1. Sentaurus TCAD Tutorial
With specific focus on Radiation Detector issues
Francisco Rogelio Palomo Pinto
Dept. Ingeniería Electrónica, Escuela Superior de Ingenieros, Universidad de Sevilla, Spain
Pablo Fernández-Martínez
Centro Nacional de Microelectrónica (IMB-CNM- CSIC)
26th RD 50 Workshop
Santander 24th June 2015

2. I- Synopsys Sentaurus TCAD as a Finite Element Simulation Suite
I. Sentaurus TCAD as a FEM Simulation Suite
I- Synopsys Sentaurus TCAD as a Finite Element Simulation Suite

3. Finite Element Simulation (I)
I. Sentaurus TCAD as a FEM Simulation Suite
Finite Element Simulation (I)
Our Problem: Solution of Laplace Equation and Continuity equations in regions
Physics models: Works by modelling electrostatic potential (Poisson’s equation) and carrier continuity (drift-diffusion, dd, mainly)
Poisson
Electron continuity
Hole continuity
where (dd)
See Fichtner, Rose, Bank, “Semiconductor Device Simulation”, IEEE Trans. Electron Devices 30 (9), pp1018, 1983
where (dd)
Different versions of physics models available
Different models of mobility, bandgap…
Generation and recombination rates may include avalanche effects, charge generation by high-energy particles…

4. Finite Element Simulation (II)
I. Sentaurus TCAD as a FEM Simulation Suite
Finite Element Simulation (II)
Equations and solving methods
Poisson and Continuity Equations to solve the Electrostatic potential carrier concentration
Different Current Models for carrier transport (three options)
1. Drift-diffusion (isothermal)
2. Thermodynamics (temperature gradient)
3.Hydrodynamics (other gradients: temperature, concentration, effective mass)
1. Drift Difussion
General Drift-Diffussion +
Einstein relations +
Lattice Temperature
gradient
3. General Hydrodinamics
2. Thermodinamics

5. Finite Element Simulation (III)
I. Sentaurus TCAD as a FEM Simulation Suite
Finite Element Simulation (III)
Finite Element Method for Numerical Simulations (or how to solve Electromagnetic Partial Differential Equations, PDE, in a computer)
1. Discretizing the solution región into a finite number of elements
2. Deriving governing equations for a typical element (Test Functions)
3. Assembling all elements in the solution región (Variationals)
4. Solving the system of equations obtained (Iteration Solver)
Test Function
in terms of finite
element vertex
values
Element Variational
(potential energy)
Total Energy
PDE Solution in discretized region
is the variational minimum 1 2 3 4
From Numerical Techniques in Electromagnetics, M.N.O.Sadiku, 2nd Ed. CRC Press

6. Finite Element Simulation (IV)
I. Sentaurus TCAD as a FEM Simulation Suite
Finite Element Simulation (IV)
Newton-Raphson + Bank-Rose (damping) numerical solver
4. FEM analysis produces a set of nonlinear equations F(x)=0
to be solved by the Newton-Raphson (Bank-Rose) numerical algorithm
x0= Initial Guess, k=0
Repeat {
Compute F(xk),JF(xk)
Solve JF(xk)Dxk+1=-F(xk) for Dxk
xk+1=xk+limited(Dxk+1)
k=k+1
} Until
||Dxk+1||, ||F(xk+1)|| small enough
General N-R (B-R) algorithm
Ex. Newton-Raphson for f(x)=0
Global approximate Newton methods, R.E.Bank, D.J.Rose, Numerische Mathematik, 1981, 37(2), pp

7. Finite Element Simulation (V) generate volumes for FEM meshing
I. Sentaurus TCAD as a FEM Simulation Suite
Finite Element Simulation (V)
Basic tools in a Finite Element simulator
Automatic Mesher Creator tool
(Sentaurus Structure Editor, SSE)
Visualization tool
(SVisual)
Solver tool
Sentaurus Device
SVisual
SSE:
A CAD tool to
generate volumes for FEM meshing

8. II- Working with Structures:
II. Working with Structures: S. Structure Editor
II- Working with Structures:
Sentaurus Structure Editor & Sentaurus Visual

9. Sentaurus Structure Editor:
II. Working with Structures: S. Structure Editor
Sentaurus Structure Editor:
Can be fully managed with the comprehensive user interface options and menus
Or introducing command code from a .scm file
(more flexible and powerful)
Tool used for creating the structures (devices) to be simulated
Defining Device Materials and Geometry
Defining and Placing Doping Regions
Defining and Placing Contacts
Command Script:
> sde

10. Working with a .scm file:
II. Working with Structures: S. Structure Editor
Working with a .scm file:
Diode.scm
Example of a PiN Diode with Gaussian-Shaped N- and P-type electrodes, and constant lowly doped p-type substrate
The .scm file includes the commands to:
Create the structure (boundary)
Define and place the contacts and doping regions
Build a proper discretization mesh for the subsequent FEM simulation

11. Defining Regions and Materials:
II. Working with Structures: S. Structure Editor
Defining Regions and Materials:
; *** Creation of the substrate bulk (SUB) ***
(sdegeo:create-rectangle (position Xmin Ymin 0) (position Xmax Ymax 0) “Silicon” “SUB”)
;*** Creation of the Oxide layers (OX_L & OX_R)
(sdegeo:create-rectangle (position Xmin Ymin 0) (position XElectrodeN_Min YOx_max 0) “Oxide” “OX_L”)
(sdegeo:create-rectangle (position XElectrodeN_Max Ymin 0) (position Xmax YOx_max 0) “Oxide” “OX_L”)
SILICON
OXIDE
Entity Viewer

12. Identifying the edge segment where the contact will be placed
II. Working with Structures: S. Structure Editor
Defining and Placing Contacts:
; *** Contact Declaration***
(sdegeo:define-contact-set “ElectrodeN” 4.0 (color:rgb ) “##”)
(sdegeo:define-contact-set “ElectrodeP” 4.0 (color:rgb ) “##”)
;*** Contact placement (Electrode N)***
(define Xn (+ XElectrodeN_Min (/< DElectrodeN 2)))
(define CN (find-edge-id (position Xn Ymin 0)))
(sdegeo:set-current-contact-set “ElectrodeN”
(sdegeo:set-contact-edges CN)
;*** Contact placement (Electrode P) ***
(define Xp (+ Xmin (/ Xmax 2)))
(define CP (find-edge-id (position Xp Ymax 0)))
(sdegeo:set-current-contact-set “ElectrodeP”
(sdegeo:set-contact-edges CP)
Identifying the edge segment where the contact will be placed
Electrode N
Electrode P

13. Defining and Placing Doping Regions:
II. Working with Structures: S. Structure Editor
Defining and Placing Doping Regions:
Regions with Constant Doping
Single Command for defining and placing
Doping Value
; *** Substrate: Constant Doping***
(sdepe:doping-constant-placement “Sub_Dop_Placement” “BoronActiveConcentration” Dop_Sub “SUB”)
Regions with Gaussian Profile
; *** N-Type Electrode: Gaussian profile***
(sdedr:define-refeval-window "DRW_NPlus" "Line" (position XElectrodeN_Min Ymin 0) (position XElectrodeN_Max Ymin 0))
(sdedr:define-gaussian-profile "DGP_NPlus" "PhosphorusActiveConcentration" "PeakPos" YElectrodeN_Peak "PeakVal" Dop_Nplus "ValueAtDepth" Dop_Sub "Depth" YElectrodeN_Junction "Gauss" "Factor" LatFactor)
(sdedr:define-analytical-profile-placement "APP_NPlus" "DGP_NPlus" "DRW_NPlus" "Positive" "NoReplace" "Eval")
Window
Profile
Placement
Window Nplus
Window Pplus
Before the mesh building, SDE only shows Ref. windows

14. Defining and Placing a discretization mesh:
II. Working with Structures: S. Structure Editor
Defining and Placing a discretization mesh:
; *** N-Type Electrode Refinement***
(sdedr:define-refeval-window "RFW_Nplus" "Rectangle" (position XElectrodeN_Min Ymin 0) (position XElectrodeN_Max YElectrodeN_Junction 0))
(sdedr:define-refinement-size "RFS_Nplus" (/ DElectrodeN 10) (/ tElectrodeN 2) (/ DElectrodeN 2000) (/ tElectrodeN 50))
(sdedr:define-refinement-function "RFS_Nplus" "DopingConcentration" "MaxTransDiff" 0.4)
(sdedr:define-refinement-placement "RFP_Nplus" "RFS_Nplus" "RFW_Nplus")
Window
Size
Placement
A function can be defined to adapt the mesh size to the Doping variation
Ref. General
Ref. NPlus
Ref. PPlus

15. Recent Versions only include Svisual as the viewer tool
II. Working with Structures: S. Structure Editor
Building the discretization mesh:
Recent Versions only include Svisual as the viewer tool

16. Imput File for the FEM Simulations
II. Working with Structures: S. Structure Editor
Building the discretization mesh: SDE viewer
Several files are created while building the mesh
Diode_msh.cmd
Diode_msh.log
Diode_bnd.tdr
Diode_msh.tdr
Imput File for the FEM Simulations

17. II. Working with Structures: SVisual
Sentaurus Visual:
Preferred tool for visualizing structures and representing fields and curves

18. In Recent Versions Build mesh Command links directly to svisual
II. Working with Structures: SVisual
Inspecting the created structure: Visualizing mesh
In Recent Versions Build mesh Command links directly to svisual

19. Inspecting the created structure: Visualizing Fields (Doping)
II. Working with Structures: SVisual
Inspecting the created structure: Visualizing Fields (Doping)
Phosphorus Active Concentration
Boron Active Concentration

20. III- Finite Element Method Simulations:
III. FEM Simulations: SDevice
III- Finite Element Method Simulations:
Sentaurus Device

21. Sentaurus Device: Device Mode Mixed Mode Tool used for FEM Simulations
II. FEM Simulations: SDevice
Sentaurus Device:
Sdevice has not a graphical interface. Instructions are introduced from a command file (.cmd)
Tool used for FEM Simulations
Device Mode
Mixed Mode
Devices in the Circuit
Files to Solve the Model
File with Spice elements
Physics Models
Elements in the Circuit and their connections
Types of Analysis: Quasistationary, Transient, ACCoupled

22. Device Mode Simple Simulation: I-V curve on a Diode
III. FEM Simulations: SDevice
Device Mode Simple Simulation: I-V curve on a Diode
Diode_IV.cmd
File {
Grid = “Diode_msh.tdr”
Current = “Diode_IV.plt”
Plot = “Diode_IV.tdr”
Output = “Diode_IV.log” }
Electrode {
{Name=“ElectrodeN” Voltage = 0.0} }
Physics {
AreaFactor = 1
Temperature = 300
Mobility (
DopingDependence
eHighFieldSaturation
hHighFieldSaturation
Enormal
CarrierCarrierScattering )
Recombination (
SRH (DopingDependence)
Auger (withGeneration)
Avalanche (UniBo Eparallel)
Band2Band (Hurkx)
EffectiveIntrinsicDensity (OldSlotboom) }
Math {
#Cylindrical
Method=Pardiso
Number_of_threads = 4
Stacksize=
Extrapolate
Derivatives
AvalDerivatives
RelErrControl
Iterations=15
Notdamped=60
BreakCriteria {
Current (Contact = "ElectrodeN" maxval = 1e-8) }

23. Device Mode Simple Simulation: I-V curve on a Diode (Quasistationary)
III. FEM Simulations: SDevice
Device Mode Simple Simulation: I-V curve on a Diode (Quasistationary)
Diode_IV.cmd
Plot {
eDensity hDensity
eCurrent/Vector hCurrent/Vector
Current/Vector
Potential
ElectricField/Vector
SpaceCharge
eMobility hMobility
eVelocity hVelocity
DopingConcentration
DonorConcentration AcceptorConcentration
srhRecombination AugerRecombination
AvalancheGeneration
eAvalanche hAvalanche
TotalRecombination }
Solve {
Coupled (Iterations=50) {Poisson}
Coupled (Iterations=15) {Hole Poisson}
Coupled (Iterations=15) {Electron Hole Poisson}
QuasiStationary (
InitialStep = 1e-6
MaxStep = 0.01
MinStep = 1e-9
Goal {Name="ElectrodeN" Voltage=1000}
Plot {Range = (0 1) Intervals=2} ) {
Coupled {Hole Electron Poisson}
Plot (
FilePrefix="IV_"
Time=(0.01; 0.05; 0.1; 0.5)
NoOverwrite }

24. Device Mode Simple Simulation: I-V curve on a Diode
III. FEM Simulations: SDevice
Device Mode Simple Simulation: I-V curve on a Diode
Diode_IV.plt

25. Device Mode Simple Simulation: I-V curve on a Diode
III. FEM Simulations: SDevice
Device Mode Simple Simulation: I-V curve on a Diode
.tdr Files

26. Device Mode Simple Simulation: I-V curve on a Diode
III. FEM Simulations: SDevice
Device Mode Simple Simulation: I-V curve on a Diode

27. Device Mode Simple Simulation: I-V curve on a Diode
III. FEM Simulations: SDevice
Device Mode Simple Simulation: I-V curve on a Diode

28. Mixed Mode Simple Simulation: C-V curve on a Diode (AC Coupled)
III. FEM Simulations: SDevice
Mixed Mode Simple Simulation: C-V curve on a Diode (AC Coupled)
Diode_CV.cmd
device Diode {
Electrode {
.…. }
File {
Grid = "Diode_msh.tdr"
Current = "Diode_CV_1kHz.plt"
Plot = "Diode_CV_1kHz.tdr"
Physics {
.....
Plot {
} #End device Diode
System {
Diode diodesystem ("ElectrodeN"=front "ElectrodeP"=0)
Vsource_pset vn (front 0) {dc=0} }
File {
Output ="Diode_CV_1kHz.log"
ACExtract = "Diode_CV_AC_1kHz.plt"

29. Mixed Mode Simple Simulation: C-V curve on a Diode (AC Coupled)
III. FEM Simulations: SDevice
Mixed Mode Simple Simulation: C-V curve on a Diode (AC Coupled)
Diode_CV.cmd
Solve {
Coupled (Iterations=50) {Poisson}
Coupled (Iterations=15) {Hole Poisson}
Coupled (Iterations=15) {Electron Hole Poisson}
Coupled (Iterations=15) {Electron Hole Poisson Contact}
QuasiStationary (
InitialStep = 1e-6
MaxStep = 1e-2
MinStep = 1e-7
Increment = 2
Decrement = 4
Goal {Parameter = vn.dc Voltage=100} ) {
ACCoupled (
StartFrequency=1e3
EndFrequency=1e3
NumberOfPoints =1 Decade
Iterations=15
Node (front)
ACMethod=Blocked
ACSubMethod("diodesystem")=ParDiSo
){ Poisson Electron Hole Contact Circuit} }

30. Mixed Mode Simple Simulation: C-V curve on a Diode (AC Coupled)
III. FEM Simulations: SDevice
Mixed Mode Simple Simulation: C-V curve on a Diode (AC Coupled)

31. Transient Simulation: Heavy Ion Impact
III. FEM Simulations: SDevice
Transient Simulation: Heavy Ion Impact
Diode_HI.cmd
Physics {
…...
HeavyIon (
Direction = (0,1)
Location = (200, 0)
Time = 1e-9
Length = [ ]
Wt_hi = [ ]
LET_f =[0 8.7e-6 8.7e-6 0]
Gaussian
PicoCoulomb ) }
Solve {
…….
NewCurrentPrefix = "trans_"
Transient (
InitialTime = 0
FinalTime = 35e-9
MinStep = 1e-17
MaxStep = 1e-10
){Coupled { Poisson Electron Hole Circuit }
Plot (FilePrefix="TransHI_" Time=(0.5e-9; 1e-9; 2e-9; 5e-9; 10e-9) NoOverwrite) }

32. Transient Simulation: Heavy Ion Impact
III. FEM Simulations: SDevice
Transient Simulation: Heavy Ion Impact

33. Transient Simulation: Heavy Ion Impact
III. FEM Simulations: SDevice
Transient Simulation: Heavy Ion Impact
HeavyIonGeneration

34. HeavyIonChargeDensity
III. FEM Simulations: SDevice
Transient Simulation: Heavy Ion Impact
HeavyIonChargeDensity

35. Transient Simulation: Heavy Ion Impact
III. FEM Simulations: SDevice
Transient Simulation: Heavy Ion Impact
hDensity

36. Transient Simulation: Laser Illumination
III. FEM Simulations: SDevice
Transient Simulation: Laser Illumination
Diode_Opt.cmd
Optics (
OpticalGeneration (
ComputeFromMonochromaticSource ()
TimeDependence (
WaveTime = (1e-9 1e-9)
WaveTSigma = 50e-12 )
Scaling = 0
Excitation (
Wavelength = 0.8 *um
Intensity = 0.06 *W/cm2
Window("L1") (
Origin = (200,0)
XDirection = (1,0,0)
Line (Dx = 10)
Theta = 0 * Angle from positive y-axis
OpticalSolver (
OptBeam (
LayerStackExtraction (
WindowName ="L1"
WindowPosition = Center
Mode = ElementWise
ComplexRefractiveIndex (WavelengthDep (real imag))
Solve {
…….
NewCurrentPrefix = "trans_"
Transient (
InitialTime = 0
FinalTime = 60e-9
MinStep = 1e-17
MaxStep = 1e-10
){Coupled { Poisson Electron Hole Circuit } }

37. Transient Simulation: Laser Illumination
III. FEM Simulations: SDevice
Transient Simulation: Laser Illumination

38. Transient Simulation: Laser Illumination
III. FEM Simulations: SDevice
Transient Simulation: Laser Illumination
Optical Generation 800 nm

39. Transient Simulation: Laser Illumination
III. FEM Simulations: SDevice
Transient Simulation: Laser Illumination
Optical Generation 1064 nm

40. Transient Simulation: Laser Illumination
III. FEM Simulations: SDevice
Transient Simulation: Laser Illumination
hDensity 800 nm

41. Transient Simulation: Laser Illumination
III. FEM Simulations: SDevice
Transient Simulation: Laser Illumination
hDensity 1064 nm

42. Mixed Simulation with a more complicated circuit
III. FEM Simulations: SDevice
Mixed Simulation with a more complicated circuit
System { Set(ground=0)
Vsource_pset V_bias (cathode ground) {dc=0}
Diode diodesystem ("ElectrodeN"=cathode "ElectrodeP"=anode)
Inductor_pset L_leak(anode ground){inductance=1e6}
#CSF input capacitance
Capacitor_pset C_in (anode ground){capacitance=1e-12}
#CSF passive feedback network:
Capacitor_pset C_csf (anode out) {capacitance=8e-15}
Resistor_pset R_csf (anode out) {resistance=100e6}
#CSA amp internal out resistence
Resistor_pset R_sh(out ground){resistance=1}
#CSA external capacitance
Capacitor_pset C_out (out ground){capacitance=1e-12}
Plot "CircuitCSF" (time() v(anode ground) v(out ground) v(anode out) i(L_leak anode) i(C_in anode)
i(R_sh out) i(C_out out))}
# Detector connected to a CSF (charge sensitive filter)
#Vbias between ground and cathode
#Detector between cathode and anode
#C_in between anode and ground
#CSF Passive network
#L_leak between anode and ground
#C_csf and R_csf between anode and outamp
#R_outamp between outamp and ground

43. Mixed Simulation with a more complicated circuit
III. FEM Simulations: SDevice
Mixed Simulation with a more complicated circuit

44. Simulation of the Radiation Effects
III. FEM Simulations: SDevice
Simulation of the Radiation Effects
Diode_Rad_IV.cmd
Diode_Rad_CV.cmd
Physics (material="Silicon") {
Traps (
(Acceptor Level EnergyMid=0.42 fromCondBand Conc=2.3226E15 Randomize=0.29 eXsection=9.5E-15 hXsection=9.5E-14)
#Conc=Fluence*1.1613
(Acceptor Level EnergyMid=0.46 fromCondBand Conc=1.8E15 Randomize=0.23 eXsection=5E-15 hXsection=5E-14 )
#Conc=Fluence*0.9
(Donor Level EnergyMid=0.36 fromValBand Conc=1.8E15 Randomize=0.31 eXsection=3.23E-13 hXsection=3.23E-14 ) ) }
Physics (MaterialInterface="Oxide/Silicon") {
# Traps (FixedCharge Conc=5e10 )
Charge(Conc=1.5e11)

45. Simulation of the Radiation Effects : I-V Simulation
III. FEM Simulations: SDevice
Simulation of the Radiation Effects : I-V Simulation

46. Simulation of the Radiation Effects : C-V Simulation
III. FEM Simulations: SDevice
Simulation of the Radiation Effects : C-V Simulation

47. Sentaurus Workbench & Sentaurus Process
IV. Additional Tools: SWorkbench & SProcess
IV- Additional Tools:
Sentaurus Workbench & Sentaurus Process

48. Sentaurus Workbench (SWB)
IV. Additional Tools: Sentaurus Workbench
Sentaurus Workbench (SWB)
A window-like interface to manage the different tools and the simulation flow
It creates simulation trees with variation of parameter in a matrix organization
Every instance in SWB is called “project”. When a project is saved, a directory is created, containing ASCII files with the details of the saved project.

49. Sentaurus Workbench (SWB)
IV. Additional Tools: Sentaurus Workbench
Sentaurus Workbench (SWB)
Essential vocabulary:
Tool: one of the Sentaurus TCAD tools (e.g. sde, sdevice, svisual, etc…)
Parameter: a variable (it can be a dimension, a physical property, a logic flag, etc…)
Experiment: a row in the simulation matrix (with a certain value for each parameter)
Node: a point in the simulation matrix. They can be real (if they can be executed) or virtual (if they cannot be executed)

50. Sentaurus Workbench (SWB)
IV. Additional Tools: Sentaurus Workbench
Sentaurus Workbench (SWB)
Command file used to execute the simulations without SWB, can be used as the input file when a new tool is added to the SWB project
Parameters should be indicated in the file always between
SDE input File
Sdevice input File
.....
(define Thickness
…….
(sde:build-mesh “snmesh” “ “
File {
Grid =
Current =
Plot =
Output = }
…..
Solve { ……
ACCoupled ( )
…….
Build-mesh command should be included at the end of the script
A number of complete examples are included in SWB

51. IV. Additional Tools: SProcess
Sentaurus Process
Tool for emulating the technological steps of a fabrication process
It allows emulating:
Deposition of layers of different materials
Localized etching of material with a mask
Ion implantation
Diffusion of the implanted species (thermal steps)
Oxide and epitaxial growth
Etc… (almost any process you can perform in a real clean room)
A specific mesh is created to solve the process emulation equations
It is a powerful tool, that can faithfully reproduce the fabrication processes of a given clean room.
Usually, this mesh is not suitable for device simulation

52. Complete Process Emulation Re-meshing and adjustment
IV. Additional Tools: SProcess
Sentaurus Process: Point of view from a foundry
General Simulation flow
Complete Process Emulation
Re-meshing and adjustment
FEM Simulation
Regular use of Sprocess in a foundry (at least at IMB-CNM)
1st Mode: From device performance to fabrication process
Combined SDE and Sdevice Simulations are performance to obtain a given characteristic
Sprocess simulation is performed to determine the technological steps that can give us the desired characteristic
2nd Mode: From fabrication process to device performance
A given technological step is simulated with sprocess
The performance of the whole device is analyzed with the aid of a SDE+Sdevice simulation

53. Thanks for your attention
IV. Additional Tools: SProcess
Thanks for your attention