1. Multiscale Approach for the Analysis of Channeling Profile Measurements of Ion Implantation Damage
G. Hobler, G. Otto, D. Kovac L. Palmetshofer1, K. Mayerhofer², K. Piplits²
1 Inst. Semiconductor and Solid State Physics, Univ. Linz ² Inst. Chem. Technol. and Analytics, TU Vienna
Institute of Solid-State Electronics

2. Damage Models in BC Simulations
Traditional model:
defect positions: generated statistically
atom positions: random interstitial model
dynamic annealing: „recombination factor“
Proposed model:
defect positions: trace each defect during the whole simulation
atom positions: take from ab-initio simulations
dynamic annealing: kinetic lattice Monte Carlo simulation (kLMC) after each collision cascade

3. Overview Introduction BC-kLMC approach
Application to channeling profile measurement (CPM) experiments
Introduction: implant damage and implant damage modeling

4. Damage Measurements
Channeling
profile
RBS

5. Channeling Implantations
Fit dose dependence of channeling implantation profiles  recombination factor
frec=0.125
Nsat=41021cm-2
(G.Hobler et al., J. Vac. Sci. Technol B14 (1) 272, 1996)

6. Channeling Profile Measurements
Measure pre-existing crystal damage with a low-dose channeling implant
(M. Giles et al., MRS Symp. Proc. 469, 253, 1997)

7. The Role of Dynamic Annealing in Si
Temperature dependence of implant damage:
(J.E. Westmoreland et al., Appl. Phys. Lett. 15, 308, 1969)

8. The Role of Dynamic Annealing in Si
Dose-rate dependence of implant damage:
70µA/cm²
0.14µA/cm²
T=300K
(O.W. Holland et al., Rad. Eff. 90, 127, 1985)

9. Overview Introduction BC-kLMC approach
Application to channeling profile measurement (CPM) experiments
Introduction: implant damage and implant damage modeling

10. Coupled BC-kLMC Approach
Traditional approach:
BUT: type and amount of defects influence BC trajectories (dechanneling)
point
defects BC
loop
over
cascades
1 cascade
as used for annealing simulations at elevated temperatures
kLMC
point defects + clusters

11. Coupled BC-kLMC Approach
Proposed new approach:
defects
atom positions
for each defect
loop
over
cascades BC
old defects + new point defects
kLMC
point defects + clusters

12. Details of kLMC
Each defect is associated with one or more lattice sites
Defects: Vn, In (n=1,2,3,...)
Events:
Diffusion hops (I, V)
Reactions of defects located within capture radius
Vn+V  Vn Vn+I  Vn In+I In In+V In-1
Parameters:
DV=310-13 cm²/s DI=6.3510-17 cm²/s
(Capture radii)

13. Details of kLMC
„Old“ defects: restricted to column (periodic boundary conditions)
„New“ defects: anywhere
Interaction between „new“ and „old“ defects: Using periodicity of „old“ defects
(x,y) parallel to the surface

14. Details of BC Read defects from kLMC (columnar domain)
Use periodicity to generate defects around projectile
Atom positions from ab-initio calculations (VASP)
defect structure
strain around defect
All defects composed of individual I and V (currently)
stain fields of I and V superposed

15. Overview Introduction BC-kLMC approach
Application to channeling profile measurement (CPM) experiments
Introduction: implant damage and implant damage modeling

16. CPM Experiments Damage implant: N, 30 keV, 31014 cm-², 10° tilt
CPM implant: B, 30 keV, 1013 cm-2, 0° tilt
(110)-Si
shield

17. CPM Experiments
Results:

18. CPM Simulation Results
Simulation results without strain:

19. CPM Simulation Results
Strain from vacancies:

20. CPM Simulation Results
Strain from interstitials:

21. What is wrong? Lack of amorphous pockets?
Defects: Vn, In (n=1,2,3,...)
Events:
Diffusion hops (I, V)
Reactions of defects located within capture radius
Vn+V  Vn Vn+I  Vn In+I In In+V In-1
Parameters:
DV=310-13 cm²/s DI=6.3510-17 cm²/s
(Capture radii)
Lack of amorphous pockets?

22. What is wrong? Lack of amorphous pockets? NO
Defects: Vn, In (n=1,2,3,...)
Events:
Diffusion hops (I, V)
Reactions of defects located within capture radius
Vn+V  Vn Vn+I  Vn In+I In In+V In-1
Parameters:
DV=310-13 cm²/s DI=6.3510-17 cm²/s
(Capture radii)
Lack of amorphous pockets? NO
Approximate treatment of I-Clusters?

23. What is wrong? I-Clusters:
Similar study on RBS-C: Efficiency of I2, I3, I4 within 40% of split-110 interstitial I I2 I3
I4a
I4b
80% of interstitial atoms in clusters with size <= 4
(G. Lulli et al., Phys. Rev. B69, , 2004)

24. What is wrong? Lack of amorphous pockets? NO
Defects: Vn, In (n=1,2,3,...)
Events:
Diffusion hops (I, V)
Reactions of defects located within capture radius
Vn+V  Vn Vn+I  Vn In+I In In+V In-1
Parameters:
DV=310-13 cm²/s DI=6.3510-17 cm²/s
(Capture radii)
Lack of amorphous pockets? NO
Approximate treatment of I-Clusters? Probably not
Attraction of I+Vn, V+In and/or Repulsion of I+In, V+Vn

25. Conclusions New approach for implant damage simulations
coupled BC and kLMC
atom positions from ab-initio
Consistent simulation of both defect generation and analysis
Simulations yield too much damage  need to use
interaction radii to favor recombination and/or
reaction barriers to impede clustering