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RADSAFE - An Integrated Radiation Effects Simulation Framework Robert A. Weller, Robert A. Reed & Marcus H. Mendenhall Vanderbilt University 9-10 May 2005 [email protected] 1 Electrical Engineering & Computer Science RADSAFE - The Objective To create a system for firstprinciples 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. [email protected] 2 Electrical Engineering & Computer Science 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. [email protected] 3 Electrical Engineering & Computer Science The RADSAFE System [email protected] 4 Electrical Engineering & Computer Science Implementation? How it works… Events VUmps (GEANT4) C++ Tools, Scripting Automatic Meshing Geometry Mathematica & Python ISE TCAD (DESSIS) QuickTime™ and a MPEG-4 Video decompressor are needed to see this picture. Gaussian charge generation [email protected] 5 Electrical Engineering & Computer Science The single event - a collection of segments Particle Trajectories Incident proton: blue Electrons: red [email protected] Energy in the transistor: 44.7 keV 6 Electrical Engineering & Computer Science 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: r r r f ( x,t) Q (2 )3/2 v 2 r v 2 v2 r 2 e 2v2 2 r r r r t t0 2 v2 2r v v 2 2 r v e 2 2 ) erf ( ) erf ( t 2 2 v 2 2 v 1 erf ( 0 2 ) 1 r r x0 ( x1 x2 ) 2 r r r r x x0 [email protected] r r r v x2 x1 r v v etc. 7 Electrical Engineering & Computer Science 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 [email protected] 8 Electrical Engineering & Computer Science TCAD Geometry Interface Complex layers • High energy protons incident on advanced CMOS integrated circuit • Interaction with metallization layers dramatically increases energy deposition Radiation Events Device Description [email protected] 9 Electrical Engineering & Computer Science 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 [email protected] 10 Electrical Engineering & Computer Science Displacement Damage in GaAs [email protected] 11 Electrical Engineering & Computer Science A Displacement Single Event How does energy translate to electrical activity? [email protected] 12 Electrical Engineering & Computer Science Single Event Simulation • System: Si diode, a 5 µm cube. • Events: 1 GeV/nucleon 12C. 106 total incident. • Pre-selection: >1.5 MeV in a 1 µm cube, 0.5 µm below the junction. 267 candidate events. [email protected] 13 Electrical Engineering & Computer Science The radiation event - Trajectories 3.8 MeV 10.6 MeV 14.1 MeV Event 037 Event 256 Event 267 [email protected] 14 Electrical Engineering & Computer Science Ion Tracks for Event 037 1018 e-/cm3 [email protected] 1014 e-/cm3 15 Electrical Engineering & Computer Science Ion Tracks for Event 256 1018 e-/cm3 [email protected] 1014 e-/cm3 16 Electrical Engineering & Computer Science Ion Tracks for Event 267 1018 e-/cm3 [email protected] 1014 e-/cm3 17 Electrical Engineering & Computer Science Radiation event: Meshing Event 267 Slice at y = 1.0 µm [email protected] Slice at x = 0 µm 18 Electrical Engineering & Computer Science Validation: Charge Conservation [email protected] 19 Electrical Engineering & Computer Science RADSAFE - Future Developments (12-24 mos.) • Unified xml-based command and geometric description language using W3C xercesc parser • Additional Python integration (Replacing Geant4style 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) [email protected] 20 Electrical Engineering & Computer Science 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 electronhole 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 [email protected] 21 Electrical Engineering & Computer Science