SMART

Study of radiation damage induced by 26MeVStudy of radiation damage induced by 26MeV protons and reactor neutrons on heavily irradiated MCz, protons and reactor neutrons on heavily irradiated MCz,

FZ and Epi silicon detectors FZ and Epi silicon detectors N. Manna

Dipartimento Interateneo di Fisica & INFN di Barion behalf of the SMART Collaboration*

8th RD50 - Workshop on Radiation hard semiconductor devices for very high luminosity colliders PRAGUE, 25-28 June, 2006

(*) INFN sections of Bari, Firenze, Perugia, Pisa;

External collaborators INFN Padova, Trieste & ITC-IRST Trento

Layout and materials of SMART detectors

Post-irradiation measurements Analysis: MCz n Inversion or Double Junction? CCE MCz p

Epitaxial MOS – Interstirp Capacitance

Conclusions

SMART

Wafer LayoutWafer Layout

RD50 common wafer procurement (produced by Okmetic - Vantaa, Finland)

Wafer Layout designed by the SMART Collaboration

Masks and process by ITC-IRST

10 different strip geometriesMicrostrip detectors

Inter-strip Capacitance test

Test2: GCD, Van der Paw Test1: Diode+Mos

Square MG-diodes

Round MG-diodes

50 mm pitch 64

strips

100 mmpitch 32

strips

S1 S2 S3 S4 S5 S6 S7 S8 S9 S10

SMART

PRODUCTIONPRODUCTION

RUN II n-on-p

24 wafers

<100> ρ>500 *cm thick=300μm

Standard: LTO, sintering @ 420C

no LTO (pass. layer), sint. @ 380C

no LTO, sintering @ 350C

no LTO, sintering @ 380C + TDK

<111> ρ>6KΩ*cm th.=300μm

Standard Process

<100> ρ>1.8 K*cm thick=300μm

No over-glass passivation

Low dose p-spray (3.0E12 cm-2)

High dose p-spray (5.0E12 cm-2)

<100> ρ>5KΩ*cm th.=200 mm

Low dose p-spray (3.0E12 cm-2)

High dose p-spray (5.0E12 cm-2)

MCz Samples Fz Samples

RUN I p-on-n

22 wafers

MCz Samples

ρ≈500Ω*cm th.=150μm

Epi Samples

SMART

Irradiation with reactor neutrons in Ljubljana

12 fluences: 5.0x1013 8.5x1015 1-MeV n/cm2

27 mini-sensors, 11 test structure (capts),100 diodes

60 % n-type, 40 % p-type

Thanks to V.Cindro and G.KrambergerIrradiation with 26 MeV protons at the

Cyclotron of the Forschungszentrum Karlsruhe

10 fluences: 1.2x1014 - 6x1015 1-MeV n/cm2

20 mini-sensors, 8 test structure(capts), 100 diodes

60 % n-type, 40 % p-type

Thanks to A. Furgeri

April 2006

June 2006

Set up for the irradiation @ JSI(Ljubljana)

Set up for the irradiation @ FZK(Karlsruhe)

IrradiationIrradiation

SMART

Post Irradiation CharacterizationPost Irradiation Characterization

On Diodes: IV and CV measurements (@ 0 °C or 20 °C) - immediately after irradiation before annealing - repeated after annealing steps (@ 20, 60 or 80 °C)

- Charge Collection Efficiency in order to: (1) follow the radiation damage evolution on bulk current and effective doping concentration; (2) determine the effective irradiation fluences (3) estimate the inversion and double junction fluence

(4) test Vdep with charge collection to validate CV measurements and Determine Charge Collection Efficiency at full depletion

On Mos devices: CV (@ 0 0C)

- immediately after irradiation before annealing - repeated after annealing steps(@ 80 0C)

in order to study: variation of the oxide charge as a function of the irradiation fluence

in order to understand the behavior of the interstrip capacitans

SMART

Depletion voltage after irr.Depletion voltage after irr.(Fz n Type inversion)(Fz n Type inversion)

T=200C

PROTON IRRADIATION We are following annealing at room

temperatureTypical behaviour for

standard FZ_n

SMART

Depletion voltage after irr.Depletion voltage after irr.(MCz n Type inversion?)(MCz n Type inversion?)

The annealing behaviour is typical of type inverted (p-type) material after Φ4 , but ……

T=200C

PROTON IRRADIATION

SMART

0.0E+00

5.0E+03

1.0E+04

1.5E+04

2.0E+04

2.5E+04

3.0E+04

0 0.01 0.02 0.03x (cm)

E (

V/c

m)

V = 282 V

Double Junction (DJ) effectDouble Junction (DJ) effect

For very high fluences (of the order of 1014 neq/cm2) a depletion region can be observed on both sides of the device for STFZ p+/n diodes. In STFZ DJ arises after inversion. The opposite in MCz! This may explain Vdep(,t) profiles.

•Double junction effect has been observed on MCz already at= 3×1014 n/cm2

•At the fluence =1.3×1015 n/cm2 the dominant junction is still on the p+ side

Fake “SCSI” on MCz at ~2×1014 neq/cm2

1. Minimum on Vdep vs fluence

2. Slope of annealing curves

Electric field extracted from fit - TCT data

p+ n+

No SCSI on MCz up to

~1.3×1015 neq/cm2

TCT measurements

Strip readoutside: no overdepletion

SMART

Double junction modelDouble junction model

21

2121

3NNNN

NNVdep

022

11

bN

bN i

bi = introduction rate of defect in the junctions

PROTON IRRADIATION

Фi =inversion fluence

Ф0 =double junction formation

fluence

SMART

Annealing @60 Annealing @60 00CC (MCz n Type)(MCz n Type)

NEUTRON IRRADIATION

T=600C

Φ (1014n*cm-2) Φ (1014n*cm-2)

SMART

Annealing @ 80Annealing @ 8000CC

The difference in the annealing for protons started at longer ann. Times, where MCz improved.

NEUTRON IRRADIATIONPROTON IRRADIATION

Up to 60 min at 80 C for

neutron irr. Fz and MCz show

the same behavior.

extrapolated

SMART

0 100 200 300 400 500

0.0

0.2

0.4

0.6

0.8

1.0

0.0

0.2

0.4

0.6

0.8

1.0

VCCE

=2700V

VCV

=27020V

No

rma

lized

C-2

CC

E

Voltage, V

CCE CV

300m Cz p-type diode

=0.68x1014cm-2 annealed for 252' at 80°C

Charge Collection EfficiencyCharge Collection Efficiency Si detectors MCz p-type

= 6.8 1013 cm-2

CCE 100%At full depletion

VCCE ~ VCV

0

100

200

300

400

500

600

700

0 50 100 150 200 250 300 Annealing time (min)

De

ple

tio

n V

olt

ag

e (

V)

SMG16 f=0.68E15SMG12 f=5.4E14SMG10 f=4E14SMG7 f=2.7E14SMG5 f=2E14SMG4 f=1.4E14SMG26 f=1E14 SMG2 f=0.68E14SMG1 f=0.4E14

PROTON IRRADIATION

Carlo Tosi, Mara Bruzzi II Workshop Trento 2006

SMART

= 2.7 1014 cm-2

CCE ~ 86% 500VCCE ~ 96% 700V

VCCE = 540 V VCV = 500V

but

0

100

200

300

400

500

600

700

0 50 100 150 200 250 300 Annealing time (min)

De

ple

tio

n V

olt

ag

e (

V)

SMG16 f=0.68E15SMG12 f=5.4E14SMG10 f=4E14SMG7 f=2.7E14SMG5 f=2E14SMG4 f=1.4E14SMG26 f=1E14 SMG2 f=0.68E14SMG1 f=0.4E14

Charge Collection EfficiencyCharge Collection Efficiency of Si detectors MCz p-type

PROTON IRRADIATION

Carlo Tosi, Mara Bruzzi II Workshop Trento 2006

SMART

= 1.36 1014 cm-2

CCE of single pad MCz Si n-on-p

0 100 200 300 400 500 600

0,0

0,2

0,4

0,6

0,8

1,0

0,0

0,2

0,4

0,6

0,8

1,0

VCCE

=3500VV

CV=34020V

300m Cz p-type diode

=2x1014cm-2 annealed for 60' at 80°C

No

rmal

ized

C-2

CC

E,

%

Voltage, V

CCE CV CCE 100%

at full depletion VCCE ~ VCV = 340V

= 6.8 1014 cm-2

V = 800VT = - 30°C

CCE 75 % @ Vfd = 350VCCE 90% @ 700V

PROTON IRRADIATION

SMART

0 10 20 30 40 50

0

100

200

300

400

500

600

Lubiana neutrons (Padova) Lubiana neutrons (Firenze) 26 MeV protons

Dep

leti

on

Vo

ltag

e (V

)

Fluence (x1014

cm-2

1 MeV n)

Epitaxial 150µmEpitaxial 150µm

• Strong increase of the depletion voltage vs fluence

• Vdepl at the minimum is around 10 V: inversion or double junction effect?

SMART

Epitaxial AnnealingEpitaxial Annealing

0 20 40 60 80 100 120 1400

100

200

300

400

500

600

700

=8.5x1014 cm-2

=16x1014 cm-2

= 42.5 x1014 cm-2Dep

leti

on

Vo

ltag

e (V

)

Annealing Time at 80oC (min)

Neutrons Irradiation - Annealing

0 10 20 30 4040

60

80

100

120

140

=6.05 x 1014 cm-2

Annealing Time at 80oC (min)

Dep

leti

on

Vo

ltag

e (V

) Proton Irradiation - Annealing

Neutrons: “inverted-like” behaviour

Protons: “not inverted-like” behaviour

SMART

MOSMOS

-50 -25 0 25 50 75 100 125 150

1.12x10-10

1.16x10-10

1.20x10-10

1.24x10-10

1.28x10-10

1.32x10-10

1.36x10-10

= Pre-irr

= 1.2 x1014

cm-2

=3.6 x1014

cm-2

=6.1 x1014

cm-2

=18 x1014

cm-2

Ca

pa

cit

an

ce

(F

)

-V gate (V)

vfbCint

See Piemonte’s talk 7th RD50 - Workshop

Measured before annealing @ 0oC

SMART

1.16E-10

1.17E-10

1.18E-10

1.19E-10

1.20E-10

1.21E-10

1.22E-10

1.23E-10

1.24E-10

1.25E-10

1.26E-10

-200 -100 0 100 200 300

W084 T1 14 1KHz 6E14

W084 T1 14 2 min

W084 T1 14 4 min

W084 T1 14 12 min

W084 T1 14 20 min

Annealing studies at 80 °C on the MOS structure

Fz p-type with high p-spray f= 1K Hz

The Vfb decreases with annealing time until saturation

- Vgate (V)

SMART

ConclusionsConclusions

1. From TCT measurements the MCz n-type diodes irradiated with protons are not type inverted up to fluence 1*1015 ncm-2 and DJ observed above 3*1014ncm-2

2. Experimental measurements are in better agreement with a Double Junction model than standard one.

3. Work in progress to improve this model in agreement with the experimental measurements and investigate the annealing behavior through this model.

4. No difference with the irradiation (proton-neutron) in terms of DJ model.

5. CV and CCE profiles and full depletion voltage values in good agremeent up to Φ = 1.36 1014 cm-2.

6. CCE 96% and 90% at the highest fluences tested (2.7 - 6.8*1014cm-2 ) and at different annealing steps ( 0 and 252min at 80°C).

7. Epitaxial-150μm n-type diodes behaves like “inverted” @ 8*1014cm-2

8. The Vfb increases continuously with fluence9. Interstrip Capacitance variation observed on Microstrip sensors up to 6*1014cm-2.