1. robert.a.weller@vanderbilt.eduElectrical Engineering & Computer Science 1 RADSAFE - An Integrated Radiation Effects Simulation Framework Robert A. Weller, Robert A. Reed & Marcus H. Mendenhall Vanderbilt University 9-10 May 2005

2. robert.a.weller@vanderbilt.eduElectrical Engineering & Computer Science 2 RADSAFE - The Objective To create a system for first- principles predication of device, circuit and system response to radiation. RADSAFE is a strategy for implementation of the “third paradigm” of scientific discovery in the field of the interaction of semiconductor electronics with physical systems, in general, and with radiation, in particular.

3. robert.a.weller@vanderbilt.eduElectrical Engineering & Computer Science 3 The RADSAFE System A revolutionary, modular computational system for predicting the radiation response of electronic devices, circuits, and systems from basic device structure, circuit topology, and fundamental radiation characteristics. Its goals – to be informed by the best available physics, implemented by robust algorithms, enabled by supercomputer technology, and calibrated by data.

4. robert.a.weller@vanderbilt.eduElectrical Engineering & Computer Science 4 The RADSAFE System

5. robert.a.weller@vanderbilt.eduElectrical Engineering & Computer Science 5 Implementation? How it works… ISE TCAD (DESSIS) Geometry VUmps (G EANT 4) Mathematica & Python C++ Tools, Scripting Automatic Meshing Events Gaussian charge generation

6. robert.a.weller@vanderbilt.eduElectrical Engineering & Computer Science 6 The single event - a collection of segments Particle Trajectories Incident proton: blue Electrons: red Energy in the transistor: 44.7 keV

7. robert.a.weller@vanderbilt.eduElectrical Engineering & Computer Science 7 The single event - trajectory segment math The radiation event is a collection of trajectory segments Each segment has an associated energy Each segment is convolved with a Gaussian yielding:

8. robert.a.weller@vanderbilt.eduElectrical Engineering & Computer Science 8 TCAD geometry parsing The key simulation step: Importing a TCAD structure The strategy: Reduce the structure to tetrahedra A constructive solid tetrahedron has been created for Geant4

9. robert.a.weller@vanderbilt.eduElectrical Engineering & Computer Science 9 TCAD Geometry Interface - Complex layers Device Description Radiation Events High energy protons incident on advanced CMOS integrated circuit Interaction with metallization layers dramatically increases energy deposition

10. robert.a.weller@vanderbilt.eduElectrical Engineering & Computer Science 10 Displacement Damage (Screened scattering) Screened Rutherford scattering is not part of Geant4 However - It is vital for displacement damage MRED includes screened scattering using algorithms that have been tested for more than a decade Results accomplish the intent of NIEL but with enhanced microscopic detail Results point to an important research area for the future

11. robert.a.weller@vanderbilt.eduElectrical Engineering & Computer Science 11 Displacement Damage in GaAs

12. robert.a.weller@vanderbilt.eduElectrical Engineering & Computer Science 12 A Displacement Single Event How does energy translate to electrical activity?

13. robert.a.weller@vanderbilt.eduElectrical Engineering & Computer Science 13 Single Event Simulation System: Si diode, a 5 µm cube. Events: 1 GeV/nucleon 12 C. 10 6 total incident. Pre-selection: >1.5 MeV in a 1 µm cube, 0.5 µm below the junction. 267 candidate events.

14. robert.a.weller@vanderbilt.eduElectrical Engineering & Computer Science 14 The radiation event - Trajectories Event 037 Event 267 Event 256 3.8 MeV 14.1 MeV 10.6 MeV

15. robert.a.weller@vanderbilt.eduElectrical Engineering & Computer Science 15 Ion Tracks for Event 037 10 18 e - /cm 3 10 14 e - /cm 3

16. robert.a.weller@vanderbilt.eduElectrical Engineering & Computer Science 16 Ion Tracks for Event 256 10 18 e - /cm 3 10 14 e - /cm 3

17. robert.a.weller@vanderbilt.eduElectrical Engineering & Computer Science 17 Ion Tracks for Event 267 10 18 e - /cm 3 10 14 e - /cm 3

18. robert.a.weller@vanderbilt.eduElectrical Engineering & Computer Science 18 Radiation event: Meshing Event 267 Slice at y = 1.0 µmSlice at x = 0 µm

19. robert.a.weller@vanderbilt.eduElectrical Engineering & Computer Science 19 Validation: Charge Conservation

20. robert.a.weller@vanderbilt.eduElectrical Engineering & Computer Science 20 RADSAFE - Future Developments (12-24 mos.) Unified xml-based command and geometric description language using W3C xercesc parser Additional Python integration (Replacing Geant4- style message passing in VU code) Output Mathematica ® /xml selectable Improved sensitive volume definition - coincidences Time-stamped segments in TCAD FLOODS integration-With U. Florida (USAF MURI)

21. robert.a.weller@vanderbilt.eduElectrical Engineering & Computer Science 21 Outstanding Scientific Issues and Questions Experimental and computational tests of heavy-ion nuclear reactions. All ions. E < 1 TeV/nucleon Theory-based heavy ion stopping (Sigmund theory?) including spatial and energy distribution of electron- hole pairs Energy deposition in sub 100 nm structures Energy deposition and persistent defects Structure of electrically active defects Fundamental device modeling in the quantum regime Spatially-dependent tensor mobility - Next talk! “Deep Impact” - Core vacancy effects