• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.1
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• pp.16-22
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• 2008

We fabricated thermally-evaporated 10 nm-Ni/30 nm and 70 nm Poly-Si/200 nm-$SiO_2/Si$ structures to investigate the thermal stability of nickel silicides formed by rapid thermal annealing(RTA) of the temperature of $300{\sim}1100^{\circ}C$ for 40 seconds. We employed for a four-point tester, field emission scanning electron microscope(FE-SEM), transmission electron microscope(TEM), high resolution X-ray diffraction(HRIXRD), and scanning probe microscope(SPM) in order to examine the sheet resistance, in-plane microstructure, cross-sectional microstructure evolution, phase transformation, and surface roughness, respectively. The silicide on 30 nm polysilicon substrate was stable at temperature up to $900^{\circ}C$, while the one on 70 nm substrate showed the conventional $NiSi_2$ transformation temperature of $700^{\circ}C$. The HRXRD result also supported the existence of NiSi-phase up to $900^{\circ}C$ for the Ni silicide on the 30 nm polysilicon substrate. FE-SEM and TEM confirmed that 40 nm thick uniform silicide layer and island-like agglomerated silicide phase of $1{\mu}m$ pitch without residual polysilicon were formed on 30 nm polysilicon substrate at $700^{\circ}C\;and\;1000^{\circ}C$, respectively. All silicides were nonuniform and formed on top of the residual polysilicon for 70 nm polysilicon substrates. Through SPM analysis, we confirmed the surface roughness was below 17 nm, which implied the advantage on FUSI gate of CMOS process. Our results imply that we may tune the thermal stability of nickel monosilicide by reducing the height of polysilicon gate.

• Korean Chemical Engineering Research
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• v.51 no.6
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• pp.774-779
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• 2013

We synthesized the solution processible monodispersed $TiO_2$ crystalline nano-sol with ~ 5 nm in size by sol-gel method. Through the spin-coating of crystalline $TiO_2$ nano-sol at low processing temperature, we could make even blocking interlayer on the rough FTO transparent electrode substrate. The rough FTO surface could be gradually smoothed by the spin-coating of nano-crystalline $TiO_2$ sol based blocking interlayer. The 1, 2.5, 5, and 10 wt% of nanocrystalline $TiO_2$ sol formed 29, 38, 62, and 226 nm-thick of blocking interlayer in present experimental condition, respectively. The 5 and 10 wt% of $TiO_2$ nano-sol could effectively fill up the valley part of bare FTO with 48.7 nm of rms (root mean square) roughness and consequently enabled the ZnO to be grown to vertically aligned one dimensional nanorods on the flattened blocking interlayer/FTO substrate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.2
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• pp.303-310
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• 2008

We fabricated hydrogenated amorphous silicon(a-Si:H) 140 nm thick film on a $180\;nm-SiO_2/Si$ substrate with an inductively-coupled plasma chemical vapor deposition(ICP-CVD) equipment at $250^{\circ}C$. Moreover, 30 nm-Ni film was deposited with a thermal-evaporator sequently. Then the film stack was annealed to induce silicides by a rapid thermal annealer(RTA) at $200{\sim}500^{\circ}C$ in every $50^{\circ}C$ for 30 minuets. We employed a four-point tester, high resolution X-ray diffraction(HRXRD), field emission scanning electron microscope(FE-SEM), transmission electron microscope(TEM), and scanning probe microscope(SPM) in order to examine the sheet resistance, phase transformation, in-plane microstructure, cross-sectional microstructure evolution, and surface roughness, respectively. We confirmed that nano-thick high resistive $Ni_3Si$, mid-resistive $Ni_2Si$, and low resistive NiSi phases were stable at the temperature of <300, $350{\sim}450^{\circ}C$, and >$450^{\circ}C$, respectively. Through SPM analysis, we confirmed the surface roughness of nickel silicide was below 12 nm, which implied that it was superior over employing the glass and polymer substrates.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.67-67
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• 2011

Pulsed DC $BCl_3/SF_6$ 플라즈마를 사용하여 GaAs와 AlGaAs의 건식 식각을 연구하였다. 식각 공정 변수는 가스 유량 (50~100 % $BCl_3$ in $BCl_3/SF_6$), 펄스 파워 (450~600 V), 펄스 주파수 (100~250 KHz), 리버스 시간 (0.4~1.2 ${\mu}s$)이었다. 식각 공정 후 표면 단차 측정기 (Surface profiler)를 사용하여 표면의 단차와 거칠기를 분석하였다. 그 결과를 이용하여 식각률 (Etch rate), 표면거칠기 (Surface roughness), 식각 선택비 (Selectivity)와 같은 특성 평가를 하였다. 실험 후 주사 현미경 (FE-SEM, Field Emission Scanning Electron Microscopy)을 이용, 식각 후 시료의 단면과 표면을 관찰하였다. 실험 결과에 의하면 1) 18 sccm $BCl_3$ / 2 sccm $SF_6$, 500 V (Pulsed DC voltage), 0.7 ${\mu}s$ (Reverse time), 200 KHz (Pulsed DC frequency), 공정 압력이 100 mTorr인 조건에서 GaAs와 Al0.2Ga0.8As의 식각 선택비가 약 48:1로 우수한 결과를 나타내었다. 2) 펄스 파워 (Pulsed DC voltage), 리버스 시간(Reverse time), 펄스 주파수(Pulsed DC frequency)의 증가에 따라 각각 500~550 V, 0.7~1.0 ${\mu}s$, 그리고 200~250 KHz 구간에서 AlGaAs에 대한 GaAs의 선택비가 감소하게 되는 것을 알 수 있었다. 이는 척 (chuck)에 인가되는 전류와 파워를 증가시키고, 따라서 GaAs의 식각률이 크게 증가했지만 AlGaAs 또한 식각률이 증가하게 되면서 GaAs에 대한 식각 선택비가 감소한 것으로 생각된다. 3) 표면 단차 측정기와 주사전자현미경 사진 결과에서는 GaAs의 경우 10% $SF_6$ (18 sccm $BCl_3$ / 2 sccm $SF_6$)가 혼합된 조건에서 상당히 매끈한 표면 (RMS roughness < 1.0 nm)과 높은 식각률 (~0.35 ${\mu}m$/min), 수직의 식각 측벽 확보에서 매우 좋은 결과를 보여주었다. 또한 같은 공정 조건에서 AlGaAs는 식각이 거의 되지 않은 결과 (~0.03 ${\mu}m$/min)를 보여주었다. 위의 결과들을 종합해 볼 때 Pulsed DC $BCl_3/SF_6$ 플라즈마는 GaAs와 AlGaAs의 선택적 식각 공정에서 매우 우수한 공정 결과를 나타내었다.

• Journal of the Korean Vacuum Society
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• v.15 no.3
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• pp.259-265
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• 2006

We measured sputtering yield of RF $O_2-plasma$ treated MgO protective layer for AC-PDP(plasma display panel) using a Focused ion Beam System(FIB). A 10 kV acceleration voltage was applied. The sputtering yield of the untreated sample and the treated sample were 0.33 atoms/ion and 0.20 atoms/ion, respectively. The influence of the plasma-treatment of MgO thin film was characterized by XPS and AFM analysis. We observed that the binding energy of the O 1s spectra, the FWHM of O 1s spectra and the RMS(root-mean-square) of surface roughness decreased to 2.36 eV, 0.6167 eV and 0.32 nm, respectively.

• Tribology and Lubricants
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• v.23 no.6
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• pp.288-297
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• 2007

Adhesion and friction tests were carried out in order to investigate the effect of temperature on the tribological characteristics of poly (methylmethacrylate) (PMMA) film using AFM. The pull-off and friction forces on the PMMA film were measured under a high vacuum condition (below $1{\times}10^{-4}$ Pa) as the temperature of the PMMA film was increased from 300 K to 420 K (heating) and decreased to 300K (cooling). Friction tests were also conducted in both high vacuum and air conditions at room temperature. When the temperature was 420 K, which is 25 K higher than the glass transition temperature $(T_g)$ of PMMA, the PMMA film surface became deformable. Subsequently, the pull-off force was proportional to the maximum applied load during the pull-off force measurement. In contrast, when the temperature was under 395 K, the pull-off force showed no correlation to the maximum applied load. The friction force began to increase when the temperature rose above 370 K, which is 25 K lower than the $T_g$ of PMMA, and rapidly increased at 420 K. Decrease of the PMMA film stiffness and plastic deformation of the PMMA film were observed at 420 K in force-displacement curves. After the heating to 420 K, the fiction coefficient was measured under the air condition at room temperature and was found to be lower than that measured before the heating. Additionally, the RMS roughness increased as a result of the heating.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.196-196
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• 2008

We have investigated that the effect of post annealing on the structural and electrical properties of $Ba_{0.5}Sr_{0.5}TiO_3$ thin films. The BST thin films were deposited on n-type 4H-silicon carbide(SiC) using pulsed laser deposition (PLD). The deposition was carried out in oxygen ambient 100mTorr for 5 minutes, which results in about 300nm-thick BST films. For the BST/4H-SiC, 200nm thick silver was deposited on the BST films bye-beam evaporation. The X-ray diffraction patterns of the BST films revealed that the crystalline structure of BST thin films has been improved after post-annealing at $850^{\circ}C$ for 1 hour. The root mean square (RMS) surface roughness of the BST film measured by using a AFM was increased after post-annealing from 5.69nm to 11.49nm. The electrical properties of BST thin film were investigated by measuring the capacitance-voltage characteristics of a silver/BST/4H-SiC structure. After the post-annealing, dielectric constant of the film was increased from 159.67 to 355.33, which can be ascribed to the enhancement of the crystallinity of BST thin films.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.261-261
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• 2011

펄스 직류 전원 $BCl_3/SF_6$ 플라즈마를 이용하여 GaAs/$Al_{0.2}Ga_{0.8}As$의 선택적 식각을 연구하였다. 식각 주요 공정 변수는 $BCl_3/SF_6$ 플라즈마에서 $SF_6$ 가스 유량(0~50%)이었다. $BCl_3/SF_6$의 총 가스 유량은 20 sccm이었다. 다른 공정 조건인 공정 압력(100 mTorr), 펄스 파워(500 V), 펄스 주파수(200 kHz), 리버스 시간 (0.7 ${\mu}s$)은 일정하게 고정시켰으며 기계적 펌프만을 이용하여 공정을 진행하였다. 오실로스코프(Oscilloscope) 데이터에 의하면 가스의 조성 변화에도 척에 걸리는 입력 전압과 전류가 거의 변화가 없었다. $BCl_3/SF_6$ 가스가 10%의 조성에서 GaAs와 $Al_{0.2}Ga_{0.8}As$의 식각 선택비가 약 48 : 1로 우수한 결과를 나타내었다. 그러나 $BCl_3/SF_6$ 가스의 증가는 GaAs의 식각율과 선택도를 감소시켰다. 그리고 $SF_6$ 가스의 조성비가 30% 이상일 경우에는 GaAs와 $Al_{0.2}Ga_{0.8}As$가 식각되지 않았다. 식각 후에 GaAs의 표면 거칠기(RMS surface roughness)는 0.7~1.3 nm로 나타났다. 위의 결과들을 종합적으로 보면 펄스 직류 전원 $BCl_3/SF_6$의 조성비가 10%일 때 가장 좋은 식각 선택비를 얻을 수 있었다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.4
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• pp.199-203
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• 2017

$ZrO_2/PSS$ thin film with a high refractive index was fabricated on a glass substrate by a layer-by-layer self-assembly method. The surface morphology and thickness of the fabricated $ZrO_2/PSS$ thin films were measured as a function of the number of $(ZrO_2/PSS)n$. As the number of $(ZrO_2/PSS)n$ increased from n = 5 to n = 20, RMS roughness decreased from 29.01 nm to 8.368 nm. The $ZrO_2$ thin films exhibited high transmittance of 85% or more; and the 15-bilayer thin film exhibited the highest transmittance among the samples. The transmittance of the fabricated $(ZrO_2/PSS)_{15}$ thin film was ca. 90.8% in the visible range. The refractive index of the glass substrate coated by a $(ZrO_2/PSS)_{15}$ thin film with a thickness of 160 nm increased from ca. 1.52 to 1.74 at the 632 nm wavelength.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.26.2-26.2
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• 2009

이 논문은 반응성 $BCl_3$ 플라즈마로 GaAs의 건식 식각을 진행한 후 그 결과에 대하여 연구 분석 한 것이다. 이 때 사용한 식각 공정 변수는 $BCl_3$ 플라즈마에서의 가스유량, 공정 압력과 RIE 척 파워의 변화이다. 먼저 공정 압력을 75 mTorr 고정시킨 후 $BCl_3$ 유량을 변화 (2.5~10 sccm)해서 실험하였다. 또한 BCl3의 유량을 5 sccm으로 고정시킨 후 공정압력을 변화(47~180 mTorr)해서 식각 실험을 실시하였다. 마지막으로 47 mTorr와 100 mTorr 의 각각의 공정압력에서 RF 척 파워를 변화시켜 (50~200 W) 실험하였다. GaAs 플라즈마 식각이 끝난 후 표면단차 측정기 (Surface profiler)를 사용하여 표면의 단차와 거칠기를 분석하였다. 그 후 그 결과를 이용하여 식각율 (Etch rate), 식각 표면 거칠기 (RMS roughness), 식각 선택비 (Selectivity) 등의 식각 특성평가를 하였다. 또한 식각 공정 중에 샘플 척에 발생하는 자기 바이어스와 $BCl_3$ 플라즈마 가스를 광학 발광 분석기 (Optical Emission Spectroscopy)를 이용하여 플라즈마의 상태를 실시간으로 분석하였다. 이 실험 결과에 따르면 공정 압력의 증가는 샘플 척의 자기 바이어스의 값을 감소시켰다. $BCl_3$ 압력 변화에 의한 GaAs의 식각 결과를 정리하면 5 sccm의 $BCl_3$ 가스유량과 RF 척 파워를 100 W로 고정시켰을 때 식각율은 47 mTorr에서 가장 높았으며, 그 값은 $0.42{\mu}m/min$ 이었다. GaAs의 식각 속도는 공정압력이 증가할수록 감소하였으며 180 mTorr에서는 식각율이 $0.03{\mu}m/min$로 거의 식각되지 않았다. 또한 공정압력을 75 mTorr, RF 척 파워를 100 W로 고정시키고, $BCl_3$ 가스유량을 2.5 sccm에서 10 sccm까지 변화시켰을 때, 10 sccm 의 $BCl_3$ 가스유량에서 가장 높은 식각율인 $0.87{\mu}m/min$이 측정되었다. 압력에 따른 GaAs의 식각 후 표면 거칠기는 최대 2 nm 정도로 비교적 매끈하였으며, 거의 식각되지 않은 180mTorr의 조건에서는 약 1 nm로 낮아졌다. 본 실험 조건에서 GaAs의 감광제에 대한 식각 선택비는 최대 약 3:1 이내였다.