface of the etched $HfAlO_3$ thin films were investigated by X-ray photoelectron spectroscopy. Auger electron spectroscopy was used for elemental analysis on the surface of the etched $HfAlO_3$ thin films. These surface analyses confirm that the surface of the etched $HfAlO_3$ thin film is formed with nonvolatile by-product. Also, Cl-O can protect the sidewall due to additional $O_2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.382-382
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• 2010

The etch characteristics of the $HfAlO_3$ thin films and selectivity of $HfAlO_3$ to $SiO_2$ in $Cl_2/BCl_3$/Ar plasma were investigated in this work. The maximum etch rate was 108.7 nm/min and selectivity of $HfAlO_3$ to $SiO_2$ was 1.11 at $Cl_2$(3sccm)/$BCl_3$(4sccm)/Ar(16sccm), RF power of 500 W, DC-bias voltage of - 100 V, process pressure of 1 Pa and substrate temperature of $40^{\circ}C$. As increasing RF power and DC-bias voltage, etch rates of the $HfAlO_3$ thin films increased. Whereas as decreasing of the process pressure, those of the $HfAlO_3$ thin films were increased. The chemical reaction on the surface of the etched the $HfAlO_3$ thin films was investigated with X-ray photoelectron spectroscopy (XPS).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.129-130
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• 2009

The P/E characteristics of $HfO_2$ CTF memory capacitor with $SiO_2/HfO_2/Al_2O_3$(OHA) engineered tunnel barrier were investigated. After a growth of thermal oxide with a thickness of 2 nm, 1 nm $HfO_2$ and 3 $Al_2O_3$ layers were deposited by atomic layer deposition (ALD) system. The band offset was calculated by analysis of conduction mechanisms through Fowler-Nordheim (FN) plot and Direct Tunneling (DT) plot. Moreover the PIE characteristics of $HfO_2$ CTF memory capacitor with OHA tunnel barrier was presented.

• Journal of the Korean Ceramic Society
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• v.22 no.6
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• pp.42-52
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• 1985

Several $Al_2O_3$-based polycrystalline which had different dopant ratio in the range of 0.5mol% were prepared by doping pure $Cr_2O_3$ $HfO_2$. Single crystalline which had same composition with above polycrystalline were made by means of floating zone method. This study examined the role of each dopant for enhancing the mechanical properties of $Al_2O_3$-based Ceramics. Optical micrographs $({ imes}200)$ of $Al_2O_3-Cr_2O_3$ single crystal showing not only radial crack (rc) on the specimen surface but median crack(mc) and lateral crack(lc) under surface at the edge of indentation mark. Fracture toughness of Al2O3-based Ceramics was increased with $ZrO_2$ content. Alloying effect of $Cr_2O_3$ contributed to the hardness of $Al_2O_3$ based ceramics.

• Korean Journal of Metals and Materials
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• v.48 no.3
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• pp.256-261
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• 2010

In this work, high-k dielectric stacks of $HfO_2$ and $HfO_2$/$Al_2O_3$/$HfO_2$ (HAH) were deposited on $SiO_2/Si$ substrates by atomic layer deposition as charge trapping layers in charge trapping devices. The structural stability and the charge trapping characteristics of such stacks were investigated using Metal-Alumina-Hafnia-Oxide-Silicon (MAHOS) structure. The surface roughness of $HfO_2$ was stable up to 11 nm with the insertion of 0.2 nm thick $Al_2O_3$. The effect of the thickness of the HAH stack and the thickness of intermediate $Al_2O_3$ on charge trapping characteristics were investigated for MAHOS structure under various gate bias pulse with duration of 100 ms. The threshold voltage shift after programming and erase showed that the memory window was increased with increasing bias on gate. However, the programming window was independent of the thickness of HAH charge trapping layers. When the thickness of $Al_2O_3$insertion increased from 0.2 nm to 1 nm, the erase window was decreased without change in the programming window.

• Journal of IKEEE
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• v.25 no.3
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• pp.501-505
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• 2021

In this study, we fabricated amorphous indium-tin-gallium-zinc-oxide thin-film transistors (a-ITGZO TFTs) with gate dielectrics of HfO₂ and the mixed layers of HfO₂ and Al₂O₃, and investigated the effect of gate dielectric on electrical characteristics of a-ITGZO TFTs. When only HfO₂ was used as the gate dielectric, the mobility and subthreshold swing (SS) were 32.3 cm²/Vs and 206 mV/dec. For the a-ITGZO TFTs with gate dielectric made of HfO₂ and Al₂O (2:1, 1:1), the mobilities and SS were 26.4 cm²/Vs (2:1), 16.8 cm²/Vs(1:1), 160 mV/dec (2:1) and 173 mV/dec (1:1). On the other hand, the hysteresis window shown in transfer curves of the a-ITGZO TFTs was lessened from 0.60 to 0.09 V by the increase of Al₂O₃ ratio in gate dielectric, indicating that the interface trap density between the gate dielectric and channel layer decreases due to Al₂O₃.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2003.12a
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• pp.42-44
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• 2003

최근 logic 소자의 gate oxide로 기존의 $SiO_2$, SiON보다 고유전, 작은 누설전류를 가지는 물질의 개발이 중요한 이슈가 되고 있다. 본 실험실에서는 Si 기판위에 $HfO_2$ 를 바로 증착하는 경우, 기판의 Si 이박막내로 확산하여 유전율이 저하되는 문제점을 인식하고, 기판과 $HfO_2$ 사이에 $AlO_x$를 방지막으로 사용하였다. 이 때, $AlO_x$의 Al precursor 는 TMA 로 고정하고, 산화제로는 $H_2O, O_2$-plasma, O_3$ 를 각각 사용하였다. 모든 $AlO_x/HfO_y$ 박막에서 매우 우수한 누설전류특성을 얻을 수 있었는데, 특히 $O_3$ 를 산화제로 사용한 $AlO_x$ 방지막의 경우 가장 우수한 특성을 보였다. 또한 질소 분위기에서 $800^{\circ}C$ 10 분간 열처리한 후, 방지막을 사용한 모든 경우에서 보다 향상된 열적 안정성을 관찰할 수 있었다.