TRIGGERING EXCIMER LASERS BY PHOTOIONIZATION FROM A CORONA DISCHARGE* Zhongmin Xiong and Mark J. Kushner University of Michigan Ann Arbor, MI 48105 USA [email protected][email protected]Thomas Duffey and Daniel Brown Cymer, Inc. San Diego, CA 92127 [email protected]October 2009 * Work supported by Cymer, Inc.
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TRIGGERING EXCIMER LASERS BY PHOTOIONIZATION FROM A CORONA DISCHARGE*
TRIGGERING EXCIMER LASERS BY PHOTOIONIZATION FROM A CORONA DISCHARGE*. Zhongmin Xiong and Mark J. Kushner University of Michigan Ann Arbor, MI 48105 USA [email protected][email protected] Thomas Duffey and Daniel Brown Cymer, Inc. San Diego, CA 92127 [email protected] October 2009. - PowerPoint PPT Presentation
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TRIGGERING EXCIMER LASERS BY PHOTOIONIZATION FROM A CORONA
DISCHARGE*
Zhongmin Xiong and Mark J. KushnerUniversity of Michigan
Operating pressures of 3 atm emphasize 3-body reactions leading to rapid dimerization.
e + Ne Ne+ + e + e Ne + Ne+ + M Ne2+ + M
e + Ne Ne* + e Ne + Ne* + M Ne2* + M
e + Ar Ar+ + e + e Ar + Ar+ + M Ar2+ + M
e + Ar Ar* + e Ar + Ar* + M Ar2* + M
Ne2
+ + Ar Ar+ + Ne + Ne Ne2* + Ar Ar+ + Ne + Ne + e
e + F2 F- + F Ion-Ion neutralization
Ar2+ + F- ArF* + Ar Ar+ + F- + M ArF* + M
University of MichiganInstitute for Plasma Science & Engr.ANDY_GEC2009
Excited stats generated by corona discharge produce VUV photons which propagate to main discharge gap to photo-ionize low ionization potential species for pre-ionization.
Many species likely contribute to VUV flux – here we used Ne2* as VUV source.
Sufficient density and short enough lifetime to account for VUV flux required to produce observed preionization densities – radiation is not trapped.
Xe has the lowest ionization potential in mixture and is the photoionized atom.
PHOTOIONIZATION
e + Ne Ne* + e
Ne* + 2Ne Ne2* + Ne
Ne2* Ne + Ne + h (15.5 eV, 800 A)
University of MichiganInstitute for Plasma Science & Engr.ANDY_GEC2009
h + Xe Xe+ + e Ionization potential: 12.13 eV [Xe] = 7.5 x 1014 cm-3
= 10-16 cm2
RADIATION TRANSPORT
Emission species j
Ionized Species i
Absobers k
')',()'()()( 3rdrrGArNrN
t
rNijjj
jji
i
2'
|'|4
")"(exp
)',(rr
rdrN
rrGkj
k
r
r
k
j
A Einstein coefficient
ij Photo-ionization cross section
kj Photo-absorption cross section
University of MichiganInstitute for Plasma Science & Engr.ANDY_GEC2009
Radiation transport modeled using propagator or Greens function approach which relates photo flux at r to density of excites states at r’.
Includes view-factors.
Rate of ionization
COMPUTATIONAL MESHFrame 001 05 Oct 2009 CYMER_01E NE/AR/F2/XE (cymer_nlist_01b.nlist)
Unstructured mesh used to resolve chamber geometry and large dynamic range in dimensions.
Total number of nodes: 9,336 Plasma nodes: 5,607
University of MichiganInstitute for Plasma Science & Engr.ANDY_GEC2009