• Journal of Magnetics
• /
• v.7 no.3
• /
• pp.63-71
• /
• 2002

Three fabrication techniques for forming thin barrier layer with uniform thickness and large barrier height in magnetic tunnel junction (MTJ) are discussed. First, the effect of immiscible element addition to Cu layer, a high conducting layer generally placed under the MTJ, is investigated in order to reduce the surface roughness of the bottom ferromagnetic layer, on which the barrier is formed. The Ag addition to the Cu layer successfully realizes the smooth surface of the ferromagnetic layer because of the suppression of the grain growth of Cu. Second, a new plasma source, characterized as low electron energy of 1 eV and high density of $10^{12}$ $cm^{-3}$, is introduced to the Al oxidation process in MTJ fabrication in order to reduce damages to the barrier layer by the ion-bombardment. The magnetotransport properties of the MTJs are investigated as a function of the annealing temperature. As a peculiar feature, the monotonous decrease of resistance area product (RA) is observed with increasing the annealing temperature. The decrease of the RA is due to the decrease of the effective barrier width. Third, the influence of the mixed inert gas species for plasma oxidization process of metallic Al layer on the tunnel magnetoresistance (TMR) was investigated. By the use of Kr-O$_2$ plasma for Al oxidation process, a 58.8 % of MR ratio was obtained at room temperature after annealing the junction at $300{^{\circ}C}$, while the achieved TMR ratio of the MTJ fabricated with usual Ar-$0_2$ plasma remained 48.4%. A faster oxidization rate of the Al layer by using Kr-O$_2$ plasma is a possible cause to prevent the over oxidization of Al layer and to realize a large magnetoresistance.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.49 no.5
• /
• pp.265-269
• /
• 2000

$(Ba, Sr)TiO_3$thin films were etched with a magnetically enhanced inductively coupled plasma (MEICP) at different CF4/Ar gas mixing ratios. Experimental was done by varying the etching parameters such as rf power, dc bias and chamber pressure. The maximum etch rate of the BST films was $1800{AA}/min$ under $CF_4/(CF_4+Ar)$ of 0.1, 600 W/350 V and 5 mTorr. The selectivity of BST to Pt and PR was 0.6, 0.7, respectively. X-ray photoelectron spectroscopy (XPS) results show that surface reaction between Ba, Sr, Ti and C, F radicals occurs during the (Ba, Sr)TiO3 etching. To analyze the composition of surface residue after the etching, films etched with different CF_4/Ar$ gas mixing ratio were investigated using XPS and secondary ion mass spectroscopy (SIMS).

• ETRI Journal
• /
• v.27 no.1
• /
• pp.118-121
• /
• 2005

Silicon dioxide ($SiO_2$) films prepared by plasma-enhanced atomic-layer deposition were successfully grown at temperatures of $100\;to\;250^{\circ}C$, showing self-limiting characteristics. The growth rate decreases with an increasing deposition temperature. The relative dielectric constants of $SiO_2$ films are ranged from 4.5 to 7.7 with the decrease of growth temperature. A $SiO_2$ film grown at $250^{\circ}C$ exhibits a much lower leakage current than that grown at $100^{\circ}C$ due to its high film density and the fact that it contains deeper electron traps.

• Journal of Korea Multimedia Society
• /
• v.19 no.1
• /
• pp.80-85
• /
• 2016

It costs high in both memory usage and time consuming to sample the space to compute charge density and calculate electric field on that with large size of plasma data. In real-time and interactive application, accelerating the compute time is critical problem. In this paper, we suggest new method to visualize electric field by using convolution theorem, and the parallel computing to accelerate computing time by using GPGPU. We conduct a simulation that compare running time between the methods with convolution and without convolution. We discussed the method of visualization of multivariate data in three dimensional space using colored volume rendering and surface construction.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.14 no.10
• /
• pp.850-854
• /
• 2001

In this study, carbon nanotubes was vertically grown pm Ni/Cr-deposited glass substrates by Inductively Coupled Plasma Chemical Vapor Deposition. Using Radio-Frequence(RF) plasma below temperature of 600$^{\circ}C$. The grown CNTs shows field emission properties and high quality materials. Turn-on fields and current density showed 5V/${\mu}$m and 1.06${\times}$10$\^$-6/ A/$\textrm{cm}^2$, respectively.

• Proceedings of the KIEE Conference
• /
• 1989.11a
• /
• pp.145-148
• /
• 1989

Plasma diagnostics using Langmuir Probe is of wide application because of its simplicity in measurement of electron temperatures and densities. Current methods using simple circuit and analog meters, however, have troubles when they are applied to time-varying or thermal plasmas. To overcome these problems and expand the area of applicability, we have designed fast electronic voltage sweeping circuit in which we can detect digital data. Diagnostics using our digital Langmuir Probe is performed in various kinds of plasmas and the results are shown. Our method can be applied to measuring electron temperature and density of high temperature or time-varying plasmas. And we expect further knowledge of each state of plasma.

• Transactions on Electrical and Electronic Materials
• /
• v.1 no.1
• /
• pp.1-5
• /
• 2000

Diamond films have been achieved on Si(100) substrates using helicon plasma chemical vapor deposition(HPCVD), Gas mixtures with methane and hydrogen have been used. The growth characteristics were investigated by means of X-ray photoelectroton spectroscopy, Atomic force microscopy and X-ray diffraction. We obtained a plasma density as high as 10$\^$10/~10$\^$11/ cm$\^$-3/ by helicon source. The smooth(100) faces of submicron diamond crystallites were found to exhibit pyramidal shaped architecture, The XPS spectrum for the nucleation layer indicates the presence of diamond at 285.4 eV, close to the reported value of 285.5 eV for diamond , XRD results demonstrates the existence of polycrystalline diamond as the diamond (111) and (220) peaks.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.31A no.4
• /
• pp.63-69
• /
• 1994

The Ultrahigh Vacuum Electron Cyclotron Resonance Chemical Vapor Deposition(UHV-ECRCVD) system whose base pressure is 1${\times}10^{9}$ torr has been constructed. In-situ cleaning prior to the epitaxial growth was carried out at 56$0^{\circ}C$ by ECR generated uniform hydrogen plasma whose density is $10^{10}/cm{3}$. The natural oxide was effectively removed without damage by applying positive DC bias(+10V) to the substrate. RHEED(Reflection High Energy Electron Diffraction) analysis has been used to confirm the removal of the surgace oxide and the streaky 2$\times$1 reconstruction of the Si surface, and the suppression of the substrate damage is anaylized by X-TEM(cross-sectional Transmission Electron Microscopy). Surface cleaning technique by ECR hydrogen plasma confirmed good quality epitaxial growth at low temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.11a
• /
• pp.124-125
• /
• 2005

ZnS:Mn thin films have attracted great interest as electroluminescence devices. In this study, inductively coupled BCl$_3$/Ar plasma was used to etch ZnS:Mn thin films. We obtained the maximum etch rate of ZnS:Mn thin films was 2209 ${\AA}$/min at a BCl$_3$(20%)/Ar(80%) gas mixing ratio, an RF power of 700 W, a DC bias voltage of-250 V, a total gas flow of 20 sccm, and a chamber pressure of 1 Pa. It was proposed that sputter etching is dominant etching mechanism while the contribution of chemical reaction is relatively low due to low volatility of etching products.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2009.05a
• /
• pp.202-203
• /
• 2009

Plasma etching was studied to obtain high-efficiency Si solar cells. SiN nanoparticles were observed upon the plasma treatment using SF6 gas. The mechanism of the nanoparticles formation has been studied. A net increase in the current density (Jsc) of the cells of $1.7mA/cm^2$ and in the conversion efficiency ($\eta$) of 2.1% is obtained after the plasma treatment for 10s, thanks to the significant decrease of reflection in the shorter wavelength range.