1. Annealing of damages created by Ionimplantations & Masking during Implantation +
characterization of doped layers
Presented By :
M.Vikas Vardhan Reddy
M.Tech in Computational Engg.
ID:B61301007
9492634651
mvvr09402@gmail.com
2. Annealing and its use…
Process of repairing implant damage (i.e., “healing”
the surface) is called annealing .Also puts dopant
atoms in substitutional sites where they will be
electrically active
2 objectives of annealing:
1) healing, recrystallization (500 - 600 oC)
2) renew electrical activity (600 - 900 oC)
parameters that get most affected are conductivity, the
mobility and the life time.
Region of maximum damage?
Annealing of damages created by Ion-implantations &
Masking during Implantation + characterization of doped
layers
12/14/2013
3. Annealing Classes
Divided into two classes(based on type of material) they
are
1.
2.
Pre-amorphised
No pre-amorphised
Pre-amorphised
T<=600 degrees centigrade
T<=400 degrees centigrade
1.
Partial recovery(clusters disappear)
2.
20% to 30% activation
Recovery life time is extreme low
3.
1.
Recrystallization takes place
2. 50% to 90% activation
3. Recovery life time is low
T>=950 degrees centigrade
1.
Fast recovery
Annealing of damages created by Ion-implantations &
Masking during Implantation + characterization of doped
layers
12/14/2013
4. No Pre-amorphisation
Low dose , light ion implantation, we can fully recover
of all the parameters ,conductivity, mobility, as well as
life time by 800 to 950 degree centigrade.
Heavy ion implantation, low dose we can fully recover
of all the parameters by 1000 degree centigrade.
It is difficult to get full activation for high dose heavy
ion implantation.
if the life time recovery is not very important than pre
amorphisation is better than not pre amorphisation
material.(at 600c we get 90% activation)
Annealing of damages created by Ion-implantations &
Masking during Implantation + characterization of doped
layers
12/14/2013
5. Practical cases…
Phosphorous in silicon
Boron in silicon
Arsenic in silicon
Phosphorous in silicon
Phosphorus is a relatively heavy ion, so it loses its
energy primarily by the nuclear stopping mechanism
Projected range proportional to incident energy
lot of energy to put phosphorus deep into the silicon
Rp=1.1 μm/M ev.
Annealing of damages created by Ion-implantations &
Masking during Implantation + characterization of doped
layers
12/14/2013
6. Annealing of phosphorus and arsenic
As the temperature increases the carrier activation
increases till eventually at a point it sort of acquires full
activation or let us say, 90% of activation.
arsenic in silicon, arsenic also
behaves in a manner very similar
to that of phosphorus.
Rp=0.58 μm/M ev.
Annealing of damages created by Ion-implantations &
Masking during Implantation + characterization of doped
layers
12/14/2013
7. Annealing of boron
boron is a light ion
Rp=3.1 μm/M ev.
for boron, for the incident energy range in 10 to 100
kilo electron volt
Annealing behavior of Boron.
Annealing of damages created by Ion-implantations &
Masking during Implantation + characterization of doped
layers
12/14/2013
9. Masking in ion implantation
Ion implantation is a room temperature process and
therefore you have a larger choice of mask material.
You do not have to use silicon dioxide always, like in
case of diffusion.
Ion implantation can use photoresist as the mask
Silicon and mask layer generate energic ions when ion
beam is incident on semiconductor and these energy
ions will have Gaussian principle.
Annealing of damages created by Ion-implantations &
Masking during Implantation + characterization of doped
layers
12/14/2013
10. Gaussian profile
d is the masking layer thickness.
If d is large less impurity is put
inside silicon
If d is less large amount of impurity
is put inside silicon
Annealing of damages created by Ion-implantations &
Masking during Implantation + characterization of doped
layers
12/14/2013
11. Masking layer efficiency
Annealing of damages created by Ion-implantations &
Masking during Implantation + characterization of doped
layers
12/14/2013
12. Annealing of damages created by Ion-implantations &
Masking during Implantation + characterization of doped
layers
12/14/2013
13. Amount of impurity not protected by
mask
Practical case
Annealing of damages created by Ion-implantations &
Masking during Implantation + characterization of doped
layers
12/14/2013
14. Evaluation of doped layer
Junction depth
Doping profile
Junction depth
Junction depth is measured by lapping and straining
Cylindrical groove technique
Interference fringe method
Annealing of damages created by Ion-implantations &
Masking during Implantation + characterization of doped
layers
12/14/2013
15. Junction depth by lapping and straining
Angled lapping
Cross sectional diagram of the junction
Annealing of damages created by Ion-implantations &
Masking during Implantation + characterization of doped
layers
12/14/2013
16. Cylindrical groove method
Annealing of damages created by Ion-implantations &
Masking during Implantation + characterization of doped
layers
12/14/2013
17. Interference fringe method
Third method to find the junction depth
Lapped sample
Provide optical flat and subject to monochromatic
radiation usually sodium vapour lamp.
Dull fringes appear in p region and we can count it.
Now junction depth=no.of dull fringes * wavelength of
monochromatic light.
Annealing of damages created by Ion-implantations &
Masking during Implantation + characterization of doped
layers
12/14/2013
18. Doping distribution
doping distribution, the impurity distribution. Now we
can measure the total impurity distribution by doing
spectroscopy analysis like SIMS, Secondary Ion Mass
Spectroscopy, which will tell us exactly how much
impurity is put inside the material.
But, it will not tell us whether this impurity is
electronically active or not, whether it is sitting in the
substitutional site or it is just sitting anywhere inside
the semiconductor
Annealing of damages created by Ion-implantations &
Masking during Implantation + characterization of doped
layers
12/14/2013
Good morning to one and all. I am Vikas Vardhan Reddy Persuing M.Tech first year in RGUKT. Now Iam going to give presentation on Annealing of damages created by Ion-implantations & Masking during Implantation + characterization of doped layers
After ion implantation conductivity is very Low and electronic activity is minimum. The region become semi Insulating. Mobility is low. So we have to get back the required levels of conductivity, the mobility and the life time. In order to anneal out the damages, the semiconductor must be subjected to high temperature . Damage is created mostly by nuclear stopping mechanism.
For low dose ,light ion the damages are much less. heavy ions still with low dose,you will get back about 1000 degree centigrade, will give you recovery of all the parameters.
E 0=1.1 micrometer per mega electron volt, per thousand kilo electron volt. That means if you have 100 kilo electron volt energy, R p will be 0.11 micrometer.
relative active carrier concentration that is n/ⱷ versus the annealing temperature. ⱷ is the total dose, n is active carrier concentration. annealing schedule depends entirely on the dose, the lighter dose gets annealed faster, the heavier dose gets annealed later.
if the incident energy is greater than 100 kilo electron volt, then nuclear stopping will no longer dominate. It will be dominated by electronic stopping and in that case R p will be no longer proportional to the energy, but it will be proportional to the square root of energy.
Masking during Implantation + characterization of doped layers
Diffusion by contrast, is a high temperature process; therefore you must use a masking material that can withstand this high temperature.
Q0 that is the total dose.
Angled lappingprovides an ease of measurement. You are visually magnifying the junction area. Strain it by using a copper sulphate and dilute HF solution.Dilute HF will etch the surface oxide .now under microscope we can measure the junction depth
A cylinder with particular a radius R and it is used to grind a groove the semiconductor. Destructive technique
