• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.04a
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• pp.78-80
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• 2006

The hybrid thin-film (HTF) passivation layer composed of the Ultra Violet (UV) curable acrylate layer and MS-31 (MgO:$SiO_2$=3:1wt%) layer was adopted in organic light emitting device (OLEO) to protect organic light emitting materials from penetrations of oxygen and water vapors. The results showed that the HTF layer possessed a very low WVTR value of lower than $0.007gm/m^{2+}day$ at $37.8^{\circ}C$ and 100% RH. This value was within the limited range of the sensitivity of WVTR measurements. And the lifetime of the HTF passivated device became almost three times longer than that of the bare device. The HTF on the OLEO was found to be very effective in protect what from the penetrations of oxygen and moisture.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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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.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.26 no.2
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• pp.77-83
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• 2020

A series of foamed plastic sheets containing biomass (as HMR container) were developed via different foaming process temperatures, and their density, porosity, WVTR, and pore morphology were evaluated. Thermal stability of samples during re-heating the food in oven, change in morphology, density, porosity, and WVTR were investigated using a simulated thermal shock process according to MIL-STD-883E assay. As such, the pore size of samples was generally increased with increasing temperature of the foaming process. It can be explained that as foaming temperature increased, the viscosity of molten resins and the repulsive force against pore expansion decreased. In addition, an increase in the thermal shock cycle reduced the pore size and WVTR, while density increased because high temperature treatment that softened the sheet matrix was followed by a low temperature incubation, which contracted the matrix, thereby changing the physical and morphological properties of samples. However, an insignificant change in density was observed and WVTR tended to be decreased, indicating that as-prepared foamed plastic sheets could be used as a high thermal stable container for HMR application. Therefore, it found that the properties of newly developed HMR containers containing biomass were dependent on the foaming process temperature. Moreover, to better understanding of these newly developed containers, further investigations dealing with foaming process temperature based on various food items and cooking conditions are needed.

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.05a
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• pp.24.1-24.1
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• 2007

• ETRI Journal
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• v.27 no.5
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• pp.545-550
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• 2005

We have carried out the fabrications of a barrier layer on a polyethersulfon (PES) film and organic light emitting diode (OLED) based on a plastic substrate by means of atomic layer deposition (ALD). Simultaneous deposition of 30 nm $AlO_x$ film on both sides of the PES film gave a water vapor transition rate (WVTR) of $0.062 g/m^2/day (@38^{\circ}C,\;100%\;R.H.)$. Further, the double layer of 200 nm $SiN_x$ film deposited by plasma enhanced chemical vapor deposition (PECVD) and 20 nm $AlO_x$ film by ALD resulted in a WVTR value lower than the detection limit of MOCON. We have investigated the OLED encapsulation performance of the double layer using the OLED structure of ITO / MTDATA (20 nm) / NPD (40 nm) / AlQ (60 nm) / LiF (1 nm) / Al (75 nm) on a plastic substrate. The preliminary life time to reach 91% of the initial luminance $(1300 cd/m^2)$ was 260 hours for the OLED encapsulated with 100 nm of PECVD-deposited $SiN_x$ and 30 nm of ALD-deposited $AlO_x$.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.249-249
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• 2012

최근 주목받고 있는 Flexible Organic Light Emitting Diode (OLED) display에서는 Flexible 특성이 요구된다. 이는 현재 쓰이는 유리기판 대신 플라스틱기판으로 만들어야 가능하다. 하지만 플라스틱기판은 구성물질로 유기물을 사용하므로 수분과 산소의 투과에 매우 취약하다. 이는 장시간 사용 시 기판 위에 제작된 소자성능저하를 야기하는 등의 소자 신뢰도에 치명적 결함을 갖게 하는 원인이 된다. 따라서 기판 위의 소자를 보호할 수 있는 봉지기술 개발이 필요한데 가장 잘 알려진 플라스틱 기판에 적합한 Barrier기술로 유기물과 무기물을 교대로 적층하는 기술[1] 등이 있다. 본 연구에서는 PE-CVD 공정기술을 이용한 Flowable Oxide 박막과 ALD 공정기술을 이용한 Al2O3 무기물 박막을 적층하여 봉지박막을 구성하려 한다. Flowable Oxide는 저온공정이 가능하며 높은 증착속도와 뛰어난 Gap fill 특성을 가지고 있는데 이는 플라스틱기판의 엉성한 분자구조를 치밀하게 만들 것으로 예상되며 표면의 Pin-hole 또한 쉽게 채우는 특성이 있다. 실험은 Polyethylene Naphthalate (PEN) film 위에 PE-CVD 공정을 이용하여 Flowable Oxide를 증착하고, 그 후에 ALD 공정을 이용하여 Al2O3을 적층한 것을 하나의 샘플로 하였다. 샘플의 분석은 Ca test를 이용한 Water Vapor Transmission rate(WVTR)과 FT-IR, FE-SEM을 이용하여 분석하였다. FT-IR로 박막의 구성요소를 확인 하고 FE-SEM으로 박막의 Cross section image를 얻을 수 있었으며 또한 $4.85{\times}10^{-5}g/m^2$ day의 초기 WVTR 값을 얻을 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.270-270
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• 2016

We fabricated an organic-inorganic nano laminated encapsulation layer using molecular layer deposition (MLD) combined with atomic layer deposition (ALD). The $Al_2O_3$ inorganic layers as an effective single encapsulation layer were deposited at 80 degree C using ALD with alternating surface-saturation reactions of TMA and $H_2O$. A self-assembled organic layers (SAOLs) were fabricated at the same temperature using MLD. MLD and ALD deposition process were performed in the same reaction chamber. The prepared SAOL-$Al_2O_3$ organic-inorganic nano laminate films exhibited good mechanical stability and excellent encapsulation property. The measurement of water vapor transmission rate (WVTR) was performed with Ca test. We controlled thickness-ratio of organic and inorganic layer, and specific ratio showed a lowest WVTR value. Also this encapsulation layer contained very few pin-holes or defects which were linked in whole area by defect test. To apply into real OLEDs panels, we controlled a film stress from tensile to compressive and flexibility defined as an elastic modulus with organic-inorganic ratio. It has shown that OLEDs panel encapsulated with nano laminate layer exhibits better properties than single layer encapsulated in acceleration conditions. These results indicate that the organic-inorganic nano laminate thin films have high potential for flexible display applications.

• Applied Chemistry for Engineering
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• v.29 no.4
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• pp.484-487
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• 2018

In this paper, the optical and electrical properties of ytterbium films were studied for water vapor transmission rate (WVTR) analysis of encapsulation films used in organic electronic devices. Ytterbium thin films show a wide range of light transmittance (70-10%) and resistivity ($6.0-0.16m{\Omega}{\cdot}cm$) depending on various film thicknesses (20-100 nm). The Yb thin films were oxidized with moisture and its transmittance and resistance changed in real time. As a result, the WVTR of parylene and aluminum nitride (AlN) laminated thin encapsulation film was measured to be $4.3{\times}10^{-3}g/m^2{\cdot}day$ with the 25 nm thick ytterbium thin film.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.269-270
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• 2005

A hybrid passivation method using parylene and silicon dioxide combination layer for a flexible organic light emitting diode (FOLED) was applied on a polycarbonate substrate. A parylene coating by vapor polymerization method is a highly effective passivation process for the FOLED, and it applies all top surface and the edges of the FOLED device. In order to minimize the permeation of moisture and oxygen from the top surface of the device, an additional layer of silicon dioxide was deposited over the parylene coated layer. It was found that the water vapor transmittance rate (WVTR) of parylene (15 m-in-thickness) / SiO2 (0.3$\mu$m-in-thickness) combination layers deposited on polycarbonate film was decreased under the value of 10-3 g/m2day. The FOLED with the hybrid passivation showed remarkably longer lifetime characteristics in the ambient conditions than the non-passivated FOLED. The lifetime of the passivated FOLED was 400 hours and it was more than ten times over the lifetime of the convectional non-passivated FOLED.

• Journal of the Semiconductor & Display Technology
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• v.16 no.1
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• pp.1-5
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• 2017

Encapsulation of organic based devices is essential issue due to easy deterioration of organic material by water vapor. Thin layer of encapsulation film is required to preserve transparency yet protecting materials in it. Atomic layer deposition(ALD) is a promising solution because of its low temperature deposition and quality of the deposited film. $Al_2O_3$ or $Al_2O_3/TiO_2/Al_2O_3$ multilayer film has shown excellent environmental protection characteristics despite of thin thicknesses of the films. $Al_2O_3/TiO_2/Al_2O_3$ multilayer and 1.5 dyad layer of $Al_2O_3/polymer/Al_2O_3$ deposited by ALD was measured to have water vapor transmittance rate(WVTR) well below the detection limit($5.0{\times}10^{-5}g/m^2day$) of MOCON Aquatran 2 equipment.