Results on proton irradiation tests in...

October 2001 General Tracker Meeting IEKP - Universität Karlsruhe (TH)

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ResultsResults on on protonproton iirradiation rradiation teststests in Karlsruhein Karlsruhe

F. HartmannIEKP - Universität Karlsruhe (TH)

• p do Bulk & Surface DamageStrip parameters after irrad.

• VFD for (300µm) and 500µm sensors after 10 years LHC• Expected power for 500 µm sensors after 10 years LHC• Outlook


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Irradiation FacilityIrradiation Facility

Compact Cyclotron at Forschungszentrum Karlsruhe

• 34 MeV protons• 1000 nA• Beam spot:

2cm O• T < -10°C• Area: 20x40cm2

• Duration:100cm2 in 15min(1 sensor, 5e13p/cm2)


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Cold BoxCold Box

• Dry N2 atmosphere at –10°C.• Flexible box to hold sensors, teststructures

and/or modules!

• Laser focus• Simple power lines• Temp. monitor


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SimulateSimulate LHC LHC bias conditions bias conditions with respectwith respect to to surface damagesurface damage!!

Running @ LHCDuring proton irrad.:Diode acts as a current sourcedue to the p ionising effect

SOLVE: 1V potentialby applying Vbias = 1V,But AC must also be on GND!

Current source

RpolyDC

CC

AC

Here we need potential like in LHC 1M at 1 A = 1VΩ µ

Rpoly

Strip current after irrad

readout(on GND)

Vbias

diode


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How toRealize?

SimulateSimulate LHC LHC bias conditions bias conditions with respectwith respect to to surface damagesurface damage!!

Conductive rubber

Vbias = 1V during irrad

Bias ring--> GND

RpolyDC

ACShort all AC to bias (GND)

Backplane to +Vbias= 1V


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Sensors Sensors beforebefore//afterafter IrradiationIrradiation


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FluencesFluences in in the Trackerthe Tracker~1.5e14 n/cm2

for 320µm

~0.5e14 n/cm2

for 500µm

Upper limits:UFD<500VP(-10°C)<400mW


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Irradiation SchemeIrradiation Scheme2 fluences chosen:• Inner Tracker: 1.8e14 p/cm2 (~3e14 n/cm2):

– expected for low resisitivity silicon (300µm) * 1.8 ≈ 18yLHC• Outer Tracker: 0.5e14 p/cm2 (~8e13 n/cm2):

– expected for high resistivity silicon (500µm) *1.5 ≈ 15yLHC

Material (6“, 500µm thick):1 sensor W6b from Hamamatsu1 sensor OB2 from ST Microelectronics6 teststructures from Hamamatsu

Biasing:1V, 12V, 100V, non

Notice: Inner Tracker fluence on Outer Tracker (500µm) sensors instead of 300µm, PRO: 1. resistivity almost right 2. No 320µm sensors present, 3. HPK will in future deliver inner 300µm sensors

CON: unusual high VFD


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FluenceFluence MeasurementMeasurement1.) Measurement by Ni-foil activation behind sensors:• Calibration at 26 MeV• Scaling with cross section to higher energies• Fluence in [p/cm2]• Hardness factor κ(E) scales to neutron equivalent

2.) Ileak measurement:• Temperature scaling to 20°C

I(20°C)=I(T)*R(T); R(T)=(293K/T)2 ·e(-E/k(1/293K-1/T)); E=1.4eV• I/V=α*Φ• α(T=20°C)=4e-17 A/cm• Fluence in [n(1MeV)/cm2]


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Karlsruhe Karlsruhe probing equipmentprobing equipment

Bias

stencil/template

Measurements take ~1.5 - 2 hours Changing of sensor ~ 5 min

Environment: –10°C, RH~1%


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IVIV--Curve Curve beforebefore//afterafter IrradIrrad..

0 200 400 600 800 1000 12000

2µ4µ6µ8µ

10µ

500µ

1m

2m

2m

Cur

rent

[A]

Sensor HPK Sensor ST Sensor HPK irradiated (1.8e14 p/cm2) Sensor ST irradiated (0.5e14 p/cm2)

Voltage [V]


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Power Power ConsumptionConsumption

0.0 5.0x1013 1.0x1014 1.5x1014 2.0x1014 2.5x1014 3.0x1014

0.0

50.0µ

100.0µ

150.0µ

200.0µ

250.0µ

300.0µ

350.0µ

400.0µ

Data (500µm sensors, ~5kΩcm) Linear Fit Extrapolated value for 500µm sensor

at r=60cm

α(T=-10°C) = 1.2 10-18 A/cm

I / V

[A/c

m3 ]

eq. Fluence [n/cm2]

60µA/cm3 => Ileak(-10°C)=270µA (W6b) => P(500V, -10°C)=135mW/sensor

Actual designed cooling power 400mW for each module (at least).

P ~ UFD I ~ d2 d ~d3


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CVCV--Curve Curve beforebefore//afterafter IrradIrrad..

0 200 400 600 800 1000 1200

0,0

5,0x1016

1,0x1017

1,5x1017

2,0x1017

2,5x1017

3,0x1017

3,5x1017

Sensor HPK Sensor ST Sensor HPK irradiated (1.8e14 p/cm2) Sensor ST irradiated (0.5e14 p/cm2)

Cap

acita

nce-2

[F-2]

Voltage [V]

UFD ~ d2 => UFD(320µm) = 410V

ST and HPK sensors are stable up to Vbias=1000V after irradiation!Even strip tests were done at Vbias= 1000V!


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Hamburg ModelHamburg Model

UFD(Neff)~d2

Beneficial annealing

ga τa(20°C)

Stable Damage

gcc

Reverse Annealing

gYτY(20°C)

1 5 10 50 100 500

0.0

5.0x1011

1.0x1012

1.5x1012

2.0x1012

2.5x1012

Beneficial Annealing Stable Damage Reverse Annealing

N [c

m-3]

Time at RT [days]

PhD Thesis M. Moll:ga=(1.81±0.14)e-2 cm-1

τa(20°C) =55hgc=(1.49±0.04)e-2 cm-1

c=(10.9±0.8)e-2 cm-1/NeffgY=(5.16±0.09)e-2 cm-1

τY(20°C)=475d


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DevelopementDevelopement of Uof UFDFD

0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,50

100200300400500600700800900

10001100

ST

Hamamatsu

Data (FS sensors) Hamburg Model

Full

Dep

letio

n Vo

ltage

[V]

eq. Fluence [1014n(1MeV)/cm2]

Data is fully compatible with the „Hamburg model“ fit!Predictions for different annealing scenarios possible!


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Full Full depletion as function depletion as function of of annealing annealing time and time and fluencefluence

Fluence given at once, then annealing.


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Annealing scenario:Annealing scenario:14 days at RT each year14 days at RT each year

0 14 28 42 56 70 84 98 112 126 140 154

0

100

200

300

400

500

600

500µm, 4.4kΩ, 5e13n/cm2

" Fluence at once 320µm, 2.2kΩ, 16e13n/cm2

Full

Dep

letio

n Vo

ltage

[V]

Annealing Time at RT [days]

Iterative calculation of full depletion voltage


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Depletion voltages for diodeDepletion voltages for diodeminisensor minisensor and and full sensorfull sensor

0 200 400 600 800 10000,0

5,0x1019

1,0x1020

1,5x1020

2,0x1020

2,5x1020

3,0x1020

~600V

~600V

~1000V

values shifted in y for comparison to compensate for different sizes

Diode 2.6e14 n/cm2

Full sensor 3e14 n/cm2

Mini sensor 2.6e14 n/cm2

Cap

acita

nce-2

[F-2]

Voltage [V]Future: diode measurements as reference!


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Strip Strip Leakage CurrentLeakage Current

0 5 10 15 20 25 30 35 40 45 50

0.01

0.1

1

10

100

1000

Minisensor 41

Before Irradiation After Irradiation and Annealing

(Measurement at -10°C)

Leak

age

Cur

rent

@ 4

00V

[nA]

Strip numberAs expected: Increase in leakage current!


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Bias ResistanceBias Resistance

0 5 10 15 20 25 30 35 40 45 50 55 60

1,8

1,9

2,0

2,1

2,2

2,3

Strip number

Minisensor H41

Before Irradiation Raw Data: After Irradiation and Annealing

(Measurement at -10°C) Corrected values due to high Ileak

Poly

Res

ista

nce

[MΩ

] Measurement:• Apply U=2V• Measure I• Calculate R=U/I

Correction:• Measure Ileak (high after irrad)• Correct Rc=U/(U/R+Ileak)

No change in bias resistances !


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Coupling CapacitanceCoupling Capacitance

0 5 10 15 20 25 30 35 40 45 506065707580859095

100105110115120

Strip number

Minisensor H39

Before Irradiation After Irradiation and Annealing

(Measurement at -10°C)

Cou

plin

g C

apac

itanc

e [p

F]

No change in coupling capacitances !


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Interstrip Interstrip capacitancecapacitance of HPK of HPK full full sensorsensor (1 (1 neighbourneighbour))

100 fF

<Cint>=3.2 pF

20 fF

Wedgeshaped sensor:Longer strips on the sides,but less neighbours!

structure


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InterstripInterstrip CapacitanceCapacitance

0 200 400 600 800 1000

0.15

0.30

0.45

0.60

0.75

0.90

Non irradiated: 1 MHz 100 kHz

Irradiated: 1 MHz 100 kHzIn

ters

trip

Cap

acita

nce

[pF]

Bias Voltage [V]

No change in interstrip capacitance before/after irrad.@ 1MHz.Homogeneous interstrip distribution before/after irrad.

70 72 74 76 78 80 82 84 86 88 901,4p

1,5p

1,5p

1,6p

1,6p

1,7p

1,7p

Before Irradiation After Irradiation

Inte

rstri

p C

apac

itanc

e [F

](2

nei

ghbo

urs)

Strip No.


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Future CMS Future CMS dedicated teststand dedicated teststand at at the Cyclotron the Cyclotron

•Scan area:20 x 50 [cm]

•Scan speed:1.25x 2.5 [cm/s]

•Maximum load:20kg

(New (New dedicated beamdedicated beamlineline))


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Future: Future: irradiation irradiation of a of a full modulefull module

• TEC outer, TEC inner,TOB,TIB• Longterm with high voltage, current, power

• Test of S/N, CCE, (pedestal,noise,shape)

• Test of components: sensor, electronics, mechanics

. First IEKPTEC module


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Conclusion Conclusion

1. Both: ST and HPK comply with the specification of irradiation hardness

2. Data fits „Hamburg model“ well and shows a decent behavior after 10 years of LHC operation

3. No changes in the strip parameters observed

4. Future dedicated teststand promise easy access to the cyclotron

5. Further plans: 300µm sensors and full modules will be irradiated!


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NEW:NEW: Ingot Ingot prepre--qualificationqualification((junejune 2001)2001)

• All measurements on diode and minisensorSave large sensors as spares!

INGOT: IV & CV on diodeTo determine Vdepletion, fluence estimation and α-factor.

PROCESS: Cint, Rint, leakage current, Rpoly vs. Vbias upto Vdepletion + 50V (for ~10 strips)

Hamamatsu proposed to produce a couple of additional sensors out of each new ingot for irradiation pre-qualification

Special procedure in addition to the standard task.

Results on proton irradiation tests in...

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