• Analytical Science and Technology
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• v.7 no.4
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• pp.527-540
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• 1994

The surface microstructure modification by $N^+ion$ implantation into 7050A1 alloy was investigated. Ion implantation method is to implant physically accelerated ions to the surface of a substrate. High doses of nitrogen($5{\times}10^{15}ions/cm^2$, $5{\times}10^{17}ions/cm^2$, $8{\times}10^{17}ions/cm^2$) were implanted into 7050A1 alloy using accelerating voltage of 100KeV and current density of $23.1{\mu}A/cm^2$. The implanted layers were characterized by EPMA, AES, XRD, and TEM. The experimental results were compared with computer simulation data. The results showed that AlN was formed from the surface to $4000{\AA}$ depth with Gaussian distribution and the damage region was also observed. This surface modification by $N^+ion$ implantation increased the microhardness of 7050A1 alloy surface.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.3
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• pp.6-13
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• 2000

Ultra-thin gate oxide was grown on nitrogen implanted silicon substrates. For nitrogen implantation, the energy was fixed at 25keV, but the dose was split into 5.0$\times$10$^{13}$ /c $m^{2}$ and 1.0$\times$10$^{14}$ /c $m^{2}$. The grown gate oxide thickness were 2nm, 3nm and 4nm. The oxidation time to grow 3nm was increased by 20% and 50% for the implanted wafers of 5.0$\times$10$^{13}$ /c $m^{2}$ and 1.0$\times$10$^{14}$ /c $m^{2}$ doses, respectively, when it was compared with control wafers which were not implanted by nitrogen. The value of charge-to-breakdown ( $Q_{BD}$ ) is decreased with increasing nitrogen doses. If an annealing process( $N_{2}$, 85$0^{\circ}C$, 60min.) is peformed after nitrogen implantation, $Q_{BD}$ is increased. It is indicated that nitrogen implantation damage affect gate oxide reliability and the damage can be removed by post-implantation annealing process.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.557-560
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• 1998

We previously developed and presented the 3D ion implantation simulation code, TRICSI. In this paper, we performed the multiple implants into (100) silicon substrate with our recently enhanced version. Our results for the multiple implants were compared with the previously published SIMS data and obtained the good agreements. In this paper the channeling behaviour of implanted impurity and the damage accumulation are analyzed and discussed in the simple 3D structure, named the Hole structure which has a rectangular implant window.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.5
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• pp.407-413
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• 2005

Ion implantation provides a unique way to modify the mechanical, optical and electrical properties of polymer by depositing the energy of ions in the material on the atomic scale. Implantation of ions into the polymers generally leads to a radiation damage, which, in many cases, modifies the properties of the surface and bulk of the material. These modifications result from the changes of the chemical structure caused in their turn by changing the chemical bonding when the incident ions cut the polymer chains, breaks covalent bonds, promotes cross-linking, and liberates certain volatile species. We studied the relation among the linear energy transfer (LET) and changes of surface microstructure and surface resistivity on PPS material using the high current ion implantation technology The surface resistivity of nitrogen implanted PPS decreased to $10^{7}{\Omega}/cm^{2}$ due to the chain scission, cross linking, ${\pi}$ electron creation and mobility increase. In this case, the surface conductivity depend on the 1-dimensional hopping mechanism.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.7
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• pp.9-16
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• 1999

We have investigated effects of local damage accumulation for ultra-low energy As and B ion implant using highly efficient molecular dynamics(MD) scheme. We simulated ion implantation by MD simulation using recoil ion approximation (RIA) method and local cell damage accumulation (LCDA) model proposed in the paper. Local damage accumulation probability function consisted of deposited energy in a unit cell, implant dose rate, target material, projectile atom, and recoil event number. The simulated results were good agreement with the experimental and other simulated results. The MDRANGE results without damage accumulation were different from SIMS data in the tail region. We also simulated 2 dimensional dopant and damage profiles using the local damage accumulation model and recoil ion approximation method.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.178-178
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• 2016

Every display is equipped with a cover glass to protect the underneath displaying devices from mechanical and environmental impact during its use. The strengthened glass such as Gorilla glass.$^{TM}$ has been exclusively adopted as a cover glass in many displays. Conventionally, the strengthened glass has been manufactured via ion-exchange process in wet salt bath at high temperature of around $500^{\circ}C$ for hours of treatment time. During ion-exchange process, Na ions with smaller diameter are substituted with larger-diameter K ions, resulting in high compressive stress in near-surface region and making the treated glass very resistant to scratch or impact during its use. In this study, PIIID (plasma immersion ion implantation and deposition) technique was used to implant metal ions into the glass surface for strengthening. In addition, due to the plasmonic effect of the implanted metal ions, the metal-ion implanted glass samples got colored. To implant metal ions, plasma immersion ion implantation technique combined with HiPIMS method was adopted. The HiPIMS pulse voltage of up to 1.4 kV was applied to the 3" magnetron sputtering targets (Cu, Ag, Au, Al). At the same time, the sample stage with glass samples was synchronously pulse-biased via -50 kV high voltage pulse modulator. The frequency and pulse width of 100 Hz and 15 usec, respectively, were used during metal ion implantation. In addition, nitrogen ions were implanted to study the strengthening effect of gas ion implantation. The mechanical and optical properties of implanted glass samples were investigated using micro-hardness tester and UV-Vis spectrometer. The implanted ion distribution and the chemical states along depth was studied with XPS (X-ray photo-electron spectroscopy). A cross-sectional TEM study was also conducted to investigate the nature of implanted metal ions. The ion-implanted glass samples showed increased hardness of ~1.5 times at short implantation times. However, with increasing the implantation time, the surface hardness was decreased due to the accumulation of implantation damage.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.735-738
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• 2003

In this paper, we report a molecular dynamics (MD) simulation of the ion implantation for nano-scale devices with ultra-shallow junctions. In order to model the profile of ion distribution in nanometer scale, the molecular dynamics with a damage model has been employed. As an exemplary case, we calculate the dopant profile during the ion implantation of B, As, and Ge.

• Journal of the Korean institute of surface engineering
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• v.32 no.3
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• pp.389-392
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• 1999

We employed cobalt-disilicide for high-speed logic devices. We prepared stable and low resistant $CoSi_2$ through typical fabrication process including wet cleaning and rapid thermal process (RTP). We sputtered 15nm thick cobalt on the wafer and performed RTP annealing 2 times to obtain 60nm thick $CoSi_2$. We observed spherical shape voids with diameter of 40nm in the surface and inside $CoSi_2$ layers. The voids resulted in taking over abnormal junction leakage current and contact resistance values. We report that the voids in $CoSi_2$ layers are resulted from surface pits during the ion implantation previous to deposit cobalt layer. Silicide reaction rate around pits was enhanced due to Gibbs-Thompson effects and the volume expansion of the silicidation of the flat active regime trapped dimples. We confirmed that keeping the buffer oxide layer during ion implantation and annealing the silicon surface after ion implantation were required to prevent void defects in CoSi$_2$ layers.

• Proceedings of the Korean Vacuum Society Conference
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• 2004.08a
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• pp.239-239
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• 2004

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.164-166
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• 2003

Despite recent advances in the treatment of acute myocardial infarction, the ability to repair extensive myocardial damage is limited. Revascularization in ischemic myocardium is required to improve cardiac function and prevent further scar tissue formation. Bone marrow contains endothelial precursors that can be used to induce neovascularization in ischemic myocardium. To develop a new therapy for myocardial infarction, we investigated if implantation of bone marrow mononuclear cells (BM-MNCs) using biodegradable matrices could enhance neovascularization in ischemic myocardium. Eight weeks after implantation, the damaged myocardium implanted with BM-MNCs and fibrin gels exhibited significantly greater angiogenic responses than those implanted with either fibrin gels or BM-MNCs alone. Fibrin gels disappeared completely 8 weeks after implantation. Echocardiography revealed improved heart functions. These results suggest that implantation of BM-MNCs using fibrin gel matrix efficiently induces neovascularization and improved heart functions in ischemic myocardium.