Ione Implantasjon

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Ione Implantasjon
FYS4310
Doping
2
I
Ion Implantation
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Fys4310 I2, Program
What is I2
How it is done
Characteristics
Ranges
Rf(?), Sn(E), Se(E)- qualitatively
LSS
Impulse approximation
Examples, measurements
Disorder
Channelling
Annealing of disorder
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What is I2
How See next slide
Characteristics
Energy 15 keV - 250 keV, ( 5 keV.. MeV )
Dose 1e12 - 1e15(1e18) cm-2
The benefits of I2 technology
Control, reproducibility, uniformity, flexibility
Dose ( QT) measured accurately by integrating
current
High purity obtainable by mass separation
The less ideal things about I2 technology
Cost of an ion implanter machine
High throughput even more expensive Radiation
damage Impossible to implant delta function/the
ultimate shallow profile
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The Ion Implanter
Ion implanter in a FAB
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Ranges, Rprojected range Rp
Rp
Straggling ? Rp
Nuclear (elastic)
electron (inelestic
Concentration
?Rp
Depth
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S(E), Sn Se
LSS
s
n
e
e0.5
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Binary collision
Projectile
Impact parameter
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Impulse-approximation
M1, E0
q
x
a
r
b
M2
The force F acts on the projectile through the
traveled distance dx
The time it takes is
Integrate -inf. inf.
(Momentum change parallel path 0)
perpendicular
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Impulse-approximation, exampleCoulomb potential
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Impulse-approximation, example Coulomb potensial
Enter this in expression for b
Impulse approximation gives analytical results
for potentials of the type 1/r, 1/r2, 1/rs,
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LSS Impulse approx. with Thomas Fermi potential
Thomas-Fermi screening func.
e
s
n
e0.5
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LSS nuclear and electronic stopping
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Implant profiles
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Implant profiles
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Implant profiles
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Implant profiles
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Implant profiles through masks
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Implant profiles through masks
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Rp As,P,B,O,..
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Rp C,Zn,..
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SRIM
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Channeling
Steering of ion, small angle correlations between
collisions
Also feed in is possible
Range becomes larger than in an amorphous material
Critical angle - dependence on E, Z
Low energy largest problem/challenge
Implant in pre-amorphised Si with Si, Si with Ge
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Critical angle channeling
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Critical angle channeling
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Implantation disorder
Caused by elastic collisions
?t 10-13 sec, 10-12 thermal equilibrium, 10-9
reordering
Boron loss -mostly inelastic at start of
trajectory. Most displacement close to
the end
Arsenic starts large elastic loss, disorder
similar to As distribution
Density displaced atoms Dose/Energy Sn
FdisordergtFamorphous -gt amorph
Buried amorphous layer
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Damage profile
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Damage distribution
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Damage distribution
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RBS implant B
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Critical dose amorphous
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Annealing
Amorphous anneals different than non amorphous
Amorphous -SPEG
Epi growth , ?x prop. T, ?Ea 2.3 eV,
collective bond flipping
Two-stage annealing
Ion straggling disorder
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Annealing P
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Annealing B
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Equipment/Limitation, implant angle
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Equip./limitations, scan angle
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Equip., sector magnet
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Equip., Mass separation
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Equip., Scanning