Si-Detector Developments at BARC

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Si-Detector Developments at BARC
Dr. S.K.Kataria Electronics Division, BARC,
Mumbai
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Collaborators

• M.D. Ghodgaonkar, Anita Topkar, M.Y. Dixit, V.B.
  Chandratre, A.Das, Vijay Mishra, V.D. Srivastava,
  R.V. Shrikantaiah, Acharyulu, R.K. Choudhari,
  Bency John,A.K. Mohanty
• BARC
• H.V. Ananda, Subash Chandran, Prabhakararao,
  N. Shankaranarayana
• BEL
• O.P. Wadhawan, G.S. Virdi
• CEERI
• R.K. Shivpuri, Ashutosh Bharadwaj, Kirti Ranjan
• DU

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Plan of the Talk

• Development of the CMS preshower silicon strip
  detector
• Silicon Drift Detectors
• Si-Detector Readout Electronics

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CMS
Compact Muon Solenoid
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Preshower Disc
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Advantages of silicon detectors

• Fast response of the order of few ns
• High level of segmentation possible- strips,
  microstrips, pixels,etc
• High energy and position resolution
• Room temp operation possible
• Use of silicon IC technology enables batch
  fabrication with very good uniformity low cost
  of production

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Applications of Silicon Detectors Detection of
radiation - ?, ?, ?, protons, neutrons, charged
particles, photons

• Silicon detectors with multielement geometries of
  strips, microstrips, pixels, etc
• - Physics experiments such as that at CERN,
  Nuclear Science
  experiments in our country
• - Astronomy ( low energy X-rays)
• - Medical imaging (pixel detectors)
• Single element detectors
• Small area diodes area 25-100 mm2
• Personal dosimeters / area monitors for
  ?-radiation
• Neutron dose measurement using boron coating/thin
  foil
• Low energy X-ray spectroscopy with preamp ( low
  noise)
• at 100C ( lt60KeV with few 100 eV resolution)
• High resolution ?-spectroscopy
• Charged particle detection
• Large area diodes 100-300 mm2
• Detection of low activity radiation such as 239
  Pu in air
• Silicon photodiode/scintillator system

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Various types of silicon strip detectors used for
high energy physics experiments other
applications

• Single sided and double sided Strip detectors (
  DC coupled, 2D Position sensing)
• Pixel detectors (suitable for imaging
  applications)
• Silicon microstrip detectors ( AC coupled, single
  or double sided)
• Silicon drift detectors ( high energy and
  position resolution, suitable for imaging
  applications)
• Monolithic active pixel detectors
• Single element detectors with high energy
  resolution/large sensitive area

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Silicon strip/microstrip detector ( SS, DC
coupled)
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Active Pixel DetectorsMonolithic Has readout
inside the detector substrateHybrid Readout is
bump bonded to the pixel
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CMS Preshower Silicon Strip Detector
Development(These detectors will be used as the
preshower detectors for photons in the CMS at
CERN).

• Prototype Development phase
• (CEERI and BEL)
• Preproduction (BEL)
• Production (BEL)
• Important activities involved
• Detector design and fabrication
• Detector qualification
• Micro module assembly

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Prototype / Technology Development

• 16-strip silicon detector developed at CEERI on a
  2 Wafer
• strips of geometry 20x1.65 mm2 enclosed in
  three P guard-rings
• 32-strip silicon detector of geometry 60x60 mm2
  developed at BEL
• strips of geometry 60x1.69 mm2 enclosed in
  seven P guard-rings
• PIN diode detectors of various areas 3x3 mm2
  10x10 mm2 developed at BEL along with strip
  detector
• 70 diodes enclosed in two guard rings

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Detector specifications and Detector design

• Electrical
• Breakdown voltage for all strips gt 300V/500V
• Total current of all strips lt 5 µA at full
  depletion voltage (VFD) and
• lt 10 µA at 150VFD
• Maximum 1 strip with leakage current gt 1 µA at
  VFD gt 5 µA at VFD150V
• Geometrical
• Length 63.0 - 0.1 mm
• Width 63.0 0.0, -0.1 mm
• Detector specifications are very stringent as
  these are to be operated in a high radiation
  background of neutrons ( 2x10 14 /cm2) gamma (
  10Mrad) for a long period of ten years

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Scanned picture of BEL and CEERI Detectors (
Prototype)
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Characterization of the strip detector

• Probe-jigs to make contact to the 32 strips
  simultaneously
• Simulaneous measurement of strip current of 32
  strips ( IV)
• Simulaneous measurement of strip capacitance of
  32 strips ( CV)
• Probe-jigs, measurement setups were developed by
  BARC.
• Testing facility has been setup at BEL for
  qualification of detectors as per the CERN
  specifications

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• Argon implantation at Back plane
• Sacrificial Oxide Grown

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Back-Plane Ohmic Side Processing Technology

• Single step implantation
• Energy of the ion-beam 80 KeV
• Dose 7E15 ions/cm2
• Annealing 30 min, 950 ºC in N2
• Double step implantation
• First Step
• Energy of the ion-beam 110 KeV
• Dose 1E15 ions/cm2
• Annealing 10 min, 1050 ºC in O2 N2
• Second Step
• Energy of the ion-beam 50 KeV
• Dose 1E16 ions/cm2
• Annealing 30 min, 950 ºC in N2

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IV and CV measurement system developed by BARC
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Reverse IV characterstics of all 32 strips of a
detector ( production phase)
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Capacitance vs Voltage Characterstics of all 32
strips of a detector ( Production phase)
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Micromodule assembly

• The detector is mounted on the ceramic which
  would have the radiation hard front end hybrid
• The ceramic is mounted on an aluminum tile
• Alignment accuracy of about 100 microns is
  required
• Mechanical jigs would be used for alignmnet
  during assembly

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Detector Micromodule
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Fabrication of Detectors of modified geometry (63
63 mm2)
IV characteristics of 32 strips a 63 63 mm2
detector fabricated at BEL
Composite diagram for all the layers of Mask2
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Simulation Studies
The cross-section of the simulated device showing
different layers and contour for the junction
depth
Doping Profile after each of thermal treatment
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Silicon Detectors with Inbuilt JFET Simulation
Studies Design

• An extension of PIN diode development work
• Fabrication of JFET along with PIN diode detector
  avoids stray capacitances and micro phonic noise
  pickups
• SDD is based on the lateral charge transport
  scheme. The signal charge generated by radiation
  is collected by a small area anode (small
  capacitance 0.1pF). The capacitance of the
  detector is independent of the detector area
• These detectors can be cooled down to -20ºC that
  would give energy resolution of 180 eV ( PIN
  diodes) and 150 eV (SDD)

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Radial Cross Section of SDD JFET
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Process Simulations

• Fabrication of the proposed detectors require 10
  Masks layers
• Back plane alignment needed
• Process simulations for fabrication of the
  detectors have been carried out and implant
  energy, dose values and temperature cycles have
  been studied
• Starting substrate 4 K?-cm
• P-well 1E12 cm-2 _at_ 80
  KeV
• N-channel 8E12 cm-2 _at_ 80 KeV
• P Gate 1E14 cm-2 _at_ 60 KeV
• N Source Drain 1E15 cm-2 _at_ 80 KeV
• The temperature cycles are 1000 -1050 C
• Long annealing temperature cycle to recover the
  bulk carrier life time.

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N-JFET Characteristics
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Silicon Drift Detector with Integrated Front-end
electronics

• Low noise operation with large active area
• Energy and position sensing capability
• High energy resolution 150eV
• High position resolution 11 ?m
• High count rate capability 2e6 cps/cm2
• Applications of Silicon drift detectors
• X-ray ?-ray Spectroscopy
• Simulation studies for SDD and inbuilt JFET
  completed

Analog X-ray AcquisitionSystem (AXAS)
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CMOS ASIC from SCL Concept to CHIP
Full custom designs
DETECTOR(S)
FRONT END DOSIMETER ASIC. CODA
OCTAL Charge Preamp OCTPREM
8 CHANNEL SILICON STRIP PULSE PROCESSOR. SPAIR
8 CHANNEL CURRENT PULSE PREAMPLIFIER MICON
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The preamplifier FOR OCTPREM
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Block Diagram SPAIR
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MICON
ref
Error amp
in
out
I to V SHAPER/ Buffer
FICON
bias
KEY FEATURES LEAKAGE CURRENT COMPENSATION IDEAL
FOR PROPORTIONAL CHAMBERS, GEM, PMTS 50 NS
PEAKING TIME 1800 e RMS noise 8 CHANNELS WITH
SERIAL ANALOG READOUT
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• The process technology for large area silicon
  detectors has been successfully developed and
  silicon strip detectors meeting all the
  electrical and technological specifications for
  its qualification as preshower sensors have been
  produced
• The leakage current in detectors is around 2-5
  nA/cm2 and breakdown voltage is in excess of 500V
  
• The approach of employing gettering techniques
  during fabrication has sustained the bulk
  effective carrier lifetime to high value gt 10 ms
  
• The injection of carriers from the back plane at
  full depletion voltage which was the major
  problem for high voltage operation of the
  detectors has been effectively tackled by
  incorporating double implantation at back side so
  as to have thicker and uniform n layer
• the strip detectors that show high leakage
  current in strips can become usable detectors
  with one of the Guard Rings grounded
• Guardring collects most of the signal charge
  generated close to or outside of the active area
  avoiding the number of interactions in which
  imperfect or incomplete charge collection would
  occur.
• Simulation studies for designing Silicon Drift
  Detector with integrated N-JFET have been done
  and results are presented

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Preshower Readout Architecture
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DDU Functional Requirements

• Optical to electrical conversion
  de-serialization of incoming data streams
• Integrity verification of incoming data
  packets/event fragments
• Data reformatting
• Data reduction
• DDU event formation
• Transmission of DDU events to the global DAQ
  through the S-Link64 interface
• Transmission of spying events to the local DAQ
  through VME interface

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DDU Input Data Format
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Data Processing in DDU

• Pedestal Subtraction
• Common mode noise Subtraction
• Threshold Comparison
• Synchronization Check
• Deconvolution
• a Y1 v0
• ß Y1 v1 Y2 v0
• ? Y1 v2 Y2 v1 Y3 v0
• Charge Extraction
• Q W1 v1 W2 v2
• Data concentration and output formatting

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DDU Output Data Format
Header _BOE Begin Of Event 4 bits _FOV FOrmat
Version 4 bits _LV1_id Trigger Number 24
bits _BX_id Bunch Number 12 bits _Source_id Source
Id 12 bits _Evt_ty Event Type 4 bits
Trailer _Evt_lgth Event size in 64 bit words 24
bits _Evt_stat Event status 8 bits Integrity CRC
16 bits
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Data Concentrator Card (DCC)
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DDU Architecture in DCC