Study of irradiated 3D detectors

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Study of irradiated 3D detectors
Patrick Roy
G. Pellegrini, A. Al-Ajili, L. Haddad, J. Melone,
V. O'Shea, K.M. Smith, V. Wright, M. Rahman
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Overview
Introduction Fabrication -Dry
etching -Laser machining
-Photoelectrochemical etching
-Electrical contacts Results -Before
irradiation -After irradiation Conclusi
on
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Introduction
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Motivation

• 3D detector!

Vdep ? qw2Neff/2e
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Fabrication steps
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Dry etching
Inductively Coupled Plasma

• Mask photoresist
• Gas SF6
• Coating C4F8

• Diameter 10 mm
• Spacing 85 mm
• Depth 130 mm
• Etch time 100 minutes

Aspect ratio 131 Expect lt 201
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Laser machining in Si
TiSapphire laser (TOPS facility at Strathclyde
University) 3 mJ pulse with duration of 40 fs
at 1 kHz repetition rate 810 nm wavelength or
405 nm wavelength (doubling crystal)

• Diameter
• Front 8 -10 mm
• Back 6 - 8 mm
• Spacing 85 mm
• Depth 200 mm
• Power 75 mW
• Time 5 sec/holes

Aspect ratio 251

• In collaboration with D.A. Jaroszynski and D.
  Jones of Strathclyde University

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PEC etching in Si

• Mask 100 nm l/s SiN
• Solution 2.5 aqueous HF

• Diameter 10 mm
• Spacing 25 mm
• Depth 120 mm
• Etch time 480 minutes

Aspect ratio 121 Expect gt 1001
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Electrical contacts

• Tracks of Al (150 nm)
• (over the SiO2 layer)

• Metal evaporation
• Ti (33 nm)
• Pd (33 nm)
• Au (150 nm)

• Wire bonding
• (25 mm wire)

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Results with a particles
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Results with X-Ray in GaAs
Resolution 44 CCE 70
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Irradiation at PSI
Irradiation with 300 MeV/c p at PSI
(Villigen) Bunch of 1 ns every 19 ns. Flux of
1014 p/cm2/day. Fluences between 1012 and 1014
p/cm2.
Irradiation performed by K. Gabathuler, M. Glaser
and M. Moll.
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Leakage current
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Fabrication comparison
Aspect ratios
Sidewall damages
Technique
currently
expected
Standard process Expensive Most promising
Dry etching Laser drilling PEC etching
131 251 121
lt201 501 gt1001
yes yes no
Metal evaporation n or p type doping
Simple process Complex process
Good for GaAs Good for Si
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Conclusion
Dry etching gt 131 in silicon Laser machining
gt 251 material independent PEC etching gt
121 in silicon Irradiated working devices in Si
and GaAs
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In development
Run II with fs laser in GaAs and SiC Improvement
of PEC etching Improvement of dry
etching Connection to DAC readout chip Better
contacts Proton irradiation of samples