• Title/Summary/Keyword: boron diffusion

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Computational Study of Intermetallic Reaction Propagation in Nanoscale Boron/Titanium Metallic Multilayers (보론/티타늄 나노박막다층 내 이종금속간 화학반응 전파특성 해석연구)

  • Kim, Kyoungjin;Park, Joong-Youn
    • Journal of the Korean Society of Propulsion Engineers
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    • v.21 no.3
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    • pp.10-17
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    • 2017
  • The analytical modeling has been established on the self-propagation of intermetallic reaction in the spanwise direction of highly reactive boron and titanium nanoscale multilayers. Assuming that the reaction obeys Arrhenius kinetics, two-dimensional computations are carried out for heat and atomic species diffusion with exothermic reaction model in order to simulate the self-propagation of intermetallic reaction. The effects of bimetallic layer thickness and thickness ratio on the reaction propagation speed are tested and discussed in addition to the assessment of pre-mixing zone effects.

Effects of Drive-in Process Parameters on the Residual Stress Profile of the p+ Silicon Film (후확산 공정 변수가 p+ 실리콘 박막의 잔류 응력 분포에 미치는 영향)

  • Jeong, Ok-Chan;Yang, Sang-Sik
    • Proceedings of the KIEE Conference
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    • 2002.11a
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    • pp.245-247
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    • 2002
  • The paper represents the effects of the drive-in process parameters on the residual stress profile of the p+ silicon film. For the quantitative determination of the residual stress profiles, the test samples are doped via the fixed boron diffusion process and four types of the thermal oxidation processes and consecutively etched by the improved process. The residual stress measurement structures with the different thickness are simultaneously fabricated on the same silicon wafer. Since the residual stress profile is not uniform along the direction normal to the surface, the residual stress is assumed to be a polynomial function of the depth. All of the coefficients of the polynomial are determined from the deflections of cantilevers and the displacement of a rotating beam structure. As the drive-in temperature or the drive-in time increases, the boron concentration decreases and the magnitude of the average residual tensile stress decreases. Also, near the surface of the p+ film the residual tensile stress is transformed into the residual compressive stress and its magnitude increases.

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Fluorine Effects on CMOS Transistors in WSix-Dual Poly Gate Structure (텅스텐 실리사이드 듀얼 폴리게이트 구조에서 CMOS 트랜지스터에 미치는 플로린 효과)

  • Choi, Deuk-Sung;Jeong, Seung-Hyun;Choi, Kang-Sik
    • Journal of the Institute of Electronics and Information Engineers
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    • v.51 no.3
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    • pp.177-184
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    • 2014
  • In chemical vapor deposition(CVD) tungsten silicide(WSix) dual poly gate(DPG) scheme, we observed the fluorine effects on gate oxide using the electrical and physical measurements. It is found that in fluorine-rich WSix NMOS transistors, the gate thickness decreases as gate length is reduced, and it intensifies the roll-off properties of transistor. This is because the fluorine diffuses laterally from WSix to the gate sidewall oxide in addition to its vertical diffusion to the gate oxide during gate re-oxidation process. When the channel length is very small, the gate oxide thickness is further reduced due to a relative increase of the lateral diffusion than the vertical diffusion. In PMOS transistors, it is observed that boron of background dopoing in $p^+$ poly retards fluorine diffusion into the gate oxide. Thus, it is suppressed the fluorine effects on gate oxide thickness with the channel length dependency.

Diffusion and Thermal Stability Characteristics of W-B-C-N Thin Film (W-B-C-N 확산방지막의 특성 및 열적 안정성 연구)

  • Kim, Sang-Yoon;Kim, Soo-In;Lee, Chang-Woo
    • Journal of the Korean Magnetics Society
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    • v.16 no.1
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    • pp.75-78
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    • 2006
  • In case of contacts between semiconductor and metal in semiconductor circuits, they become unstable because of thermal budget. To prevent these problems, we use diffusion barrier that has a good thermal stability between metal and semiconductor. So we consider the diffusion barrier to prevent the increase of contact resistance between the interfaces of metals and semiconductors, and the increase of resistance and the reaction between the interfaces. In this paper we deposited tungsten boron carbon nitride (W-B-C-N) thin film on silicon substrate. The impurities of the $1000\;{\AA}-thick$ W-B-C-N thin films provide stuffing effect for preventing the inter-diffusion between metal thin films $(Cu-2000\;{\AA})$ and silicon during the high temperature $(700\~1000^{\circ}C)$ annealing process.

Application and evaluation of boron nitride-assisted liquid silicon infiltration for preparing Cf/SiC composites

  • Kim, Jin-Hoon;Jeong, Eui-Gyung;Kim, Se-Young;Lee, Young-Seak
    • Carbon letters
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    • v.12 no.2
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    • pp.116-119
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    • 2011
  • C/SiC composites were prepared by boron nitride (BN)-assisted liquid silicon infiltration (LSI), and their anti-oxidation and mechanical properties were investigated. The microstructures, bulk densities, and porosities of the C/SiC composites demonstrated that the infiltration of liquid silicon into the composites improved them, because the layered-structure BN worked as a lubricant. Increasing the amount of BN improved the anti-oxidation of the prepared C/SiC composites. This synergistic effect was induced by the assistance of BN in the LSI. More thermally stable SiC was formed in the composite, and fewer pores were formed in the composite, which reduced inward oxygen diffusion. The mechanical strength of the composite increased up to the addition of 3% BN and decreased thereafter due to increased brittleness from the presence of more SiC in the composite. Based on the anti-oxidation and mechanical properties of the prepared composites, we concluded that improved anti-oxidation of C/SiC composites can be achieved through BN-assisted LSI, although there may be some degradation of the mechanical properties. The desired anti-oxidation and mechanical properties of the composite can be achieved by optimizing the BN-assisted LSI conditions.

Characteristics of Mono Crystalline Silicon Solar Cell for Rear Electrode with Aluminum and Aluminum-Boron (Aluminum 및 Aluminum-Boron후면 전극에 따른 단결정 실리콘 태양전지 특성)

  • Hong, Ji-Hwa;Baek, Tae-Hyeon;Kim, Jin-Kuk;Choi, Sung-Jin;Kim, Nam-Soo;Kang, Gi-Hwan;Yu, Gwon-Jong;Song, Hee-Eun
    • 한국태양에너지학회:학술대회논문집
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    • 2011.11a
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    • pp.34-39
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    • 2011
  • Screen printing method is a common way to fabricate the crystalline silicon solar cell with low-cost and high-efficiency. The screen printing metallization use silver paste and aluminum paste for front and rear contact, respectively. Especially the rear contact between aluminum and silicon is important to form the back surface filed (Al-BSF) after firing process. BSF plays an important role to reduces the surface recombination due to $p^+$ doping of back surface. However, Al electrode on back surface leads to bow occurring by differences in coefficient of thermal expansion of the aluminum and silicon. In this paper, we studied the properties of mono crystalline silicon solar cell for rear electrode with aluminum and aluminum-boron in order to characterize bow and BSF of each paste. The 156*156 $m^2$ p-type silicon wafers with $200{\mu}m$ thickness and 0.5-3 ${\Omega}\;cm$ resistivity were used after texturing, diffusion, and antireflection coating. The characteristics of solar cells was obtained by measuring vernier callipers, scanning electron microscope and light current-voltage. Solar cells with aluminum paste on the back surface were achieved with $V_{OC}$ = 0.618V, JSC = 35.49$mA/cm^2$, FF(Fill factor) = 78%, Efficiency = 17.13%.

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Characterization of Aluminum Coated Layer in Hot Press Forming of Boron Steel (고온 프레스성형시 보론강 알루미늄 코팅층 거동특성)

  • Jang, Jeong-Hwan;Joo, Byeong-Don;Lee, Jae-Ho;Moo, Young-Hoon
    • Journal of the Korean Society for Heat Treatment
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    • v.21 no.4
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    • pp.183-188
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    • 2008
  • Hot press forming allows geometrically complicated parts to be formed from sheet and the rapid cooling hardens them to extremely high strength. The main purpose of this research is to characterize Al coated layer in Al coated boron steel during hot press forming. For the hot press hardening experiment, test specimens were heated up to $810{\sim}930^{\circ}C$ and held for 3, 6 and 9 minutes, respectively. And then, some specimens were press hardened and others were air-cooled without any pressing for the comparison purpose. Al coated layer shows four distinct micro-structural regions of interest; diffusion zone, Al-Fe zone(I) low-Al zone(LAZ) and Al-Fe zone(II). Band-like LAZ is clearly shown at temperature ranges of $810{\sim}870^{\circ}C$ and sparsely dispersed at temperature higher than 900oC. The micro-cracking behavior in the Al coated layer during forming were also analyzed by bending and deep drawing tests. The strain concentration in softer LAZ is found to be closely related with micro-cracking and exfoliation in coated layer during forming.

Physics study for high-performance and very-low-boron APR1400 core with 24-month cycle length

  • Do, Manseok;Nguyen, Xuan Ha;Jang, Seongdong;Kim, Yonghee
    • Nuclear Engineering and Technology
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    • v.52 no.5
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    • pp.869-877
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    • 2020
  • A 24-month Advanced Power Reactor 1400 (APR1400) core with a very-low-boron (VLB) concentration has been investigated for an inherently safe and high-performance PWR in this work. To develop a high-performance APR1400 which is able to do the passive frequency control operation, VLB feature is essential. In this paper, the centrally-shielded burnable absorber (CSBA) is utilized for an efficient VLB operation in the 24-month cycle APR1400 core. This innovative design of the VLB APR1400 core includes the optimization of burnable absorber and loading pattern as well as axial cutback for a 24-month cycle operation. In addition to CSBA, an Er-doped guide thimble is also introduced for partial management of the excess reactivity and local peaking factor. To improve the neutron economy of the core, two alternative radial reflectors are adopted in this study, which are SS-304 and ZrO2. The core reactivity and power distributions for a 2-batch equilibrium cycle are analyzed and compared for each reflector design. Numerical results show that a VLB core can be successfully designed with 24-month cycle and the cycle length is improved significantly with the alternative reflectors. The neutronic analyses are performed using the Monte Carlo Serpent code and 3-D diffusion code COREDAX-2 with the ENDF/B-VII.1.

Methyl Viologen Mediated Oxygen Reduction in Ethanol Solvent: the Electrocatalytic Reactivity of the Radical Cation

  • Lin, Qianqi;Li, Qian;Batchelor-McAuley, Christopher;Compton, Richard G.
    • Journal of Electrochemical Science and Technology
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    • v.4 no.2
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    • pp.71-80
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    • 2013
  • The study of methyl viologen ($MV^{2+}$) mediated oxygen reduction in electrolytic ethanol media possesses potential application in the electrochemical synthesis of hydrogen peroxide mainly due to the advantages of the much increased solubility of molecular oxygen ($O_2$) and high degree of reversibility of $MV^{2+/{\bullet}+}$ redox couple. The diffusion coefficients of both $MV^{2+}$ and $O_2$ were investigated via electrochemical techniques. For the first time, $MV^{2+}$ mediated $O_2$ reduction in electrolytic ethanol solution has been proved to be feasible on both boron-doped diamond and micro-carbon disc electrodes. The electrocatalytic response is demonstrated to be due to the radical cation, $MV^{{\bullet}+}$. The homogeneous electron transfer step is suggested to be the rate determining step with a rate constant of $(1{\pm}0.1){\times}10^5M^{-1}s^{-1}$. With the aid of a simulation program describing the EC' mechanism, by increasing the concentration ratio of $MV^{2+}$ to $O_2$ electrochemical catalysis can be switched from a partial to a 'total catalysis' regime.

Thermal Stability Improvement of Ni-Silicide on the SOI Substrate Doped B11 for Nano-scale CMOSFET (나노급 CMOSFET을 위한 SOI기판에 도핑된 B1l을 이용한 니켈-실리사이드의 열안정성 개선)

  • Jung, Soon-Yen;Oh, Soon-Young;Lee, Won-Jae;Zhang, Ying-Ying;Zhong, Zhun;Li, Shi-Guang;Kim, Yeong-Cheol;Lee, Ga-Won;Wang, Jin-Suk;Lee, Hi-Deok
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.11
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    • pp.1000-1004
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    • 2006
  • In this paper, thermal stability of Ni-silicide formed on the SOI substrate with $B_{11}$ has been characterized. The sheet resistance of Ni-silicide on un-doped SOI and $B_{11}$ implanted bulk substrate was increased after the post-silicidation annealing at $700^{\circ}C$ for 30 min. However, in case of $B_{11}$ implanted SOI substrate, the sheet resistance showed stable characteristics after the post-silicidation annealing up to $700^{\circ}C$ for 30 min. The main reason of the excellent property of $B_{11}$ sample is believed to be the retardation of Ni diffusion by the boron and bottom oxide layer of SOI. Therefore, retardation of Ni diffusion is highly desirable lot high performance Ni silicide technology.