• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.3
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• pp.208-213
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• 2020

Four types of BaTiO₃ powders are prepared and successfully deposited on glass and Pt/Si substrates using the aerosol deposition process. Particles with sizes of 0.45 ㎛ and 0.3 ㎛ are selected as the starting powder, while those powders are treated using a different milling method. The jet-milled and ball-milled powders not only showed a smaller particle-size distribution, but compared with the non-milled powder, it also had a higher deposition rate using the uniformly generated aerosol. Although the films deposited using particles with size 0.45 ㎛ exhibited some craters on the surface, significantly flat film surfaces were obtained. However, particles with size 0.3 ㎛ create a slightly rough film surface, but the dielectric constant was greater than in the case involving particles with size 0.45 ㎛. Consequently, a suitably large particle size significantly influences the deposition rate and improvement in the surface roughness, and a uniform particle size distribution appears to contribute to an improved dielectric constant. Therefore, it is believed that the dielectric properties along with the growth characteristics can be enhanced by limiting particle size and shape.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.3
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• pp.219-224
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• 2020

Al₂O₃ powders with particle sizes of 0.35 ㎛, 0.5 ㎛, 1.5 ㎛, and 2.5 ㎛ are deposited onto glass and Cu substrates using the aerosol deposition (AD) process. The deposition characteristics of Al₂O₃ films using those four types of Al₂O₃ powders are investigated to determine the influence of the particle size on the films. To observe detailed micro-structures of the films, the cross-section and surface morphology are observed. Then, the crystalline size and internal strain are calculated from X-ray diffraction peaks in order to confirm the hammering effect as well as the micro-strain during the AD deposition. From the above results, deposition mechanisms related to the particle size are studied. The results of this study indicate the optimal particle size and formation mechanisms for dense Al₂O₃ film with a smooth surface roughness as well as for a porous Al₂O₃ film with a rough surface roughness.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.4
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• pp.608-613
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• 2000

The present study has proposed a novel aerosol CVD utilizing an internal jet in the conventional MCVD reactor for the purpose of enhancing the deposition efficiency(and rate) and the uniformity of deposited film. The use of impingement of high temperature jet through a thin inner tube ensures the reduction of non-uniform particle deposition zone as well as higher thermophoretic particle deposition. It is shown that significant improvements have been achieved for both aspects of deposition efficiency and uniformity. As jet temperatures increase, the tapered length is reduced and deposition efficiency is significantly increased.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.5
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• pp.375-382
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• 2010

A layered perovskite photocatalysts, $SrBi_2Nb_2O_9$ (SBN), was synthesized by the conventional solid-state reaction method and characterized by X-ray diffraction (XRD) and UV-visble spectrophotometry. The results showed that the structure of $SrBi_2Nb_2O_9$ is orthorhombic. Diffuse reflectance spectra for calcined and attrition-milled SBN showed the main absorption edges were less 400 nm, that is ultraviolet region. SBN under micron-sized powder was deposited on the $Al_2O_3$ by room temperature powder spray in vacuum process, so called aerosol deposition (AD), and nano-grained $SrBi_2Nb_2O_9$ photocatalytic thick film was fabricated. AD-deposited SBN thick films were characterized by XRD, scanning electron microscopy (SEM) and UV-visable spectrophotometry, Moreover, it was found that several nano-sized SBN film by AD process can improve the photocatalytic activity under visable reflectance.

• Journal of the Korean Ceramic Society
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• v.40 no.8
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• pp.715-719
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• 2003

The Aerosol Deposition (AD) process will be proposed as a new fabrication technology for the integrated RF modules. $\alpha$-A1$_2$O$_3$ thick films were successfully grown on glass and Al substrates at room temperature by the AD process. Relative dielectric permittivity and loss tangent of the $Al_2$O$_3$ thick films on Al showed 9.5 and 0.005, respectively. To form microstrip lines on aerosol-deposited A1903 thick films, copper electroplating and lithography processes were employed, and the square-type cross section with sharp edges could be obtained. Low-pass LC filters with 10 GHz cutoff frequency were simulated by an electromagnetic analysis, exhibiting the validity of the AD process as a fabrication technology f3r integrated RF modules.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.1
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• pp.6-12
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• 2013

Aerosol deposition(AD) coating that enable fabricate films at low temperature have begun to be widely researched for the integration of ceramics as well to realize high-speed deposition rates. For application of ceramic thick film by AD to display and electronic ceramic industry, fabrication of dense structure with a no cracking is required. In this study, to fabricate dense ceramic thick film, the effect of crystal phase of starting powder was investigated. For this study, amorphous and crystalline $SiO_2$ powders were used as starting powders. Two types of $SiO_2$ powders were deposited on glass substrate by AD. In the case of amorphous $SiO_2$ powder, the deposited films had extremely incompact and opaque layer, irrespective of particle size. In contrast to amorphous powder, in the case of crystalline powder, porous structure layer and dense microstructure with no cracking layer were fabricated depending on the particle size. The optimized starting powder size for dense coating layer was $1{\sim}2{\mu}m$. The transmittance of film reached a maximum of 76% at 800 nm.

• Journal of the Korean Ceramic Society
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• v.32 no.11
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• pp.1246-1254
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• 1995

A numerical model for fabrication and deposition of ultrafine SiO2 particles were proposed in the simplified horizontal MCVD apparatus using tube furnace reactor. The model equations such as energy and mass balance equations and the 0th, 1st and 2nd moment balance equations of aerosols were considered in the reactor. The phenomena of SiCl4 chemical reaction, SiO2 particle formation and coagulation, diffusion and thermophoresis of SiO2 particles were included in the aerosol dynamic equation. The profiles of gas temperature, SiCl4 concentration and SiO2 particle volume were calculated for standard conditions. The concentrations, sizes and deposition efficiencies of SiO2 particles were calculated, changing the process conditions such as tube furnace setting temperature, total gas flow rate and inlet SiCl4 concentration.

• Particle and aerosol research
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• v.5 no.3
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• pp.95-109
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• 2009

A low temperature plasma process has been widely used for semiconductor fabrication and can also be applied for the preparation of solar cell, MEMS or NEMS, but they are notorious in the point of particle contamination. The nano-sized particles can be generated in the low temperature plasma process and they can induce several serious defects on the performance and quality of microelectronic devices and also on the cost of final products. For the preparation of high quality thin films of high efficiency by the low temperature plasma process, it is desirable to increase the deposition rate of thin films with reducing the particle contamination in the plasmas. In this paper, we introduced the studies on the generation and growth of nanoparticles in the low temperature plasmas and tried to introduce the recent interesting studies on nanoparticle generation in the plasma reactors.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.6
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• pp.239-244
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• 2015

Lead zirconate titanate (PZT) thick films with thickness of $10{\sim}20{\mu}m$ were fabricated on silicon substrate by aerosol deposition method. As-deposited films on silicon were annealed at the temperatures of $700^{\circ}C$. The electrical properties of films deposited by PZT powders were characterized using impedance analyzer and Sawyer-Tower circuit. The PZT powder was prepared by both conventional solid reaction process and sol-gel process. The remanent polarization, coercive field, and dielectric constant of the $10{\mu}m$ thick film with solid reaction process were $20{\mu}C/cm^2$, 30 kV/cm and 1320, respectively. On the other hand, the PZT films by sol-gel process showed a poor dielectric constant of 635. The reason was probably due to the presence of pores produced from organic residue during annealing.

• Journal of the Korean Ceramic Society
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• v.43 no.2 s.285
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• pp.106-113
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• 2006

PMN-PZT films with thickness of $5\;{\mu}m$ were deposited on $Pt/Ti/SiO_2/Si$ substrate at room temperature using aerosol deposition process. The films showed fairly dense microstructure without any crack. XRD and TEM analysis revealed that the films consisted of randomly oriented nanocrystalline and amorphous phases. Post-annealing process was employed to induce crystallization and grain growth of the as-deposited films and to improve the electrical properties. The annealed film showed markedly improved electrical properties in comparison with as-deposited film. The film after annealing at $700^{\circ}C$ for 1h exhibited the best electrical properties. Dielectric constant $(\varepsilon_r)$, remanent polarization $(P_r)$ and piezoelectric constant $(d_{33})$ were 1050, $13\;{\mu}C/cm^2$ and 120 pC/N, respectively.