performance of thin edgeless n -on- p planar pixel sensors for atlas upgrades
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Performance Of Thin Edgeless n-on-p Planar Pixel Sensors for ATLAS
Upgrades
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A. Bagolini1, M. Bomben2, M. Boscardin1, L. Bosisio3, G. Calderini2,4, J. Chauveau2, G. Giacomini1, A. La Rosa5, G. Marchiori2, N. Zorzi1
1 - Fondazione Bruno Kessler (FBK), Trento, Italy
2- Laboratoire de Physique Nucleaire et de Hautes Énergies (LPNHE), Paris, France
3- Università di Trieste, Dipartimento di Fisica and INFN, Trieste, Italy
4- Dipartimento di Fisica, Università di Pisa, and INFN Sez. di Pisa, Pisa, Italy
5- Section de Physique (DPNC), Université de Genève, Genève, Switzerland9th “Trento” Workshop on Advanced Silicon Radiation Detectors (3D and p-type Technologies)Genova, February 26th-28th 2014
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Edgeless pixels via DRIE
• Joint FBK-LPNHE project Goal: thin, edgeless pixel sensors Target: intermediate layers How: make the border a damage
free ohmic contact by DRIE• 200 μm thick n-on-p production
• 500 μm temporary support wafer
• Pixel-to-trench distance as low as 100 μm
Main production splits:• p-spray dose• p-stop: present/absent• metal overhang: present/absent • 1 wafer with no DRIE
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FEI4 sensors characteristics
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The active edge project
Goal: HL-LHC ATLAS intermediate pixel layer
n-on-p production Pixel/trench distance as low as 100 μm
oxide
oxideSupport wafer
Field plate
p-substrate
Substrate contact
Trench(poly filling)
p-sprayp-stop n-pixel
EdgeLess Pixel Test Structures
No GR 1 GR 2 GR
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Pixel pitch = 250 mm x 50 mm
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Breakdown studies
p-spray dose = 3e12 cm-2 p-spray dose = 5e12 cm-2
Little dependence on trench distance
I-V on FE-I4 sensorAutomatic measurement with Temporary metal
trench
Temporary metal
Pads of temporary metal
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I-V vs p-spray doses
P-spray dose: 5x1012/cm2
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VBD as expected from IV on test structures
p-spray dose = 3e12 cm-2 p-spray dose = 5e12 cm-2
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• Samples were irradiated with reactor neutrons (JSI, Ljubljana)– Limited annealing at room temperature
α ~ 4.7x10-17 A/cm
Results in agreement with literature
Measurements on a pad diode
log(C) – log(V)
I – V
Irradiation at JSI (Ljubljana)F: 2.5E15 1-MeV neq /cm2
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Interpixel resistance after irradiation
p-spray dose = 3x1012/cm2
Excellent pixel isolation even after irradiation
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Irradiated FEI4 test structures
p-spray dose = 3x1012/cm2I PA
D [A
]
No GR
1,2,3 GRs
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Irradiated FEI4 test structuresI G
R [A
]
3 GRs
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FE-I4 modules
trenchTemporary metal
• Modules are being assembled at IZM by bump-bonding a few FE-I4 sensors to FE-I4B ROC• Delivery expected by end of November
after resist patterning
Before temporary metal removal After temporary metal removal
2 modules assembled for test
sensor S9 400 µm & 10 GRs sensor S7 200 µm & 3 GRs
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400 µm, 10 GRs
It wasIt is
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Source scan
Disconnected pixels
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Conclusions & Outlook
• Irradiates structures: OK• FE-I4 two test modules: mixed results
– Tackling issues• Next: 10 modules to be assembled• Goal: on beam next autumn
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