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ComparisonComparison of of RRadiationadiation HHardnessardness of Pof P--inin--N, N, NN--inin--N and NN and N--inin--P Silicon P Silicon PPad ad DDetectors etectors
G.Pellegrini, M.Lozano, F.Campabadal, C.Fleta, C.Loderer, M.Ullan
bCentro Nacional de Microelectronica, Barcelona, 08193, Spain
P.Allport, G.CasseaOliver Lodge Laboratory, The University of Liverpool, UK
CERN-RD50Giulio Pellegrini
OutlineOutline
•Introduction
•Fabrication technology
•Preliminary results
•Conclusion and future work
CERN-RD50Giulio Pellegrini
Object of the investigationObject of the investigation
• Silicon diodes were fabricated simultaneouslyP-in-N N-in-P N-in-N
•Standard and oxygenated silicon
•Diodes were irradiated with 24GeV protons to fluences up to 1x1015cm-2
To understand influence of the fabrication technology in the radiation-induced degradation:
CERN-RD50Giulio Pellegrini
Pad detectorsPad detectors
•Mask designed by Liverpool•Area= 5x5mm2
•Guard ring=200µm•Thickness=280±15µm
N-in-P and N-in-Np-stop
1013 cm-3 1014 cm-3
Std Oxg Std Oxg
P-in-N
Std Oxg
CERN-RD50Giulio Pellegrini
Silicon Silicon MicrostripMicrostrip DetectorsDetectors
•770 strips diodes• 80 µm wide• 61570 µm long• polysilicon biasing resistors•Strips capacitively coupled
Mask set was designed between University of Liverpool and IMB-CNM
CERN-RD50Giulio Pellegrini
Technology: PTechnology: P--inin--N N
• Simple technology, only 5 mask levels.• Bulk inversion to p-type at around 2x1013 1 MeV n. equ. • Collection of holes.
P-in-N
N+ N
P+Guard ring
Inversion Layer
CERN-RD50Giulio Pellegrini
Technology: NTechnology: N--inin--P P
• More complex technology, 7 masks levels• Extra surface insulation, p-stop or p-spray• No type inversion expected• Collection of electrons
N-in-P
P+P
N+
P+ implant
Guard ring
CERN-RD50Giulio Pellegrini
Technology: NTechnology: N--inin--N N
• Complex technology, 10 mask levels• Both surfaces processing• Type inversion but at high radiation fluences
bulk silicon depletes from the N+ side • Collection of electrons after type inversion
N-in-N
N
N+
P+Guard ring
P+ implant
CERN-RD50Giulio Pellegrini
SimulationSimulation
0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,51E9
1E10
1E11
1E12
1E13
1E14
1E15
1E16
1E17
1E18
1E19
1E20
1E21
Con
cent
ratio
n(cm
-3)
Distance(µm)
Measurement Net concentration Boron concentration (after Annealing) Boron concentration (before Annealing)
Boron:Implantation energy=50KeVDose=4.2 *1015cm-3
•Spreading resistance
•Oxide charges 5x1011 cm-2
•Cylindrical coordinates
•Irradiation studies.
0 100 200 300 400 500 600 700
1E-13
1E-12
1E-11
1E-10
1E-9
1E-8
1E-7
1E-6
1E-5
1E-4
1E-3
Cur
rent
(A/c
m2 )
Bias(V)
Pad Simulation Pad experimental
0 50 100 150 200 250 3000,00
2,50x10-11
5,00x10-11
7,50x10-11
1,00x10-10
1,25x10-10
1,50x10-10
Cap
acita
nce(
F/cm
2 )
Bias(V)
Capacitance Simulation Capacitance Experimetal
CERN-RD50Giulio Pellegrini
CharacterisationCharacterisation
1) I-V: Leakage current measurements: Effect of the p-stop on N-in-P and N-in-N diodesBreakdown voltage.
2) C-V: capacitance measurementsfull depletion voltage
3) Radiation hardness: 2 parametersα: “damage” constantβ: the introduction rate of stable defects
CERN-RD50Giulio Pellegrini
Probe station IV and CVProbe station IV and CV
Karl Suss PA200
Low noise measurements
CERN-RD50Giulio Pellegrini
Measurements IV Measurements IV andand CVCV
1: Impedance Analyzer HP 4192A 2, 3: Keithley 2410 SourceMeter4: CERN Bench 5: RS Clock ThermometerCapacitance measured in parallelf=10kHz
4
CERN-RD50Giulio Pellegrini
Irradiation at CERNIrradiation at CERN
7.87E+137.87E+137.87E+13
2.70E+142.70E+142.70E+14
1.02E+151.02E+151.02E+15
7.73E+12-7.73E+12
0.00E+000.00E+000.00E+00
P-in-NN-in-PN-in-N •Protons 24GeV
•Diodes measured before annealing.
•Diodes irradiated without bias.
•Diodes stored at –35C.
•NIEL factor= 0.62 keVcm²/g
Fluences (protons/cm2)
CERN-RD50Giulio Pellegrini
Leakage current measurementsLeakage current measurements
CERN-RD50Giulio Pellegrini
Leakage current for Leakage current for PP--inin--N diodesN diodes
CERN-RD50Giulio Pellegrini
Leakage current for Leakage current for NN--inin--PP diodesdiodes
CERN-RD50Giulio Pellegrini
Leakage current for NLeakage current for N--inin--N diodesN diodes
CERN-RD50Giulio Pellegrini
Parameter Parameter αα
0,0 2,0x1014 4,0x1014 6,0x1014 8,0x1014 1,0x1015 1,2x10150,00
0,01
0,02
0,03
0,04
0,05
0,06
0,07
Cur
rent
Vol
ume
(A/c
m3 )
Fluence(proton/cm2)
P-in-N oxg. N-in-P oxg p-stop 1e13 N-in-N oxg p-stop 1e13
Currents were normalized to 20ºC according to equation: I~T2 exp(-E0/2kT) with E0=1.12 eV. ∆IVol=αφ
CERN-RD50Giulio Pellegrini
CV measurementsCV measurements
f = 10kHz
CERN-RD50Giulio Pellegrini
Full depletionFull depletion
VFD was extrapolated by crossing two straight lines in the logC-logV plot near the kink.
CERN-RD50Giulio Pellegrini
Full depletion vs. fluenceFull depletion vs. fluence
0,0 2,0x1014 4,0x1014 6,0x1014 8,0x1014 1,0x1015 1,2x10150
50100150200250300350400450500550600
0
1x1012
2x1012
3x1012
4x1012
5x1012
6x1012
7x1012
8x1012
9x1012
Effe
ctiv
e do
ping
con
cent
ratio
n N
eff (1
/cm
3 )
Full
depl
etio
n vo
ltage
(V)
Fluence φ (protons/cm2)
NP p-stop 10**14 (Std) NP p-stop 10**13 (Std) NN p-stop 10**14 (Std.) NN p-stop 10**13 (Std.) PN (Std.)
Standard Silicon
0,0 2,0x1014 4,0x1014 6,0x1014 8,0x1014 1,0x1015 1,2x10150
50100150200250300350400450500550600
0
1x1012
2x1012
3x1012
4x1012
5x1012
6x1012
7x1012
8x1012
9x1012
Effe
ctiv
e do
ping
con
cent
ratio
n N
eff (1
/cm
3 )
Full
depl
etio
n vo
ltage
(V)
Fluence φ (protons/cm2)
NP p-stop 10*14 (Oxg.) NP p-stop 10**13 (Oxg.) NN p-stop 10**13 (Oxg.) PN Oxg.
Oxygenated Silicon
The last two points in these plots were used to calculated the value of β.
CERN-RD50Giulio Pellegrini
Parameter Parameter ββ
CERN-RD50Giulio Pellegrini
Conclusions and future workConclusions and future work
Conclusions • Oxygenated detectors have low full depletion voltage after irradiation.• α is lower for N-in-N detectors• Detectors with p-stop of 1014cm-3 have breakdown voltages lower than
detectors with p-stop of 1013 cm-3.• N-in-P oxygenated detectors show a bulk inversion at a fluence of
2.7x1014 p/cm2
Future work:• Annealing studies• Charge collection efficiency• Measurements of microstrip• Simulation• Irradiation up to 1016 protons/cm2