ranjeet center for detector & related software technology (cdrst)
DESCRIPTION
TCAD Simulation of Geometry Variation under HPK campaign. Ranjeet Center for Detector & Related Software Technology (CDRST) Department of Physics and Astrophysics, University of Delhi (DU), Delhi, INDIA On behalf of Si Sensor Simulation Group. Overview. MSSD - PowerPoint PPT PresentationTRANSCRIPT
Ranjeet Center for Detector & Related Software Technology (CDRST)
Department of Physics and Astrophysics,University of Delhi (DU), Delhi, INDIA
On behalf of Si Sensor Simulation Group
TCAD Simulation of Geometry Variation under HPK campaign
2
Overview
MSSD Simulations for different Geometries of MSSD’s Comparison with Measurements
Simulations for Diodes Summary and Future Outlook
MSSD
3
Multi-geometry Silicon Strip Detectors (MSSD) 12 configurations, 32 strips Different strip-width and pitch
Four different pitch values Three classes of w/p: 0.121 – 0.142 ; 0.221 – 0.242 ; 0.321-0.342
Different thicknesses of the sensors (120 / 200 / 290 mm) N-type and P-type substrates
Interstrip capacitance (Cint) contributes to noise significantly –Measurement vs. Simulation
Effect of isolation on Cint => See Martin’s talk
Effect of Radiation damage on Cint =>See Robert’s talk
All device parameters are not known from manufacturer Tune these parameters in simulations Sensitivity of sensor characteristics to various physical and geometrical parameters12 Configurations
4
Interstrip Capacitance (Cint)
Total Interstrip Capacitance:Cint = CAC + CDC + 2 * CACDC
In the range 0.18 < w/p < 0.36, 50 < p < 200 mm & thickness = 300 mm a good approximation is given by:
C int ≈ [ 0.1 + 1.6*(w+20 mm)/p ] pF/cm
where w and p are in mm
Ref: S. Braibant et. al, NIMA 485 (2002), 343-361
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Cint : General Trends
Effect of QF on Cint (n-type)
QF(cm-2)
C int (
pF)
Cint increases with surface charge density (QF) for values of QF > 1x1011 cm-2
Cint increases with increase in w/p For given w/p , Cint is higher for smaller pitch
QF(cm-2)
SYNOPSYS
7• For Y-type : Smallest Cint at all biases for thickness of 300 mm
Effect of Active Area on Cint (n-type & Y-type)2-strip structure;Non-irradiated
• Np = 1e16 cm-3 • dp = 0.5 μm
Cint vs. Bias Voltage for N-type for all 12 regions
For n-type : • Cint increases with increase in active area• Cint increases with increase in w/p Cint vs. Bias Voltage for Y-type all 12 regions
SYNOPSYSActive (total) thickness: 120 mm (320 mm) Active (total) thickness: 200 mm (320 mm ) Active (total) thickness: 300 mm (320 mm )
Active (total) thickness: 120 mm (320 mm) Active (total) thickness: 200 mm (320 mm ) Active (total) thickness: 300 mm (320 mm )
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TCAD Simulation vs. MeasurementActive thickness: 300 mm
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Simulated Structure (zoomed)
5-STRIP Simulation 5-strip Structure Simulations
We have considered five strips in which Cint is evaluated by sending AC signal to central electrode and measuring it w.r.t. two adjacent strips (which are shorted).
SILVACO
Simulation of Cint for FZ320N Performed Sensitivity Studies
Substrate Doping Concentration, NB (range: 1.0x1012 cm-3 - 4.0x1012 cm-3 ) Metal Overhang Width(WMO) Oxide Thickness (tox) Junction Depth (XJ) Coupling Oxide Thickness Surface charge density , QF (range: 1x1010 cm-2 - 1x1012cm-2 )
Compared simulated results for various set of (NB , QF) for one structure, keeping other parameters fixed with the experimental results. Once we found the optimized parameter set , we kept the same values of NB and QF for all other designs.
2.5x1011 cm-2
1.5x1011 cm-2 1.0x1011 cm-2
2.5x1012 cm-3
3.5x1012 cm-3
3.0x1012 cm-3
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SILVACO
1.Substrate Doping Conc. (NB) = 3.0x1012 cm-3
2. Surface Charge Density (QF) = 1.0x1011 cm-2
3. Temp = 21 deg C corresponding to 294 K
4) n+ implant of 30 micron from the back side
5) Junction depth of 1.5 micron
6) Strip length for normalization = 3.0490 cm
7) Total device depth is 320 micron.
8.) Frequency = 1MHz
Simulation Parameters – Same for all 12 configurations
Only Width and Pitch are changed in 12 configurations (according to MSSD design) keeping all other parameters same.
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SILVACO
FZ320N (regions #5 to #8)
Meas.#3Meas.#2
SIMULATION
Meas.#1
12
SILVACO
MSSD Structure No-5
One of the Expt. result
Excellent agreement with One and within 10% of other two
Excellent agreement with One and within 10% of other two
Excellent agreementExcellent agreement
MSSD Structure No-8MSSD Structure No-7
MSSD Structure No-6
Reverse Bias (V)
Reverse Bias (V)
Reverse Bias (V)
Reverse Bias (V)
C int (
pF)
C int (
pF)
C int (
pF)
C int (
pF)
MSSD Structure No-5
• FZ320N (regions #5 to #8)
Red Color – SimulationOthers - Measurements
MSSD Structure No-5
C int (
pF)
Reverse Bias (V)
C int (
pF)
Reverse Bias (V)
MSSD Structure No-6
MSSD Structure No-7
C int (
pF)
Reverse Bias (V)
MSSD Structure No-8
C int (
pF)
Reverse Bias (V)
SYNOPSYS
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Cross - Validation
Simulation results consistent between SILVACO and SYNOPSYS
SYNOPSYS
SILVACOMSSD Structure No-3
Cint vs. Bias Voltage Only Width and Pitch are changed in 12 configurations (according to MSSD design) keeping all other parameters same Mostly excellent agreement for all 12 configurations
Meas.#3Meas.#2
SIMULATION
Meas.#1
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Results – Cint for FZ320N All regions SILVACO
FZ200N (regions #5 to #8)
MSSD Structure No-5
C int (
pF)
Reverse Bias (V)
C int (
pF)
Reverse Bias (V)
MSSD Structure No-6
MSSD Structure No-7
C int (
pF)
Reverse Bias (V)
MSSD Structure No-8
C int (
pF)
Reverse Bias (V)
Red Color – SimulationOthers - Measurements
SYNOPSYS
FZ120N (regions #5 to #8)
MSSD Structure No-5
C int (
pF)
Reverse Bias (V)
C int (
pF)
Reverse Bias (V)
MSSD Structure No-6
MSSD Structure No-7
C int (
pF)
Reverse Bias (V)
MSSD Structure No-8
C int (
pF)
Reverse Bias (V)
Red Color – SimulationOthers - Measurements
SYNOPSYS
w (mm
)p
(mm)
Simulated Cint (pF)
FZ120N
Simulated Cint (pF)
FZ200N
Simulated Cint (pF)
FZ320N
C int ≈ [ 0.1 + 1.6*(w+20 mm)/p ] (pF), for d=300µm
16 120 1.2 1.3 1.6 1.8
34 240 0.5 0.6 1.1 1.4
10 80 1.7 1.7 1.8 2.1
8.5 70 1.8 1.8 1.9 2.3
28 120 1.6 1.7 2.1 2.3
58 240 0.7 1.1 1.4 1.9
18 80 2.1 2.1 2.3 2.6
15.5 70 2.3 2.3 2.4 2.8
40 120 1.9 2.2 2.5 2.7
82 240 0.9 1.4 1.8 2.4
26 80 2.6 2.7 2.8 3.1
22.5 70 2.8 2.8 3.0 3.3
Cint simulated matches well with the parameterization within 20% Slight variation in Cint for approx. same w/p Three classes of w/p: 0.121 – 0.142 ; Cint: 1.1 – 1.9 w/p: 0.221 – 0.242 ; Cint: 1.4 – 2.4 w/p: 0.321 - 0.342 ; Cint: 1.8 – 3.0Increase in width for given pitch increases Cint
Cint of Non-Irradiated MSSD
SILVACO
SYNOPSYS
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Diode SimulationsFor Large and Small Diodes (non-
irradiated)
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Simulation structureFor Small Diode
Periphery
Total implant area 2mm x 2mm
Guard Diode center
Zoomed view
1mmTotal implant area 2mm x 2mm
22.5µm 12.5µm
17µm 28µm
32.5µm
660µm
50µm
Implant Guard Periphery
SchematicsDiode center
SILVACO
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IV & CV comparison at 293K
Measurements were reproduced by simulation No temperature effect on Capacitance in simulations as well as in measurement
Full depletion voltage ~ 200V Parameterization of Nb = 3x1012cm-3
From MSSD simulations – seems good
Simu. With Guard grounded
Simu. With Guard floatingThree Exp results
(pF-2
)
Red color: Experimental resultBlue: Sim. with guard groundedGreen : Sim. with guard floating
SILVACO
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For Large Diode
Periphery
mmTotal implant area mm x mm
Guard
Zoomed view
Zoomed view
Total implant area 4.893 mm x 4.893mm
Diode centerGuard
Periphery
Diode center
2.4465mmTotal implant area 4893mm x 4893mm
22.5µm 12.5µm
17µm90µm 660µm
Implant Guard Periphery
Schematics
SILVACO
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CV comparison for large diode
Same parameters are used in Large Diode simulations (Nb, Tau0, QF etc) Full depletion ~ 200V for measurements and simulations
Slightly lower Capacitance for simulations
(pF-2
)
SILVACO
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Summary & Outlook• Converged to same set of simulation parameters• Cross-calibrated SILVACO & SYNOPSYS • Simulations are performed for all MSSD configurations for different
thicknesses• Interstrip Capacitance simulations match well with measurements
for MSSD as well as for diodes• Simulations also match within 20% with parameterization• Difficult to manage experimental data : spread of values is very
large ( both in low & high voltage). We agree with a "preferred" subset of measurement.
• Maintaining TWikihttps://twiki.cern.ch/twiki/bin/viewauth/CMS/SiSensorSimulation
Outlook• Cint is measured experimentally up to 400 V : we cannot check breakdown
performance at High voltage. – Simulations on breakdown voltage and CCE for MSSD ongoing
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Backup
Results – Cint vs Bias for FZ320N Simulation at DESY (SYNOPSYS) Red Color – Simulation, Others - Measurements
QF = 1x1011cm-2
Region -5 Region-6 Region-7 Region-8
Region -1 Region -4Region -3Region -2
Region -12Region -11Region -9 Region -10
Results – Cint vs Bias for FZ200N Simulation at DESY (SYNOPSYS) Red Color – Simulation, Others - Measurements
QF = 1x1011cm-2
Region -5 Region-6 Region-7 Region-8
Region -1 Region -4Region -3Region -2
Region -12Region -11Region -9 Region -10
Results – Cint vs Bias for FZ120N Simulation at DESY (SYNOPSYS) Red Color – Simulation, Others - Measurements
QF = 1x1011cm-2
Region -5 Region-6 Region-7 Region-8
Region -1 Region -4Region -3Region -2
Region -12Region -11Region -9 Region -10
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Participating Groups
DESY Thomas Eichhorn Tool: Synopsys
Helsinki Institute of Physics Timo Peltola Tool: Synopsys
Karlsruhe Institute of Technology Alexander Dierlamm, Robert Eber, Andreas Nürnberg, Martin Strelzyk Tool: Silvaco, Synopsys
University of Pisa
University of Delhi Ashutosh Bhardwaj, Kirti Ranjan, Ranjeet, R K Shivpuri Tool: Silvaco
Sensor Upgrade Meeting 1.11.2012
CompArison with Claudio’s paper
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Comparison with Review article: “Device Simulations of Isolation Techniques for Silicon Microstrip Detectors Made on p-Type Substrates” by Claudio Piemonte, IEEE TRANS. NUCL. SCI., VOL. 53, NO. 3, JUNE 2006.
General Trends were same (although we don’t have exact simulation parameters as used by Claudio). Validation with some other papers are also carried out.
PaperSilvaco TCAD Sim.
Silvaco TCAD Sim. Paper
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large variations in Leakage currents for different Large diodes !
293K
Apparently, there seems to be large variation in Tau0s for different samples!
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IV Measurements at 253K
Large fluctuation as well as variation in currents at 253K between different Diodes Measurements are not reproducible due to large fluctuation for same diode
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IV comparison at 253K
Large fluctuation in currents even for the same diodes TauN0=TauP0 = 1.6x10-2 sec. was used to match the current