Sputtering

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Sputtering

• The removal of surface atoms due to energetic
  particle bombardment

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Sputtering
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Sputtering
First observations of cathode erosion in gas
discharges W.R. Grove 1853
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Sputtering
Removal of surface material as a result of
energetic particle bombardment.

• First observations W.R. Grove 1853, J.P. Gassiot
  and M. Faraday 1854, 1858. J. Plücker 1858.
  Useful for thin film coating?
• First systematic studies W. Crookes 1891, G.
  Granquist 1897. Independent of target
  temperature.
• J. Stark 1908, 1909. Hot spots? Binary elastic
  collisions?
• Cosine emission distribution R. Seeliger 1935.
  Rules out the collision theory?
• Crystal structure effects, G.K. Wehner 1956.
  Collisions back in. Sputtering yields always
  decrease at high energy 1/E.
• Linear collision cascades, relation to nuclear
  stopping power, J. Lindhard et al. 1963, J.
  Davies et al. 1960-64. P. Sigmund 1967-69.
• BCA Monte Carlo, MARLOWE, TRIM. M.T. Robinson
  1974, J. Biersack and J.F. Ziegler 1974
• Applications in semiconductor industry, coating
  industry, surface analysis, fusion plasma physics
  and and space physics

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Sputter deposition
DC- and RF sputter deposition is a convenient and
inexpensive coating Technique.
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Sputter deposition
Magnetron sputter deposition is very widely used
and allows low pressure discharge, high coating
quality and fast deposition
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Secondary Ion Mass Spectrometry (SIMS)
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Secondary Ion Mass Spectrometry (SIMS)
JET divertor
1999-2001
1998-2004
Elemental mapping by static SIMS
J.P. Coad et al. J. Nucl. Mater 363-365(2007)
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Sputtering
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Sputtering yield measurements
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Sputtering yield measurements
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Sputtering yield measurements
Yield energy dependence.
Ejection angle distribution, B. Emmoth, H.
Bergsåker et al 1989, 1990
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Sputtering
Velocity distribution of sputtered atoms,
measured by laser induced fluoresence. W.
Husinsky et al. 1986
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Sputtering
Energy distribution of sputtered Tungsten atoms
and tungsten clusters. G. Staudenmaier 1984
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Crystal structure effect in Sputtering
Single crystal effects in sputtering, G. K.
Wehner, Phys. Rev. 102(1956)690-704
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Non linear Sputtering yield with heavy ions
Non linear sputtering yield, evidence of spikes .
H.H. Andersen and H. Bay 1974
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Three different regimes for theory
Single knock-on regime
Linear cascade regime
Spike regime
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Nuclear stopping power
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Electronic stopping power
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Results from linear cascade theory
The linear cascade regime theory got its
semi-final form from P. Sigmund, 1969
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Monte Carlo calculations
TRIM , J.P. Biersack and W. Eckstein 1984
MARLOWE
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Monte Carlo calculations
Molecular dynamics, C. Erginsoy et al 1964
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Monte Carlo calculations
TRIM
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A simple plasma impurity model
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Sputtering in fusion devices
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Sputtering in fusion devices
Impurity fluxes in TEXTOR
I. Gudowska, H. Bergsåker et al. J. Nucl. Mater.
176-177(1990)363
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Conclusions

• Sputtering by particle bombartment has been
  observed since 150 years. Apart from being a
  nuisance in many technical systems it also has a
  wide range of useful applications.
• Physical sputtering is well understood today,
  especially in the linear cascade regime.
  Monte-Carlo methods are very useful in the
  single-knockon regime and with special boundary
  conditions.
• Physical sputtering is a central physical
  phenomenon in fusion devices. For plasma modeling
  Monte Carlo codes and semi-empirical fits are
  used and give satisfactory results.