Analytical model for ion angular distribution functions at rf biased surfaces with collisionless plasma sheaths
(2002) In Applied Physics Reviews 92(12). p.70327040 Abstract
 The article presents an analytical model for evaluation of ion angular distribution functions (IADFs) at a radio frequency (rf)biased surface in a highdensity plasma reactor. The model couples a unified rf sheath model to an assumed ion velocity distribution functionbased formulation for determining the IADF under any general rfbias condition. Under directcurrent (dc) bias conditions the IADF profile shape shows a strong dependence on the bias voltage and the ion temperature is relatively independent of the plasma electron temperature, ion density, and the ion mass. The model establishes the importance of rfbias frequency in determining the IADF. For conditions where the sheath current wave form is sinusoidal, low bias frequencies... (More)
 The article presents an analytical model for evaluation of ion angular distribution functions (IADFs) at a radio frequency (rf)biased surface in a highdensity plasma reactor. The model couples a unified rf sheath model to an assumed ion velocity distribution functionbased formulation for determining the IADF under any general rfbias condition. Under directcurrent (dc) bias conditions the IADF profile shape shows a strong dependence on the bias voltage and the ion temperature is relatively independent of the plasma electron temperature, ion density, and the ion mass. The model establishes the importance of rfbias frequency in determining the IADF. For conditions where the sheath current wave form is sinusoidal, low bias frequencies result in a largeangle tail contribution to the IADF which can potentially lead to poor anisotropic plasma etching behavior. The largeangle tail is absent at higher bias frequencies. An increase in bias power leads to a general narrowing of the IADF, but the largeangle tail for the IADF at low frequencies persists despite increasing bias powers. Therefore, plasma etch anisotropy can be improved by increasing bias powers only if the bias frequency is sufficiently high. Tangential ion drift velocities introduce azimuthal angle dependence on the IADF and a shift in the peak IADF to offnormal polar angles. While the location of the peak IADF in the azimuthal direction is dictated purely by the direction of the drift velocity, the shift in peak IADF in the polar angle depends on both the drift velocity as well as the bias frequency. (C) 2002 American Institute of Physics. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/record/322384
 author
 Raja, LL and Linne, Mark ^{LU}
 organization
 publishing date
 2002
 type
 Contribution to journal
 publication status
 published
 subject
 keywords
 radiofrequency discharges highdensity plasmas energydistributions bombardment argon simulation chlorine reactors dynamics
 in
 Applied Physics Reviews
 volume
 92
 issue
 12
 pages
 7032  7040
 publisher
 American Institute of Physics
 external identifiers

 wos:000179495100010
 scopus:0037115568
 ISSN
 00218979
 DOI
 10.1063/1.1524020
 language
 English
 LU publication?
 yes
 id
 8fe0a2d202cf4f6da2fd50ec841694c3 (old id 322384)
 date added to LUP
 20071109 14:07:09
 date last changed
 20180114 03:33:08
@article{8fe0a2d202cf4f6da2fd50ec841694c3, abstract = {The article presents an analytical model for evaluation of ion angular distribution functions (IADFs) at a radio frequency (rf)biased surface in a highdensity plasma reactor. The model couples a unified rf sheath model to an assumed ion velocity distribution functionbased formulation for determining the IADF under any general rfbias condition. Under directcurrent (dc) bias conditions the IADF profile shape shows a strong dependence on the bias voltage and the ion temperature is relatively independent of the plasma electron temperature, ion density, and the ion mass. The model establishes the importance of rfbias frequency in determining the IADF. For conditions where the sheath current wave form is sinusoidal, low bias frequencies result in a largeangle tail contribution to the IADF which can potentially lead to poor anisotropic plasma etching behavior. The largeangle tail is absent at higher bias frequencies. An increase in bias power leads to a general narrowing of the IADF, but the largeangle tail for the IADF at low frequencies persists despite increasing bias powers. Therefore, plasma etch anisotropy can be improved by increasing bias powers only if the bias frequency is sufficiently high. Tangential ion drift velocities introduce azimuthal angle dependence on the IADF and a shift in the peak IADF to offnormal polar angles. While the location of the peak IADF in the azimuthal direction is dictated purely by the direction of the drift velocity, the shift in peak IADF in the polar angle depends on both the drift velocity as well as the bias frequency. (C) 2002 American Institute of Physics.}, author = {Raja, LL and Linne, Mark}, issn = {00218979}, keyword = {radiofrequency discharges highdensity plasmas energydistributions bombardment argon simulation chlorine reactors dynamics}, language = {eng}, number = {12}, pages = {70327040}, publisher = {American Institute of Physics}, series = {Applied Physics Reviews}, title = {Analytical model for ion angular distribution functions at rf biased surfaces with collisionless plasma sheaths}, url = {http://dx.doi.org/10.1063/1.1524020}, volume = {92}, year = {2002}, }