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 cm 1.0 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
Studies on n and p-type MCz and FZ structures of the SMART Collaboration irradiated at fluences from 1.0 E+14 to 5.6E+15 p cm -2. L. Borrello, A.Messineo, G. Segneri, D. Sentenac Università di Pisa & INFN Pisa A. Macchiolo Università di Firenze & INFN Firenze - PowerPoint PPT Presentation
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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
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
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
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
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
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..
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
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