• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.177.1-177.1
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• 2015

플라즈마 건식 식각공정은 반도체 공정에 있어 증착 및 세정 공정과 함께 중요한 공정중 하나이다. 기존 연구에서는 높은 식각 속도, 종횡비, 대면적에 대한 균일도 증가를 위하여 플라즈마 이온 밀도의 증가와 전자 온도를 감소시키기 위한 노력을 하고 있으며 플라즈마 식각분석 연구에서는 분광학 분석 기법을 활용하여 플라즈마에 의하여 활성화된 식각 가스와 박막 표면의 반응 메커니즘 연구가 진행 중에 있다. 그러나 지금까지의 플라즈마 식각연구에서는 플라즈마 식각 공정에서 발생되는 박막의 damage에 대한 연구는 전무하다. 본 연구에서는 플라즈마 식각과정에서 발생되는 박막 표면의 damage 연구를 위하여 Nano-indenter에 의한 분석 기법을 제시하였다. Nano-indentation 기법은 박막 표면을 indenter tip으로 직접 인가하여 박막 표면의 기계적 특성을 분석하고 이를 통하여 플라즈마에 의한 박막 표면의 물성 변화를 정량적으로 측정한다. 실험에서 플라즈마 소스는 Adaptively Coupled Plasma (ACP)를 사용하였고 식각 가스로는 HBr 가스를 주로 사용하였으며, 플라즈마 소스 파워는 1000 W로 고정 하였다. 연구 결과에 의하면 식각공정 챔버 내 압력이 5, 10, 15 및 20 mTorr로 증가함에 따라 TEOS SiO2 박막의 강도가 7.76, 8.55, 8.88 및 6.29 GPa로 변화되는 것을 측정하였고 bias power에 따라서도 다르게 측정됨을 확인하였다. 이 결과를 통하여 Nano-indentation 분석 기법을 활용하여 TEOS SiO2 박막의 식각공정의 변화에 따른 강도변화를 측정함으로써 플라즈마에 의한 박막 표면의 damage를 정량적으로 측정 가능함을 확인하였다.

• 한국표면공학회지
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• 제49권2호
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• pp.152-158
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• 2016

We investigated the effect of capacitively coupled Ar plasma treatment on contact resistance ($R_c$) and channel sheet resistance ($R_{sh}$) of graphene field effect transistors (FETs), by varying their channel length in the wide range from 200 nm to $50{\mu}m$ which formed the transfer length method (TLM) patterns. When the Ar plasma treatment was performed on the long channel ($10{\sim}50{\mu}m$) graphene FETs for 20 s, $R_c$ decreased from 2.4 to $1.15k{\Omega}{\cdot}{\mu}m$. It is understood that this improvement in $R_c$ is attributed to the formation of $sp^3$ bonds and dangling bonds by the plasma. However, when the channel length of the FETs decreased down to 200 nm, the drain current ($I_d$) decreased upon the plasma treatment because of the significant increase of channel $R_{sh}$ which was attributed to the atomic structural disorder induced by the plasma across the transfer length at the edge of the channel region. This study suggests a practical guideline to reduce $R_c$ using various plasma treatments for the $R_c$ sensitive graphene and other 2D material devices, where $R_c$ is traded off with $R_{sh}$.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1386-1389
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• 2006

In this study, a plasma flat fluorescent lamp having a new structure was fabricated by screen printing technique. Coplanar types of silver electrodes with a dielectric layer were screen-printed on a rear glass plate, and then fired at $550^{\circ}C$ and $580^{\circ}C$, respectively. Phosphor was spin-coated on the dielectric layer with firing at $490^{\circ}C$. Several types of lamps were designed and its properties wee investigated with electrode shape, gas pressure, etc.

• Tribology and Lubricants
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• 제19권2호
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• pp.109-115
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• 2003

Nanotribological characteristics between a Si$_3$N$_4$ AFM tip and hydrophobic thin films were experimentally studied. Tests were performed to measure the nano adhesion and friction in both AFM (atomic force microscope) and LFM (lateral force microscope) modes in various .ranges of normal load. Plasma-modified thin polymeric films were deposited on Si-wafer (100). Results showed that wetting angle of plasma-modified thin polymeric film increased with the treating time, which resulted in the hydrophobic surface and the decrease of adhesion and friction. Nanotribological characteristics of these surfaces were compared with those of other hydrophobic surfaces, such as DLC, OTS and IBAD-Ag coated surfaces. Those of OTS coated surface were superior to those of others, though wetting angle of plasma-modified thin polymeric film is higher.

• 한국재료학회지
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• 제19권2호
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• pp.68-72
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• 2009

This study investigated dry etching of acrylic in capacitively coupled $SF_6$, $SF_6/O_2$ and $SF_6/CH_4$ plasma under a low vacuum pressure. The process pressure was 100 mTorr and the total gas flow rate was fixed at 10 sccm. The process variables were the RIE chuck power and the plasma gas composition. The RIE chuck power varied in the range of $25{\sim}150\;W$. $SF_6/O_2$ plasma produced higher etch rates of acrylic than pure $SF_6$ and $O_2$ at a fixed total flow rate. 5 sccm $SF_6$/5 sccm $O_2$ provided $0.11{\mu}m$/min and $1.16{\mu}m$/min at 25W and 150W RIE of chuck power, respectively. The results were nearly 2.9 times higher compared to those at pure $SF_6$ plasma etching. Additionally, mixed plasma of $SF_6/CH_4$ reduced the etch rate of acrylic. 5 sccm $SF_6$/5 sccm $CH_4$ plasma resulted in $0.02{\mu}m$/min and $0.07{\mu}m$/min at 25W and 150W RIE of chuck power. The etch selectivity of acrylic to photoresist was higher in $SF_6/O_2$ plasma than in pure $SF_6$ or $SF_6/CH_4$ plasma. The maximum RMS roughness (7.6 nm) of an etched acrylic surface was found to be 50% $O_2$ in $SF_6/O_2$ plasma. Besides the process regime, the RMS roughness of acrylic was approximately $3{\sim}4\;nm$ at different percentages of $O_2$ with a chuck power of 100W RIE in $SF_6/O_2$ plasma etching.

• 한국재료학회지
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• 제19권3호
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• pp.132-136
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• 2009

This study investigates GaAs dry etching in capacitively coupled $BCl_3/N_2$ plasma at a low vacuum pressure (>100 mTorr). The applied etch process parameters were a RIE chuck power ranging from $100{\sim}200W$ on the electrodes and a $N_2$ composition ranging from $0{\sim}100%$ in $BCl_3/N_2$ plasma mixtures. After the etch process, the etch rates, RMS roughness and etch selectivity of the GaAs over a photoresist was investigated. Surface profilometry and field emission-scanning electron microscopy were used to analyze the etch characteristics of the GaAs substrate. It was found that the highest etch rate of GaAs was $0.4{\mu}m/min$ at a 20 % $N_2$ composition in $BCl_3/N_2$ (i.e., 16 sccm $BCl_3/4$ sccm $N_2$). It was also noted that the etch rate of GaAs was $0.22{\mu}m/min$ at 20 sccm $BCl_3$ (100 % $BCl_3$). Therefore, there was a clear catalytic effect of $N_2$ during the $BCl_3/N_2$ plasma etching process. The RMS roughness of GaAs after etching was very low (${\sim}3nm$) when the percentage of $N_2$ was 20 %. However, the surface roughness became rougher with higher percentages of $N_2$.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2009년도 춘계학술대회 논문집
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• pp.230-230
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• 2009

• 한국전기전자재료학회논문지
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• 제20권11호
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• pp.943-947
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• 2007

The effect of hydrogen and oxygen plasma treatments on the structural properties of carbon nanotube(CNT) has been systematically investigated. As the plasma power was increased, nano particles were appeared at the surface of CNTs. At high plasma power(300 Watt), the structure of CNT was changed from nanotube type to nano particles. However, in case of hydrogen plasma treatment, there was no change in microstructure of CNT. From the Raman analysis, the crystallinity of CNT was deteriorated by the plasma treatment, regardless of gas types.

• Transactions on Electrical and Electronic Materials
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• 제11권4호
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• pp.186-189
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• 2010

Nano-sized MgO single crystal powders have recently been reported to emit ultraviolet by stimulation of electrons in a vacuum. In this study, nanocrystalline MgO powders were applied to a xenon plasma flat fluorescent lamp (FFL) for a liquid crystal display backlight to improve its emission efficiency through the extra ultraviolet from the nano-MgO crystals. For comparison, a MgO nano-thin film was applied directly on the phosphors inside a lamp panel through e-beam evaporation. Adding MgO nano-crystal powders to the phosphors improved the luminance and efficiency of FFLs by around 20% and MgO nano-crystal coverage of 40% of the phosphor provided the best FFL emission characteristics; however, application of MgO thin film to the phosphors degraded the emission characteristics, even compared to FFLs without MgO. This was due to insufficient ultraviolet stimulation of the phosphors and the crystallinity and low secondary electron coefficient of the MgO.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.251-252
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• 2012

Recently, the growing interest in organic microelectronic devices including OLEDs has led to an increasing amount of research into their many potential applications in the area of flexible electronic devices based on plastic substrates. However, these organic devices require a gas barrier coating to prevent the permeation of water and oxygen because organic materials are highly susceptible to water and oxygen. In particular, high efficiency OLEDs require an extremely low Water Vapor Transition Rate (WVTR) of $1{\times}10^{-6}g/m^2$/day. The Key factor in high quality inorganic gas barrier formation for achieving the very low WVTR required ($1{\times}10^{-6}g/m^2$/day) is the suppression of defect sites and gas diffusion pathways between grain boundaries. In this study, we developed an $Al_2O_3$ nano-crystal structure single gas barrier layer using a Neutral Beam Assisted Sputtering (NBAS) process. The NBAS system is based on the conventional RF magnetron sputtering and neutral beam source. The neutral beam source consists of an electron cyclotron Resonance (ECR) plasma source and metal reflector. The Ar+ ions in the ECR plasma are accelerated in the plasma sheath between the plasma and reflector, which are then neutralized by Auger neutralization. The neutral beam energies were possible to estimate indirectly through previous experiments and binary collision model. The accelerating potential is the sum of the plasma potential and reflector bias. In previous experiments, while adjusting the reflector bias, changes in the plasma density and the plasma potential were not observed. The neutral beam energy is controlled by the metal reflector bias. The NBAS process can continuously change crystalline structures from an amorphous phase to nano-crystal phase of various grain sizes within a single inorganic thin film. These NBAS process effects can lead to the formation of a nano-crystal structure barrier layer which effectively limits gas diffusion through the pathways between grain boundaries. Our results verify the nano-crystal structure of the NBAS processed $Al_2O_3$ single gas barrier layer through dielectric constant measurement, break down field measurement, and TEM analysis. Finally, the WVTR of $Al_2O_3$ nano-crystal structure single gas barrier layer was measured to be under $5{\times}10^{-6}g/m^2$/day therefore we can confirm that NBAS processed $Al_2O_3$ nano-crystal structure single gas barrier layer is suitable for OLED application.