• Journal of the Microelectronics and Packaging Society
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• v.23 no.2
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• pp.43-47
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• 2016

This paper covers the study on the properties of $TiO_2$ film deposited by atomic layer deposition (ALD) using TTIP and water at various temperatures including the low temperature range of <$150^{\circ}C$. At low deposition temperature, ALD $TiO_2$ films showed uniform growth rate per cycle ($0.3{\AA}/cycle$), good uniformity, smooth surface, and homogenous amorphicity. They also showed good conformality of >80% on the trench structure with the high aspect ratio of up to 75. However, relatively high concentration of impurities (C~4-7 at%) in the film was observed due to low deposition temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.5-5
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• 2009

Thin-film-transistors (TFTs) that can be prepared at low temperatures have attracted much attention because of the great potential for transparent and flexible electronics. One of the mainstreams in this field is the use of organic semiconductors such as pentacene. But device performance of the organic TFTs is still limited due to low field-effect mobility and rapid degradation after exposing to air. Alternative approach is the use of amorphous oxide semiconductors as a channel. Amorphous oxide semiconductors (AOSs) based TFTs showed the fast technological development, because AOS films can be fabricated at room temperature and exhibit the possibility in application like flexible display, electronic paper, and larges solar cells. Among the various AOSs, a-IGZO has lots of advantages because it has high channel mobility, uniform surface roughness and good transparency. [1] The high mobility is attributed to the overlap of spherical s-orbital of the heavy post-transition metal cations. This study demonstrated the effect of the variation in channel thickness from 30nm to 200nm on the TFT device performance. When the thickness was increased, turn-on voltage and subthreshold swing was decreased. The a-IGZO channels and source/drain metals were deposited with shadow mask. The a-IGZO channel layer was deposited on $SiO_2$/p-Si substrates by RF magnetron sputtering, where RF power is 150W. And working pressure is 3m Torr, at $O_2/Ar$ (2/28 sccm) atmosphere. The electrodes were formed with electron-beam evaporated Ti (30 nm) and Au (70 nm) bilayer. Finally, Al (150nm) as a gate metal was thermal-evaporated. TFT devices were heat-treated in a furnace at 250 $^{\circ}C$ and nitrogen atmosphere for 1hour. The electrical properties of the TFTs were measured using a probe-station. The TFT with channel thickness of 150nm exhibits a good subthreshold swing (SS) of 0.72 V/decade and on-off ratio of $1{\times}10^8$. The field effect mobility and threshold voltage were evaluated as 7.2 and 8 V, respectively.

• Polymer(Korea)
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• v.37 no.3
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• pp.373-378
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• 2013

The interfacial adhesion strength is very important in $SiO_x$ deposited PC film for the barrier enhanced polycarbonate (PC) flexible substrate. In this study, PC films were treated by undercoating, UV/$O_3$ and low temperature plasma and then the effect of physical and chemical surface modifications on the interfacial adhesion strength between PC film and $SiO_x$ barrier layer were studied. It was found that untreated PC film shows significantly low interfacial adhesion strength due to the smooth surface and low surface free energy of PC. Low temperature plasma treatments resulted in the increase of both surface roughness and surface free energy due to etching and the appearance of polar molecules on the PC surface. However, UV/$O_3$ treatment only shows the increase of surface free energy by developed polar molecules on the surface. These surface modifications caused the enhancement of surface interfacial strength between PC film and $SiO_x$ barrier. In the case of undercoating, it was found that the increase of surface interfacial strength was achieved by adhesion between various acrylic acid on acrylate coated surface and $SiO_x$ without increase of polar surface energy. In addition, the barrier property is also improved by organic-inorganic hybrid multilayer structure.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.2
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• pp.13-21
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• 2000

Au-black for the application of the long wavelength infrared absorber has been prepared by evaporating Au under nitrogen gas-filled low vacuum condition. Characteristics of the deposited Au-black were carefully investigated through structural analysis, infrared absorbance measurement, and patterning of the layer, all of which are dependent on the deposition condition. High density of micro-cavity that trapped infrared were obtained, and infrared absorbance in the wavelength range from 3 $\mu\textrm{g}$ to 14 $\mu\textrm{g}$ was found to be about 90% when the Au-black layer was produced under the deposition condition of mass Per area of about 600 $\mu\textrm{g}$/cm$^{2}$ and chamber pressure of above 1 Torr. Photoresist lift-off process could be performed to pattern the Au-black, of which mass per area was below 900 $\mu\textrm{g}$/cm/ sup 2/. In view of absorbance, heat capacity, and pattern formation, the deposition condition of chamber pressure of about 1 Tow and mass per area of about 600$\mu\textrm{g}$/cm$^{2}$ was most adequate for preparing the Au-black as an infrared absorber.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.122-122
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• 1999

Graphite with its advantages of high thermal conductivity, low thermal expansion coefficient, and low elasticity, has been widely used as a structural material for high temperature. However, graphite can easily react with oxygen at even low temperature as 40$0^{\circ}C$, resulting in CO2 formation. In order to apply the graphite to high temperature structural material, therefore, it is necessary to improve its oxidation resistive property. Silicon Carbide (SiC) is a semiconductor material for high-temperature, radiation-resistant, and high power/high frequency electronic devices due to its excellent properties. Conventional chemical vapor deposited SiC films has also been widely used as a coating materials for structural applications because of its outstanding properties such as high thermal conductivity, high microhardness, good chemical resistant for oxidation. Therefore, SiC with similar thermal expansion coefficient as graphite is recently considered to be a g행 candidate material for protective coating operating at high temperature, corrosive, and high-wear environments. Due to large lattice mismatch (~50%), however, it was very difficult to grow thick SiC layer on graphite surface. In theis study, we have deposited thick SiC thin films on graphite substrates at temperature range of 700-85$0^{\circ}C$ using single molecular precursors by both thermal MOCVD and PEMOCVD methods for oxidation protection wear and tribological coating . Two organosilicon compounds such as diethylmethylsilane (EDMS), (Et)2SiH(CH3), and hexamethyldisilane (HMDS),(CH3)Si-Si(CH3)3, were utilized as single source precursors, and hydrogen and Ar were used as a bubbler and carrier gas. Polycrystalline cubic SiC protective layers in [110] direction were successfully grown on graphite substrates at temperature as low as 80$0^{\circ}C$ from HMDS by PEMOCVD. In the case of thermal MOCVD, on the other hand, only amorphous SiC layers were obtained with either HMDS or DMS at 85$0^{\circ}C$. We compared the difference of crystal quality and physical properties of the PEMOCVD was highly effective process in improving the characteristics of the a SiC protective layers grown by thermal MOCVD and PEMOCVD method and confirmed that PEMOCVD was highly effective process in improving the characteristics of the SiC layer properties compared to those grown by thermal MOCVD. The as-grown samples were characterized in situ with OES and RGA and ex situ with XRD, XPS, and SEM. The mechanical and oxidation-resistant properties have been checked. The optimum SiC film was obtained at 85$0^{\circ}C$ and RF power of 200W. The maximum deposition rate and microhardness are 2$mu extrm{m}$/h and 4,336kg/mm2 Hv, respectively. The hardness was strongly influenced with the stoichiometry of SiC protective layers.

• Korean Journal of Materials Research
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• v.9 no.8
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• pp.837-842
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• 1999

The Ta/TaN multilayer structure with repeating layers of a poly-crystalline Ta layer of high ductility and a TaN layer of high hardness is expected to exhibit toughness. This paper reports the results on the hardness and the adhesion strength of Ta/TaN multilayers and compositional gradient Ta/TaN layers deposited on the high speed steel substrate by reactive sputtering as a function of annealing temperature. The TaN film deposited with the $N_2$/Ar ratio of 0.4 in the reactive sputtering process exhibits the highest crystallinity, and the highest hardness and the results of scratch test of the Ta/TaN multilayers. The hardness and adhesion strength of the Ta/TaN multilayers becomes deteriorated with increasing the annealing temperature in the heat treatment right after depositing the layers. Therefore, post-annealing treatments are not desirable in the case of the Ta/TaN multilayers from the standpoint of mechanical properties. Also the hardness of Ta/TaN multilayers increases with decreasing the compositional modulation wavelength, but the adhesion property of the layers is nearly independent of the wavelength. On the other hand, the compositional gradient Ta/TaN film exhibits the highest hardness and the value of scratch test for the post-annealing temperatures of 20$0^{\circ}C$ and 40$0^{\circ}C$, respectively. This tendency of the compositional gradient Ta/TaN films differs from that of the Ta/TaN multilayers.

• Korean Journal of Materials Research
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• v.6 no.7
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• pp.723-732
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• 1996

Cu films were deposited by chemical wapor deposition on the as-received substrates (TiN/Si) and three kinds of Cu-seeded substrates (Cu/TiN/Si) which had seeding layer in the thick ness of 5 ${\AA}$ and 130 ${\AA}$ coated by ICB(Ionized Cluster Beam) method. The effect of Cu seeding layers on the growth rate, crystallinity, grain size uniformity and film adhesion strength of final CVD-Cu films was investigated by scanning eletron microscopy(SEM), X-ray diffractometry and scratch test. The growth rate was found to incresase somewhat in the case of ICB-seeding. The XRD patterns of the Cu films on the as-received substrate and ICB Cu-seeded substrates exhibited the diffraction peaks corresponding to FCC phase, but the peak intensity ratio($I_{111}/I_{200}$) of Cu films deposited on the ICB Cu-seeded substrates increased compared with that of Cu films on the as-received substrate. The resistivity of final Cu film on 40 ${\AA}$ seeded substrate was observed as the lowest value, 2.42 $\mu\Omega\cdot$cm compared with other Cu films. In adhesion test, as the seeding thickness increased from zero to 130 ${\AA}$, the adhesion strength increased from 21N to 27N.

• Korean Journal of Materials Research
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• v.7 no.1
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• pp.69-75
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• 1997

Thin films of $Si0_2(1000{\AA})/CoNiCr(400{\AA})/Cr$ were fabricated as a function of Cr thickness by KF magnetron sputtering. The saturation magnetization, coercive force and squareness with annealing temperature for these films were investigated. The values of saturation magnetization of $SiO_2/CoNiCr/Cr$ thin films decreased as the thickness of Cr underlayer increased, whereas coercive force increased as the thickness of Cr underlayer increased. The value of Ms was 600 emu/cc and the maximum value of Hc was 550 Oe. Especially, the value of saturation magnetization was rapidly decreased $SiO_2/CoNiCr/Cr(1700{\AA})$ thin films as the annealing temperature increased And the coercive force increased as the annealing temperature increased When annealing temperature was $650^{\circ}C$, the Ms was reduced to 90 % of the as-deposited film. And the Hc was showed maximum 1600 Oe. It was thought that Cr diffusion into CoNiCr layer reduced the magnetic moment of CoKiCr layer. In addition. Hc might he increased due to grain growth perpendicular to the film plane.

• Journal of the Korean Magnetics Society
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• v.14 no.3
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• pp.99-104
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• 2004

We have studied to understand the barrier and interface qualities and structural changes through measuring temperature dependent spin-polarization as functions of plasma oxidation time and annealing time. Magnetic tunnel junctions consisting of SiO2$_2$/Ta 5/CoFe 17/IrMn 7.5/CoFe 5/Al 1.6-Ox/CoFe 5/Ta 5 (numbers in nm) were deposited and annealed when necessary. A 30 s,40 s oxidized sample showed the lowest spin-polarization values. It is presumed that tunneling electrons were depolarized and scattered by residual paramagnetic Al due to under-oxidation. On the contrary, a 60s, 70 s oxidized sample might have experienced over-oxidation, where partially oxidized magnetic dead layer was formed on top of the bottom CoFe electrode. The magnetic dead layer is known to increase the probability of spin-flip scattering. Therefore it showed a higher temperature dependence than that of the optimum sample (50 s oxidation). temperature dependence of 450 K annealed samples was improved when the as-deposited one compared. But the sample underwent 475 K and 500 K annealing exhibits inferior temperature dependence of spin-polarization, indicating that the over-annealed sample became microstucturally degraded.

• Journal of the Korean earth science society
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• v.30 no.4
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• pp.409-426
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• 2009

In the four sedimentary cores from Yeoja Bay, the analyses of grain size, benthic foraminiferal species compositions, assemblages and statistics were carried out to investigate the effects of late Holocene sea-level change on benthic foraminifera. The core sediments were mainly composed of fine-grained silt and clay. The benthic foraminifera were classified into 27 species of 16 genera, 30 species of 21 genera, 50 species of 29 genera and 52 species of 29 genera in Core YC-1 to 4, respectively. In the result of cluster analysis, it seemed that Group 1 (Core YC-1 and 2) of representative A. beccarii assemblages was deposited in upper bay environment and Group 2 (Core YC-3 and 4) of representative E. clavatum-A. beccarii assemblages was deposited in inner bay environment affected by offshore water. In the result of species composition analysis, the production frequency of A. beccarii was gradually decreased from low layer to upper layer, whereas production frequency of E. clavatum and P.F./T.F. was gradually increased to upward. These change patterns appeared in benthic and planktonic foraminifera seemed to reflect the late Holocene sea-level rise in Yeoja Bay.