• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.08a
• /
• pp.288-288
• /
• 2012

The oxidation characteristics of tungsten line pattern during the carbon-based mask layer removal process using oxygen plasmas and the reduction characteristics of the WOx layer formed on the tungsten line surface using hydrogen plasmas have been investigated for sub-50 nm patterning processes. The surface oxidation of tungsten line during the mask layer removal process could be minimized by using a low temperature ($300^{\circ}K$) plasma processing instead of a high temperature plasma processing for the removal of the carbon-based material. Using this technique, the thickness of WOx on the tungsten line could be decreased to 25% of WOx formed by the high temperature processing. The WOx layer could be also completely removed at the low temperature of $300^{\circ}K$ using a hydrogen plasma by supplying bias power to the tungsten substrate to provide an activation energy for the reduction. When this oxidation and reduction technique was applied to actual 40 nm-CD device processing, the complete removal of WOx formed on the sidewall of tungsten line could be observed.

• Korean Journal of Materials Research
• /
• v.22 no.3
• /
• pp.118-122
• /
• 2012

We synthesized porous $Co_3O_4/RuO_2$ composite using the soft template method. Cetyl trimethyl ammonium bromide (CTAB) was used to make micell as a cation surfactant. The precipitation of cobalt ion and ruthenium ion for making porosity in particles was induced by $OH^-$ ion. The porous $Co_3O_4/RuO_2$ composite was completely synthesiszed after anealing until $250^{\circ}C$ at $3^{\circ}C$/min. From the XRD ananysis, we were able to determine that the porous $Co_3O_4$/RuO2 composite was comprised of nanoparticles with low crystallinity. The shape or structure of the porous $Co_3O_4/RuO_2$ composite was studied by FE-SEM and FE-TEM. The size of the porous $Co_3O_4/RuO_2$ composite was 20~40 nm. From the FE-TEM, we were able to determine that porous cavities were formed in the composite particles. The electrochemical performance of the porous $Co_3O_4/RuO_2$ composite was measured by CV and charge-discharge methods. The specific capacitances, determined through cyclic voltammetry (CV) measurement, were ~51, ~47, ~42, and ~33 F/g at 5, 10, 20, and 50 mV/sec scan rates, respectively. The specific capacitance through charge-discharge measurement was ~63 F/g in the range of 0.0~1.0 V cutoff voltage and 50 mAh/g current density.

• Journal of Surface Science and Engineering
• /
• v.50 no.5
• /
• pp.345-351
• /
• 2017

A double-layered anti-reflective coating with hydrophilic/abrasion-resistant properties was studied using anatase titanium dioxide($TiO_2$) and silicon oxycarbide($SiO_xC_y$) thin film. $TiO_2$ and $SiO_xC_y$ thin films were sequentially deposited on a glass substrate by DC sputtering and PECVD, respectively. The optical properties were measured by UV-Vis-NIR spectrophotometer. The abrasion-resistance and the hydrophilicity were observed by a taber abrasion tester and a contact angle analyzer, respectively. The $TiO_2/SiO_xC_y$ double-layer thin film had an average transmittance of 91.3%, which was improved by 10% in the visible light region (400 to 800 nm) than that of the $TiO_2$ single-layer thin film. The contact angle of $TiO_2/SiO_xC_y$ film was $6.9^{\circ}$ right after UV exposure. After 9 days from the exposure, the contact angle was $10.2^{\circ}$, which was $33^{\circ}$ lower than that of the $TiO_2$ single-layer film. By the abrasion test, $SiO_xC_y$ film showed a superior abrasion-resistance to the $TiO_2$ film. Consequently, the $TiO_2/SiO_xC_y$ double-layer film has achieved superior anti-reflection, hydrophilicity, and abrasion resistance over the $TiO_2$ or $SiO_xC_y$ single-layer film.

• Elastomers and Composites
• /
• v.50 no.2
• /
• pp.126-131
• /
• 2015

$C_{60}$ nanowhiskers were synthesized from $C_{60}$ by liquid-liquid interfacial precipitation (LLIP) using $C_{60}$-saturated toluene and isopropyl alcohol. The $WO_3$ nanoparticles were synthesized by adding $3.8{\times}10^{-4}$ mole amount of ammonium metatungstate hydrate ($H_{26}N_6O_{40}W_{12}{\cdot}H_2O$) to 500 ml of distilled water, and the resulting solution was heated on a hot plate for 4 h. The $C_{60}$ nanowhiskers/$WO_3$ nanocomposites were prepared with $C_{60}$ nanowhiskers and $WO_3$ nanoparticles in an electric furnace at $700^{\circ}C$ in an argon gas atmosphere for 2 h. The $C_{60}$ nanowhiskers/$WO_3$ nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. UV-vis spectroscopy was used to evaluate the performance of the $C_{60}$ nanowhiskers/$WO_3$ nanocomposites as a photocatalyst in the degradation of organic dyes, such as methylene blue (MB) and brilliant green (BG) under ultraviolet light (254 nm).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.30 no.8
• /
• pp.474-478
• /
• 2017

We report on thin-film transistors based on $TiO_x$ pre-annealed by femtosecond laser pulses. A 30-nm thick $TiO_x$ active channel layer was initially deposited by an ALD system. The $TiO_x$ semiconducting films were annealed by irradiation with a femtosecond laser (power: $3W/cm^2$) for 5, 25, and 50s. Atomic force microscopy images revealed that the surface of a $TiO_x$ film without femtosecond laser pre-annealing was relatively rough, while after annealing with femtosecond laser pulses, the surface of the $TiO_x$ films became smooth. With increasing radiation time, the surrounding gas atmosphere could have a larger impact on the $TiO_x$ surface; meanwhile, the thin-film roughness decreased. Thin-film transistors with $TiO_x$ active channels pre-annealed at 50s exhibited good transfer characteristics and an on-to-off current ratio of ${\sim}10^3$.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2017.05a
• /
• pp.123.2-123.2
• /
• 2017

Fe-Ni-Cu 합금 전주를 위하여 황화물 용액에의 상의 열역학적 안정도를 작성하고 전주 조건을 선정하였다. $Fe-Ni-Cu-S-H_2O$ 용액의 열역학적 상의 안정도를 전산모사하기 위한 프로그램은 C#으로 작성하였다. JANAF 자료를 근거한 적정 전주 조건은 $130mA/cm^2$, $50{\sim}55^{\circ}C$, pH 2.4 이었다. XRF을 이용한 Fe-Ni-Cu의 합금 도막의 평균 조성은 Fe-42Ni-1Cu [wt.%] 이었다, 전류밀도가 낮아질수록 Ni과 Cu량은 증가하였다. 구리 농도가 증가하면 표면조도는 60 nm로 변화하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2012.05a
• /
• pp.209-209
• /
• 2012

고 해상도를 요구하는 차세대 디스플레이에서 ITO 박막은 매우 얇은 두께에서 높은 투과율과 고 전도성을 동시에 가져야 한다. 이러한 박막 물성을 함께 가지는 고품질 ITO 초박막을 제조하기 위해서 DC와 RF의 장점을 동시에 가지는 DC/RF 중첩형 마그네트론 스퍼터링법을 이용하여 다양한 $SnO_2$ 함량을 가진 ITO 초박막(~50 nm)을 증착하여 물성 및 미세 구조 변화를 관찰 하였다. 또한, 상온과 결정화 온도 이상에서 증착한 ITO 초박막의 $SnO_2$ 함량에 따른 박막의 전기적, 광학적 거동 및 미세구조의 변화를 확인하는 동시에, RF/(DC+RF) 중첩 비율에 따른 ITO 초박막의 물성 변화를 확인 하였다.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.32 no.2
• /
• pp.45-50
• /
• 2022

Ga₂O₃ thin films were grown on n-type Si substrates at various growth temperatures of 500, 550, 600, 650 and 700℃. The Ga₂O₃ thin films grown at 500℃ and 550℃ were characterized as featureless flat surface. Grown at higher temperatures (600, 650, and 700℃) showed very rough surface morphology. To figure out the annealing effect on the thin films grown at relatively low temperatures (500, 550, 600, 650 and 700℃), the Ga₂O₃ films were thermally treated at 900℃ for 10 minutes. Crystal structure of the Ga₂O₃ films grown at 500 and 550℃ were changed from amorphous to polycrystalline structure with flat surface. Ga₂O₃ film grown at 550℃ was chosen for the fabrication of a Schottky barrier diode (SBD). Electrical properties of the SBDs depend on the thermal treatment were evaluated. A MSM type photodetector was made on the low temperature grown Ga₂O₃ thin film. The photocurrent for the illumination of 266 nm wavelength showed 5.32 times higher than dark current at the operating voltage of 10 V.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.8 no.1
• /
• pp.11-20
• /
• 2008

The structure of 2-bit/cell flash memory device was characterized for sub-50 nm non-volatile memory (NVM) technology. The memory cell has spacer-type storage nodes on both sidewalls in a recessed channel region, and is erased (or programmed) by using band-to-band tunneling hot-hole injection (or channel hot-electron injection). It was shown that counter channel doping near the bottom of the recessed channel is very important and can improve the $V_{th}$ margin for 2-bit/cell operation by ${\sim}2.5$ times. By controlling doping profiles of the channel doping and the counter channel doping in the recessed channel region, we could obtain the $V_{th}$ margin more than ${\sim}1.5V$. For a bit-programmed cell, reasonable bit-erasing characteristics were shown with the bias and stress pulse time condition for 2-bit/cell operation. The length effect of the spacer-type storage node is also characterized. Device which has the charge storage length of 40 nm shown better ${\Delta}V_{th}$ and $V_{th}$ margin for 2-bit/cell than those of the device with the length of 84 nm at a fixed recess depth of 100 nm. It was shown that peak of trapped charge density was observed near ${\sim}10nm$ below the source/drain junction.

• Korean Journal of Materials Research
• /
• v.14 no.5
• /
• pp.328-333
• /
• 2004

Transparent ZnO:Al conductor films for the optoelectronic devices were deposited by using the capacitively coupled DC magnetron sputtering method. The effect of Al doping concentration and discharge power on the electrical and optical properties of the films was studied. The film resistivity of $8.5${\times}$10^{-4}$ $\Omega$-cm was obtained at the discharge power of 40 W with the ZnO target doped with 2 wt% $Al_2$$_O3$. The transmittance of the 840 nm thick film was 91.7% in the visible waves. Increasing doping concentration of 3 wt% $Al_2$$O_3$ in ZnO target results in significant decrease of film resistivity, which may be due to the formation of $Al_2$$O_3$ particles in the as-deposited ZnO:Al film and the reduced ZnO grain sizes. Increasing DC power from 40 to 60 W increases deposition rate by more than 50%, but can induce high defect density in the film, resulting in higher film resistivity.