Studies on n and p-type MCz and FZ Studies on n and p-type MCz and FZ structures structures

of the SMART Collaboration of the SMART Collaboration irradiated at fluences from irradiated at fluences from 1.0 E+14 to 5.6E+15 p cm1.0 E+14 to 5.6E+15 p cm-2-2

RD50 Trento Workshop

ITC-IRST 28/02/2005-01/03/2005

L. Borrello, A.Messineo, G. Segneri, D. Sentenac Università di Pisa & INFN Pisa A. Macchiolo Università di Firenze & INFN Firenze

SMART Collaboration

Overview

•The SMART run I and II: layout and material

•Pre-irradiation measurements

•Irradiation fluences and layout

•Experimental set-up

•Results on diodes and mini.sensor for n and p-type MCz and Fz at = 1.0 and 4.4 E+14 p cm-2

•Results at =5.5 E+15 p cm-2

Microstrip detectors

Inter strip Capacitance test

Test2

Test1

Pad detector

Edge structures

Square MG-diodes

Round MG-diodes

50 um pitch

100 um pitch

Wafer layout - SMART

RUN I p-on-n

22 wafers Fz, MCz, Cz, Epi

RUN II n-on-p

24 wafers Fz, MCz

Material under investigationMaterial under investigation

p-on-n MCz <100> p-on-n MCz <100> > 500 > 500 cm cm

standard process standard process W364 W364

no LTO, sintering @ 380 no LTO, sintering @ 380 ooC

W115,W130,W164 no LTO, sintering @ 380 no LTO, sintering @ 380 ooC + TD killing C + TD killing W160W160

n-on-p MCz, no OG <100> n-on-p MCz, no OG <100> > 1.8 K> 1.8 K cm cm

low dose p-spray 3E+12 cm low dose p-spray 3E+12 cm -2 -2 W66 high-dose p-spray 5E+12 cm high-dose p-spray 5E+12 cm -2 -2 W182 Fz reference samples Fz reference samples n-type <111> n-type <111> W1254 (std) , W1255 (T=380 C)W1254 (std) , W1255 (T=380 C) p-type (passivated) p-type (passivated) W14 (low dose p-spray),W14 (low dose p-spray), W37W37 (high dose p-spray)(high dose p-spray)

Pre-irradiation measurementsPre-irradiation measurements

Bulk current & Depletion VoltageBulk current & Depletion Voltage Diodes & Mini-sensorsDiodes & Mini-sensors

Strip capacitive loadStrip capacitive load Cap-ts & Mini-sensorsCap-ts & Mini-sensors

Surface currentSurface current GCD (Metal, Poly)GCD (Metal, Poly)

Oxide trapped charge Oxide trapped charge MOSMOS

Wafers qualified : Fz, MCz (n) , MCz(p) , Cz

Wafer MCz Wafer MCz n-typen-type 160 pre irr 160 pre irr

Diodes Mini-sensors

Wafer MCz Wafer MCz n-type 160 160

380 < Vdepl mini-sensor < 500 V

Mapping of the wafer resistivity

Strong variation of the bulk resistivity both in n-type and p-type MCz wafers.

This reflects also in the depletion voltage spread for the mini-sensors.

MCz n-type – no LTO -

W164 430 < Vdepl < 520 V

W115 520 < Vdepl < 580 V

W130 400 < Vdepl < 460 V

Wafer MCz Wafer MCz p-type

Measured in IRST

Wafer MCz Wafer MCz p-typep-type 66 pre-irr 66 pre-irr

MCz and Fz p-type mini-sensors of 100 m pitch show an early breakdown before irradiation.

The problem may be related to the fact that no special mask has been used to diffuse the p-spray.

Diodes Mini-sensors

Irradiation Fluences- SPS 24 GeV protons

•A hardness factor of 0.62 for the 24 Gev protons has been adopted when calculating the alpha parameter

Total

9.63E+13  

Total

4.42E+14  

Total

5.56E+15

TR 8.06E+13 TR 4.19E+14 TR5.35E+15

TL 8.56E+13 TL 4.16E+14 TL4.92E+15

BR 1.13E+14 BR 4.34E+14 BR5.95E+15

BL 1.18E+14   BL 4.50E+14   BL5.48E+15

p cm-2 p cm-2 p cm-2

Irradiated Structures

Irradiation set-up

The mini-sensors (active area=0.32 x 4.5 cm22) have been placed with an inclination of about 26o to be irradiated uniformely by the beam (section = 2x2 cm22)

The diodes and the the test-structures T1, T2 and T3 have been placed orthogonally to the beam direction

Experimental Set-up in Firenze and Pisa

• Karl-Suss Probe-Station instrumented with a Thermo-Chuck and an air-chiller that can operate in the temperature range -40 oC < T < 200 oCz

Firenze

Pisa

• Karl-Suss Probe-Station SOM3 Chiller : - 40 oC +80 oC

Chuck liquid cooled

Measurement procedure

The structures have been kept in the fridge (T< -10 oC) whenever not in use

A first measurement (IV and CV) has been performed before any annealing

Two annealing temperatures have been used for these structures: 60oC and 80oC

After each annealing step the following measurements have been performed:

I-V curves at T=20oC or at 0oC

CV curve at T=0oC and f=10 KHz

Alpha parameter calculated with currents at depletion voltage + 50 V, at T=20oC (or with currents at T=0oC normalized to T=20oC) , after 8 minutes at Tannealing=80oC or 80 minutes at Tannealing=60oC

Neff dependence on fluence calculated after full beneficial annealing

Measurements on the structures irradiated at a fluence of 1.0 E+14 at a fluence of 1.0 E+14 and 4.4 E+14 p cm-2and 4.4 E+14 p cm-2

All results are

preliminary!

0

1E-17

2E-17

3E-17

4E-17

5E-17

6E-17

7E-17

0 5E+13 1E+14 1.5E+14 2E+14 2.5E+14 3E+14 3.5E+14 4E+14 4.5E+14

Fluence [p/cm2]

a (A

/cm

)

MCz p-on-n

MCz n-on-p

FZ p-on-ns

Average MCz p-on-n= 4.37E-17 A/cm

Average MCz n-on-p= 4.16E-17 A/cm

Parametera - MCz p and n-type

Alpha parameter calculated with currents at depletion voltage +50V, at T=20oC (or with currents at T=0oC normalized to T=20oC) , after 8 minutes at Tannealing=80oC or 80 minutes at Tannealing=60oC

a Annealing MCz p and n-type

0

1

2

3

4

5

6

7

8

9

10

1 10 100 1000 10000 100000

Annealing Time at T=60 C (min)

a v

alue

s (1

0 17

[A

cm

-1])

W164 MGD17 W164 MGD21

W164 T1-10 W164 SENSOR 3

W164 SENSOR 5 W164 SENSOR 7

W160 MGD 10 W160 MGD21

W160 T3-1 W130 T1-6

W130 T1-4 W182 MGD9

W182 MGD10 W182 MGD11

W182 MGD12

80 min at T=60C

0

5E+21

1E+22

1.5E+22

2E+22

2.5E+22

3E+22

3.5E+22

4E+22

4.5E+22

0 100 200 300 400 500 600

Bias voltage

Cap

acita

nce

-2 (F

-2)

W164 MGD17Fluence=1.0E+14W164 MGD21Fluence=4.4E+14W182 MGD12Fluence=1.0E+14W182 MGD11Fluence=4.4E+14

Examples of CV curves on MCz diode after irradiation

-600

-500

-400

-300

-200

-100

0

100

200

1 10 100 1000 10000

Annealing Time at T=80 C [min]

D N

eff [

10

10 cm

-3]

W182 MGD12 Fluence=1.0E+14

W182 MGD 9 Fluence=1.0E+14

W182 MGD10 Fluence=4.4E+14

W182 MGD11 Fluence=4.4E+14

W164 MGD 17 Fluence=1.0 E+14

W164 T1-10 Fluence=4.4E+14

W164 SENSOR 3 Fluence=1.0E+14

W164 MGD 21 Fluence=4.4E+14

W164 SENSOR 7 Fluence=4.4E+14

W164 SENSOR 5 Fluence=4.4E+14

Annealing studies MCz n and p-type

MCz p-type

=1.0 and 4.4 E+14 p cm-2

MCz n-type

=1.0 E+14 p cm-2

MCz n-type

=4.4 E+14 p cm-2

= 1.0 E+14 p cm-2

= 4.4 E+14 p cm-2

Annealing studies (Vdepl) MCz n-type

W164 MCz n-type

Annealing at T=80oC

Fz and MCz n-type

Annealing at T= 60oC

Fz

Annealing studies (Vdepl) MCz and Fz p-type

W182 MCz p-type

Annealing at T=80oC

Fz and MCz p-type

Annealing at T= 60oC

Fz

= 1.0 E+14 p cm-2

= 4.4 E+14 p cm-2

Na : beneficial annealed fraction

ga*

MCz p-type

MCz n-type

Fz n-type

0

50

100

150

200

250

300

350

400

450

500

-0.5 0.5 1.5 2.5 3.5 4.5 5.5

Fluence [1014 p cm-2]

Dep

leti

on

Vo

ltag

e (

V)

W1255 MGD10 Fz 380W1255 MGD11W160 MGD10 MCz 380+TDKW160 MGD21W160 T3 1W160 T1 6W130 T1 4 MCz 380W130 T1 6W164 MGD17 MCz 380W164 MGD21W164 T1 10

Depletion Voltage after full beneficial annealing

MCz and Fz p-on-n

before irradiation

Depletion Voltage after full beneficial annealing

MCz and Fz n-on-p

before irradiation

Neff variation with fluence

V depletion after 4 minutes at Tannealing=80oC or 40 minutes at Tannealing=60oC

o

0

100

200

300

400

500

600

700

0 5E+13 1E+14 1.5E+14 2E+14 2.5E+14 3E+14 3.5E+14 4E+14 4.5E+14 5E+14

Fluence [p cm-2]

|Nef

f|

[10

10

cm-3

]

W160 MCz p-on-n 380 + TDKW164 MCz p-on-n 380W130 MCz p-on-n 380W182 MCz n-on-pW1255 FZ p-on-n

Studies on mini-sensorsStudies on mini-sensors

Leakage current after irradiation as expected from the Leakage current after irradiation as expected from the studies on the diodes of the same wafer studies on the diodes of the same wafer

Neff annealing follows behaviour observed on diodesNeff annealing follows behaviour observed on diodes

Moderate increase of inter-strip capacitance after Moderate increase of inter-strip capacitance after irradiationirradiation

0.0E+00

2.0E-054.0E-05

6.0E-05

8.0E-05

1.0E-041.2E-04

1.4E-04

1.6E-041.8E-04

2.0E-04

2.2E-04

2.4E-04

0 100 200 300 400 500 600

Vbias(V)

Leak

age

Cur

rent

(A)

s2-66 MCz(p) f3 s4-w37 MCz(p) f3 s1-14 MCz(p) f2 s1-37 MCz(p) f2 s1-66 MCz(p) f2

s1-w1255 Fz(n) f3 s3-w115 MCz(n) f3 s4-115 MCz(n) f3 s1-w160 MCz(n) f3 s7-w130 MCz(n) f2

IV on mini-sensors

= 4.4 E+14

= 1.0 E+14

f= 1.0 E+14 p cm-2

f= 4.4 E+14 p cm-2

Fz W37 – n-on-p mini-sensors High p-spray

Breakdown voltage after irradiation is higher than before irradiation for the same mini-sensors

Variation of the depletion voltage with fluence

0

100

200

300

400

500

600

0 1E+14 2E+14 3E+14 4E+14 5E+14

Fluence [p cm-2]

De

ple

tio

n V

olt

ag

e (

V)

W164 diode -MCz n-type

W164 mini-sensors MCz n-type

0

50

100

150

200

250

300

350

400

0 2E+14 4E+14 6E+14

Fluence [p cm-2]

Dep

leti

on

Vo

ltag

e (V

)W66-S1 MCz p-type

W66-S2 MCz p-type

W37-S1 Fz p-type

W37-S4 Fz p-type

Fz

MCz n-type

Diodes and mini-sensors

MCz p-type

Mini-sensors

Inter-strip capacitance measured on mini-sensors

50 m pitch 100 m pitch

Pre-irradiated n-type 0.8 pF/cm 0.6 pF/cm

MCZ p and n-type = 1-4.4 E+14 p cm-2 1.5-1.7 pF/cm 0.9-1.2 pF/cm

n-type MCz mini-sensors

f= 1.0 E+14 p cm-2

f= 4.4 E+14 p cm-2<111> FZ

C-int decreases for the p-type sensors at increasing fluences. The opposite holds for the n-type sensors.

Strip leakage current in the mini-sensors

0.91.01.11.21.31.41.51.61.71.81.92.0

0 20 40 60 80

strip position

frac

tion

of d

amag

e

Istrip s1 66 Istrip s3 115 Istrip S1 14

Istrip S7 130 Istrip S1 1255

All the strip in the border and in the central region are functioning well.

The current level depends on the position with respect to the beam that is not uniform.

Studies performed at =5.6E+15 p cm-2

No clear depletion voltage found for n-type and p-type MCz diodes

• W164 MCz n-type: measured up to an annealing time of 34 min at T=80oC –

• W182 MCz p-type: up to an annealing time of 230 minutes at T=80 oC

• Estimation of the depletion voltage from the slope of the CV curve after 4 minutes of annealing at T=80 oC: Vdepl>2000 V

0

5E+21

1E+22

2E+22

2E+22

3E+22

3E+22

4E+22

4E+22

0 100 200 300 400 500 600 700 800 900 1000

Bias Voltage (V)

Cap

acit

ance

-2

(F

-2)

C-2V W182 MGD01 annealing=8 min

MCz p-type - F=5.5E+15 p cm-2

Taking into account only the region where the bulk capacitance decrease a slight improvement is seen with annealing

Pre-irradiationPre-irradiation1.1. MCz p-type wafers have a stronger resistivity spread than MCz p-type wafers have a stronger resistivity spread than

MCz n-type.MCz n-type.

2.2. The performance of p-type mini-sensors need additional The performance of p-type mini-sensors need additional masks to implant the p-stop. masks to implant the p-stop.

3.3. The n-type MCz mini-sensors perform comparably to the Fz The n-type MCz mini-sensors perform comparably to the Fz ones.ones.

After-irradiationAfter-irradiation1.1. Up to a fluence of 4.4 E+14 p cmUp to a fluence of 4.4 E+14 p cm-2-2 both p-type and n-type both p-type and n-type

MCz material have comparable depletion voltages MCz material have comparable depletion voltages (additional fluence points are needed to draw clearer (additional fluence points are needed to draw clearer conclusions).conclusions).

2.2. p-type mini-sensors show an improved IV after irradiation p-type mini-sensors show an improved IV after irradiation with p-spray.with p-spray.

3.3. Fairly good overall performance of all irradiated mini-Fairly good overall performance of all irradiated mini-sensors with good inter-strip capacitancesensors with good inter-strip capacitance..

Comments

Future plansFuture plans

Increase measured sample (mini-sensors)Increase measured sample (mini-sensors)

Detailed study of higher fluence radiation effectDetailed study of higher fluence radiation effect

Irradiate other n and p-type MCz structures with Irradiate other n and p-type MCz structures with 26 Mev Protons in Karlsruhe, especially at 26 Mev Protons in Karlsruhe, especially at fluences around 1E+15 p cmfluences around 1E+15 p cm-2-2 and with neutrons and with neutrons in Liubiana in Liubiana

CCE MeasurementsCCE Measurements1.1. Laser & Laser & source/spectrometer system equipped source/spectrometer system equipped 2.2. Few hybrid (CMS tracker) available Few hybrid (CMS tracker) available 3.3. DAQ system (40 MHz) set-up and running DAQ system (40 MHz) set-up and running

Next slides are BACK-UPNext slides are BACK-UP

Comparison between leakage currents at two fluence point

Currents of W182 MGD01 has been divided by the fluence ratio

0.00E+00

2.00E-12

4.00E-12

6.00E-12

8.00E-12

1.00E-11

1.20E-11

0 100 200 300 400 500 600 700 800 900 1000

Bias Voltage (V)

Cap

acit

ance

(F

)

CV W182 MGD01 annealing=8 min

0

5E+21

1E+22

2E+22

2E+22

3E+22

3E+22

4E+22

4E+22

0 100 200 300 400 500 600 700 800 900 1000

Bias Voltage (V)

Ca

pa

cit

an

ce

-2 (

F -2

)

C-2V W182 MGD01 annealing=8 min

0.00E+00

1.00E-12

2.00E-12

3.00E-12

4.00E-12

5.00E-12

6.00E-12

7.00E-12

8.00E-12

9.00E-12

-25 -20 -15 -10 -5 0 5 10 15

Bias Voltage (V)

Cap

acit

ance

(F

)

CV W182 MGD01 around Vbias=0

MCz p-type - =5.5E+15 p cm-2

-2.50E-05-2.00E-05-1.50E-05-1.00E-05-5.00E-060.00E+005.00E-061.00E-05

-30 -20 -10 0 10 20

Bias Voltage (V)

Cu

rre

nt

(A)

IV W182 MGD01 around Vbias=0

Convolution of a landau and a gaussian functions to extract the average energy loss

Measurement of the Charge Collection efficiency on a MCZ n-on-p MG diode

W160 MCz380+no LTO + TD killing

Florence CCE set-up for single channel devices (thanks to S. Sciortino)

Measurement done before irradiation

Calibration factor e/mV=218.9

e / m = 89

cce

0

0.2

0.4

0.6

0.8

1

1.2

0 100 200 300 400 500

Bias Voltage (V)

Eff

icie

nc

y (

%)

0

5E+21

1E+22

1.5E+22

2E+22

2.5E+22

0 100 200 300 400 500 600

Bias Voltage (V)

Ca

pa

cit

an

ce

-2 (

F-2)

C-V curve on the diode

CCE before irradiation

At V=Vdepl (measured with a CV curve on the diode) the effective thickness for charge collection corresponds to practically all the physical thickness of the wafer

The annealing time spent at T=80oC has been multiplied by ten in this plot

Comparison between annealing at T=60oC and T=80oC

Wafer 164 = 4.4 E+14 p cm-2

Starting Vdepl W164 MGD21= 454 V T1-10 = 440 V

The annealing time spent at T=60oC has been divided by ten in this plot

Comparison between annealing at T=60oC and T=80oC

Wafer 182 = 4.4 E+14 p cm-2

CV on MOS MCZ n-on-p – High dose p-spray

f=100 HzFlat Band Voltage has changed sign