Full-size ATLAS Sensor Testing

Full-size ATLAS Sensor Full-size ATLAS Sensor TestingTesting

On behalf of the ATLAS R&D group Development of n-in-p Silicon Sensors for very high

radiation environment

Jan BohmInstitute of Physics AS CR, Prague

R&D50 Workshop, CERN, 16-18.11.2009

Total number of tested sensors: 19

ATLAS institutes involved in testing:

University of Cambridge 2 sensors: W15, W16

J.R.Carter, B. Hommels, D. Robinson

Stony Brook University 9 sensors: W19, W21-23, W25-29

B. DeWilde, R. Maunu, D. Puldon, R. McCarthy, D. Schamberger

Institute of Physics AS CR and Charles University, Prague

6 sensors: W32, W33, W35, W37, W38, W39

J. Bohm, J. Broz, Z. Dolezal, P. Kodys, P. Kubik, M. Mikestikova

Geneva University 2 sensors: W17, W18

A. Clark, D. Ferrèrre, S. G. Sevilla

J.Bohm, R&D50 Conference, CERN 17.11.09

Testing before irradiation

Testing of large area ATLAS07 Series I sensors manufactured by Hamamatsu Photonics

0

50

100

150

200

250

300

350

400

450

0 200 400 600 800 1000Bias voltage [-V]

Lea

kag

e cu

rren

t [-n

A]

w32 PRGw33 PRGw35 PRGW37 PRGw38 PRGw39 PRGw32 HPKW33 HPKw35 HPKw37 HPKw38 HPKw39 HPKW19 SBUW19HPKW21SBUW21 HPKW22 SBUW22 HPKW23 SBUW23 HPKW25 SBUW25 HPKW26 SBUW26 HPKW27 SBUW27HPKW28 SBUW28 HPKW29 SBUW29HPKW18 GeUW17 GeUW15 CAMW16 CAM

. IV characteristics of large area ATLAS07 Series I sensors normalized to 20°C.

No microdischargeswith exception of W18having slow breakdown at ~420Vbut after a “training”, no microdischarge up to 1000V.

All tested sensors satisfy the ATLAS07 Technical Specification Ileak<20µA

Note: Leakage current should be measured with time delay of several seconds (10s) after ramping up bias voltage and measured for both cases, the ramping up and the ramping down of Vbias. See note of A.Chilingarov at RD50 Recommendations.


“Training of detectors” :

Detector is biased by the breakdown voltage at current ~10µA for10-20 min or longer time.

IV of sensor W37

-2500

-2000

-1500

-1000

-500

0

-600-500-400-300-200-1000

Reverse bias voltage

Lea

kag

e cu

rren

t [n

A]

After testing06/08Before currentstability 26/10after currentstability 27/10After training14/08

Leakage Current Time EvolutionSensor W35

-290

-270

-250

-230

-210

0 200 400 600 800 1000 1200

time [min]

Lea

kag

e cu

rren

t [n

A]

Leakage Current Time Evolution

-600

-500

-400

-300

-200

-100

0

0 200 400 600 800 1000 1200 1400

time [min]

Leak

age

Curr

ent [

nA]

W37

Time Evolution of Leakage CurrentLeakage current is decreasing with time for sensors having slow breakdown after testing.

Vbias=-240V

After ~20 hours of “training” slow breakdown of W37 at -360V disappeared and IV characteristic was restored.


RH=35%

After the quality acceptance tests the measured leakage current was usually higher by 10-30%.

Depletion Voltage

5

Bulk capacitance measured between backplane andbias ring by LCR meter with CSRS function at 1kHz

Vdep extracted as crossing of the linear rise 1/C^2 and the saturated valueVery smooth behavior of CV

Summary: All tested sensors satisfy specifications: Vdep<500V

Estimated values of VdepPrague 6 sensors 199-203VStony Brook 2 190-210VCambridge 2 235, 245V

Frequency dependence of Cbulk

1

1.5

2

2.5

3

3.5

1.E+02 1.E+03 1.E+04 1.E+05 1.E+06Freq [Hz]

Cbu

lk [n

F]

W37

W38

CSRS Vbias=-240V

ATLAS07 - Series I Depletion Voltage

0.00E+00

2.00E-02

4.00E-02

6.00E-02

8.00E-02

1.00E-01

1.20E-01

0 100 200 300 400 500 600

-Vbias [V]

1/C

2 [nF

-2]

W32 Vdep=202.5W33 Vdep=202.3W35 Vdep=201.4W37 Vdep=198.8W38 Vdep=200.3W39 Vdep=199.4W15 Vdep=245.5W16 Vdep=234.9

ATLAS07-P-SSSD_Series I

1kHz with CR in Series

Cbulk =3.25nF on plateau

Frequency dependence of a bulk capacitance of sensors W37 and W38 measured at 240 V with CR in series.


Cinter CpRp 100kHz Sensor W37

0.6

0.8

1

1.2

1.4

1.6

1.8

2

2.2

0 100 200 300 400 500 600

Vbias [-V]

Cin

t [p

F]

2 probes

5 probes

3 probes5 needles

Cint/0.89cm CpRp /1MHz W375 probe method

0.5

0.55

0.6

0.65

0.7

0.75

0.8

0 100 200 300 400 500 600

Vbias [-V]

Cin

t/cm

[pF

]

S1

S2

S3

S4Comparison with mini sensors

2-probes

3-probes

5-probes

LCR High

DC pad

LCR LowGND GND

Inter-strip Capacitance – Methods of Measurement

Different methods of Cint measurementFive-probe method: S.Lindgren et al.Santa Crus University

S.Lindgren et al.

Mini-sensorsLstrip=0.89cm

Cint(5-pr)/Cint(3-pr)=0.939 and 0.913 for100kHz and 1MHz, respect.Cint(2-pr)/Cint(5-pr)=0.53

J.Bohm, R&D50 Conference, CERN 17.11. 09

Isolated strips

GND

AC pad

0

0.5

1

1.5

2

2.5

1 10 100 1000

Frequency [kHz]

Inte

rstr

ip c

apac

itanc

e [p

F]

3 probe method

5 probe method

0.5

1.0

1.5

2.0

2.5

3.0

0 100 200 300 400 500 600

Bias voltage [-V]

Inte

rstr

ip c

ap

acit

an

ce [

pF

]

W33-Seg1

W33-Seg2

W33-Seg3

W33-Seg4

W35-Seg1

W35-Seg2

W35-Seg3

W35-Seg4

W37-Seg1

W37-Seg2

W37-Seg3

W37-Seg4

W38-Seg1

W38-Seg2

W38-Seg3

W38-Seg4

W39-Seg1

W39-Seg2

W39-Seg3

W39-Seg4

W32-Seg1

W32-Seg2

W32-Seg3

W32-Seg4

W37-Seg1

3 probe method at 100kHz

5 probe method at 100kHz and 1MHz

Frequency dependence of inter-strip capacitance measured with three-probe method (full symbols) and with five-probe method (open symbols) at Vbias= -240 V.

Inter-strip Capacitance – Bias Scan

Inter-strip capacitance as a function of thereverse bias voltage measured at randomlyselected strips from each sensor segment with the three-probe method at 100 kHz (full symbols) and with the five-probe method (open symbols) at 100 kHz and 1 MHz test frequencies.

Technical Specification defines upper limit:Cint / 1cm < 1.1pF measured by three-probemethod at 100kHz with CR in parallel.


Cint has complicated behavior at low bias voltages but becomes constant beyond FDV

Recommendation: Measure Cint at 1MHz Test frequency with function CR in parallel by three- probe method.

0

50

100

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200

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350

400

1.85 1.87 1.89 1.91 1.93 1.95

Interstrip Capacitance [pF]

Seg4

Seg3

Seg2

Seg1

Three-Probe Method Strip Scan of Cinter

1.4

1.5

1.6

1.7

1.8

1.9

2

2.1

0 500 1000strip#

Cin

t [p

F]

Seg1

Seg2

Seg3

Seg4

Three-Probe MethodStrip Scan of Cinter

1.865

1.87

1.875

1.88

1.885

1.89

1.895

1.9

1.905

1.91

0 200 400 600 800 1000 1200

strip #

Cin

t [pF

]

W37Seg1

W37Seg2

0

20

40

60

80

100

120

140

160

180

0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4

Interstrip Capacitance [pF]

Segment4

Segment3

Segment2

Segment1

00.20.40.60.8

11.21.41.61.8

2

0 200 400 600 800 1000 1200

S trip Num ber

Inte

rstr

ip c

apac

itan

ce [

pF

]

S egment 1S egment 2

S egment 3S egment 4

Strip Scan of Cint by Two-probe and Three-probe methods

Hartmut Sadrozinski initiated three-probe method for the Strip Scan of Cint

The aim of strip-to-strip measurements is to study strip integrity and uniformity of electrical characteristics over the whole sensor .It requires probing 1280 strip pads on each of four sensor segments. A switching matrix was used to perform multiple tests on adjacent strips at each step of an automatic probe station (simultaneous measurement of Ccoupl, Rbias, Istrip, Idiel, Rint,Cint)

Very probably capacitance of the switching matrix is not stable and it changes by several hundreds of fF.

Similar non-stability observed in Stony Brook and Prague

FWHM=12fF

Three-probe method confirmed perfect parameter uniformity over whole large Hamamatsu sensor

Measurement in Prague with three-probe method without switching matrix


Two-probe method

Time Evolution of Cint

1.81.821.841.861.88

1.91.921.941.961.98

2

0 100 200 300 400 500 600 700

Time [min]

Cin

t[p

F] 1MHz

100kHz

Bias Scan of Cint

1

1.5

2

2.5

3

3.5

4

-250-150-50 Vbias[V]

Cin

t[pF

]

1MHz

100kHz

Time Evolution of Inter-strip Capacitance

RH=32-35%, T=22C

Cint measured by three-probe method at 100kHz and 1MHz test frequency

A. Chilingarov, Nucl. Instr. and Meth. A 560 (2006) 118-121.

There is no decrease of Cint with time as it was observed on SCT sensors

Very good surface isolation of ATLAS07 sensors


Coupling Capacitance/Bias Resistance

10

Coupling Capacitance / strip

64.0

65.0

66.0

67.0

68.0

69.0

70.0

71.0

72.0

73.0

74.0

0 100 200 300 400 500 600 700

-Vbias [V]

Ccp

l [p

F]

W32-Seg2

W35-Seg2

W37-Seg1

W37-Seg2

W37-Seq3

W37-Seg4

W38-Seg1

W38-Seg2

W38-Seg3

W38-Seg4

W39-Seg1

W39-Seg2

W39-Seg3

W39-Seg4

ATLAS07-Series

1 kHz test frequency, CR in ParallelVdep

ATLAS07 Specification: Ccpl measured between strip metal (AC pad) andstrip implant (DC pad) at 1kHz with CR in parallel ≥ 20pF/cm

Ccpl/cm>27.8pF

Frequency Dependence of Coupling Capacitance

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10

20

30

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50

60

70

80

0.1 1 10 100 1000

Freq [kHz]

Ccp

l [p

F]

W38-Seg1

W38-Seg2

W38-Seg3

W38-Seg4

W35-Seg2

W37-Seg1

W37-Seg2

W37-Seg3

W37-Seg4

W39-Seg1

W39-Seg2

W39-Seg3

W39-Seg4

ATLAS07 Series I

Vbias = -20V, CR in Parallel

Polysilicon Bias Resistance

1.0001.0501.1001.1501.2001.2501.3001.3501.4001.4501.500

0 200 400 600-Vbias [V]

Rb

ias [

MO

hm

]

W32-Seg1

W32-Seg2

W37-Seg1

W37-Seg2

W37-Seg3

W37-Seg4

W38-Seg1

W38-Seg2

W38-Seg3

W38-Seg4

ATLAS07 Series I

IV scan made by SMU for voltages 1V-6V applied to implant DC pad. Rbias=dUappl/dI

Rbias is constant while n-p junction is closed (Vbias=-0.7V)

ATLAS07 Specification: Rbias = 1.5±0.5MΩ


Strip Scan of Coupling Capacitance and Bias Resistor

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500

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2000

2500

0 200 400 600 800 1000 1200

S trip Num be r

Bia

s r

es

ista

nc

e [

kO

hm

]

S egment 1

S egment 2

S egment 3

S egment 40

200

400

600

800

1000

12001

1.0

8

1.1

6

1.2

4

1.3

2

1.4

1.4

8

1.5

6

1.6

4

1.7

2

1.8

1.8

8

1.9

6

Bias Resistance [MOhm]

Segment 4

Segment 3

Segment 2

Segment 1

In the strip scan Ccoupl and Rbias are measured by LCR meter between AC pad and Bias Ring, CR in series at 100kHz test frequency


FWHM=120kΩ

AC pad

DC pad

Rinter

Bias Ring

2 DC pads contacted: Rint, Istrip1 AC pad and BR: Ccoupl, Rbias, Idiel3 AC pads contacted: Cinter

FWHM=1.5pF

No openings and shorts were found on tested sensors W15, W16, W23, W25, W38 – in total 23040 strips

Strip Scan of the Strip Current and Inter-strip Resistor

7

7.2

7.4

7.6

7.8

8

8.2

8.4

8.6

0 50 100 150 200 250

B ia s Volta g e [-V]

Inte

rstr

ip C

on

du

ctan

ce [

pA

/V]

W25-1

-0.9-0.8-0.7-0.6-0.5-0.4-0.3-0.2-0.1

0

0 200 400 600 800 1000 1200 1400

S trip Num be r

Str

ip c

urr

ent

(nA

)

S ec tion 1

S ec tion 2

S ec tion 3

S ec tion 4

0

50

100

150

200

250

300

0 5 10 15 20 25 30

Conductance [pA/V]

Series4

Series3

Series2

Series1

Rinter=1/conductance is equal to 300GΩ/cm

W23

The inter-strip resistance has been measured on pair of strips of a fully depleted sensor:SMU applied voltages ±10V to the DC pad and current to ground was measured on second strip.

Strip current was measured between the DC pad on an implant strip and the ground of a fully depleted sensor.Istrip probes the bulk and n-implant homogeneity


Current through the coupling dielectric

The current flowing through the couplingdielectric was measured by SMU at 100V applied to the AC pad


Sensor W25 Idiel

0

0.1

0.2

0.3

0.4

0.5

0.6

0 500 1000 1500

Strip Number

I die

l (nA

) Section 1

Section 2

Section 3

Section 4

No pinhole have been observed on all tested sensors W23, W25, W38 – in total 12800 strips

ATLAS07 Specification

Measurement

Leakage Current < 200 µA at 600 V 200 nA – 370 nA

Full Depletion Voltage

< 500 V 190 V – 245 V

Coupling Capacitance at 1 kHz

> 20 pF/cm >28 pF/cm

Silicon Bias Resistance

1.5±0.5 MΩ 1.3 MΩ -1.6 MΩ

Current through dielectric

Idiel < 10 nA

Pinhole: Idiel

>>10 nA

< 10 nA

Strip Current No explicit limit < 2 nA

Inter-strip Capacitance3 probe method 100kHz5 probe method

< 1.1 pF/cm 0.7 pF/cm – 0.8 pF/cm0.66pF/cm- [1]0.75pF/cm

Inter-strip Resistanceper cm

> 10x Rbias ~

15 MΩ

> 150 GΩ

[1] For a noise estimate the five-probe method

Comparison of measured parameter values with Technical Specification

All tested sensors satisfied Technical Specification of non-irradiated sensors for leakage current and full depletion voltage as well as for coupling capacitance, bias resistance, inter-strip capacitance and resistance measured with the bias voltage scan. The onset voltage of micro-discharges for ATLAS07 large area sensors is VMD > 1000V.

Strip scans were performed on six sensors. Measurements of coupling capacitance and the current going through coupling dielectric show that there are no defects on 23040 tested strips: no pinholes, punch-through defects, shorts, or openings of metal strips. Measurements of coupling capacitance and bias resistance on one strip as well as measurements on pairs of strips ofthe inter-strip resistance and the three-probe measurement of Cint confirmed no systematic deviations from uniform distributions.


All evaluated sensors passed the quality acceptance tests

Punch-through Voltage

Effective ResistanceSensor W37

0

0.5

1

1.5

2

-80 -60 -40 -20 0 20 40 60 80 100 120

Uappl

Eff.

Re

sist

an

ce {

MO

hm

]

Seg1

Seg2

Seg3

Seg4

Punch-through voltage vs Vbias

0

5

10

15

20

25

30

0 100 200 300 400 500

Baias voltage [-V]

Punc

h-th

roug

h vo

ltage

[-V]

Eff. Resistance of large W37 sensor

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

-30 -20 -10

Uappl [V]

Effe

ctiv

e R

esis

tan

ce

[M

Oh

m]

#1240 BR

#1180 BR

#1080 BR

# 880 BR

#320 BR

#40 BR

#2 BR

#2 Opp BR

#40 Opp BR

#320 Opp BR

#640 Opp BR

#1000 Opp BR

#1240 Opp BR

#640 BR

Eff. Resistance dependence on reverse bias voltage

0.1

1

10

-30 -20 -10

Uappl [V]

Effe

ctiv

e re

sist

ance

[M

Ohm]

-20V

-60V

-120V

-240V

-360V

-500V

It was found that the behavior of 1 cm test structures with and without PTP was very similar (Z3 and Z4)(S.Lindgren et al) Voltage is applied on DC pad and currentis measured on bias ring.Hartmut Sadrozinski initiated measurement for full sizesensor

Full size sensors with 2.38cm strips with p-stop only have similarbehavior (Sensor W37) as mini-sensors.

PRELIMINARYa) DC pad closely to bias resistor (BR)b) DC pad on opposite side to BR

Case b) has PTV higher by 1,2V than case a) and eff. res. is also higher by 0.1MOhm for b) than for a). No dependence on strip # was seen.

Punch-through voltage (PTV) depends on bias voltage

Mini-sensors


Full-size ATLAS Sensor Testing

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