178 research outputs found
Characterization of FBK small-pitch 3D diodes after neutron irradiation up to 3.5x10**16 neq cm**-2
We report on the characterization by a position resolved laser system of
small-pitch 3D diodes irradiated with neutrons up to an extremely high fluence
of 3.5x10**16 neq cm**-2. We show that very high values of signal efficiency
are obtained, in good agreement with the geometrical expectation based on the
small values of the inter-electrode spacings, and also boosted by charge
multiplication effects at high voltage. These results confirm the very high
radiation tolerance of small-pitch 3D sensors well beyond the maximum fluences
expected at the High Luminosity LHC.Comment: 10 pages, 7 figures, submitted to Proceedings of IWORID 2018 on JINS
Development of New 3D Pixel Sensors for Phase 2 Upgrades at LHC
We report on the development of new 3D pixel sensors for the Phase 2 Upgrades
at the High-Luminosity LHC (HL-LHC). To cope with the requirements of increased
pixel granularity (e.g., 50x50 or 25x100 um2 pixel size) and extreme radiation
hardness (up to a fluence of 2e16 neq cm-2), thinner 3D sensors (~100 um) with
electrodes having narrower size (~ 5 um) and reduced spacing (~ 30 um) are
considered. The paper covers TCAD simulations, as well as technological and
design aspects relevant to the first batch of these 3D sensors, that is
currently being fabricated at FBK on 6-inch wafers.Comment: 4 pages, 8 figures, 2015 IEEE Nuclear Science Symposium and Medical
Imaging Conferenc
Carbon nanotube film/silicon heterojunction photodetector for new cutting-edge technological devices
Photodetector (PD) devices based on carbon nanotube/n-silicon heterojunction (NSH) have been realized, with a linear response in a large optical power range, proving competitive performances with respect to a recent nanostructure-based detector and those currently available on the market. The core of these devices is a thin semi-transparent and conductive single-walled carbon nanotubes film with a multitask role: junction element, light absorber and transmitter, photocarrier transporting layer, and charge collector. The PD exhibits rise times of some nanoseconds, detecting light from ultraviolet (240 nm) to infrared (1600 nm), and external quantum efficiency reaching 300% in the VIS spectra region
First Production of New Thin 3D Sensors for HL-LHC at FBK
Owing to their intrinsic (geometry dependent) radiation hardness, 3D pixel
sensors are promising candidates for the innermost tracking layers of the
forthcoming experiment upgrades at the Phase 2 High-Luminosity LHC (HL-LHC). To
this purpose, extreme radiation hardness up to the expected maximum fluence of
2e16 neq.cm-2 must come along with several technological improvements in a new
generation of 3D pixels, i.e., increased pixel granularity (50x50 or 25x100 um2
cell size), thinner active region (~100 um), narrower columnar electrodes (~5
um diameter) with reduced inter-electrode spacing (~30 um), and very slim edges
(~100 um). The fabrication of the first batch of these new 3D sensors was
recently completed at FBK on Si-Si direct wafer bonded 6-inch substrates.
Initial electrical test results, performed at wafer level on sensors and test
structures, highlighted very promising performance, in good agreement with TCAD
simulations: low leakage current (<1 pA/column), intrinsic breakdown voltage of
more than 150 V, capacitance of about 50 fF/column, thus assessing the validity
of the design approach. A large variety of pixel sensors compatible with both
existing (e.g., ATLAS FEI4 and CMS PSI46) and future (e.g., RD53) read-out
chips were fabricated, that were also electrically tested on wafer using a
temporary metal layer patterned as strips shorting rows of pixels together.
This allowed a statistically significant distribution of the relevant
electrical quantities to be obtained, thus gaining insight into the impact of
process-induced defects. A few 3D strip test structures were irradiated with
X-rays, showing inter-strip resistance of at least several GOhm even after 50
Mrad(Si) dose, thus proving the p-spray robustness. We present the most
important design and technological aspects, and results obtained from the
initial investigations.Comment: 8 pages, 7 figures, 2016 IWORI
PECVD low stress silicon nitride analysis and optimization for the fabrication of CMUT devices
Two technological options to achieve a high deposition rate, low stress plasma-enhanced
chemical vapor deposition (PECVD) silicon nitride to be used in capacitive micromachined
ultrasonic transducers (CMUT) fabrication are investigated and presented. Both options are
developed and implemented on standard production line PECVD equipment in the framework
of a CMUT technology transfer from R & D to production. A tradeoff between deposition rate,
residual stress and electrical properties is showed.
The first option consists in a double layer of silicon nitride with a relatively high deposition
rate of ~100 nm min−1 and low compressive residual stress, which is suitable for the fabrication
of the thick nitride layer used as a mechanical support of the CMUTs. The second option
involves the use of a mixed frequency low-stress silicon nitride with outstanding electrical
insulation capability, providing improved mechanical and electrical integrity of the CMUT
active layers. The behavior of the nitride is analyzed as a function of deposition parameters
and subsequent annealing. The nitride layer characterization is reported in terms of interfaces
density influence on residual stress, refractive index, deposition rate, and thickness variation
both as deposited and after thermal treatment. A sweet spot for stress stability is identified at
an interfaces density of 0.1 nm−1, yielding 87 MPa residual stress after annealing. A complete
CMUT device fabrication is reported using the optimized nitrides. The CMUT performance
is tested, demonstrating full functionality in ultrasound imaging applications and an overall
performance improvement with respect to previous devices fabricated with non-optimized
silicon nitride
Characterization of timing and spacial resolution of novel TI-LGAD structures before and after irradiation
The characterization of spacial and timing resolution of the novel Trench Isolated LGAD (TI-LGAD) technology is presented. This technology has been developed at FBK with the goal of achieving 4D pixels, where an accurate position resolution is combined in a single device with the precise timing determination for Minimum Ionizing Particles (MIPs). In the TI-LGAD technology, the pixelated LGAD pads are separated by physical trenches etched in the silicon. This technology can reduce the interpixel dead area, mitigating the fill factor problem. The TI-RD50 production studied in this work is the first one of pixelated TI-LGADs. The characterization was performed using a scanning TCT setup with an infrared laser and a Sr source setup
Characterization of timing and spacial resolution of novel TI-LGAD structures before and after irradiation
The characterization of spacial and timing resolution of the novel Trench
Isolated LGAD (TI-LGAD) technology is presented. This technology has been
developed at FBK with the goal of achieving 4D pixels, where an accurate
position resolution is combined in a single device with the precise timing
determination for Minimum Ionizing Particles (MIPs). In the TI-LGAD technology,
the pixelated LGAD pads are separated by physical trenches etched in the
silicon. This technology can reduce the interpixel dead area, mitigating the
fill factor problem. The TI-RD50 production studied in this work is the first
one of pixelated TI-LGADs. The characterization was performed using a scanning
TCT setup with an infrared laser and a Sr source setup
Results on Proton-Irradiated 3D Pixel Sensors Interconnected to RD53A Readout ASIC
Test beam results obtained with 3D pixel sensors bump-bonded to the RD53A
prototype readout ASIC are reported. Sensors from FBK (Italy) and IMB-CNM
(Spain) have been tested before and after proton-irradiation to an equivalent
fluence of about cm (1 MeV
equivalent neutrons). This is the first time that one single collecting
electrode fine pitch 3D sensors are irradiated up to such fluence bump-bonded
to a fine pitch ASIC. The preliminary analysis of the collected data shows no
degradation on the hit detection efficiencies of the tested sensors after high
energy proton irradiation, demonstrating the excellent radiation tolerance of
the 3D pixel sensors. Thus, they will be excellent candidates for the extreme
radiation environment at the innermost layers of the HL-LHC experiments.Comment: Conference Proceedings of VCI2019, 15th Vienna Conference of
Instrumentation, February 18-22, 2019, Vienna, Austria. arXiv admin note:
text overlap with arXiv:1903.0196
Status and upgrade of the visible light diagnostics port for energy spread measurements at KARA
At the visible light diagnostic (VLD) port at the Karlsruhe Research Accelerator (KARA), it is possible to measure the energy spread of electron bunches by measuring the horizontal bunch profile of the incoherent synchrotron radiation. KALYPSO, a MHz-rate line-array detector has been used to measure the bunch profile. Recently, the KALYPSO system has been upgraded to a version incorporating a microstrip sensor based on TI-LGAD. The performed measurements have shown that the overall sensitivity of the system was significantly improved, which enables measurements at low bunch charges. In this contribution, a brief overview of the upgraded setup and preliminary measurement results will be presented
Charge collection measurements with p-type Magnetic Czochralski silicon single pad detectors
Abstract The charge collected from beta source particles in single pad detectors produced on p-type Magnetic Czochralski (MCz) silicon wafers has been measured before and after irradiation with 26 MeV protons. After a 1 MeV neutron equivalent fluence of 1 × 10 15 cm - 2 the collected charge is reduced to 77% at bias voltages below 900 V. This result is compared with previous results from charge collection measurements
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