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High-Fidelity Simulations of Radiation Effects in Complex Systems

This paper discusses the development of high-fidelity simulations for analyzing and predicting radiation effects in nanoscale electronics in extreme environments such as space. The paper focuses on the use of the NanoTCAD software, which has automated interfaces to the Geant4 radiation models and the Cadence Spectre circuit simulator. The paper also highlights the importance of proper meshing and resolution of fine details in simulating complex nuclear events. Additionally, the paper introduces the advanced mixed-mode tools in NanoTCAD, including the coupling of the 3D solver with the Cadence Spectre circuit simulator.

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High-Fidelity Simulations of Radiation Effects in Complex Systems

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  1. Towards High-Fidelity Simulations of Radiation Effects in Complex Systems Ashok Raman, Marek Turowski, Alex Fedoseyev, and Robert Arslanbekov CFD Research Corporation (CFDRC) Huntsville, Alabama, USA Geant4 Space Users Workshop, 18-20 August 2010 This work was sponsored by DTRA RHM Program and NASA SBIR programs

  2. Space Exploration = Extreme Environments ! Moon, Mars, and Beyond…. Extreme Temperatures: -230°C to +130°C Radiation: Solar Events, Galactic Cosmic Rays… Single Event Effects • Many Different Circuit Needs: • digital building blocks • analog building blocks • data conversion (ADC/DAC) • RF communications • actuation and control • sensors / sensor interfaces Current Rovers / Robotics Require “Warm Box” Highly Mixed-Signal Flavor

  3. Goal: Analysis and Prediction of Radiation Effects in Nanoscale Electronics (Space, Extreme Environments) 3D Device Simulation Mixed-Mode or Circuit Model Signal “Upset” CHIP CROSS SECTION (cm2) (Sensitivity to Radiation) time (s)

  4. Increasing Importance of Nuclear Reactions and Secondary Particles on SEE Event Rate Direct ionization (LET) does not reflect the latest IC data SEU measured data on a NASA mission Measured SEU cross sectionfor a 256-Kbit SOI SRAM [R. Reed et al., NSREC’07 + IEEE Trans. NS, Dec. 2007] [P. Dodd et al., NSREC’07 + IEEE Trans. NS, Dec. 2007] High Energy Low Energy IRPP (LET) * IRPP = Integral Rectangular Parallelepiped * MRED = Monte Carlo Radiative Energy Deposition (including Geant4 nuclear physics) LET

  5. New Developments in NanoTCAD • Automated interface to Geant4 (MRED) radiation models • Unique mixed-modeinterface to the Cadence Spectre circuit simulator • Ongoing: NanoTCAD 3D solver capability to model very low temperature behavior (‑245ºC)

  6. CFDRC NanoTCAD IC Layout  3D Model  3D Mesh  Simulation Automatic Generation of 3D Model Imported Layout(GDSII, CIF, DXF, GIF) 3D Mesh Simulation

  7. CFDRC NanoTCAD IC Layout  3D Model with Metallization Imported IC Layout(GDSII) Automatically Generated 3D Model

  8. MRED/Geant4 Radiation Tracks in CFDRC 3D Model Vanderbilt MRED (Monte Carlo Radiative Energy Deposition) MRED/Geant4 simulated ion beam, focused on the tungsten via

  9. Geant4 in TCAD - Needs • Simulations with complex nuclear events require proper meshing on fine details • Proper meshing on fine details, only where it is necessary, allows user to keep efficiency high • Resolution of fine details of complex nuclear events is essential for correct prediction of “global” device characteristics, such as transient contact currents and voltages in response to radiation • NanoTCAD very fast and efficient solver which is particularly important for mixed mode simulations where large number of transient solutions need to be obtained

  10. New Feature:MRED/Geant4 Tracks in NanoTCAD IC Layout  3D Model  3D Mesh Adaptation Simulation Micromesh (.utsv) mesh adaptation controller file Status Window small number of segments, fast mesh generation Total 20847 cells Geant4 track segments 3D Mesh x1 y1 z1 x2 y2 z2 Ener Width • File Header: • FilterThreshold: what to refine • RefineThreshold: where to refine • RefineResolution: how to refine • Because initial grid is too coarse, special technique of capturing fine details has been developed

  11. NanoTCAD: Mesh Adaptation to Geant4 Tracks Example of using FilterThreshold to remove track segments with low deposited energy • works also with additional adaptation (e.g., doping ) Total 20847 cells Example of fine mesh generation on 4 segments and a coarser mesh on 3 segments

  12. NanoTCAD: Geant4 Energy Depostion  Simulation IC Layout  3D Model  3D Mesh  Adaptation Simulation Energy deposition on adapted mesh GUI Window Data need to be transferred to the solver Material density and EHP energy Implementation in Micromesh allows track data to be transferred directly to NanoTCAD solver without performing extra steps Data available to the solver

  13. Source Terms NanoTCAD solver: Equations Drift-Diffusion (DD) or Hydrodynamic (HD) Semiconductor Equations Electric Potential Equation Carrier Continuity Equations where current densities are Structured or Unstructured Meshes 4

  14. CFDRC NanoTCAD Transient Simulations with Vanderbilt MRED/Geant4 Ion Tracks NMOS Transistor NanoTCAD 3D simulation of … MRED/Geant4 radiation “event 10255” Transient currents and collected charges MRED/Geant4 radiation “event 12423”

  15. Enhanced NanoTCAD Mixed-Mode Tools • Advanced mixed-mode simulation tools - upgraded with new Spice compact models for latestCMOS technologies- BSIM4, BSIMSOI, …as well as for the latest BiCMOS (SiGe) technologies and devices, including VBIC and Mextram models for heterojunction bipolar transistors (HBTs). • Latest enhancement: unique mixed-mode coupling of CFDRC NanoTCAD3D solver withCadence Spectre circuit simulator • This new capability enables mixed-mode simulations of SEEs in latest high-speed BiCMOS technologies and circuits, directly using compact models from PDK (process design kit) provided by foundries.

  16. Test/Demo Circuit • SiGe HBT Mixed-Signal Circuit: • 130-nm SiGe BiCMOS Technology (IBM 8HP) • 7.2 GHz comparator • part of an Analog-to-Digital Converter (ADC), • - tested for SEE response:bit error rates introduced by radiation events

  17. Mixed-Mode Model Demo Mixed-Signal circuit: 7.2 GHz comparator (NGC)

  18. Mixed-Mode Results • CFDRC MixCad: NanoTCAD 3D coupled with Cadence Spectre Analog / Mixed-Signal SEUs Demo Mixed-Signal circuit: 7.2 GHz comparator 4A 4B 4B 4A

  19. Experimental Validation • CFDRC MixCad: NanoTCAD 3D coupled with Cadence Spectre CFDRC MixCad Simulation Results match Experimental Data very well(7.2 GHz comparator, SiGe BiCMOS) CFDRC Mixed-Mode Simulations NG Experiments (SEE induced by Laser) 4A 4B Varying LET ...

  20. Cellular Injury Mechanisms Insult Ionizing radiation time Sub-acute - Acute Chronic effects (progressive; latency ~ 6 months or more) • Direct injury/ near immediate cellular toxicity • Sub-acute: Organ specific (lung; spinal cord) • Tissue radiosensitivity • (skin; bone; teeth; muscle; • reproductive organs) • Releases energy to break chemical bonds • Generates free radicals (oxidative/nitrosative stress) • Cytokine release (interleukins…) • Damage to macromolecules (RNA; DNA) • Cataract; Cell death (cancer trigger via apoptosis/necrosis) Consequential Cellular compartments Oxidative stress model Apoptosis model: cytokines trigger Mitochondrial failure initiates a bunch of secondary biochemical cascades >>>>> Cell Death via Ox. Stress or Apoptosis/Necrosis Dash et al., 2008

  21. Systems Physiology Whole body physiology Tissue Organ Perfusion Cellular metabolism Injury Modeling • Multiscale framework coupling whole body physiology • Existing Computational Biology tools for top-down multiscale human/animal body physiology-injury TOP-DOWN BOTTOM-UP Whole body physiology Systems Physiology Top-down Organ Tissue Perfusion Cellular metabolism Subcellular Cellular Injury

  22. Systems Biology and Bioinformatics Expertise and Capabilities Provide solutions to problems in military and civilian medicine through the strategic development of advanced bioinformatics and systems biology tools. SBMLForge Software that merges canonical pathways from KEGG database into one single SBML model for analysis Produces a quantitative, objective ranking of interactions in the network leading to the identification of critical biological pathways BNDTI – Boolean Network Dynamics and Target Identification Organize experimental data via easy archival abilities along with various data and mining analysis capabilities CipherDB – Genomic and Proteomic data storage and Analysis Identification of natural compounds with maximum bioactivity against disease-specific bioassays NELI – Natural Extract Lead Identification

  23. Systems Biology and Bioinformatics: Applications / Projects Electrophysiology [In collaboration with UCF] Development of kinetic models to describe electrochemical behavior under perfusion of specific drugs Development of a detailed model using BNDTI to identify the role of SNPs in Mefloquine Neurotoxicity Malaria [In collaboration with Vanderbilt] Development of a pathway model for low dose radiation induced cardiovascular pathologies Radiation and Atherosclerosis [In collaboration with Temple U] Development of enzyme cascade model using kinetics of immobilized enzymes for sucrose oxidation Enzyme Cascade Modeling Development of models for the feedback loop control of yeast dynamics under drug perfusion Automated Model Inference [In collaboration with Vanderbilt]

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