• Applied Chemistry for Engineering
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• v.8 no.5
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• pp.742-748
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• 1997

Diamond films which have high hardness and thermal conductivity can be used to improve the performance of WC-Co as a cutting tool material. However, it is difficult to get such coatings of good uniformity and adhesiveness due to the surface characteristics of WC-Co. To get better coatings, some techniques, such as the surface treatment of substrate or the formation of interlayer between substrate and diamond film, have been tried. In the present work, the nickel interlayer is formed onto WC-Co by electroless Ni-P plating, which is introduced as a new method, and then diamond film is deposited on the interlayer. Formation and uniformity of three layers, i.e., substrate, electroless plate, and diamond film, and the adhesiveness of interlayers were studied. To investigate the effects of pretreatment on electroless plating, two different methods such as acid treatment and diamond powder treatment were used. The effects of heat treatment of the electroless plated surface on adhesiveness between the substrate and the interlayer were examined. It was found that as the temperature increases, the Ni crystals grow and then result in improved adhesiveness. Diamond film coatings of pure diamond phase were obtained at $800^{\circ}C$. It is concluded that the heat treated electroless Ni-P plating can be effectively used as a interlayer between WC-Co substrate and diamond film.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.4
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• pp.91-96
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• 2007

The light extraction efficiency in GaN-on-sapphire LEDs based on a simple model was analyzed qualitatively. The light extraction efficiency in the LEDs is simulated numerically by using ray tracing method. In the present study, the extraction efficiency was simulated on flat LED and PSS(patterned sapphire substrate) LED. The role of the patterned sapphire substrate in PSS LED are analyzed and discussed. And, the effects of reflectance on flat LED and PSS LED were investigated. This analysis of simulation results provide a numeric figure for the extraction efficiency of LEDs and are helpful in the design of high brightness GaN LEDs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.208-211
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• 2000

We prepared Co-Cr-Ta and Co-Cr-Ta/Ti thin film for perpendicular magnetic recording media by facing targets sputtering system (FTS system). Ti underlayer effects on crystallographic and magnetic characteristics of Co-Cr-Ta perpendicular magnetic recording media have been investigated. Crystallgraphic and magnetic characteristic of prepared thin films were evaluated by x-ray diffractometry(XRD), vibrating sample magnetometer(VSM) and kerr hysteresis loop measurement. The coercivity and anisotropy field increase by introduced Ti underlayer when substrate temperature is higher than 150$^{\circ}C$. The c-axis dispersion angle and grain size of Co-Cr-Ta/Ti thin film is decrease than Co-Cr-Ta when substrate temperature is higher than 100$^{\circ}C$. Consequently, the use of a Ti underlayer highly orientated can be improved crystallographic and magnetic characteristics of Co-Cr -Ta perpendicular media layer.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.857-859
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• 2007

Durability of LCD glass, OA-10 and OA-21, to $SiCl_4$ and $SF_6$ gases was investigated. Reaction products are generated on the glass surface. The reaction products are reduced by changing the etching conditions. the durability of OA-10 and OA-21 to the dry etching gases is comparable.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.167-170
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• 1995

LiCoO$_2$is a electrode material of Li ion Cell which is expected as the cell with a very high electric charge density. The recent study is mainly to focused on a high power secondary cell. If very thin Li ion Cell can be made in the scale of IC substrate it can be a electric souse in IC chip , micro machine or very thin electrical display etc. LiCoO$_2$thin film can be made by CVD, Laser ablation, E-Beam, ton Beam process, sputtering etc. But to make the material with a high quality for a cell is difficult as the electrode in cell have the fitable ratio in components and a lattice structure of bulk etc. In this study, LiCoO$_2$is made by R.F magnetron sputtering with the variance of substrate temperature and oxygen partial pressure etc. In the substrate temperature of 600$^{\circ}C$ and the oxygen rate of 10%, we can acquire the good thin film LiCoO$_2$compared wish a bulk material.

• Journal of the Korean Ceramic Society
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• v.53 no.1
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• pp.81-86
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• 2016

The effect of substrate rotation speed on the phase forming behavior and microstructural variation of 8 wt% yttria ($Y_2O_3$) stabilized $ZrO_2$ (8YSZ) coatings as a thermal barrier coating has been investigated. 8YSZ coatings with $100{\sim}200{\mu}m$ thickness were deposited by electron beam-physical vapor deposition onto a super alloy (Ni-Cr-Co-Al) substrate with a bond coating (NiCo-CrAlY). The width of the columnar grains of the 8YSZ coatings increased with increasing substrate rotation speed from 1 to 30 rpm at a substrate temperature range of $900{\sim}950^{\circ}C$. In spite of the different growth behaviors of coatings with different substrate rotation speeds, the phases of each coating were not changed remarkably. Even after post heat treatments with various conditions of the coated specimens fabricated at 20 rpm, only a change of color was noticeable, without any remarkable change in the phase or microstructure.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.10
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• pp.826-831
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• 2009

In this paper, a high power RF amplifier module using AlN substrate of high thermal conductivity has been proposed. This RF amplifier module has the advantage of compact size and effective heat dissipation for the packaging of high power chip. To fabricate the thru-hole and scribing line on AlN substrate, the key parameters of $CO_2$ laser were experimented. And then, microstrip lines and spiral planar inductors were fabricated on an AlN substrate using the thin-film process. The fabricated microstrip lines on the AlN substrate has an attenuation value of 0.1 dB/mm up to 10 GHz. The fabricated spiral planar inductor has a high quality factor, a maximum of about 62 at 1 GHz for a 5.65 nH inductor. Packaging of a RF power amplifier was implemented on an AlN substrate with thru-hole. From the measured results, the gain is 24 dB from 13 to 15 GHz and the output power is 33.65 dBm(2.3 W).

• Journal of the Semiconductor & Display Technology
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• v.6 no.4
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• pp.5-9
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• 2007

Phase transition and dopant redistribution during silicidation of $CoSi_2$ thin films were characterized depending on their preparation methods. Our results indicated that cleanness of the substrate surface played an important role in the formation of the final phase. This effect was found to be reduced by addition of W resulting in the formation of $CoSi_2$. However, even in this case, the formation of the final phase was achieved at the cost of extra thermal energy, which induced rough interface between the substrate and the silicide film. As for the dopant redistribution, the deposition sequence of Co and Si on SiGe was observed to induce significant differences in the dopant profiles. It was found that co-deposition of Co and Si resulted in the least redistribution of dopants thus maintaining the original dopant profile.

• Korean Journal of Materials Research
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• v.14 no.10
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• pp.731-736
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• 2004

Herein, we report on the co-firing of a low-K wiring substrate and a middle-K functional substrate in LTCC. Firstly, we researched the sintering behavior and dielectric properties of the low-k wiring substrate comprised by alumina and glass frit with ${\varepsilon}_r$, of $\sim7$ and the middle-k functional substrate comprised by $Ba_{5}Nb_{4}O_{15}$ and glass frit with ${\varepsilon}_r$, of $20\sim30$. The warpage and delamination between the hetero layers of the low-K and the middle-K composition were also studied. In particular, physical matching of the hetero layers could be possible by adjusting of the sintering properties of the composition. We observed that an introduction of the glass frit to the low- and middle-K substrate gives rise to a minimization of an effect given by separation of the hetero layers, and modification of the fraction of the glass frit accompanied by a variation of the composition could control the sintering behavior and its beginning temperature. In the case of co-firing of the L03 as the low-K wiring substrate composition and the M03 as the middle-K functional substrate composition at $875^{\circ}C$, we could fabricate a desirable structure of hetero layers without any kinds of structural defects such as separation, warpage, delamination, pore trap, etc. We suppose that the co-firing techniques described in this study would provide a helpful method to fabricate a LTCC multi-functional for the next generation.

• Korean Journal of Materials Research
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• v.8 no.10
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• pp.956-960
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• 1998

The interfacial reaction between the CoINb bilayer and the $SiO_2$ substrate in the temperature range of $330^{\circ}C$-$800^{\circ}C$ in a vacuum has been investigated by X-ray photoelectron spectroscopy, glancing angle XRD, Auger Electron Spectroscopy and Atomic force microscopy. The Co and Nb were actively interdiffused at $600^{\circ}C$, and the layer inversion completed at $700^{\circ}C$. NbO was formed by interfacial reaction between the Nb interlayer and the $SiO_2$ substrate, while $Nb_20_5$ was formed on the surface by reaction of Nb with oxygen in the ambients. Free Si atoms obtained by the reaction between Nb and $SiO_2$ formed silicides like CoSi and $Nb_5Si_3$ by reacting with Co and Nb remnants. The sheet resistance of the Co/Nb bilayer increased substantially after annealing at $800^{\circ}C$. which is due to the agglomeration of the Co layer to reduce its surface energy.