1. Ion Implantation and Temperature  HEROS Modeling
Qiyang Hu , Shahram Sharafat, Nasr Ghoniem
Mechanical & Aerospace Engineering
University of California, Los Angeles
San Diego, Aug 8th, 2006

2. Leads to confidence in predicting IFE conditions
Objectives
Calibrate HEROS with a wide range of applications:
Deep implantation in pulses by UNC
Shallow implantation in steady states by IEC condition
Shallow implantation in steady states by Nishijima’04
Leads to confidence in predicting IFE conditions

3. HEROS Code Improvement
Simulation Discussion
Conclusions and Future Plans

4. Previous HEROS code has serious numerical instability problems:
In most cases:
Time to be simulated < 10 sec
Running Time > 6 hours
Time step > 2000 steps
Temperature range < 2000 K

5. HEROS model is improved:
Still, reaction-diffusion rate equation:
Simplify the equation
Ignore some cluster effects:
(e.g. vacancy clusters, interstitial clusters etc.)
18 variables/equations  13
Ignore bubble coalescence

6. HEROS numerical scheme:
Temperature profile
Within a bin, each C(i) is in an average sense
Implantation profile …
W back
W front
variable bin size

7. Recent Progresses in Modeling Helium Behavior:
Can integrate equations for thousands of pulses.
Can include rapid temperature transients.
Aim to calibrate model with experimental data.

8. HEROS Code Improvement
Simulation Discussions
Conclusions and Future Plans

9. First, we want to use our new HEROS code to model UNC(’05) & UWM(’04) conditions.
We re-simulated UNC & UWM’s implantation cases
Helium Implantation
Damage

10. UNC’s Temperature Profile
( L. Sneed,2005 )

11. After 1 cycle of 1019 He/m2: Temperature C Time (sec) 2000C 850C
3000
3060
Time (sec)

12. After 10 cycle of 1018 He/m2/cycle:
Temperature C
2000C
850C
300
360
720
Time (sec)

13. After 100 cycle of 1017 He/m2/cycle:
Temperature C
2000C
850C 30 90
180
Time (sec)

14. After 1000 cycle of 1016 He/m2/cycle:
Temperature C
2000C
850C 3 63
126
Time (sec)

15. Helium Retention: Diffuse too fast in HEROS Short pulse OK! Cycles:
1000
100 10 1

16. Bin Number=20; Total width=10m
Bubble & Radius Movies: HEROS also gives the spatial distribution information
Bin Number=20; Total width=10m

17. For UWM’s IEC conditions: Some notes before comparisons:
Surface bubble  Surface pore
Surface bubble density  (volume bubble density|surf)2/3
We focus on steady condition.

18. New HEROS code is stable and gives the information about bubble (pore) sizes:

19. So does the pore density …

20. We also calibrate our model by Nishijima group’s experiments (ITER):
Temperature:
= 1950 C Gh
1m x

21. HEROS also gives the spatial distribution information (average sense):
Bin Number=20; Total width=10m

22. HEROS for temperature modeling:
Surface Heating
Emissive effect
can be ignored
B.C.
Max

23. HEROS Code Improvement
Simulation Discussion
Conclusions and Future Plans

24. Total time to be simulated
Conclusions:
Capabilities of HEROs code are largely improved
Our HEROS can integrate equations :
with thousands of pulses.
with rapid temperature transients.
Need to improve:
Helium: More trapping mechanism
Heat: new mechanism
HEROs
Total time to be simulated
Running time
Required time steps
Temperature range
Previous
<10 sec
>6 hrs
>2000 steps
<2000 K
Current
>106 sec
<5 mins
< 100 steps
<3500 K

25. Planning on HEROS: Implement recent “pulsed” conditions:
UWM
UNC
Implement IFE conditions
Add bubble coalescence
Exceed the 0-order (average) description
Temperature/carbon diffusion problem

26. We wish to develop a unified temperature/diffusion/microstructure code
Containing:
Temperature transients
Helium distribution
Carbon distribution
Point defect/displacement damage

27. Thanks!

28. Backup Slides

29. Helium retention for IEC condition:
Most of He are in grain boundary