Download RADSAFE - An Integrated Radiation Effects

RADSAFE - An Integrated
Radiation Effects
Simulation Framework
Robert A. Weller, Robert A. Reed
& Marcus H. Mendenhall
Vanderbilt University
9-10 May 2005
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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.
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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.
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Electrical Engineering & Computer Science
The RADSAFE System
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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
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Electrical Engineering & Computer Science
The single event - a collection
of segments
Particle Trajectories
Incident proton: blue
Electrons: red
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Energy in the transistor: 44.7 keV
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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
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r r
r
v  x2  x1
r
v  v etc.
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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
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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
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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
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Electrical Engineering & Computer Science
Displacement Damage in GaAs
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Electrical Engineering & Computer Science
A Displacement Single Event
How does energy translate to electrical activity?
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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.
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Electrical Engineering & Computer Science
The radiation event - Trajectories
3.8 MeV
10.6 MeV
14.1 MeV
Event
037
Event
256
Event
267
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Electrical Engineering & Computer Science
Ion Tracks for Event 037
1018 e-/cm3
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1014 e-/cm3
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Electrical Engineering & Computer Science
Ion Tracks for Event 256
1018 e-/cm3
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1014 e-/cm3
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Electrical Engineering & Computer Science
Ion Tracks for Event 267
1018 e-/cm3
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1014 e-/cm3
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Electrical Engineering & Computer Science
Radiation event: Meshing
Event
267
Slice at y = 1.0 µm
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Slice at x = 0 µm
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Electrical Engineering & Computer Science
Validation: Charge Conservation
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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)
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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
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Electrical Engineering & Computer Science