• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2002.11a
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• pp.72-74
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• 2002

A submicron contact scheme using $WN_x$ diffusion barrier has been suggested for multilevel interconnect structure. The contact resistance of $0.4\times0.48\mu\textrm{m}^2$ size Al/WN/Ti/$n^+$-Si is 120-140 $\Omega$ and the leakage current density is below than $10^{-16}$$-10^{-15}A/\mu\textrm{m}^2$. The effect of F atoms on the submicron contact has been investigated with the nuclear resonance analysis method.

• KSBB Journal
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• v.23 no.1
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• pp.83-89
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• 2008

Food wastewater derived from the three-stage methane fermentation system developed in this lab contained high concentration organic substances. The organic wastewater should be treated through advanced wastewater treatment system to satisfy the "Permissible Pollutant Discharge Standard of Korea". In order to treat the organic wastewater efficiently, several optimum operation conditions of a modified $UV/TiO_{2}$ photocatalytic system have been investigated. In the first process, wastewater was pre-treated with $FeCl_{3}$. The optimum pH and coagulant concentration were 4.0 and 2000mg/L, respectively. Through this process, 52.6% of CODcr was removed. The second process was $UV-TiO_{2}$ photocatalytic reaction. The optimum operation conditions for the system were as follows: UV lamp wavelength, 254 nm; wastewater temperature, $40^{\circ}C$; pH 8.0; and air flow rate, 40L/min, respectively. Through the above two combined processes, 69.7% of T-N and 70.9% of CODcr contained in the wastewater were removed.

• Proceedings of the KWS Conference
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• v.43
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• pp.109-111
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• 2004

20 vol.$\%$ SiC를 포함한 두 층간의 $Si_{3}N_{4}/SiC$ 나노 복합재료는$\alpha$ $-Si_3N_4$,13 nm 크기의 나노탄소 분말 그리고 $5\;wt$\%\;Y_2O_3$의 분말로 두 단계 소결을 통하여 제작된다. $Si_3N_4$ 입계 사이의 결합은 소결 후 변하지 않고 남은 compact와 $51\~62\%$의 기공으로 얻어진 표면적 사이의 반응에 의해 생성된다. 이 연구에서는 Ti 합금을 SiC 층에 브레이징을 이용하여 제작하고 기계적 특성을 연구하였다. 다양한 변형율과 결합물의 강도, 변형율 증가에 따른 층간 변화를 연구하였다. 층간 파괴 형태는 금속과 브레이징 합금 사이의 파괴, 세라믹과 브레이징 합금 사이의 파괴, 그리고 세라믹 내부에서의 파괴를 보였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.139-139
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• 2010

금속 실리사이드 나노입자는 열적 및 화학적 안정성이 뛰어나고, 절연막내에 일함수 차이에 따라 깊은 양자 우물구조가 형성되어 비휘발성 메모리 소자를 제작할 수 있다. 그러나 단일 $SiO_2$ 절연막을 사용하였을 경우 저장된 전하의 정보 저장능력 및 쓰기/지우기 시간을 향상시키는 데 물리적 두께에 따른 제한이 따른다. 본 연구에서는 터널장벽 엔지니어링을 통하여 물리적인 두께는 단일 $SiO_2$ 보다는 두꺼우나 쓰기/지우기 동작을 위하여 인가되는 전기장에 의하여 상대적으로 전자가 느끼는 상대적인 터널 절연막 두께를 감소시키는 방법으로 동작속도를 향상 시킨 $SiO_2/Si_3N_4/SiO_2$ 및 $Si_3N_4/SiO_2/Si_3N_4$ 터널 절연막을 사용한 금속 실리사이드 나노입자 비휘발성 메모리를 제조하였다. 제조방법은 우선 p-type 실리콘 웨이퍼 위에 100 nm 두께로 증착된 Poly-Si 층을 형성 한 이후 소스와 드레인 영역을 리소그래피 방법으로 형성시켜 트랜지스터의 채널을 형성한 이후 그 상부에 $SiO_2/Si_3N_4/SiO_2$ (2 nm/ 2 nm/ 3 nm) 및 $Si_3N_4/SiO_2/Si_3N_4$ (2 nm/ 3 nm/ 3 nm)를 화학적 증기 증착(chemical vapor deposition)방법으로 형성 시킨 이후, direct current magnetron sputtering 방법을 이용하여 2~5 nm 두께의 $WSi_2$ 및 $TiSi_2$ 박막을 증착하였으며, 나노입자 형성을 위하여 rapid thermal annealing(RTA) system을 이용하여 $800{\sim}1000^{\circ}C$에서 질소($N_2$) 분위기로 1~5분 동안 열처리를 하였다. 이후 radio frequency magnetron sputtering을 이용하여 $SiO_2$ control oxide layer를 30 nm로 증착한 후, RTA system을 이용하여 $900^{\circ}C$에서 30초 동안 $N_2$ 분위기에서 후 열처리를 하였다. 마지막으로 thermal evaporator system을 이용하여 Al 전극을 200 nm 증착한 이후 리소그래피와 식각 공정을 통하여 채널 폭/길이 $2{\sim}5{\mu}m$인 비휘발성 메모리 소자를 제작하였다. 제작된 비휘발성 메모리 소자는 HP 4156A semiconductor parameter analyzer와 Agilent 81101A pulse generator를 이용하여 전기적 특성을 확인 하였으며, 측정 온도를 $25^{\circ}C$, $85^{\circ}C$, $125^{\circ}C$로 변화시켜가며 제작된 비휘발성 메모리 소자의 열적 안정성에 관하여 연구하였다.

• Journal of the Korean institute of surface engineering
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• v.38 no.2
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• pp.65-68
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• 2005

The effect of crystal orientation and microstructure on the mechanical properties of $TaN_x$ was investigated. $TaN_x$ films were grown on $SiO_2$ substrates by ultrahigh vacuum unbalanced magnetron sputter deposition in mixed $Ar/N_2$ discharges at 20 mTorr (2.67 Pa) and at $350^{\circ}C$. Unlike the Ti-N system, in which TiN is the terminal phase, a large number of N-rich phases in the Ta-N system could lead to layers which had nano-sized lamella structure of coherent cubic and hexagonal phases, with a correct choice of nitrogen fraction in the sputtering mixture and ion irradiation energy during growth. The preferred orientations and the micro-structure of $TaN_x$ layers were controlled by varing incident ion energy $E_i\;(=30eV\~50eV)$ and nitrogen fractions $f_{N2}\;(=0.1\~0.15)$. $TaN_x$ layers were grown on (0002)-Ti underlayer as a crystallographic template in order to relieve the stress on the films. The structure of the $TaN_x$ film transformed from Bl-NaCl $\delta-TaN_x$ to lamellar structured Bl-NaCl $\delta-TaN_x$ + hexagonal $\varepsilon-TaN_x$ or Bl-NaCl $\delta-TaN_x$ + hexagonal $\gamma-TaN_x$ with increasing the ion energy at the same nitrogen fraction $f_{N2}$. The hardness of the films also increased by the structural change. At the nitrogen fraction of $0.1\~0.125$, the structure of the $TaN_x$ films was changed from $\delta-TaN_x\;+\;\varepsilon-TaN_x\;to\;\delta-TaN_x\;+\;\gamma-TaN_x$ with increasing the ion energy. However, at the nitrogen fraction of 0.15 the film structure did not change from $\delta-TaN_x\;+\;\varepsilon-TaN_x$ over the whole range of the applied ion energy. The hardness increased significantly from 21.1 GPa to 45.5 GPa with increasing the ion energy.

• Korean Journal of Materials Research
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• v.14 no.6
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• pp.402-406
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• 2004

$WSi_2$, $TiSi_2$, $CoSi_2$, and $TaSi_2$ are general silicides used today in semiconductor devices. $WSi_2$ thin films have been proposed, studied and used recently in CMOS technology extensively to reduce sheet resistance of polysilicon and $n^{+}$ region. However, there are several serious problems encountered because $WSi_2$ is oxidized and forms a native oxide layer at the interface between $WSi_2$ and $Si_3$$N_4$. In this study, we have introduced 20 $slm-N_2$ gas from top to bottom of the furnace in order to control native oxide films between $WSi_2$ and $Si_3$$N_4$ film. In resulting SEM photographs, we have observed that the native oxide films at the surface of $WSi_2$ film are removed using the long injector system.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.136.2-136
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• 2003

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.20-20
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• 2010

The effect of excimer laser annealing on the structural and dielectric behaviors of $PbZr_{0.52}Ti_{0.48}O_3$ (PZT) thin films has been investigated. The amorphous PZT thin films were prepared on Pt/Ti/$SiO_2$/Si substrates by a sol-gel method. The PZT precursor was prepared from lead acetate, zirconium acetylacetonate, and titanium isopropoxide. The starting materials were dissolved in n-propanol and 1,3-propanediol. After, the amorphous PZT thin films were laser-annealed (using KrF excimer laser) as a function of the laser energy density and the number of laser pulse. Structural properties of PZT thin films are characterized by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The dielectric characterization was done on a RT66A test system and a Agilent 4294A impedance analyzer. The PZT thin films show that excimer laser irradiation drastically improved the crystallization and dielectric properties of the PZT thin films, depending on the energy density and the pulse number.

• Korean Journal of Materials Research
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• v.8 no.12
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• pp.1146-1151
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• 1998

The crystallization behaviour of perovskite $PbTiO_3$ for the samples heat- treated at various temperatures for various times in the $PbO-TiO_2-A1_2O_3-SiO_2$, glass system has been investigated by the means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. Higher crystallinity obtained in the sample heat-treated at higher temperature for longer time. With increasing heat-treatment time, dielectric constant of the samples heat-treated at $610^{\circ}C$ and $650^{\circ}C$ increased, but that of the sample heat- treated at $800^{\circ}C$ decreased. Loss tangent of the heat-treated samples was not much influenced by heat-treatment conditions. Piezodielectric charge constant was approximately $1.0\times10^{-12}~8.0$\times$10^{-12}C/N$ in the samples heat-treated at $800^{\circ}C$ for 1h, 2h, and 8h.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.1
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• pp.53-58
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• 2008

Purpose: To design and fabricate the small sputter coating system for the Ophthalmic lens. Methods: The design of sputter target was done using macleod program for AR coating and mirror coating of Ophthalmic lens with Si target and then the sputter system was fabricated. Results: The optimum condition of AR coating with Si target was [air|$SiO_2$(81.3)|$Si_3N_4$ (102)|$SiO_2$(19.21)|$Si_3N_4$(15.95)|$SiO_2$(102)|glass], for blue color mirror coating [air|$SiO_2$(56.61)|$Si_3N_4$(135.86)|$SiO_2$(67.64)|$Si_3N_4$(55.4)|$SiO_2$(53.53)|$Si_3N_4$(51.28)|glass], for green color coating [air|$SiO_2$(66.2)|$Si_3N_4$(22.76)|$SiO_2$(56.58)|$Si_3N_4$(140.35)|$SiO_2$(152.35)|$Si_3N_4$(70.16)|$SiO_2$(121.87)|glass], for gold color [air|$SiO_2$(83.59)|$Si_3N_4$(144.86)|$SiO_2$(11.82)|$Si_3N_4$(129.93)|$SiO_2$(90.01)|$Si_3N_4$(88.37)|glass]. Conclusions: In the fabrication of sputtering coating apparatus, Dual cathode with same Ti target were coated at the same time on both sides of Ophthalmic lens to lessen the time of coating on Ophthalmic Lens and save the cost of the lens. The distance of target-substrate of cathode was variable from 12.5 cm to 20 cm. Turbo pump was used to take the whole coating process about 15 min. instead of diffusion pump. The lens holder was made to coat 2 pairs lens every coating and was rotated to get the uniformity of thin film.