광화학증착법에 의한 직접패턴 PZT 박막의 제조 및 특성

박형호,박형호,김태송,Park, Hyeong-Ho,Park, Hyung-Ho,Kim, Tae-Song,Hill, Ross-H. 한국재료학회 2008 한국재료학회지 Vol.18 No.2

The ferroelectric properties of UV irradiated and non-irradiated PZT films prepared via photochemical metal-organic deposition using photosensitive precursors were characterized. Fourier transform infrared spectroscopy showed that complete removal of organic groups was possible through UV exposure of the spin-coated PZT precursor films at room temperature. The measured remnant polarization values of UV-irradiated and non-irradiated PZT films after annealing at $650^{\circ}C$ were 29 and $23\;{\mu}C/cm^2$, respectively. The UV irradiation was found to be effective for the enhancement of the <111> growth orientation and ferroelectric property of PZT film and in the direct patterning in the fabrication of micro-patterned systems without dry etching.

$CHF_3/C_2F_6$ 반응성이온 건식식각에 의한 실리콘 표면의 변형에 관한 연구

박형호,권광호,곽병화,이수민,권오준,김보우,성영권,Park, Hyeong-Ho,Gwon, Gwang-Ho,Gwak, Byeong-Hwa,Lee, Su-Min,Gwon, O-Jun,Kim, Bo-U,Seong, Yeong-Gwon 한국재료학회 1991 한국재료학회지 Vol.1 No.4

실리콘 산화막을 $CHF_{3/}C_2F_6$ 혼합가스를 사용하여 반응성이온 건식식각을 행할 때 실리콘 표면에 형성되는 잔류막과 손상층을 X-선 광전자 분광기(XPS)와 이차이온 질량 분석기(SIMS)를 사용, 연구하였다. 실리콘, 탄소, 산소 및 불소의 angle-resolved XPS분석기술을 이용한 비파괴적 화학결합상태의 깊이분포 분석을 통하여 잔류막의 표면부에 O-F 결합이 존재하며 잔류막은 주로 탄소와 불소의 결합체인 C-F 플리머로 구성되어져 있고 Si-O, Si-C 및 Si-F 결합 등이 존재함을 알았다. 손상층은 실리콘 표면에서 약 60nm 깊이까지 탄소와 불소의 침투에 의해 형성되어져 있음을 알았다. The effects of $SiO_2$ reactive ion etching (RIE) in $CHF_{3/}C_2F_6$ on the surface properties of the underlying Si substrate were studied by X-ray photoelectron spectroscopy(XPS) and secondary ion mass spectrometry(SIMS) techniques. Angle-resolved XPS analysis was carried out as non-destructive depth profile one for investigating the chemical bonding states of silicion, carbon, oxygen and fluorine. The residue layer consists of C-F polymer. O-F bond was found on the top of the polymer layer and Si-O, Si-C and Si-F bonds were detected between Si substrate and polymer film. A 60nm thick damaged layer of silicon surface mainly contains carbon and fluorine.

철제유물 부식인자에 대한 부식양상 및 부식화합물 실험 연구

박형호,이재성,유재은,Park, Hyung Ho,Lee, Jae Sung,Yu, Jae Eun 국립문화재연구소 2012 保存科學硏究 Vol.33 No.-

본 연구는 부식인자에 따른 부식현상을 관찰하고 구성성분과 결정구조 분석을 통하여 철제유물에 영향을 미치는 부식위험인자를 확인하고자 하였다. 부식인자가 녹아있는 HCl, $HNO_3$, $H_2SO_4$, $H_2O$ 용액에 순수한 Fe powder(99%)를 침적시켜 부식화합물을 채취하였다. 채취된 부식화합물의 색상과 형태를 파악하기 위하여 실체 현미경 관찰을 실시하였으며 부식인자와 성장성을 확인하기 위하여 SEM-EDS분석을 실시하였다. 생성된 부식화합물의 결정구조와 조성을 알아보기 위하여 XRD, Raman 분석을 실시하였다. 실험결과 산성환경에서의 부식 속도가 빠르며 HCl, $H_2SO_4$의 부식이 $HNO_3$보다 크게 나타났다. HCl의 부식화합물은 $Cl^-$이온의 영향을 받아 침상형, 밤송이형태로 성장하였으며 X-선 회절분석과 Raman 분석결과 Goethite와 Lepidocrocite가 검출되었다. $H_2SO_4$의 부식화합물은 S이온의 영향을 받아 가느다란 침상형, 원기둥형태로 성장하였으며 X-선 회절분석과 Raman 분석결과 Goethite와 Lepidocrocite가 검출되었다. $HNO_3$의 부식화합물은 O이온의 영향을 받아 구상형, 판상형태로 성장하였으며 X-선 회절분석과 Raman 분석결과 Magnetite와 Lepidocrocite가 검출되었다. $H_2O$의 부식화합물은 O이온의 영향을 받아 구상형, 판상형태로 성장하였지만 대부분 구상형으로 관찰되며 X-선 회절분석과 Raman 분석결과 부식화합물이 검출되지 않았다. 부식인자에 따른 부식양상과 부식화합물이 다양하게 나타난다는 사실을 알게 되었다. The corrosion phenomena of the iron artifacts was studied by morphology observation and instrumental analysis(EDS, XRD, Raman) with various corrosion factors in oder to verify to confirm the danger of corrosion factors. Corrosion compounds were collected by depositing pure Fe powder(99%) into a HCl, $HNO_3$, $H_2SO_4$, and $H_2O$ solution which contained the corrosion factors. Stereoscopic-microscope observations were then conducted determine the colors and shapes of the collected corrosion compounds, and SEM-EDS analysis was conducted to confirm the corrosion factors and the growth of these compounds. X-ray diffraction (XRD), Raman analyses were conducted to examine the crystal structure and compositions of the created corrosion compounds. The results of the experiment revealed that corrosion speed was faster in an acidic environment and corrosion of HCl and $H_2SO_4$ was greater than that of $HNO_3$. The corrosion compounds of HCl grew into a needle or chestnut-like shape after being affected by Cl- ion, and XRD and Raman analyses detected goethite and lepidocrocite. The corrosion compounds of $H_2SO_4$ was affected by S ion and grew into a slender-needle-like or cylindrical shape, and the XRD and Raman analyses detected goethite and lepidocrocite. The corrosion compounds of $HNO_3$ grew into a spherical or plate-like shape after being affected by O ion and the XRD and Raman analyses detected magnetite and lepidocrocite. Although the corrosion compounds of $H_2O$ grew into a spherical or plate-like shape after being affected by O ion, most of them were observed to have had spherical shapes, and the XRD and Raman analyses failed to detect corrosion compounds in them. It was found in the study that corrosion characteristics and compounds are diversely displayed according to the corrosion factor.

전기장이 형성된 관성 충돌기에서 대전 입자의 거동과 부착 특성에 대한 연구

박형호,김상수,Park, Hyung-Ho,Kim, Sang-Soo 대한기계학회 1999 大韓機械學會論文集B Vol.23 No.3

Effect of electrostatic and inertial forces on the pre-charged particle deposition was theoretically and experimentally studied by introducing the inertia impactor subjected to an electric field. To derive the analytic solution, we assumed that a flow was an ideal stagnation flow, a particle had saturation charges, and the electric field within the test section was uniform. On the other hand, $Al_2O_3$ particle groups were used as the test particles, which mean sizes were $1{\mu}m$, $3{\mu}m$, and $5{\mu}m$. To measure the deposition efficiency, the light scattering method was used. The results showed that the deposition efficiency was minimized at a certain nozzle velocity as increasing the nozzle velocity, only if the electric force was applied. As the electric field strength increased, $Stk_{50}{^{1/2}}$ was decreased, and its decreasing rate was reduced with increasing the flow velocity. Moreover the existence of electric field was against the cut-off performance of the inertia impactor.

$CHF_3/C_2F_6$ 반응성이온 건식식각에 의해 변형된 실리콘 표면의 열적 거동에 관한 연구

박형호,권광호,곽병화,이중환,이수민,권오준,김보우,성영권,Park, Hyung-Ho,Kwon, Kwang-Ho,Koak, Byong-Hwa,Lee, Joong-Whan,Lee, Soo-Min,Kwon, Oh-Joon,Kim, Bo-Woo,Seong, Yeong-Gwon 한국재료학회 1992 한국재료학회지 Vol.2 No.1

실릴콘 산화막을 $CHF_3/C_2F_6$ 혼합가스를 사용하여 반응성이온 건식식각을 행할 때 실리콘 표면에 형성되는 잔류막과 손상충의 열적 거동을 X-선 광전자 분광기(XPS)와 이차이온 질량 분석기 (SIMS)를 사용, 연구하였다. 저항가열을 통한 in-situ 분석에 의해 폴리머 잔류막은 $200^{\circ}C$부터 분해가 시작되고 $400^{\circ}C$ 이상의 가열에서는 graphite 형태의 탄소 결합체를 형성하며 분해됨을 알았다. 질소 분위기하의 급속 열처리를 통해 잔류막의 열분해는 $800^{\circ}C$ 이상에서 완료되고 손상층을 형성하는 침투 불순원소의 기판 외부로의 확산이 관찰되었다. Thermal behavior of residue and damaged layer formed by reactive ion etching (RIE) in $CHF_3/C_2F_6$ were investigated using X-ray photoelectron spectroscopy(XPS) and secondary ion mass spec-trometry(SIMS) techniques. Decomposition of polymer residue film begins at $200^{\circ}C$ and above $400^{\circ}C$ carbon compound as graphite mainly forms by in-situ resistive heating. It reveals that thermal decomposition of residue can be completed by rapid thermal anneal treatment above $800^{\circ}C$ under nitrogen atmosphere and out-diffusion of carbon and fluorine of damaged layer is observed.

MR-EMR 복합제조공정에서 환원제 위치가 탄탈륨 분말 특성에 미치는 영향

박형호,윤재식,배인성,김양수,윤동주,원대희,김병일,Park, Hyeoung-Ho,Yoon, Jae-Sik,Bae, In-Sung,Kim, Yang-Soo,Yoon, Dong-Ju,Won, Dae-Hee,Kim, Byung-Il 한국분말야금학회 2007 한국분말재료학회지 (KPMI) Vol.14 No.3

A process known as the MR and EMR combination process is able to overcome the shortcomings of the MR (metallothermic reduction) and EMR (electronically mediated reaction) process. The effects of $K_2TaF_7$ as the raw material, sodium as the reducing agent and KCl/KF as the diluent on the characteristics of tantalum powder are investigated. In this study, a MR-EMR combination process has been employed to tantalum powder on the location of reductant. The excess of reductant were varied from 25, 50 to 75 wt%. The total charge and external circuit decreases as the amount of reductant increases. The average particle size increases with increasing the amount of reductant.

MR 및 EMR제조공정에 따른 탄탈륨분말 특성

박형호,윤재식,배인성,김양수,윤동주,원대희,김병일,Park, Hyeoung-Ho,Yoon, Jae-Sik,Bae, In-Sung,Kim, Yang-Soo,Yoon, Dong-Ju,Won, Dae-Hee,Kim, Byung-Il 한국분말야금학회 2007 한국분말재료학회지 (KPMI) Vol.14 No.3

In the metallothermic reduction (MR) process used to obtain tantalum powder in one batch, it is difficult to control the morphology and location of the tantalum deposits. On the other hand, an electronically mediated reaction (EMR) process is capable of overcoming this difficulty. The effect of using $K_2TaF_7$ as the raw material and sodium as the reducting agent on the characteristics of tantalum powder are investigated. As the temperature of the reduction varied from 1023K to 1223K, the powder particles obtained with MR were relatively large $({\sim}34{\mu}m)$, while those prepared via EMR were of uniform $(13{\mu}m)$. In the MR process, the Ta powder recovery rate increased from 37% to 83% at 1123K in constrat with EMR process.

단극하전을 이용한 나노입자 응집성장 제어

박형호,김상수,장혁상,Park, Hyung-Ho,Kim, Sang-Soo,Chang, Hyunk-Sang 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.1

Effects of electric force on the morphology and growth of aggregates were studied experimentally. Nano-sized NaCl particles were supplied to a flame to perform the unipolar charging state. This electric precursor did not modify a temperature profile of the flame. The morphology of aggregates was measured by TEM image processing technique and the light scattering technique. In the unipolar charged state, the fractal dimension of aggregates was smaller than that of' the electrically neutral state. This result was in good agreement with our previous numerical simulations.

하전 입자의 비구형 응집 성장에 대한 수치적 연구

박형호,김상수,장혁상,Park, Hyeong-Ho,Kim, Sang-Su,Jang, Hyeok-Sang 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.2

A numerical technique for simulating the aggregation of charged particles was presented with a Brownian dynamic simulation in the free molecular regime. The Langevin equation was used for tracking each particle making up an aggregate. A periodic boundary condition was used for calculation of the aggregation process in each cell with 500 primary particles of 16 nm in diameter. We considered the thermal force and the electrostatic force for the calculation of the particle motion. The electrostatic force on a particle in the simulation cell was considered as a sum of electrostatic forces from other particles in the original cell and its replicate cells. We assumed that the electric charges accumulated on an aggregate were located on its center of mass, and aggregates were only charged with pre-charged primary particles. The morphological shape of aggregates was described in terms of the fractal dimension. In the simulation, the fractal dimension for the uncharged aggregate was D$\_$f/ = 1.761. The fractal dimension changed slightly for the various amounts of bipolar charge. However, in case of unipolar charge, the fractal dimension decreased from 1.641 to 1.537 with the increase of the average number of charges on the particles from 0.2 to 0.3 in initial states. In the bipolar charge state, the average sizes of aggregates were larger than that of the uncharged state in the early and middle stages of aggregation process, but were almost the same as the case of the uncharged state in the final stage. On the other hand, in the unipolar charge state, the average size of aggregates and the dispersion of particle volume decreased with the increasing of the charge quantities.

단극하전 나노입자의 응집성장 과정에서 입자의 전기전도도의 효과에 대한 연구

박형호,김상수,장혁상,Park, Hyung-Ho,Kim, Sang-Soo,Chang, Hyuk-Sang 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.2

Effects of the electric conductivity of particles were studied for the aggregation process of charged particles with a Brownian dynamic simulation in the free molecular regime. A periodic boundary condition was used for the calculation of the aggregation process in each cell with 500 primary particles of 16 nm in diameter. We considered two extreme cases, a perfect conductor and a perfect nonconductor. The electrostatic force on a particle in the simulation cell was considered as a sum of electrostatic forces from other particles in the original cell and its replicate cells. We assumed that aggregates were only charged with pre-charged primary particles. The morphological shape of aggregates was described in terms of the fractal dimension. The fractal dimension for the uncharged aggregate was D$_{f}$= 1.761. However, the fractal dimension decreased from 1.694 to 1.360 for the case of the perfect conductor, and from 1.610 to 1.476 for the case of the perfect nonconductor, with the increase of the average number of charges on the primary particle from 0.2 to 0.3. These values were smaller than that of the centered charge case.e.