Electron Impact Cross Sections for Argon

Peterson, L. R.; Allen, John E.

doi:10.1063/1.1677156

Cited by 177 publications

(45 citation statements)

References 27 publications

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“…As for ionization, Peterson and Allen's [12] integral cross section is multiplied by 0.9 to match it with Kosaki and Hayashi's data. The total number of collisional events is 27.…”

Section: "'mentioning

confidence: 99%

Velocity distribution of ions incident on a radio-frequency biased wafer

Wakayama¹,

Nanbu²

2001

AIP Conference Proceedings

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Abstract. The ion velocity distribution (IVD) is important in plasma etching of microfeatures. IVD at a rf biased wafer is studied, first analytically using probability theory and then numerically by using a particle simulation method. The analytic expression shows that IVD is governed by the parameter qVri/miuil, where q is the charge of ion, V T f is the rf bias amplitude, w is the rf bias angular frequency, I is the penetration depth of bias potential, and mi is the mass of ion. The analytical expression is applicable to the case when the ion collisions in the penetration depth are negligibly few and the rf period of biasing is much shorter than the time that ions take in traversing the depth I. The IVDs for general conditions are also examined using the self-consistent particle-in-cell/Monte Carlo simulation. I INTRODUCTIONWeakly ionized plasmas used in materials processing generally consist of positive and negative ions, electrons, and neutral species. In the case when electrons are more abundant than negative ions, a negative potential is formed near the surface of the floating wafer immersed in the plasma. In processing plasmas the electron temperature is few electron volts, while the ion temperature is roughly equal to the background gas temperature. To keep the balance between the negative and positive currents on the floating surface, low energy electrons should be reflected in the sheath region back to the plasma bulk. This is the physical reason why the potential of the floating wafer is lower than the plasma potential.Negative sheath potential (measured from the plasma bulk) accelerates the positive ions to the wafer. If no collision is assumed in the sheath region, the positive ions impinge almost perpendicularly onto the wafer. However, electrons are decelerated and lose the velocity component normal to the wafer.When ions and electrons come into a microscopic trench, electrons are easily sticked near the top of the side of the trench wall while ions can reach the bottom of the trench. This kind of charge separation inside microfeatures causes a charge build-up. The strongly localized electric field due to the charge build-up distorts the trajectories of incident ions, which results in an anomalous etch profile called "notching". The localized charge build-up also causes the electrical breakdown induced by fatal tunneling currents through gate-oxides.In order to suppress the so-called charging damages, new ideas on plasma sources are proposed, e.g., timemodulation of the source power [1] and use of ultra-high frequency (500 MHz) power [2]. These approaches are intended to lower the electron temperature and hence generate more negative ions. To understand the role of negative ions, let us consider the plasma including only positive and negative ions; when the wafer is biased at low frequency (< 3MHz), the positive and negative ions impinge on the bottom of the trench alternately. Thus no charge build-up occurs.The ion energy distribution (IED) and ion angle distribution (IAD) of ions that impinge o...

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“…As for ionization, Peterson and Allen's [12] integral cross section is multiplied by 0.9 to match it with Kosaki and Hayashi's data. The total number of collisional events is 27.…”

Section: "'mentioning

confidence: 99%

Velocity distribution of ions incident on a radio-frequency biased wafer

Wakayama¹,

Nanbu²

2001

AIP Conference Proceedings

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“…This assumption enables the authors of [13] to assume that the beam of electrons propagates without scattering. Energetic electrons generate progeny electrons with lower energies [14]. So secondary electrons are not capable of further ionization and can be excluded from consideration.…”

Section: Study Of Spatial Profiles Of Nonlocal Ionization Producementioning

confidence: 99%

“…The EDF's calculated by MCC as a function of energy are compared with the analytical estimate (14) in Fig. 8.…”

Section: Study Of Spatial Profiles Of Nonlocal Ionization Producementioning

confidence: 99%

“…The generalization of the solution (13) is possible for arbitrary functions of energy where (14) We performed the Monte Carlo simulation for comparison with the analytical formula, the cross-section set being taken from [12]. An electron beam with initial energy of 200 eV was injected into the argon gas at a pressure of 3 torr.…”

Section: Study Of Spatial Profiles Of Nonlocal Ionization Producementioning

confidence: 99%

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Semianalytical description of nonlocal secondary electrons in a radio frequency capacitively coupled plasma at intermediate pressures

Berezhnoi

Kaganovich

Mišina

et al. 1999

IEEE Trans. Plasma Sci.

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“…Tables 1-2 give the reactions taken into account in the system for the Cl 2 /Ar plasma mixture. The rate constants for electron impact are calculated knowing the electron cross sections and assuming a Maxwellian distribution of electron energy [27,28,30,31,[43][44][45][46][47][48][49][50][51][52][53].…”

Section: Global Kinetic Modelmentioning

confidence: 99%

Atomic scale study of InP etching by Cl₂-Ar ICP plasma discharge

Rhallabi

Chanson

Landesman

et al. 2011

Eur. Phys. J. Appl. Phys.

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A gas phase kinetic model combined to a 3D atomic etching model have been developed to study the etching process of InP under Cl 2 -Ar ICP plasma discharge. A gas phase global kinetic model is used to calculate the reactive particle fluxes implied in the etching mechanisms. The 3D atomic InP etching model is based on the Monte-Carlo kinetic approach where the plasma surface interactions are described in the probability way. The coupling between the plasma chemistry model and the surface etching model is an interesting approach to predict the etched surface properties in term of the etch rate, the surface roughness and surface steochiometry as a function of the operating conditions.A satisfactory agreement is obtained by comparing the experimental and the simulation results concerning the evolution of the main plasma discharge parameters such as the electron density and temperature versus the ICP source power for surface recombination coefficient of atomic chlorine fixed at γ Cl =0.04. On the other hand, simulation results show the effect of the operating conditions on the etched surface roughness and the etch rate evolutions with time in the early stage. Moreover, the simulation results show the correlation between the decrease of the ion to chlorine flux ratio and the decrease of the RRMS as a function of the pressure.

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Electron Impact Cross Sections for Argon

Cited by 177 publications

References 27 publications

Velocity distribution of ions incident on a radio-frequency biased wafer

Velocity distribution of ions incident on a radio-frequency biased wafer

Semianalytical description of nonlocal secondary electrons in a radio frequency capacitively coupled plasma at intermediate pressures

Atomic scale study of InP etching by Cl₂-Ar ICP plasma discharge

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Electron Impact Cross Sections for Argon

Cited by 177 publications

References 27 publications

Velocity distribution of ions incident on a radio-frequency biased wafer

Velocity distribution of ions incident on a radio-frequency biased wafer

Semianalytical description of nonlocal secondary electrons in a radio frequency capacitively coupled plasma at intermediate pressures

Atomic scale study of InP etching by Cl2-Ar ICP plasma discharge

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Atomic scale study of InP etching by Cl₂-Ar ICP plasma discharge