• Title/Summary/Keyword: electrostatic field

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Improvements of Extended Drain NMOS (EDNMOS) Device for Electrostatic Discharge (ESD) Protection of High Voltage Operating LDI Chip (고전압용 LDI 칩의 정전기 보호를 위한 EDNMOS 소자의 특성 개선)

  • Yang, Jun-Won;Seo, Yong-Jin
    • Journal of Satellite, Information and Communications
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    • v.7 no.2
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    • pp.18-24
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    • 2012
  • High current behaviors of the extended drain n-type metal-oxide-semiconductor field effects transistor (EDNMOSFET) for electrostatic discharge (ESD) protection of high voltage operating LDI (LCD Driver IC) chip are analyzed. Both the transmission line pulse (TLP) data and the thermal incorporated 2-dimensional simulation analysis demonstrate a characteristic double snapback phenomenon after triggering of biploar junction transistor (BJT) operation. Also, background doping concentration (BDC) is proven to be a critical factor to affect the high current behavior of the EDNMOS devices. The EDNMOS device with low BDC suffers from strong snapback in the high current region, which results in poor ESD protection performance and high latchup risk. However, the strong snapback can be avoided in the EDNMOS device with high BDC. This implies that both the good ESD protection performance and the latchup immunity can be realized in terms of the EDNMOS by properly controlling its BDC.

Spatial mapping of screened electrostatic potential and superconductivity by scanning tunneling microscopy/spectroscopy

  • Hasegawa, Yukio;Ono, Masanori;Nishio, Takahiro;Eguchi, Toyoaki
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.02a
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    • pp.12-12
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    • 2010
  • By using scanning tunneling microscopy/spectroscopy (STM/S), we can make images of various physical properties in nanometer-scale spatial resolutions. Here, I demonstrate imaging of two electron-correlated subjects; screening and superconductivity by STM/S. The electrostatic potential around a charge is described with the Coulomb potential. When the charge is located in a metal, the potential is modified because of the free electrons in the host. The potential modification, called screening, is one of the fundamental phenomena in the condensed matter physics. Using low-temperature STM we have developed a method to measure electrostatic potential in high spatial and energy resolutions, and observed the potential around external charges screened by two-dimensional surface electronic states. Characteristic potential decay and the Friedel oscillation were clearly observed around the charges [1]. Superconductivity of nano-size materials, whose dimensions are comparable with the coherence length, is quite different from their bulk. We investigated superconductivity of ultra-thin Pb islands by directly measuring the superconducting gaps using STM. The obtained tunneling spectra exhibit a variation of zero bias conductance (ZBC) with a magnetic field, and spatial mappings of ZBC revealed the vortex formation [2]. Size dependence of the vortex formation will be discussed at the presentation.

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Study on Chucking Force and Substrate Deformation Characteristics of Electrostatic Chuck for Deposition According to Substrate Sizes (증착용 정전척의 기판 크기에 따른 척킹력 및 기판 변형 특성 연구)

  • Seong Bin Kim;Dong Kyun Min
    • Journal of the Semiconductor & Display Technology
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    • v.23 no.2
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    • pp.12-18
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    • 2024
  • A Electrostatic chuck is a device that fixes the substrate, using the force between charges applied between two parallel plates to attract substrates such as wafers or OLED panels. Unlike mechanical suction methods, which rely on physical fixation, this method utilizes the force of electrostatics for fixation, making it important to verify the adhesion force. As the size of the substrate increases, deformations due to gravity or chucking force also increase, and the adhesion force decreases rapidly as the distance between the chuck and the substrate increases. The outlook for displays is shifting from small to large OLEDs, necessitating consideration of substrate deformations. In this paper, to confirm the deformation of the substrate through various patterns, a simplified 2D model using Ansys' electromagnetic field analysis program, Maxwell, and the static structural analysis program, Mechanical, was utilized to observe changes in adhesion force according to the variation in the air gap between the substrate and the chuck. Additionally, the chucking force was analyzed for the size of the substrate, and the deformation of the substrate was confirmed when gravity and chucking force act simultaneously.

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Transflective Fringe-Field Switching Liquid Crystal Device Driven by Vertical- and Fringe-field (수직전기장과 프린지 필드에 의해 구동되는 반투과형 FFS 액정소자)

  • Lim, Young-Jin;Park, Sang-Hyun;Choi, Min-Oh;Lee, Seung-Hee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.11a
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    • pp.279-280
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    • 2005
  • We have designed a single gap transflective liquid crystal display (LCD) driven by a fringe electric field and vertical field. The conventional FFS mode does not have an electrode on top substrate, it shows not only slow response time due to weak electric field but also slow discharging problem when electrostatic field is generated after fabricating the cell. To solve these problems, transflective LCD with ITO coated upper substrate was suggested but the transmittance was reduced significantly due to effects from vertical field. Hence, in the present paper, new transflective LCD with ITO coating only in the reflective region was characterized.

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3D QSAR Studies on New Piperazine Derivatives with Antihistamine and Antibradykinin Effects

  • Parkchoo, Hea-Young;Chung, Bum-Jun
    • Archives of Pharmacal Research
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    • v.23 no.4
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    • pp.324-328
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    • 2000
  • Three dimensional QSAR studies for antihistamine and antibradykinin effects of new piperazine derivatives were conducted using the comparative molecular field analysis. Electrostatic and steric factors, but not hydrophobic factor, of the synthesized compounds were correlated with the antagonistic effect.

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Theoretical Study on the [3,3]-Sigmatropic Rearrangement of Allylic Esters by Comparative Molecular Field Analysis (CoMFA)

  • Yoo, Sung-Eun;Cha, OKJa
    • Bulletin of the Korean Chemical Society
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    • v.15 no.10
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    • pp.889-890
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    • 1994
  • A comparative molecular field analysis (CoMFA) on the substituent effect of the palladium(Ⅱ) catalyzed [3,3]-sigmatropic rearrangement of allylic esters was studied to show a good correlation between the electrostatic property of substituents and the reaction rate. The CoMFA result suggests that the reaction rate will increase as the electron-donating ability of substituents increases.

Electrostatic Beneficiation of Coal Fly Ash Utilizing Triboelectric Charging with Subsequent Electrostatic Separation

  • Lee, Jae-Keun;Kim, Seong-Chan
    • Journal of Mechanical Science and Technology
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    • v.15 no.6
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    • pp.804-812
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    • 2001
  • A triboelectrostatic separation system for removing unburned carbon from coal fly ash is designed and evaluated. Fly ash from a coal-fired power plant is used as an accepted additive in concrete where it adds strength, sulfate resistance and reduced cost, provided acceptable levels of unburned carbon are maintained. Unfortunately, unburned carbon in coal fly ash absorbs some of other additives and reduces the concrete strength. This paper describes to investigate dry triboelectrostatic process to separate unburned carbon from coal fly ash and utilize it into economically valuable products. The laboratory-scale triboelectrostatic separation system consists of a particle feeding system, a tribocharger, a separation chamber, and collection systems. Particles of unburned carbon and fly ash can be imparted positive and negative surface charges, respectively, with a copper tribocharger due to differences in the work function values of the particles and the tribocharger, and can be separated by passing them through an external electric field. Results showed that fly ash recovery was strongly dependent on the electric field strength and the particle size. 70wt% of fly ash containing 6.5wt% of carbon contents could be recovered at carbon contents below 3%. The triboelectrostatic separation system showed a potential to be an effective method for removing unburned carbon from coal fly ash.

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A Study on the Simulation of the Corona Charging Process of Polypropylene Electret Cell Using Finite Element Method (유한요소법을 이용한 폴리프로필렌 일렉트렛트 셀의 코로나 대전과정 시뮬레이션에 관한 연구)

  • Lee, Su-Kil;Park, Geon-Ho;Jung, Il-Hyung;Jang, Kyung-Uk;Lee, Joon-Ung
    • Proceedings of the KIEE Conference
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    • 1993.11a
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    • pp.169-171
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    • 1993
  • In order to estimate space charging process in the corona charging apparatus which has been used to make polymer electret cell, the electrical properties of 30[${\mu}m$] thick polypropylene film were obtained from TSC measurement after corona charging between copper knife electrode and aluminum cylinder electrode with the voltage of -8, -7, -6, -5 (kV). And, the electrostatic contour and the electric field vector were calculated using Finite Element Method with the electrical properties obtained from TSC spectra analysis. The edge effect around the edge of knife electrode affects electrostatic contour on the surface of specimen and the electric field concentration inside the polymer. As a result the uneven charging state in the electret cell due to the mistake of design was calculated, and the optimal design of corona charging apparatus opprobriate to various specimen was come to be practicable.

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Analysis of Effects of Line Tension and Electrical Double Layers on Electrowetting Phenomenon (전기습윤 현상에서의 선장력과 전기 이중층의 영향에 대한 해석)

  • Chung, Sang-Kug;Kang, Kwan-Hyoung;Lee, Choung-Mook;Kang, In-Seok
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.7
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    • pp.956-962
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    • 2003
  • The Lippmann-Young equation has been widely used in electrowetting to predict the contact-angle change of a droplet on a insulating substrate with respect to the externally-applied electrical voltage. The Lippmann-Young equation is derived by assuming a droplet as a perfect conductor, so that the effect of the electrical double layer and the line tension are not taken into account. The validity of the assumption has never been checked before, systematically. In the present investigation, a modified Lippmann-Young equation is derived taking into account of the effect of the electrical double layer and the line tension. To assess their influence on contact-angle change in electrowetting, the electrostatic field around the three-phase contact line is analyzed by solving the Poisson-Boltzmann equation numerically. The validity of the numerical methods is verified by using the past theoretical results on the electrostatic field around a wedge-shaped geometry, which shows fairly good agreement. The results of the present investigation clearly indicate that the effect of the electrical double layer and the line tension is negligible for a millimeter-sized droplet. On the other hand, for a micron-sized droplet, the effect of the line tension can become a dominating factor which controls the contact-angle change in electrowetting.

Reduced ion mass effects and parametric study of electron flat-top distribution formation

  • Hong, Jinhy;Lee, Ensang;Parks, George K.;Min, Kyoungwook
    • The Bulletin of The Korean Astronomical Society
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    • v.37 no.2
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    • pp.118.2-118.2
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    • 2012
  • In particle-in-cell (PIC) simulation studies related to ion-ion two-stream instability, a reduced ion-to-electron mass ratio is often employed to save computation time. But it was not clearly verified how electrons dynamics are coupled with the slower evolution of ion-ion interactions under the external electric field. We have studied the ion beam driven instability using a 1D electrostatic PIC code by comparing different rescaling of parameter with real ion mass from the reference simulation with reduced ion mass. As the external electric field is stronger, the excited unstable mode range was more sensitively affected by the system size with the real mass ratio than the reduced ion mass. The results show that the reduced mass ratio should be used cautiously in PIC code as the electron dynamics can modify the ion instabilities. Additionally we found the formation of electron flat-top distribution in the final saturation stage. Simulation results show that in the early phase electrostatic solitary waves are quasi-periodically formed, but later they are fully dissipated resulting in heated, flat-top distributions. New electron beam components are occasionally formed. These are a consequence of the interaction with solitary wave structures. We parametrically investigate the development of electron phase space distributions for various drift speeds of ion beams and temperature ratios between ions and electrons

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