Power Device Modeling with TCAD - Silvaco · PDF fileTCAD Power Device Modeling ... GUI and...
Transcript of Power Device Modeling with TCAD - Silvaco · PDF fileTCAD Power Device Modeling ... GUI and...
Power Device Modeling with TCAD
TCAD Power Device Modeling
Introduction
Features Essential for Power Device Simulation
Device Structure Formation
Device Simulation
Case Studies
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TCAD Power Device Modeling
Key Features for Power Device Simulation
Non-Isothermal (Self Heating)
MixedMode (Physical Devices Embedded in Lumped Circuits)
Curve Tracer (for Modeling Instabilities such as Snapback)
Advanced Trap Modeling
Ionization Integrals
Advanced Numerics (methods/climit/dvmax)
Advanced Materials
Interoperability
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TCAD Power Device Modeling
Interoperability
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Device Structure Formation
TCAD Power Device Modeling
Overview
Structures
Tools
Meshing
Processing
Editing
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TCAD Power Device Modeling
Device Structure Formation: Tools
ATHENA: 1D, 2D rectangular initial grid, process
simulation
ATLAS: 1D, 2D, 3D rectangular grid analytical and
measured profiles
DevEdit: 2D, 3D arbitrary grid
GUI and command-line mode
advanced structure edit capabilities
advanced mesh capabilities
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TCAD Power Device Modeling
Device Structure Definition: Meshing
ATLAS, ATHENA:
direct specification of mesh coordinates
mesh relax
adaptive meshing for process (risk of obtuse triangles!)
appropriate for simple meshes:
very quick
unflexible
not interactive
rectangular
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TCAD Power Device Modeling
Device Structure Definition: Meshing
DevEdit:
mesh automatically created on boundary conditions, such as mesh
constraints
no obtuse triangles
refinement on quantities
manual interactive refine/unrefine
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TCAD Power Device Modeling
Device Structure Definition: Meshing
DevEdit Strategy:
set base mesh height / width bigger than device dimension (historical
feature)
locate "critical" areas, add more regions if necessary
set general max.height/width/angle by material
set tighter max constraints per region
for user defined areas (command line mode)
specify refinement quantities (net doping), tune min. spacing
manually refine/unrefine
refine on solution quantities
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TCAD Power Device Modeling
Device Structure Definition: Meshing
DevEdit Strategy:
Note:
doping regions not hit by mesh lines will not be refined correctly
Solution:
change mesh constraints
add regions in this area with appropriate mesh-constraints
Caution:
Pay special attention to surface phenomena (MOS, surface charge), define
a surface layer with finer constraints 3), or refine manually
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TCAD Power Device Modeling
Device Structure Definition: Meshing
Quality Criteria
no obtuse triangles in semiconductor region
fine grid where required
coarse grid where nothing is happening
not too many lines meeting in one node
smooth grid
smooth solution
smooth terminal characteristics
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TCAD Power Device Modeling
Device Structure Formation: Process Simulation in
ATHENA
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ATHENA models:
Models Assumption Application
Implantation
Dual Pearson empirical
Monte Carlo statistical angled implant with reflec.
Diffusion
Fermi Defects in equilibrium
two.dim Transient defect diffusion OED TED
Full.cpl defect and impurity binding co-diffusion clustering
power constant diffusivity for large structures
depending on temp
Oxidation
compress thick nitride birds-beak
viscous elastic
TCAD Power Device Modeling
Device Structure Formation: Process Simulation in
ATHENA
Example: Calibration of diffusion properties 1
select the appropriate statements from the models file:
ATHENA -models | grep aluminum > aluminum.mod
define your calibration target with EXTRACT
use the Optimizer for calibration
Tip: Introduce new dopant by redefining an unused existing one
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TCAD Power Device Modeling
Device Structure Formation: Process Simulation in
ATHENA
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TCAD Power Device Modeling
Device Structure Formation: Process Simulation in
ATHENA
Example: Double sided simultaneous doping 2
define dopant source material(s)
deposit topside material
flip the structure
deposit bottom material
Tip: to expose bottom surface, etch away infinite surface layer:
ETCH BELOW P1.Y = <NEW BOTTOM SURFACE POSITION>
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TCAD Power Device Modeling
Device Structure Formation: Process Simulation in
ATHENA
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TCAD Power Device Modeling
Device Structure Definition: Editing (Structure
Modification)
ATHENA:
oxidation, deposition, etch (physical, arbitrary polygon)
stretch, mirror, flip, cut (not interactive)
ATLAS:
scale: width, cylindrical
DevEdit:
deposit
stretch/squeeze, join, cut, move, flip, mirror, etch
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TCAD Power Device Modeling
Device Structure Definition: Editing
Example: Parametrized shape 3
run DevEdit in command-line mode within DeckBuild
use DeckBuild's SET feature to define parameter values
set a=230
use DeckBuild's SET feature to calculate dependent variables
(coordinates)
set right=$a+250
use variables for substitution
impurity id=2 imp=Boron color=0x8c5d00 \
x1=0 x2=$right y1=0 y2=0 \
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TCAD Power Device Modeling
Device Structure Definition: Editing
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TCAD Power Device Modeling
Device Structure Definition: Editing
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Device Simulation
TCAD Power Device Modeling
Device Simulation: Overview
Device Simulation
Physics
Boundary Conditions
Numerics
Mixed mode
3D
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TCAD Power Device Modeling
Device Simulation: Physics
Multiple equation solver: Fully coupled solutions for
Poisson equation
carrier continuity equation
carrier temperature equation
lattice heat flow equation (G.K. Wachutka, IEEE Trans CAD, 9,
pp1141-1149, 1990)
Joule heat
recombination/ generation heating/cooling
Peltier/Thomson
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TCAD Power Device Modeling
Device Simulation: Lifetime Tailoring
Recombination Models
Shockley-Read-Hall, fixed lifetime (SRH) or concentration
dependent (CONSRH)
single trap level (default: midgap)
low concentration lifetime defined per region, per material
(MATERIAL: TAUN0, TAUP0)
local temperature dependent model (MATERIAL: LT.TAUN, LT.TAUP)
C-Interpreter(x,y)
store recombination rate in solution: OUTPUT U.SRH
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TCAD Power Device Modeling
Device Simulation: Lifetime Tailoring
Recombination Models
additional traps can be superimposed
(TRAP or DOPING Statement)
arbitrary spatial distribution
discrete acceptor or donor-like traps
recombination parameters: cross-section or lifetime
full trap dynamics or stationary approach (FAST)
optical (OPTR)
Auger (AUGER)
Interface (INTERFACE statement)
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TCAD Power Device Modeling
Device Simulation: Physics
Models
Mobility
Doping concentration (d)
Temperature (T)
Lateral electric field (l)
Transverse electric field (f)
Carrier Carrier scattering (c)
surface mobility (s)
C-Interpreter (d,T,f,composition)
MOS regions:
CVT (l, f, d, T,s)
Bipolar:
KLAASSEN (T, d, c) FLDMOB(f)
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TCAD Power Device Modeling
Device Simulation: Physics
Models
Bandgap Narrowing
Slootboom model (BGN)
C-Interpreter
Impact Ionization (IMPACT statement)
Selberherr model (SELBER)
Grant model ()
Crowell & Sze model (CROWELL)
Light interaction (Luminous)
visible light: absorption, refraction, ray-tracing
C-Interpreter: arbitrary distributed generation (cosmic rays)
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TCAD Power Device Modeling
Device Simulation: Physics
Example: Transient IGBT Latchup
VCE ramped to 300V with drift diffusion
save solution
turn on heat flow equation:
MODELS ANALYTIC SRH AUGER FLDMOB SURFMOB LAT.TEMP
IMPACT SELBER
fully coupled solution
METHOD NEWTON
load VCE-solution
transient gate-ramp to 10V
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TCAD Power Device Modeling
Device Simulation: Physics
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TCAD Power Device Modeling
Device Simulation: Physics
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TCAD Power Device Modeling
Device Simulation: Physics
Example: Light triggered thyristor 12
cylindrical structure with amplifying gate
ramped anode to 1000V
illumination of the gate area
transient turn on
extraction of turn-on delay time
Note: Light can be used as a general tool to get thyristors latched
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TCAD Power Device Modeling
Device Simulation: Physics
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TCAD Power Device Modeling
Device Simulation: Physics
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TCAD Power Device Modeling
Device Simulation: Physics
Example: Proton irradiated diode 10
define a homogenous SRH-lifetime representing
electron irradiation
define a region where the proton induced traps are located
perform a reverse recovery simulation
extract (Von, Qrr, Irr)
perform an experiment with SRH-lifetime, proton
irradiation depth and dose as variables
create a RSM for Von, Qrr, Irr
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TCAD Power Device Modeling
Device Simulation: Physics
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TCAD Power Device Modeling
Device Simulation: Physics
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TCAD Power Device Modeling
Device Simulation: Physics
Example: Turn-off of Inhomogenous GTO 5
four finger structure created to represent a 15 cm2 device
structure devided in single cathode and gate regions
set different lifetimes in cathode regions to simulate an overall +- 10%
lifetime inhomogenity
turn on device (1000 A)
transient turn off (gate drive: with 100A/ s)
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TCAD Power Device Modeling
Device Simulation: Physics
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TCAD Power Device Modeling
Device Simulation: Physics
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TCAD Power Device Modeling
Device Simulation: Physics
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TCAD Power Device Modeling
Device Simulation: Boundary Conditions
Electrical Contacts
Topology:
define electrodes in ATHENA / DevEdit / ATLAS
Properties (CONTACT Statement):
workfunction
boundary conditions:
current, voltage, floating
options:
dipole barrier lowering, surface recombination
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TCAD Power Device Modeling
Device Simulation: Boundary Conditions
Electrical Contacts
Lumpled elements:
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R
L
C
Vapp
ATLAS Device
TCAD Power Device Modeling
Device Simulation: Boundary Conditions
Electrical Contacts
Slave:
allow one electrode to be biased as a function of another electrode
for voltage boundary conditions only
Note:
avoid to cover junctions
boundary conditions can be changed during run
don't change lumped elements
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TCAD Power Device Modeling
Device Simulation: Boundary Conditions
Example: Mixed pn-Schottky diode 7
split the anode electrode in Schottky and ohmic part
start off with voltage ramping
change to current boundary condition
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TCAD Power Device Modeling
Device Simulation: Boundary Conditions
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Example: I-V curve of a coarse gridded diode15
TCAD Power Device Modeling
Device Simulation: Boundary Conditions
Thermal Contacts
Topology:
identical with electrical contacts
boxes
regions
Properties (THERMCONTACT Statement):
external temperature
thermal resistance
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TCAD Power Device Modeling
Device Simulation: Numerics
Algorithms (DC and Transient Analysis)
Gummel
Newton
Block
Block iteration scheme:
Coupled Newton Solution of Poisson and Continuity equations
Decoupled solution of lattice heat flow equations
low power dissipation domain: BLOCK NEWTON
high power dissipation (current surges, breakdown): NEWTON
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TCAD Power Device Modeling
Device Simulation: Numerics
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Error Measures
relative error for carrier concentrations:
C = n, p
m = node identifier
K= iteration number
C0 = CLIM.DD = CLIMIT * (NC * NV)1/4
C
CK
mC
K
m
C CK
m
=
+
max
max ,
1
0
TCAD Power Device Modeling
Device Simulation: Numerics
Error Measures
Default value for CLIM.DD = 4.5e13 cm-3 (CLIMIT=1000)
OK in forward state
breakdown: 1e8 (300 K)
high injection condition 1e15
monitor terminal current balancing
Newton Parameters
DVMAX sets maximum allowed potential updates per Newton
iteration
default is 1
recommended for power applications: > 100000
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TCAD Power Device Modeling
Device Simulation: Numerics
Curvetracer
Trace out complex IV curves (Latch-up, breakdown, snapback)
Dynamic Load Line Approach (Goosens et al., IEEE Trans CAD
1994, 13, pp. 310-317)
Parameters: CONTR.NAME is the name of the electrode to be ramped
STEP.INIT initial voltage step
MINCUR current level above the dynamic load line
algorithm will be used
END.VAL stop tracing if level is reached
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TCAD Power Device Modeling
Device Simulation: Numerics
Curvetracer
Parameters:
CURR.CONT END.VAL is a current
NEXTST.RATIO multiplier for STEP.INIT in "linear" domains
Example: IGBT breakdown 11)
refined grid from 4)
curvetracer:
curvetrace curr_cont end.val=1e-2 contr.name=collector step.init=1 nextst.ratio=1.2
solve curvetrace
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TCAD Power Device Modeling
Device Simulation: Numerics
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TCAD Power Device Modeling
Device Simulation: Numerics
Example: Thyristor forward breakover 13
ramping over breakover point with curvetracer
extraction of max. bias
ramping again to max. bias
extraction of herlett-zone width
VWF experiment with n-base doping as variable
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TCAD Power Device Modeling
Device Simulation: Numerics
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TCAD Power Device Modeling
Device Simulation: Numerics
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TCAD Power Device Modeling
Device Simulation: MixedMode
How it works
numerical devices are embedded in a spice circuit (up to 100
nodes, 300 elements, 10 numerical devices)
all numerical devices are solved in a single matrix together with
the spice models
numerical devices are scaled by a width parameter or defined as cylindrical
standalone solutions can be loaded
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TCAD Power Device Modeling
Device Simulation: MixedMode
Input structure
circuit:
spice net list
initial node setting
numerics and options
arbitrary number of dc statements to sweep sources
single transient statement
models and parameters for the numerical devices
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TCAD Power Device Modeling
Device Simulation: MixedMode
Numerics
Full Newton (OPTIONS: FULLN, default): Fast with good
initial guess
Modified two-level Newton (.OPTIONS: M2LN): bad initial g.
Convergence Criteria
numerical devices (.OPTIONS):
RELPOT: relative potential criteria (large voltages)
circuit (.NUMERIC):
TOLDC, TOLTR: relative accuracy for node voltages
VMAX, VMIN: max/min value for node voltages
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TCAD Power Device Modeling
Device Simulation: MixedMode
Example: Turn-off of Inhomogenous GTO 5
simulate on-state standalone
extract terminal characteristics:
extract name="V_gate" y.val from curve(vint."anode",vint."gate") where x.val = $Von
calculate initial settings:
.nodeset v(1)=2000 v(2)=$"Von" v(3)=$"V_gate" v(4)=$"V_gate" v(5)=-25 v(6)=-15 v(7)=$"v7"
load the standalone solution
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TCAD Power Device Modeling
Device Simulation: MixedMode
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TCAD Power Device Modeling
Specialized Models
In General Device3D has the same set of physical models
as S-Pisces
Most parameters of the MODELS, CONTACT, MATERIAL
and INTERFACE statements are supported.
Examples of Supported Models:
CVT, FLDMOB
CONSRH, AUGER, Traps
IMPACT SELB, HEI
FERMI, BGN
Models for GaAs MESFETs are supported
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TCAD Power Device Modeling
Structure Creation
ATLAS/ Device3D performs 3D device simulations on a prismatic
mesh
In XY the mesh is triangular. In XZ and YZ it is rectangular.
This limits the arbitrary nature of 3D structures that can
be handled
The most complex geometry should be in the XY plane
(e.g.. field oxide bird’s beak)
The mesh in the Z direction consists of a set of planes repeating the XY mesh.
Regions can start and end in the Z-direction.
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TCAD Power Device Modeling
Structure Creation
Structure and Mesh formation for 3D simulation is very
important. Several Options exist for Device3D
1/ Structure definition using ATLAS syntax
limited to rectangular regions in XY
uses analytic functions for doping
syntax is simple extensions of the 2D syntax
2/ Structure definition using DevEdit3D
can draw materials and regions in DevEdit3D
interactive meshing
3/ ATHENA-DevEdit-Device3D interface
4/ 3D Process Simulation
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TCAD Power Device Modeling
Structure Creation
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3D process simulation.
TCAD Power Device Modeling
ATHENA-DevEdit-Device3D Interface
Step-by-step guide to getting 2D process simulation results
into 3D device simulator
1/ Do process simulation in 2D. This will be XY plane in 3D.
2/ Import structure into DevEdit3D
3/ Edit structure using REGION/MODIFY or REGION/ADD
restrict regions in Z direction
add new regions
4/ Add additional doping profiles using IMPURITY/ADD
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TCAD Power Device Modeling
ATHENA-DevEdit-Device3D Interface
5/ Setup Meshing Rules and create XY Grid
6/ Use Z_PLANE menu to define Z mesh
7/ Save 3D structure and view in Tonyplot3D
8/ Save Command File for future use
9/ Load 3D structure into Device3D using MESH statement
10/ Automate the interface by editing a single
ATHENA-DevEdit-Device3D input file
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TCAD Power Device Modeling
ATHENA-DevEdit-Device3D Interface
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ATHENA Process simulation across a MOS channel width.
TCAD Power Device Modeling
ATHENA-DevEdit-Device3D Interface
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Editing the ATHENA Result in DevEdit3D.
TCAD Power Device Modeling
ATHENA-DevEdit-Device3D Interface
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3D MOSFET prepared for Device Simulation.
TCAD Power Device Modeling
Novel Structures
Some novel structures require the mixing of circular, cylindrical
and rectangular structures. (IEDM 95 p657)
In these devices the XZ plane contains non-rectangular structures
DevEdit3D should be used to define the XZ plane.
Y direction is treated as planes of XZ mesh
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TCAD Power Device Modeling
Novel Structures
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Vertical MOSFET in Device3D.
TCAD Power Device Modeling
Novel Structures
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Insulated Gate Bipolar Transistor
TCAD Power Device Modeling
Insulated Gate Bipolar Transistor
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TCAD Power Device Modeling
Insulated Gate Bipolar Transistor
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TCAD Power Device Modeling
Insulated Gate Bipolar Transistor
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TCAD Power Device Modeling
Insulated Gate Bipolar Transistor
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TCAD Power Device Modeling
Insulated Gate Bipolar Transistor
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TCAD Power Device Modeling
Insulated Gate Bipolar Transistor
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TCAD Power Device Modeling
Insulated Gate Bipolar Transistor
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TCAD Power Device Modeling
Insulated Gate Bipolar Transistor
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Vertical Double-Diffused MOS Transistor
TCAD Power Device Modeling
Vertical Double-Diffused MOS Transistor
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TCAD Power Device Modeling
Vertical Double-Diffused MOS Transistor
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TCAD Power Device Modeling
Vertical Double-Diffused MOS Transistor
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TCAD Power Device Modeling
Vertical Double-Diffused MOS Transistor
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TCAD Power Device Modeling
Vertical Double-Diffused MOS Transistor
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TCAD Power Device Modeling
Vertical Double-Diffused MOS Transistor
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TCAD Power Device Modeling
Vertical Double-Diffused MOS Transistor
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TCAD Power Device Modeling
Vertical Double-Diffused MOS Transistor
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Gate Controlled Thyristor
TCAD Power Device Modeling
Gate Controlled Thyristor
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TCAD Power Device Modeling
Gate Controlled Thyristor
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