Aucun titre de diapositive

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Silicon ultra fast cameras for electron and gamma
sources in medical applications
Michael Deveaux
Progress in Monolithic Active Pixel Sensors
(MAPS) - development.
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Operation principle of MAPS
P-Doping
Particle trajectory
High Moderate High

• MAPS Performances
• Single track resolution 1.5µm - 5µm
• Pixel pitch 20µm - 40µm
• S/N for MIPs 20 - 40
• Radiation hardness
• gt200 kRad, 1012neq/cm²

Preamplifier (one per pixel)
Diffusing free electrons
20µm
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Headlines
Pixels with 40µm pitch tested
First ADC design submitted (MIMOSA 7)
Evaluation on digital signal processing started
up
PhotoFET under test
Possible Chip components for an CBM -
Vertexdetector
Analogue signal processing (CDS)
Digital signal processing (discrimination,
sparcification)
ADC
Sensor
Pixels with integrated CDS under test
Backthinning in progress.
Status RD, Preparation under Test Tests
completed
Radiation hardness simulation running
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Pixels with 40µm pixel - pitch (SUCCESSOR II)
SUCCESSOR II Designed for Bio-Medical
application by SUCIMA Pixel pitch 40µm. Two well
established pixel designs (Two diode sizes
each) Two different PhotoFET-designs 4 x 32 x 32
Pixels

• Results on Beam-test
• Very preliminary
• 120 GeV Pions (SPS/CERN)
• Single Track resolution lt 5 µm
• S/N gt 25
• Detection Efficiency gt99

• Conclusion
• 40µm pixels possible
• Less channels,
• faster readout
• Less power dissipation
• BUT Decrease in radiation hardness?

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Pixels with integrated CDS-Processor (MIMOSA VI)

• MIMOSA VI
• In every pixel (28µm pitch)
• Additional amplification (5.5x)
• Analogue CDS processing
• 29 transistors, 3 capacitors
• Column parallel readout

Test with Oscilloscope (one pixel only)

• Observations (Preliminary)
• Individual Pixel looks fine.
• Problems on pixel matrix
• Pixel to pixel spread not fully removed
• Additional Noise

• Open questions
• Artefacts of widely new developed readout
  system?
• Weak points on the chip?

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Backthinning
Goal Fully removing substrate for detection of
gt20keV-electrons. Thickness gets reduced to
15µm Adding 25µm glass for handling. Status Addi
tional Wafers of MIMOSA V (1MPixel) were ordered.
Industrial thinning after production.
MIMOSA V Wafer
Metall lines area Transistors area Sensitive
Volume (Epitaxial layer) Substrate (to be removed)
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Summery

• Pixels with 40µm pitch demonstrated 99
  detection efficiency with 5µm resolution.
• Individual pixel with integrated analogue CDS
  processor demonstrated functionality. Open
  questions on pixel matrix.
• Backthinning to 40µm is in progress.