Theoretical and Experimental Investigations of Chlorine RF Glow Discharges: I . Theoretical

Aydil, Eray S.; Economou, Demetre J.

doi:10.1149/1.2069419

Cited by 35 publications

(22 citation statements)

References 33 publications

(101 reference statements)

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“…9,10 It is well known that the energy of ions impinging on the silicon surface has a decisive effect on etching. 1-8 During etching, ions and radicals originating from the Cl 2 plasma impinge on the surface and cause removal of atoms from the surface.…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulations of Cl+ etching on a Si(100) surface

Gou

Neyts

Eckert

et al. 2010

Journal of Applied Physics

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Molecular dynamics simulations using improved Tersoff–Brenner potential parameters were performed to investigate Cl+ etching of a {2×1} reconstructed Si(100) surface. Steady-state Si etching accompanying the Cl coverage of the surface is observed. Furthermore, a steady-state chlorinated reaction layer is formed. The thickness of this reaction layer is found to increase with increasing energy. The stoichiometry of SiClx species in the reaction layer is found to be SiCl:SiCl2:SiCl3=1.0:0.14:0.008 at 50 eV. These results are in excellent agreement with available experimental data. While elemental Si products are created by physical sputtering, most SiClx (0<x<4) etch products are produced by chemical-enhanced physical sputtering.

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Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulations of Cl+ etching on a Si(100) surface

Gou

Neyts

Eckert

et al. 2010

Journal of Applied Physics

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“…One of the dominant pathways following the electron/Cl 2 interactions in the plasma is ionization, both dissociative and nondissociative. [2][3][4][5] However, the lack of quantitative data on the dissociative ionization of chlorine by electron-impact has been noted in the recently assembled library of data quantifying the consequences of the interaction of electrons with Cl 2 . 6 Such data is essential for modeling chlorine plasmas in order to gain a more detailed understanding of the etching process.…”

Section: Introductionmentioning

confidence: 99%

Electron-impact ionization of the chlorine molecule

Calandra

O'Connor

Price

2000

The Journal of Chemical Physics

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Relative partial ionization cross sections for the formation of Cl 2 ϩ , Cl ϩ and Cl 2ϩ from molecular chlorine have been recorded as a function of the ionizing electron energy. In these measurements particular attention has been paid to the efficient collection of fragment ions with high translational energies and the minimization of any mass-dependent discrimination effects. The cross sections show that at electron energies above the double ionization threshold the yield of fragment ions can be comparable with the ion yield of nondissociative ionization. Further analysis shows that at electron energies above 50 eV the yield of fragment ions from multiple ionization is comparable with the yield of fragment ions from single ionization: dissociative multiple ionization contributes 14% of the ion yield at 50 eV electron energy and 26% at 100 eV. The decay of Cl 2 2ϩ by heterolytic cleavage to form Cl 2ϩ is a result of approximately 5% of the dissociative double ionization events. This heterolytic process has a threshold of 41.8Ϯ1.5 eV. Electron-impact induced triple ionization to form long-lived Cl 2 3ϩ ions has been detected for the first time. This nondissociative triple ionization process makes up approximately 2% of the triple ionization events and triple ionization is responsible for approximately 2% of the ion yield above 100 eV. The threshold for dissociative triple ionization is determined to be 65.3Ϯ1.5 eV, a value in good agreement with a trication precursor state energy derived from the kinetic energy release for the fragmentation of Cl 2 3ϩ to Cl 2ϩ and Cl ϩ , which provides the first experimental estimate of the triple ionization energy of molecular chlorine.

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“…[34][35][36][37] A monoenergetic argon ion beam, described in Section II, is used to determine how the silicon etching yield changes with ion energy and with the ion to neutral flux ratio. Note that molecular chlorine is the primary neutral species in a number of chlorine rf glow discharge systems.…”

Section: Introductionmentioning

confidence: 99%

Ion-assisted etching and profile development of silicon in molecular chlorine

Levinson

Shaqfeh

Balooch

et al. 1997

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Influence of ion mixing on the energy dependence of the ion-assisted chemical etch rate in reactive plasmasAn ion beam etching study designed to characterize the kinetic and transport processes important in the ion-assisted etching of silicon in molecular chlorine was performed. Monoenergetic argon ion beams were directed normal to a silicon wafer that was simultaneously exposed to a background of molecular chlorine, thereby simulating a low temperature rf plasma etching process. The ion-induced etching yield scaled with the square root of the ion energy for a surface saturated with adsorbed chlorine. Moreover, the yield was found to depend strongly on the ion to neutral flux ratio which was varied over two orders of magnitude. A kinetic model in which the dissociative sticking probability and the yield scale linearly with surface coverage was developed and was found to be consistent with the yield data in the ion energy range of 90-300 eV. Its applicability to etching topography was tested with additional experiments where patterned silicon wafers ͑with oxide masks and with a range of features and linewidths͒ were etched at saturation in the apparatus. Minimal lag effects and some microtrenching and sidewall sloping were encountered. The etching selectivity of silicon over oxide at 100 eV was greater than 30. Computer simulations of the etching process and profile development were performed using the kinetic model and a line-of-sight re-emission model for the chlorine transport. Knudsen diffusion was found to be important in the transport of neutrals to the base of the feature, with the aspect ratio dependence of the etch rate becoming significant only at high values of the ion to neutral flux ratio. The agreement between simulation and experiment was good, with the initial sticking probability on a clean surface and the average product stoichiometry as parameters comparing favorably to published results. However, the observed microtrenching and sidewall sloping were not predicted by these simulations.

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Theoretical and Experimental Investigations of Chlorine RF Glow Discharges: I . Theoretical

Cited by 35 publications

References 33 publications

Molecular dynamics simulations of Cl+ etching on a Si(100) surface

Molecular dynamics simulations of Cl+ etching on a Si(100) surface

Electron-impact ionization of the chlorine molecule

Ion-assisted etching and profile development of silicon in molecular chlorine

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