• Title/Summary/Keyword: Electronegative plasma

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Numerical analysis of particle transport in low-pressure, low-temperature plasma environment

  • Kim, Heon Chang
    • Particle and aerosol research
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    • v.5 no.3
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    • pp.123-131
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    • 2009
  • This paper presents simulation results of particle transport in low-pressure, low-temperature plasma environment. The size dependent transport of particles in the plasma is investigated with a two-dimensional simulation tool developed in-house for plasma chamber analysis and design. The plasma model consists of the first two and three moments of the Boltzmann equation for ion and electron fluids respectively, coupled to Poisson's equation for the self-consistent electric field. The particle transport model takes into account all important factors, such as gravitational, electrostatic, ion drag, neutral drag and Brownian forces, affecting the motion of particles in the plasma environment. The particle transport model coupled with both neutral fluid and plasma models is simulated through a Lagrangian approach tracking the individual trajectory of each particle by taking a force balance on the particle. The size dependant trap locations of particles ranging from a few nm to a few ${\mu}m$ are identified in both electropositive and electronegative plasmas. The simulation results show that particles are trapped at locations where the forces acting on them balance. While fine particles tend to be trapped in the bulk, large particles accumulate near bottom sheath boundaries and around material interfaces, such as wafer and electrode edges where a sudden change in electric field occurs. Overall, small particles form a "dome" shape around the center of the plasma reactor and are also trapped in a "ring" near the radial sheath boundaries, while larger particles accumulate only in the "ring". These simulation results are qualitatively in good agreement with experimental observation.

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Characterization of oxygen plasma by using a langmuir probe in the inductively coupled plasma (정전 탐침을 이용한 유도 결합형 반응기에서 발생하는 산소 플라즈마의 특성연구)

  • 김종식;김곤호;정태훈;염근영;권광호
    • Journal of the Korean Vacuum Society
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    • v.9 no.4
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    • pp.428-435
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    • 2000
  • Negative ion generation in an inductively coupled oxygen plasma was investigated by using a Langmuir probe. It was observed that the probe current ratio of the positive ion saturation current and the negative current which is consisted of the electron current and the negative ion current, and also the potential difference between the floating potential and plasma potential vary with the RF input power and more sensitively with the operating pressure, respectively. Results show that the operating condition to achieve the maximum probe current ratio and the minimum potential difference shift from the low pressure region to the high pressure regions with increasing the input power. It implies that the generation of the negative oxygen ions increases and the recombination of the positive and negative ions are enhanced in the plasma.

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Simulation Study of Capacitively Coupled Oxygen Plasma with Plasma Chemistry including Detailed Electron Impact Reactions (전자충격반응을 포함하는 플라즈마 화학반응을 고려한 용량결합형 산소플라즈마의 전산모사 연구)

  • Kim, Heon Chang
    • Applied Chemistry for Engineering
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    • v.22 no.6
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    • pp.711-717
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    • 2011
  • Two dimensional simulation results of a capacitively coupled oxygen plasma in a cylindrical reactor geometry are presented. Detailed electron impact reaction rates, which strongly depend on electron energy, are computed from collision cross sections of electrons with $O_2$ and O. Through the coupling of a three moment plasma model with a neutral chemistry/transport model are predicted spatiotemporal distributions of both charged species (electron, $O_2{^+}$, $O^+$, $O_2{^-}$, and $O^-$) and neutral species including ground states ($O_2$ and O) and metastables, known to play important roles in oxygen plasma, such as $O_2(a^1{\Delta}_g)$, $O_2(b^1{{\Sigma}_g}^+)$, $O(^1D)$, and $O(^1S)$. The simulation results clearly verify the existence of a double layer near sheath boundaries in the electronegative plasma.

Analysis of Si Etch Uniformity of Very High Frequency Driven - Capacitively Coupled Ar/SF6 Plasmas (VHF-CCP 설비에서 Ar/SF6 플라즈마 분포가 Si 식각 균일도에 미치는 영향 분석)

  • Lim, Seongjae;Lee, Ingyu;Lee, Haneul;Son, Sung Hyun;Kim, Gon-Ho
    • Journal of the Semiconductor & Display Technology
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    • v.20 no.4
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    • pp.72-77
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    • 2021
  • The radial distribution of etch rate was analyzed using the ion energy flux model in VHF-CCP. In order to exclude the effects of polymer passivation and F radical depletion on the etching. The experiment was performed in Ar/SF6 plasma with an SF6 molar ratio of 80% of operating pressure 10 and 20 mTorr. The radial distribution of Ar/SF6 plasma was diagnosed with RF compensated Langmuir Probe(cLP) and Retarding Field Energy Analyzer(RFEA). The radial distribution of ion energy flux was calculated with Bohm current times the sheath voltage which is determined by the potential difference between the plasma space potential (measured by cLP) and the surface floating potential (by RFEA). To analyze the etch rate uniformity, Si coupon samples were etched under the same condition. The ion energy flux and the etch rate show a close correlation of more than 0.94 of R2 value. It means that the etch rate distribution is explained by the ion energy flux.