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

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

HEROS Code Improvement Simulation Discussion Conclusions and Future Plans

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

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

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

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.

HEROS Code Improvement Simulation Discussions Conclusions and Future Plans

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

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

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

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

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

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

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

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

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.

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

So does the pore density …

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

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

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

HEROS Code Improvement Simulation Discussion Conclusions and Future Plans

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

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

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

Thanks!

Backup Slides

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