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

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

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

Damage Measurements Channeling profile RBS

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)

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

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

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)

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

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

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

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+1 Vn+I  Vn-1 In+I In+1 In+V In-1 Parameters: DV=310-13 cm²/s DI=6.3510-17 cm²/s (Capture radii)

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

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

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

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

CPM Experiments Results:

CPM Simulation Results Simulation results without strain:

CPM Simulation Results Strain from vacancies:

CPM Simulation Results Strain from interstitials:

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+1 Vn+I  Vn-1 In+I In+1 In+V In-1 Parameters: DV=310-13 cm²/s DI=6.3510-17 cm²/s (Capture radii) Lack of amorphous pockets?

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+1 Vn+I  Vn-1 In+I In+1 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?

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, 165216, 2004)

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+1 Vn+I  Vn-1 In+I In+1 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

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