Simulation of Ion Trajectories near Submicron-Patterned Surface Including   Effects of Local Charging and Ion Drift Velocity toward Wafer

Ootera, Hiroki; Oomori, Tatsuo; Tuda, Mutumi; Namba, Keisuke

doi:10.1143/jjap.33.4276

Cited by 49 publications

(22 citation statements)

References 4 publications

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“…4͑b͒, is in good agreement with analytic estimates based on the Vlasov equation. 5 The respective ion angular distribution function ͑IADF͒ and electron angular distribution function ͑EADF͒ are shown in Figs. 5͑a͒ and 5͑b͒.…”

Section: B Sheath Modelmentioning

confidence: 99%

“…However, evidence for such surface ion migration on adsorbate ͑e.g., Cl͒ covered SiO 2 is hard to find; furthermore, this mechanism fails to explain the wide notches frequently seen experimentally. A more plausible explanation has been proposed, 5,6 which attributes notching to electric-fieldinduced distortion of ion trajectories. Local electric fields form as a result of microstructure charging brought about by the directionality difference between ions and electrons at the wafer surface, a mechanism first proposed by Arnold and Sawin.…”

Section: Introductionmentioning

confidence: 99%

“…Local electric fields form as a result of microstructure charging brought about by the directionality difference between ions and electrons at the wafer surface, a mechanism first proposed by Arnold and Sawin. 4 Ootera et al 5 considered the energy distribution of electrons arriving at the microstructure but neglected the ion energy distribution and the effect of the oscillating sheath. Furthermore, they also neglected the conductivity of the poly-Si, thereby ''overestimating the local electric field and the ion trajectory deflection.''…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

On the origin of the notching effect during etching in uniform high density plasmas

Hwang

Giapis

1997

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

246

166

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We present a two-dimensional Monte Carlo simulation of profile evolution during the overetching step of polysilicon-on-insulator structures, which considers explicitly ͑a͒ electric field effects during the charging transient, ͑b͒ etching reactions of energetic ions impinging on the poly-Si, and ͑c͒ forward inelastic scattering effects. Realistic energy and angular distributions for ions and electrons are used in trajectory calculations through local electric fields near and in the microstructure. Transient charging of exposed insulator surfaces is found to profoundly affect local sidewall etching ͑notching͒. Ion scattering contributions are small but important in matching experimental notch profiles. The model is validated by capturing quantitatively the notch characteristics and also the effects of the line connectivity and open area width on the notch depth, which have been observed experimentally by Nozawa et al. ͓Jpn. J. Appl. Phys. 34, 2107 ͑1995͔͒. Elucidation of the mechanisms responsible for the effect facilitates the prediction of ways to minimize or eliminate notching.

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Section: B Sheath Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

On the origin of the notching effect during etching in uniform high density plasmas

Hwang

Giapis

1997

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

246

166

View full text Add to dashboard Cite

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“…We start as others have 5,6 by assuming that the insulators are perfect with no insulator conduction and that high field electron emission can be neglected. This means that the steady state where charge accumulation stops can only be brought about by redirection of ion and electron trajectories.…”

Section: Modelingmentioning

confidence: 99%

“…Their work was not sufficient to model practical problems, such as the notching. Other previous work includes that of Ootera et al 6 who considered the electron velocity distribution but not the ion distribution. In the present work, the effects of polysilicon conductivity, ion velocity distributions, steady state charging, and aspect ratio have been considered.…”

Section: Introductionmentioning

confidence: 99%

Notching as an example of charging in uniform high density plasmas

Kinoshita

Hane

McVittie

1996

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

171

109

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Design of notched gate processes in high density plasmasOn the origin of the notching effect during etching in uniform high density plasmas Numerical simulation was used to study both surface charging and ion trajectory distortion during submicron patterning in high density plasma etching. The plasma was assumed uniform and the cause for the surface charging was the directionality difference between ions and electrons. The role of ion transit time effects on the ion energy distribution function was also considered, while the effect of discharging currents such as through insulators was not included. Using a Monte Carlo sheath simulator, a Poisson equation solver, and an ion/electron trajectory simulator, the steady state potential distribution and ion trajectories were calculated for various line-and-space structures and plasma conditions where notching, which is a local sidewall etching, has been observed after the overetching part of polysilicon etching processes. The results show significant positive charging at the bottom of high aspect ratio spaces which depends on the ion energy distribution function. Notching at the bottom of an outermost polysilicon line before a wide space is the result of ion deflection toward the line which has the lower potential from receiving more electrons from a side facing the wide space. The simulator was validated using previously reported electron cyclotron resonance etcher notching results. It was found that the calculated potential difference between the bottom of a space and the adjacent line shows the same qualitative dependence on the wide space width as experimental notch depth results show. In addition, these potential differences are large enough to substantially increase the ion flux at regions where notching occurs for the ion energy distribution function for the plasma conditions used. Thus this shows aspect ratio dependent charging effects which are not dependent on initial plasma nonuniformity.

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Plasma Engineering

Economou¹

1999

Advances in Electrochemical Sciences and Engineering

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Simulation of Ion Trajectories near Submicron-Patterned Surface Including Effects of Local Charging and Ion Drift Velocity toward Wafer

Cited by 49 publications

References 4 publications

On the origin of the notching effect during etching in uniform high density plasmas

On the origin of the notching effect during etching in uniform high density plasmas

Notching as an example of charging in uniform high density plasmas

Plasma Engineering

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