ranjeet center for detector & related software technology (cdrst)

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 )

8

TCAD Simulation vs. MeasurementActive thickness: 300 mm

9

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


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

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

https://twiki.cern.ch/twiki/bin/viewauth/CMS/SiSensorSimulation

https://twiki.cern.ch/twiki/bin/viewauth/CMS/SiSensorSimulation

25

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


QF = 1x1011cm-2




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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

ranjeet center for detector & related software technology (cdrst)

Documents

cint pf cint

smallest cint

parametrization of cint

cint ntype qfcm

active area cint

cint ntype ytype2

ntype sensors

simulation parameters