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ADVANCES IN SEMICONDUCTOR DETECTORS FOR PARTICLE TRACKING IN EXTREME RADIATION ENVIRONMENTS. Cinzia Da Via’, Brunel University, UK PowerPoint PPT Presentation


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ADVANCES IN SEMICONDUCTOR DETECTORS FOR PARTICLE TRACKING IN EXTREME RADIATION ENVIRONMENTS. Cinzia Da Via’, Brunel University, UK. OUTLINE 1-INTRODUCTION 2-PRESENT STATUS OF RADIATION HARD SILICON DETECTORS UP TO 10 15 n eq /cm 2 3-STRATEGIES FOR SURVIVAL BEYOND 10 15 n eq /cm 2 :

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ADVANCES IN SEMICONDUCTOR DETECTORS FOR PARTICLE TRACKING IN EXTREME RADIATION ENVIRONMENTS. Cinzia Da Via’, Brunel University, UK

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ADVANCES IN SEMICONDUCTOR DETECTORS FOR PARTICLE TRACKING IN EXTREME RADIATION ENVIRONMENTS. Cinzia Da Via’, Brunel University, UK

OUTLINE

1-INTRODUCTION

2-PRESENT STATUS OF RADIATION HARD

SILICON DETECTORS UP TO 1015 neq/cm2

3-STRATEGIES FOR SURVIVAL BEYOND 1015 neq/cm2:

aDEVICE GEOMETRY : short collection distance -3D,thin

bTEMPERATURE and FORWARD BIAS OPERATION

cDEFECT ENGINEERING :O and O2

4-CONCLUSIONS


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27 Km

LARGE HADRON COLLIDER

CERN - GENEVA

INTRODUCTION

new physics expected!!

BUT NEED HIGH STATISTICS

s

14TeV

~6000 tracks per bunch crossing!!


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b

PHYSICS REQUIREMENTS

p

p

b

Most probable

Higgs channel

H

Was it there already??

PRECISE

MEASUREMENTS OF

  • MOMENTUM RESOLUTION

  • TRACK RECONSTRUCTION

  • b-TAGGING EFFICIENCY

HIGHER STATISTICS NEEDED FOR

Aleph

  • ACCURACY OF STANDARD MODEL PARAMETERS

  • ACCURACY OF NEW PHYSICS PARAMETERS

  • SUPERSYMMETRIC PARTICLES

  • EXTRA DIMENSIONS

  • RARE PROCESSES (TOP DECAYS, HIGGS PAIRS ETC)

GOOD

TRACKER

ESSENTIAL!

~10 SMALLER PITCH SILICON

DETECTORS CAN DO IT!!!


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total

n

p

other

charged

hadrons

RADIATION ENVIRONMENT AT LHC AND

SLHC

B-LAYER ~4cm

1.6x1016

ATLAS

>85%

Ch hadrons

210 m2 of microstrips

silicon detectors

Multiple particle environment:

NIEL scaling 1 MeV n equivalent

Violation observed for oxygen

rich materials

~5x1014

~5x1015

Data from CERN-TH/2002-078


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-

-

-

-

-

-

+

+

+

+

+

+

SILICON DETECTORS "NORMALLY "

USED IN PARTICLE PHYSICS

  • Substrate normally:

  • n-type

  • 4 k-cm FZ

  • Doping of ~1012 cm-3

  • [O] ~1015 cm-3

  • [C] ~1015 cm-3

  • 300mm thick

  • Orientation <111>

300 mm

+V

oxide

W

Incident

particle

p-type

junctions

metallised

strips

n-type substrate


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RADIATION INDUCED BULK DAMAGE in Si

Primary Knock on Atom

Displacement threshold in Si:

Frenkel pair E~25eV

Clusters E~5keV

Vacancy

Interstitial

Van Lint 1980


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Ec

Ei

V6

VO- Ec - 0.17eV

Ev

V2(=/-)+Vn Ec-0.22eV

V2(-/0)+Vn Ec-0.40eV

V2O

CIOI(0/+)EV+0.36eV

RADIATION INDUCED STABLE DEFECTS IN SILICON

From Cern ROSE RD48

Neutron irradiated

DEFECT KINETICS ( 300K ):

IMPURITIES

V,I +

DOPANTS

  • CHARGED DEFECTS==>NEFF, VBIAS

  • DEEP TRAPS, RECOMBINATION CENTERS ==>CHARGE LOSS

  • GENERATION CENTERS==>LEAKAGE CURRENT

DLTS

spectrum

  • VO effective e and h trap

  • V2 and V2O deep acceptors

  • contribute to Neff


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PRESENT RESEARCH FOCUSES AT FLUENCES

UP TO 1x1015 n/cm2

STANDARD 300mm n-type SILICON at 1015 n/cm2

10 years of operation at L=1034 cm-2s-1 at R=4 cm

EFFECTIVE DRIFT LENGTH

Due to charge trapping~150mm e- ~50mm h

SPACE CHARGE-ve Neff (1013/cm3) ~ VFD (5000V)~F

TYPE INVERSIONdepletion from n-contact (e-field)

REVERSE ANNEALINGINCREASE OF -ve Neff temp. dep

LEACKAGE CURRENTprop to F (I/V ~5x10-17F)

  • Signal formation

  • Charge sharing

  • Speed

  • Double junction

  • Charge diffusion

  • Noise

  • Thermal

    runaway

Time [y]

  • Maintenance


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MAIN DETECTOR STRATEGIES PROPOSED FOR LIFE ABOVE 1015 n/cm2

OPTIMIZATION OF:

STRATEGIES:

  • COLLECTION DISTANCE

  • CCE (trapping)

  • SPEED

  • SPACE CHARGE

  • REVERSE ANNEALLING

  • CCE (undepletion)

  • CHARGE SHARING

  • LEAKAGE CURRENT

  • DEVICE GEOMETRY

  • 3D, THIN

  • DEFECT ENGINEERING

  • O, P-TYPE SUBSTRATE

  • MODE OF OPERATION

  • Temperature, Forward bias

MORE TO GAIN BY COMBINING TECHNIQUES!


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EFFECTIVE DRIFT LENGTH

Leff = tt x Vdrift

( mt )

V

Measured

values

Leff at 1016 proton/cm2

~ 20 mm electrons

~ 10 mm holes

Simulation by S. Watts/Brunel

Accepted for publication on NIM

Data avalable for neutron andprotons for effective trapping time 220K-300K from Kramberger et al


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e-

h+

SIGNAL FORMATION AFTER IRRADIATION

W. Shockley, Jour. Appl.Phys. 9,635 (1938)

S. Ramo, Proc. of I.R.E. 27, 584 (1939)

Gatti and coworkers

RAMO's THEOREM

Signal ~ q(Vxw-V0w) e-th/th + (Vcw-Vxw) e-te/te)

Depends on carriers drift length

0.16 A/x

collecting

Trapping

Shaping time

x

Planar device

c

0

  • Small contact area

  • Thin substrate

  • High e-field

HOLES DON' T CONTRIBUTE

Waiting potential is steeper if contact

small compared with detector thickness

moreover minimize charge sharing

with neighbours due to charge trapping

Simulation by S. Watts

Accepted for publication

On NIMA


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p

n

p

n

  • SHORT COLLECTION DISTANCE:

  • 3D DETECTOR

S. Parker, C. Kenney

1995

  • SHORT COLLECTION PATHS 50 mm (300mm)

  • LOW DEPLETION VOLTAGES <10V (60V)

  • RAPID CHARGE COLLECTION 1-2n(25 ns)

  • EDGELESS CAPABILITY active edges

  • LARGE AREA COVERAGE active edges

  • SUBSTRATE THICKNESS INDEPENDENT :

    • BIG SIGNALS

    • X-RAY DETECTION EFFICIENCY

      for low Z materials

p+

n+

n+

Same

Generated

Charge!!!

-

-

+

300 mm

+

depletion

50 mm

p+

C=0.2pF

depletion

IEEE vol46 N4 Aug. 99


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ETCHING TECHNIQUES

DEEP REACTIVE ION ETCHING

ELECTROCHEMICAL

ETCHING

LASER ABLATION

ELECTRODE

FILLED WITH

POLYSILICON

Fast, high aspect ratio

fs pulses is cleaner, any substrate

NIMA 487 (2002) 19

ASPECT RATIO = 11:1, 19:1 20:1<


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3D DETECTOR RESULTS before

irradiation

DETECTOR THICKNESS 121mm

282e noise PREAMP - SHAPING TIME 1 ms

200 mm PITCH mSTRIP TYPE DETECTOR

GAUSSIAN

RESPONSE

SPEED

1.5ns rise

AT 130K

3.5ns rise

AT 300K

350 e rms , fast electronic designed at CERN-

microelectronics group

200mm pitch detector TO BE PUBLISHED


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3D RADIATION RESULTS AT 300K

After irradiation

NON OXYGENATED

1x1015 p/cm2 (5x1014n/cm2)

100mm pitch detector

FULL DEPLETION BIAS =

105 V AFTER 2x1015 n/cm2

SPEED 3.5 ns rise time

40V bias, 300K

IEEE Trans on Nucl Sci 48 (2001) 1629

joined work Brunel, Cern, Hawaii

To be published


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Vbias

Vsig

Vbias

Vbias

Vsig

Vbias

n

p

100 m

n

n

p

n

200m

100

m

3D CHARGE COLLECTION EFFICINECY

After irradiation

More on 3D later this morning (P. Roy, 11:30)

= 40V

=40V

CCE =61%

USING THE INTEGRATED 22-25 KeV X-RAY PULSES FROM A 109Cd SOURCE

COLLECTION FROM p-ELECTRODE

134 m

1 x 1015 p/cm2, 300 K

Non-Irradiated, 300 K

No Oxygen Diffusion

Reverse Annealed

Brunel, CERN, Hawaii to be published


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MAIN DETECTOR STRATEGIES PROPOSED FOR LIFE ABOVE 1015 n/cm2

OPTIMIZATION OF:

STRATEGIES:

COLLECTION DISTANCE

CCE (trapping)

SPEED

SPACE CHARGE

REVERSE ANNEALLING

CCE (undepletion)

CHARGE SHARING

DEVICE GEOMETRY

3D, THIN

DEFECT ENGINEERING

O2, P-TYPE SUBSTRATE

MODE OF OPERATION

Temperature, Forward bias

MORE TO GAIN BY COMBINING TECHNIQUES!


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-

-

-

-

-

-

-

-

-

-

SPACE CHARGE after

Irradiation – type inversion

At 300K

Introduction of radiation induced

Deep acceptors

Active volume

before irradiation

p+

n+

W

Type inversion

d

Active volume

after irradiation

High field

AFTER TYPE INVERSION

DEPLETION STARTS FROM

n+ CONTACT


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THE OXYGEN MIRACLE : ROSE/RD48

REDUCED

VFD

3 times

Reduced

Reverse

Annealing

Saturation

(2 times)

Nucl. Instr. Meth. A 466 (2001) 308


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NEUTRON PROTON PUZZLE

COMPETING MECHANISM DUE TO COULOMB INTERACTION

MORE POINT DEFECTS WHEN CHARGED PARTICLE IRRADIATION

V+O = VO

DOES NOT CONTRINUTE TO NEFF

V2+0 = V2O

CONTRIBUTES TO NEFF


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CHARGE COLLECTION EFFICIENCY

AFTER IRRADIATION

p-type bulk

non p

-

W

p+

n+

-

d

-

-

-

High field

Qcoll = q * d/W  Vbias

Standard p on n

TRAPPING

Oxygenated p on n

25ns electronics

3x1014 n/cm2

T=-170C

0 100 200 300 400 500 600

UNDEPLETED REGION

1 – 3 x 1014 n/cm2

OXYGEN ONLY DOES NOT HELP!

NIMA 487 (2002) 465-470

Vbias

NIM A 412 (1998) 238


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ATLAS PIXELS AFTER 1015 n/cm2

Nucl Inst Meth A 456 (2001) 217-232

These data curtesy from L. Rossi, unpublished

  • n+ on n

  • oxygenated

  • 250 mm

  • Multi guard - p-spray

CCE = 97.7%

AT 600V

250mm

Time=10ns

COMBINED

STRATEGIES!!

13 mm

Spatial resolution


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>1015 n/cm2

1-5 x 1014 n/cm2

EFFECT ON CHARGE SHARING

Diffusion due to low field region after type inversion

Double sided strips

3.1014 n/cm2

p+

LHCb

n+

Resolution [mm]

Vbias

Vbias

NIM A 440 (2000) 17

p side

n side

p+

ATLAS

Efficiency

Vbias

Vbias

NIMA 426 (1999) 140

NIM A 450 (2000) 297

SIMULATION S WATTS UNPUBLISHED


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SPACE CHARGE

Below 200 K

NEFF DECREASE WITH T!!

  • CCE INCREASES!

  • Low leakage current LAZARUS effect

  • No reverse annealing

  • High carriers mobility

energy level occupancy ~ e- E/kT

NEFF

1x1014 n/cm2 > type inverted : -ve SC

TRAPPING

Neff [cm-3]

Phosphorus doping level

+ve SC

NIM..

T [K]

C Da Via

To be published

Nucl Inst Meth A 413 (1998) 475

Nucl Inst Meth A 440 (2000) 5


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FORWARD BIAS OPERATION

AT LOW TEMPERATURE

d

Reverse bias

Forward bias

NIM A 440 (2000) 5

0 min

x

f = 1015 n/cm2

T=130K

5 min

CCE %

15 min

30 min

"polarization

effect"

time

V bias

undepleted

Higher CCE

Forward bias

90 V

td ~ eE/kT

Reverse bias,

700 V

T=249K (-24C)

f = 1015 n/cm2

NIM A 439 (2000) 293.


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IF IRRADIATION AT 130K:

different kinetics!

1- formation of defects V, I, Vn, In, depending on particles

2- V + and V- observed already at 4.2K after e- irradiation

3- V present in 5 charge states V2+, V+, V0, V-, V2-.

4- the V spectra disappear at :

~70K in n-type low res

~150K in p-type

~200K in high res. material

5-at 200K new spectra appears (V2, VO) => V migrates!!

6- V migration also possible by ionisation = athermal process

7-I mobileat 4.2K in p-type, ~140-175K in n-type

After annealing at 200K

better by 20%

CCE %

Irradiated at 300K

For comparison

(G. Watkins .Mat. Sci. in Sem. Proc. 3 (2000) 227)

voltage

Systematic study needed!

NIM A 476 (2002) 583


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OXYGEN INTERSTITIAL

Si

Si

Si

Si

Oi

Oi

Oi

Si

NEW DEFECT ENGINEERED MATERIAL:

O-DIMER TO CONTROL CHARGE TRAPPING

1.1 x1011 p/cm2

OXYGEN DIMER

HIGH TEMPERATURE 60Co g IRRADIATION

AT T > 350 0COXYGEN ATOMS BECOMES

MOBILE AND START TO CLUSTER

QUASI CHEMICAL REACTIONS:

V+Oi => VOi

VOi + Oi => VO2i

I + VO2i => O2i

D= dimerized

p=proton irradiated

NIM B 186 (2002) 111

DLTS shows VO suppressed

Less trapping!

Theory predicts VO2 is NEUTRAL!


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SUMMARY

  • WE KNOW HOW TO:

  • 1- HAVE A SHORT COLLECTION DISTANCE + COLLECTING e-

  • optimise signal formation

  • spatial resolution

  • speed

  • 2- CONTROL THE SPACE CHARGE

  • power dissipation (noise)

  • CCE

  • spatial resolution

  • 3- CONTROL CHARGE TRAPPING

  • CCE

  • spatial resolution

USING :

device structure

3D – THIN (small pitch)

Defect engineering

operational mode

Temperature, forward bias

Defect engineering

p-type

operational mode

MORE GAIN BY COMBINING TECHNIQUES!!!


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CONCLUSIONS

  • THE COMBINATION OF:

  • ENGINEERED SILICON (oxygen enriched), p-type substrate

  • INNOVATIVE SHORT DRIFT LENGTH GEOMETRIES (3D, thin)

  • OPERATIONAL CONDITION (temperature, forward bias)

  • COULD PROVIDE THE RADIATION TOLERANCE OF SILICON NEEDED TO

  • GUARANTEE THE OPERATION OF PARTICLE TRACKERS AT 1016 n/cm2

  • ELECTRONICS PLAYING A KEY ROLE!!

  • Recently formed CERN R&D (RD50) will explore several of the proposed strategies

  • Interest expressed by LHC elastic scattering, Luminosity monitor collaborations to use existing technologies like 3Dand cryogenic silicon.


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ACKNOWLEDGEMENTS

Luca Casagrande/ Roma

GianLuigi Casse/Liverpool

Alex Chilingarov /Lancaster

Paula Collins/Cern

Leo Rossi /Atlas pixel

Mahfuzur Rahman/Glasgow

Angela Kok, Anna Karpenko,Gennaro Ruggiero/

Brunel

Erik Heijne/Cern

Sherwood Parker/Hawaii

Steve Watts /Brunel


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“The most important thing in science

is imagination”

A. Einstein


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