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10101616ADVANCES IN SEMICONDUCTOR DETECTORS ADVANCES IN SEMICONDUCTOR DETECTORS FOR PARTICLE TRACKING IN EXTREME FOR PARTICLE TRACKING IN EXTREME
RADIATION ENVIRONMENTS. RADIATION ENVIRONMENTS. Cinzia Da Via’, Cinzia Da Via’, Brunel University, UKUniversity, UK
OUTLINE
1- INTRODUCTION2- PRESENT STATUS OF RADIATION HARD
SILICON DETECTORS UP TO 1015 neq/cm2
3- STRATEGIES FOR SURVIVAL BEYOND 1015 neq/cm2:
a DEVICE GEOMETRY : short collection distance -3D,thin b TEMPERATURE and FORWARD BIAS OPERATIONc DEFECT ENGINEERING :O and O2
4- CONCLUSIONS
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INTRODUCTION INTRODUCTION
27 Km
LARGE HADRON COLLIDERCERN - GENEVA
Luminosity
[cm-2s-1]
pp [collisions/s]
Bunch
Spacing [ns]
LHC
2007
1034 8x108 ~25
SLHC
~2015
1035 1011 ~12
new physics expected!!new physics expected!!BUT NEED HIGH STATISTICSBUT NEED HIGH STATISTICS s
14TeV
~6000 tracks per bunch crossing!!
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p pb
bH
Most probable Higgs channel
•MOMENTUM RESOLUTION•TRACK RECONSTRUCTION•b-TAGGING EFFICIENCY
PHYSICS REQUIREMENTSPHYSICS REQUIREMENTS
•ACCURACY OF STANDARD MODEL PARAMETERS•ACCURACY OF NEW PHYSICS PARAMETERS•SUPERSYMMETRIC PARTICLES•EXTRA DIMENSIONS•RARE PROCESSES (TOP DECAYS, HIGGS PAIRS ETC)
PRECISE PRECISE MEASUREMENTS OFMEASUREMENTS OF
~10 SMALLER PITCH SILICON DETECTORS CAN DO IT!!!
HIGHER STATISTICS NEEDED FOR
GOODTRACKERESSENTIAL!
Aleph
Was it there already??
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n
otherchargedhadrons
total
RADIATION ENVIRONMENT AT LHC ANDRADIATION ENVIRONMENT AT LHC AND SLHCSLHC
210 m2 of microstrips silicon detectors
1.6x1016
>85%Ch hadrons
Data from CERN-TH/2002-078
Multiple particle environment:NIEL scaling 1 MeV n equivalentViolation observed for oxygenrich materials
~5x1015
B-LAYER ~4cmATLAS
~5x1014
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SILICON DETECTORS "NORMALLY " SILICON DETECTORS "NORMALLY " USED IN PARTICLE PHYSICSUSED IN PARTICLE PHYSICS
+V
Substrate normally:
•n-type•4 k-cm FZ •Doping of ~1012 cm-3
•[O] ~1015 cm-3
•[C] ~1015 cm-3
•300m thick•Orientation <111>
Incidentparticle
n-type substrate
metallisedstrips
oxideW
300 m
--- ---+ + + + + +
p-typejunctions
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RADIATION INDUCED BULK DAMAGE in SiRADIATION INDUCED BULK DAMAGE in Si
Van Lint 1980
Primary Knock on Atom
Displacement threshold in Si:Frenkel pair E~25eVClusters E~5keV
Vacancy
Interstitial
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Ec
Ev
EiV2(-/0)+Vn Ec-0.40eVV2(=/-)+Vn Ec-0.22eVVO- Ec - 0.17eV
V6
CIOI(0/+)
EV+0.36eV
V2O
DLTSspectrum
From Cern ROSE RD48
RADIATION INDUCED STABLE DEFECTS IN SILICONRADIATION INDUCED STABLE DEFECTS IN SILICON
Neutron irradiated
V,I +
CHARGED DEFECTS==>NEFF, VBIAS
DEEP TRAPS, RECOMBINATION CENTERS ==>CHARGE LOSS
GENERATION CENTERS==>LEAKAGE CURRENT
VOVO effective e and h trapVV22 and VV22OO deep acceptors contribute to Neff
DEFECT KINETICS ( 300K ):
IMPURITIES
DOPANTS
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STANDARD 300m n-type SILICON at 1015 n/cm2
10 years of operation at L=1034 cm-2s-1 at R=4 cm
EFFECTIVE DRIFT LENGTHDue to charge trapping ~150m e-
~50m h
SPACE CHARGE -ve Neff (1013/cm3) ~ VFD (5000V)~
TYPE INVERSION depletion from n-contact (e-field)
REVERSE ANNEALING INCREASE OF -ve Neff temp. dep
LEACKAGE CURRENT prop to (I/V ~5x10-17
PRESENT RESEARCH FOCUSES AT FLUENCESPRESENT RESEARCH FOCUSES AT FLUENCESUP TO 1x10UP TO 1x101515 n/cm n/cm22
Signal formationCharge sharingSpeed
Double junctionCharge diffusion
Noise Thermal runaway
Time [y]
Maintenance
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MAIN DETECTOR STRATEGIES MAIN DETECTOR STRATEGIES PROPOSED FOR LIFE ABOVE 10PROPOSED FOR LIFE ABOVE 101515 n/cm n/cm22
MORE TO GAIN BY COMBINING TECHNIQUES!MORE TO GAIN BY COMBINING TECHNIQUES!
COLLECTION DISTANCECCE (trapping) SPEED
SPACE CHARGEREVERSE ANNEALLINGCCE (undepletion)
CHARGE SHARING
LEAKAGE CURRENT
DEVICE GEOMETRY 3D, THIN
DEFECT ENGINEERING O, P-TYPE SUBSTRATE
MODE OF OPERATIONTemperature, Forward bias
OPTIMIZATION OF:STRATEGIES:
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EFFECTIVE DRIFT LENGTHEFFECTIVE DRIFT LENGTH
0
500
1000
1500
2000
2500
50 100 150 200 250 300 350
FOR FLUENCE = 1014 cm-2
E = 104 V cm-1
Eff
ectiv
e Tr
appi
ng L
engt
h ( m
icro
ns)
Temperature (K)
Neutron
Neutron
Proton
Proton
Electrons
Holes
Leff = t x Vdrift
Simulation by S. Watts/BrunelAccepted for publication on NIMData avalable for neutron andprotons for effective trapping time 220K-300K from
Kramberger et al
500
1000
1500
2000
2500
3000
50 100 150 200 250 300 350
Eff
ect
ive
Dri
ft L
eng
th (
mic
ron
s)
Temperature (K)
Electrons
Holes
1014 ncm -2 E = 105 cm-1
neutron
protons
neutrons
protons
10
15
20
25
30
2 106
4 106
6 106
8 106
1 107
1.2 107
50 100 150 200 250 300 350
teffnteffnh
VdeVdh
Effe
ctiv
e Tr
appi
ng T
ime
(ns)
Drift Velocity (cm s
-1)
Temperature (K)
E = 104 V cm-1 ( 1V/micron)
1014 n cm-2
Measuredvalues
V
Leff at 1016 proton/cm2
~ 20 m electrons ~ 10 m holes
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SIGNAL FORMATION AFTER IRRADIATIONSIGNAL FORMATION AFTER IRRADIATION
0
0.2
0.4
0.6
0.8
1
0 0.005 0.01 0.015 0.02 0.025 0.03 0.035
1E15 n cm-2 200KWeightPot STRIPProb e STRIPProb h STRIPProb signal STRIP
pe/p
h/S
igna
l
Distance (cm)
p+ n+
CO
LLEC
TION
ELE
CTR
OD
E
Signal ~ q(Vxw-V0
w) e-th/h + (Vcw-Vx
w) e-te/e)
Simulation by S. WattsAccepted for publicationOn NIMA
ee--hh++
HOLES DON' T CONTRIBUTE
RAMO's THEOREM
0 cx
W. Shockley, Jour. Appl.Phys. 9,635 (1938)S. Ramo, Proc. of I.R.E. 27, 584 (1939)Gatti and coworkers
Depends on carriers drift length
Waiting potential is steeper if contact small compared with detector thickness moreover minimize charge sharing with neighbours due to charge trapping
collecting
0.16 A/x
TrappingShaping time
Small contact areaThin substrateHigh e-field
Planar device
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SHORT COLLECTION DISTANCE: SHORT COLLECTION DISTANCE:
3D DETECTOR 3D DETECTOR
n+ p+
depletiondepletion
50 m
++--
pn
pnSHORT COLLECTION PATHS 50 m (300m)LOW DEPLETION VOLTAGES <10V (60V)RAPID CHARGE COLLECTION 1-2n
(25 ns)EDGELESS CAPABILITY active edgesLARGE AREA COVERAGE active edgesSUBSTRATE THICKNESS INDEPENDENT :
BIG SIGNALSX-RAY DETECTION EFFICIENCY for low Z materials
IEEE vol46 N4 Aug. 99
S. Parker, C. Kenney1995
dep
leti
on
dep
leti
on
SameGenerated Charge!!!
+-
p+
300 m
C=0.2pF
n+
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DEEP REACTIVE ION ETCHING
ETCHING TECHNIQUESETCHING TECHNIQUES
ELECTROCHEMICALETCHING
NIMA 487 (2002) 19
ASPECT RATIO = 11:1, 19:1 20:1<
ELECTRODEFILLED WITH POLYSILICON
fs pulses is cleaner, any substrate Fast, high aspect ratio
LASER ABLATION
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DETECTOR THICKNESS 121m 282e noise PREAMP - SHAPING TIME 1 s200 m PITCH STRIP TYPE DETECTOR
SPEED1.5ns riseAT 130K3.5ns riseAT 300K
3D DETECTOR RESULTS before3D DETECTOR RESULTS beforeirradiationirradiation
GAUSSIAN RESPONSE
350 e rms , fast electronic designed at CERN- microelectronics group200m pitch detector TO BE PUBLISHED
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joined work Brunel, Cern, HawaiiTo be published
1x1015 p/cm2 (5x1014n/cm2)
3D RADIATION RESULTS AT 300K3D RADIATION RESULTS AT 300KAfter irradiationAfter irradiation
FULL DEPLETION BIAS =105 V AFTER 2x1015 n/cm2
SPEED 3.5 ns rise time40V bias, 300K
IEEE Trans on Nucl Sci 48 (2001) 1629
100m pitch detectorNON OXYGENATED
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3D CHARGE COLLECTION EFFICINECY3D CHARGE COLLECTION EFFICINECYAfter irradiationAfter irradiation
CCE =61%USING THE INTEGRATED 22-25 KeV
X-RAY PULSES FROM A 109Cd SOURCECOLLECTION FROM p-ELECTRODE
200m
Vbias VbiasVsig
100 mp
n
n
134 m
VbiasVbias Vsig
n
n
p
100 m
Brunel, CERN, Hawaii to be published
Non-Irradiated, 300 K
1 x 1015 p/cm2, 300 K
No Oxygen Diffusion
Reverse Annealed
= 40V =40V
More on 3D later this morning (P. Roy, 11:30)
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MAIN DETECTOR STRATEGIES MAIN DETECTOR STRATEGIES PROPOSED FOR LIFE ABOVE 10PROPOSED FOR LIFE ABOVE 101515 n/cm n/cm22
MORE TO GAIN BY COMBINING TECHNIQUES!
COLLECTION DISTANCECCE (trapping) SPEED
SPACE CHARGEREVERSE ANNEALLINGCCE (undepletion)
CHARGE SHARING
DEVICE GEOMETRY3D, THIN
DEFECT ENGINEERINGO2, P-TYPE SUBSTRATE
MODE OF OPERATIONTemperature, Forward bias
OPTIMIZATION OF:STRATEGIES:
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At 300KAt 300KSPACE CHARGE afterSPACE CHARGE afterIrradiation – type inversionIrradiation – type inversion
AFTER TYPE INVERSIONDEPLETION STARTS FROMn+ CONTACT Si0
eff2
FD ε2ε
Ne(W)V
-
- -
--
--
-
-
-
Active volumebefore irradiation
dW
Active volumeafter irradiation
p+ nn++
High field
Introduction of radiation inducedDeep acceptors
Type inversion
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THE OXYGEN MIRACLE : ROSE/RD48THE OXYGEN MIRACLE : ROSE/RD48
REDUCEDREDUCED VVFDFD
3 times 3 times
Nucl. Instr. Meth. A 466 (2001) 308
Reduced Reduced ReverseReverseAnnealingAnnealingSaturationSaturation(2 times)(2 times)
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NEUTRON PROTON PUZZLENEUTRON PROTON PUZZLECOMPETING MECHANISM DUE TO COULOMB INTERACTIONMORE POINT DEFECTS WHEN CHARGED PARTICLE IRRADIATION
V2+0 = V2O
CONTRIBUTES TO NEFF
V+O = VODOES NOT CONTRINUTE TO NEFF
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CHARGE COLLECTION EFFICIENCYCHARGE COLLECTION EFFICIENCYAFTER IRRADIATION AFTER IRRADIATION
p-type bulkn on p
0 100 200 300 400 500 600
NIMA 487 (2002) 465-470
25ns electronics3x1014 n/cm2
T=-170C
1 – 3 x 1014 n/cm2
VbiasNIM A 412 (1998) 238
Qcoll = q * d/W Vbias
--
---
dWp+ nn++
High field
UNDEPLETED REGION
TRAPPING
OXYGEN ONLY DOES NOT HELP!OXYGEN ONLY DOES NOT HELP!
Standard p on n
Oxygenated p on n
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13 mSpatial resolution
CCEV 250mTime=10ns
ATLAS PIXELS AFTER 10ATLAS PIXELS AFTER 101515 n/cm n/cm22
Nucl Inst Meth A 456 (2001) 217-232These data curtesy from L. Rossi, unpublished
n+ on noxygenated250 mMulti guard - p-spray
COMBINEDSTRATEGIES!!
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Effi
cien
cyVbias
NIM A 450 (2000) 297
NIM A 440 (2000) 17
LHCb
ATLAS
n sidep sideR
eso
luti
on
[m
m]
Vbias
Vbias
1-5 x 1014 n/cm2 >1015 n/cm2
Diffusion due to low field region after type inversionEFFECT ON CHARGE SHARING
p+
Vbias
n+p+
1
10
100
1000
104
0 0.005 0.01 0.015 0.02 0.025 0.03 0.035
180K
5V10V20V50V200V
Ele
ctri
c F
ield
(V
/cm
)
Distance (cm)
3.1014 n/cm2
NIMA 426 (1999) 140SIMULATION S WATTS UNPUBLISHED
Double sided strips
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SPACE CHARGE SPACE CHARGE Below 200 KBelow 200 K NNEFFEFF DECREASE WITH T!! DECREASE WITH T!!
Phosphorus doping levelPhosphorus doping level
5.0 1011
6.0 1011
7.0 1011
8.0 1011
9.0 1011
1.0 1012
1.1 1012
1.2 1012
1.3 1012
80 100 120 140 160 180
Nef
f [c
m-3
]
T [K]
energy level occupancy ~ eenergy level occupancy ~ e- E/kT- E/kT
T [K]T [K]
NNef
f ef
f [cm
[cm --
33]]
1x1014 n/cm2 > type inverted : -ve SC
C Da ViaC Da ViaTo be publishedTo be published
+ve SC+ve SC
NEFFTRAPPING
NIM..
CCE INCREASES!Low leakage current LAZARUS effectNo reverse annealingHigh carriers mobility
Nucl Inst Meth A 413 (1998) 475Nucl Inst Meth A 440 (2000) 5
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FORWARD BIAS OPERATIONFORWARD BIAS OPERATION AT LOW TEMPERATUREAT LOW TEMPERATURE
d
undepletedundepleted
timetime
x
dd ~ e ~ eE/kTE/kT
NIM A 440 (2000) 5
Reverse biasForward bias
0 min
5 min
15 min
30 min
V bias
CC
E %
Reverse bias, 700 V
Forward bias 90 V
T=249K (-24C)T=249K (-24C) = 10= 101515 n/cm n/cm22
NIM A 439 (2000) 293.
f = 10f = 101515 n/cm n/cm22
T=130KT=130K
"polarization effect"
Higher CCE
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CC
E %
CC
E %
IF IRRADIATION AT 130K: IF IRRADIATION AT 130K: different kinetics!different kinetics!
0
20
40
60
80
100
0 50 100 150 200 250
0 Fluence
6e14 n/cm2
6E14n/cm2 after WU
CCE(W) 5E14
CCE(W) 2E15
CCE(W) 1E15
CC
E%
VOLTAGE (V)voltagevoltage
(G. Watkins .Mat. Sci. in Sem. Proc. 3 (2000) 227)
Systematic study needed!Systematic study needed!
After annealing at 200KAfter annealing at 200Kbetter by 20%better by 20%
Irradiated at 300KIrradiated at 300KFor comparisonFor comparison
NIM A 476 (2002) 583
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 mobile at 4.2K in p-type, ~140-175K in n-type
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NEW DEFECT ENGINEERED MATERIAL:NEW DEFECT ENGINEERED MATERIAL:O-DIMER TO CONTROL CHARGE TRAPPINGO-DIMER TO CONTROL CHARGE TRAPPING
SiSi
SiSi
SiSi
OOii
OOii
OXYGEN DIMEROXYGEN DIMER
HIGH TEMPERATURE 60Co g IRRADIATIONAT T > 350 0C OXYGEN ATOMS BECOMES MOBILE AND START TO CLUSTER
QUASI CHEMICAL REACTIONS:V+Oi => VOi
VOi + Oi => VO2i
I + VO2i => O2i
Theory predicts VO2 is NEUTRAL!
NIM B 186 (2002) 111
SiSiSiSi
OOii
OXYGEN INTERSTITIALOXYGEN INTERSTITIAL
DLTS shows VO suppressedLess trapping!
-2.5 1011
-2 1011
-1.5 1011
-1 1011
-5 1010
0
5 1010
100 150 200 250 300
366p309p366Dp309Dp
Con
cent
ratio
n (c
m-3
)
Temperature (K)
E(90)E(170)
E(225)
D= dimerizedp=proton irradiated
1.1 x1011 p/cm2
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WE KNOW HOW TO:
1- HAVE A SHORT COLLECTION DISTANCE + COLLECTING e-
optimise signal formationspatial resolutionspeed
2- CONTROL THE SPACE CHARGEpower dissipation (noise)CCE spatial resolution
3- CONTROL CHARGE TRAPPINGCCE spatial resolution
SUMMARYSUMMARY
device structure3D – THIN (small pitch)
Defect engineeringoperational modeTemperature, forward bias
Defect engineeringp-typeoperational modeMORE GAIN BY COMBINING TECHNIQUES!!!
USING :
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CONCLUSIONSCONCLUSIONS
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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ACKNOWLEDGEMENTSACKNOWLEDGEMENTS
Luca Casagrande/ RomaGianLuigi Casse/LiverpoolAlex Chilingarov /LancasterPaula Collins/CernLeo Rossi /Atlas pixelMahfuzur Rahman/GlasgowAngela Kok, Anna Karpenko,Gennaro Ruggiero/Brunel Erik Heijne/Cern Sherwood Parker/Hawaii Steve Watts /Brunel