SOIPD
Status e prospective for 2012
The SOImager2 is a monolithic pixel sensor produced by OKI in the 0.20 µm Fully DepletedSilicon On Insulator (FD-SOI) process;
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 55 mm , 256256 analog 3T pixels, 13.75 µm pitch, 1.8 V operational voltage; 8 different
layouts;
 Buried P-Well process implemented: the top electronics is effectively protected from the backgate effect (shift of top transistor threshold when a biasing voltage is applied on the backside)

Test beam with 200 GeV  - at CERN SPS
•
Plane 2
Plane 1
Cooling
Plane 0
Rotating
stage
Three detectors arranged in one cemented
“doublet” (9 mm spaced) and one rotating plane
(33 mm spaced). Single plane can be rotated up
to 20° for slanted tracks and cluster studies.
•
The doublet is optically aligned with a better
than 50 µm precision → easy and precise
coincidence cuts in cluster recognition.
Tracks are reconstructed in two layers (doublet) and extrapolated in the third layer (singlet).
Excellent Spatial resolution and detection efficiency!
Single point resolution:
(1.12±0.04) μm, for Vd ≥ 50 V
SOIPD - Consiglio di Sezione - Gruppo V – 11 luglio 2011
Detection efficiency:
>99% for Vd ≥ 50 V
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Back-side soft X-ray irradiation
• A set of sensor chips have been back-thinned to 70 μm using a grinding technique and post-processed (P implantation followed by
annealing) to create a thin entrance window (400-600nm) on the back-plane and anneal the crystal damage from the thinning;
• This process ensures good sensitivity to X-rays down to ∼1.5 keV and to electrons down to ∼9 keV.
• The quantum efficiency for X-rays is studied on data collected at the beam-line 5.3.1 of the Advanced Light Source (ALS) at LBNL. The
thin, post-processed SOI sensor has been exposed from the backside to fluorescence radiation excited in various metal foils, in the energy
range 2< E <9 keV and for 30V < Vd < 70V (Full depletion!)
Cu spectrum
8.04keV
Cluster pulse height as a function
of the energy of fluorescence X-rays
obtained at Vd = 70 V.
X-ray quantum efficiency
as a function of energy for
three different values of Vd.
Fe spectrum
6.4keV
Possible applications for pixellated sensors with large
quantum efficiency for soft X-rays and low-energy particles,
small pixels, fast readout and moderate energy resolution are:
• precision beam monitoring in linacs and storage
rings with X-rays and soft electrons.
• electron microscopy
• X-ray astronomy
•…
SOIPD - Consiglio di Sezione - Gruppo V – 11 luglio 2011
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Single Event Upset tests
• Single Event Upset (SEU) micrometric sensitivity studies on the digital circuitry of the chip
were performed at the Ion Electron Emission Microscope (IEEM) facility, located at the
15MV Tandem XTU-Accelerator of the INFN Legnaro National Laboratory
256 shift
register (SR)
cells, 13.75
µm pitch
• A known logical pattern is written in and read back from the row selection shift register
through dedicated pads during irradiation. Differences between the loaded and read-back
pattern highlight a SEU occurred in the cells
Shift register layout
latch
latch
250 MeV 79Br
22.4m
• Four pairs of hot spots: each pair
corresponds to a single SR cell and the two
spots highlight the two Flip-Flop D
structure of the cell.
• The different number of upset in the two
columns of spots accounts for the
dependence of the sensitivity from the logic
state of the Flip-Flop
SOIPD - Consiglio di Sezione - Gruppo V – 11 luglio 2011
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Activity for 2012
• Test of the new, larger chip built on Float Zone (FZ) SOI wafers with resistivity of
several 1000 ·cm, recently made available from OKI; this chip can achieve full
depletion on a thickness up to 500 m.
• Test beam at CERN SPS with - on a chip back-thinned and back-processed
• Test of a back-thinned and back-processed chip with low energy electrons (10-20 keV)
SOIPD - Consiglio di Sezione - Gruppo V – 11 luglio 2011
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Personnel and budget request for 2012
Personnel:
D. Bisello
S. Mattiazzo
R. Rando
L. Silvestrin
M. Bagatin (DEI)
Richieste economiche:
30%
70%
30%
30%
30%
Missioni interne:
Missioni estere:
Consumo:
1k€
4k€
2k€
Technical assistance:
D. Pantano
50%
SOIPD - Consiglio di Sezione - Gruppo V – 11 luglio 2011
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