Transcript Sputtering - Royal Institute of Technology

Sputtering
The removal of surface atoms due
to energetic particle bombardment
Sputtering
Sputtering
First observations
of cathode erosion in
gas discharges
W.R. Grove 1853
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
Sputter deposition
DC- and RF sputter deposition is a convenient and inexpensive coating
Technique.
Sputter deposition
Magnetron sputter deposition is very widely used and allows low pressure
discharge, high coating quality and fast deposition
Secondary Ion Mass Spectrometry (SIMS)
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)
Sputtering
Sputtering yield
atoms removed
Y ( E , ) 
incident particle
Differential sputtering yields
Y
Y
,
,Yq ,Y   Yq
E1
1
q
105  Y  103
Sputtering yield measurements
Sputtering yield measurements
Sputtering yield measurements
Yield energy dependence.
Ejection angle distribution,
B. Emmoth, H. Bergsåker et al 1989, 1990
Sputtering
Velocity distribution of sputtered atoms, measured by laser induced fluoresence.
W. Husinsky et al. 1986
Sputtering
Energy distribution of sputtered
Tungsten atoms and tungsten
clusters.
G. Staudenmaier 1984
Crystal structure effect in Sputtering
Single crystal effects in sputtering, G. K. Wehner, Phys. Rev. 102(1956)690-704
Non linear Sputtering yield with heavy ions
Non linear sputtering yield,
evidence of spikes . H.H. Andersen and H. Bay 1974
Three different regimes for theory
Single knock-on regime
Linear cascade regime
Spike regime
Nuclear stopping power
Electronic stopping power
Results from linear cascade theory
The linear cascade regime theory got its semi-final form from
P. Sigmund, 1969


   v   G (r , v , v0 , t )  Nv  K (v ; v ', v '')d 3v ' d 3v ''  G  G ' G '' 
 t

d ( E , T )  Cm E  mT 1 m dT ,0  m  1
F ( E , E0 )
 m ( E ) / E02
 1 m
E1
 2Y
 FD ( E , , 0) m
cos 1
3 2 m
E11
4 NCm ( E1  U 0 )
Monte Carlo calculations
TRIM , J.P. Biersack and W. Eckstein 1984
MARLOWE
Monte Carlo calculations
Molecular dynamics, C. Erginsoy et al 1964
Monte Carlo calculations
TRIM
A simple plasma impurity model
dN H
NH
in
 H 
dt

dN Z
NZ
in
 Z 
dt

out
 inZ  YHZ  out

Y

H
ZZ
Z
d
 j     ,  0
dt

 H YHZ

YHZ
Z 
,

1  YZZ
  1  YZZ
in
j
out
j
Sputtering in fusion devices
Sputtering in fusion devices
Impurity fluxes in TEXTOR
I. Gudowska, H. Bergsåker et al.
J. Nucl. Mater. 176-177(1990)363
Conclusions
• Sputtering by particle bombartment has been observed
since 150 years. Apart from being a nuisance in many
technical systems it alöso 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.