Radiation Hardness Qualification of the APV25 Chip Production for the CMS Experiment

1
Radiation Hardness Qualification of the APV25
Chip Production for the CMS Experiment

• Lucas Stefanutti1, R. Bainbridge2, P. Barillon2,
  D. Bisello1, A. Candelori1, M. J. French3, G.
  Hall2
• A. Kaminski1, V. Komenkov1, E Noah3, M. Raymond2,
  M. Tessaro1
• 1Istituto nazionale di fisica Nucleare and
  Dipartimento di Fisica, Universita di Padova,
  via Marzolo 8, 35100, Padova, Italy
• 2Imperial College, London, SW7 2AZ, United
  Kingdom
• 3Rutherford Appleton Laboratory, Instrumentation
  Department, Chilton, Didcot, OX110QX, United
  Kingdom

Lucas Stefanutti, 2nd Workshop Sirad, 1-2 April
2004, Legnaro Italy
2
Outlines

• The APV25 is the 128 channel front-end chip
  developed for the silicon microstrip tracker in
  the CMS experiment at the CERN Large Hadron
  Collider.
• The chip must operate for about 10 years in a
  high radiation environment. A total dose
  estimated of 10MRad(SiO2) will be received from
  every chip during this period.
• Because the large numbers of batches requested,
  the production must be continuously verified
  against the radiation tolerance.
• A setup for irradiation and electrical
  characterization of the chip was built to ensure
  the production quality control.

3
The CMS Experiment at LHC
? 16000 microstrip detectors ? 200 m2 of silicon
?105 APV25 chips are needed
4
Radiation levels expected for the CMS Tracker
Microstrip detectors and APV25 chips 25
cmltRlt110 cm gt 1013 cm-2 lt?lt 1014 cm-2
5
The 0.25 ?m CMOS Technology

• Commercial technology benefits
• Process stability
• Low cost
• Intrinsic radiation hardness thanks to the thin
  gate oxide (5.5nm)
• CMOS Tecnology
• mixed design analog-digital
• low power compsumption

6 nm
Enclosed Layout Transistor (ELT) design reduce
effects attributed to leakage paths around NMOS
Transistors
6
Test di SEU (Single Event Upset) con ioni
pesanti (Legnaro) e con pioni (PSI)
Estrapolazione per lintero sistema 120 SEU
per ora 0.15 APV25s Conclusioni la
tecnologia appare estremamente Robusta.
GuidoTonelli/Università di Pisa ed
INFN/Gruppo1/Roma 14-05-2002
6
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APV25 schematic and features

• Two operational mode
• Peak (50 ns shaping)
• Deconvolution (25 ns shaping)
• Sampling rate at the shaper output
• 40 MHz.
• synchronous with beam interactions.
• Analog Pipeline
• 192 cells x 128 channels
• Up to 4 ?s of latency

• Deconvolution Mode
• 25 ns shaping is made with 3 samples of the 50ns
  shape

8
APV25 layout
Industrial design at 0.25 ?m
The analog pipeline area is 20 of total.

• Chip size
• 8.1x7.1 mm2
• Channel Pitch
• 44 ?m
• Power
• consumption
• 2.31 mW/Channel

Analogue pipeline
APSPs
Preamplifiers Shapers
Analoge Multiplexer
Pipeline control
Bias Generator
Control Logic
Calibration Circuit

• FIFO

9

Radiation Qualification Procedure
Changes in parameters are possible due to the
process variation during the production

• 1-2 of the chip production have to be tested for
  qualifying the production
• Tests are destructive i.e. chips cannot be used
  after radiation testing.
• Radiation tests are time consuming 2 weeks are
  needed the for the full qualification of 5 chips.

10
Chip control parameter optimization
The determination of the optimal values for the
Isha and Vfs chip control registers to optimise
CR-RC shaping peaked at 50 ns.
Where A is the amplitude, e is the Neperian
constant, t0 is the signal time shift with
respect to the initial time, and ?50 ns.
The 50 ns CR-RC shaping guarantees the correct
functionality of the Deconvolution algorithm.
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Electrical Characterization setup

• DAQ hardware includes
• VME ADC CAEN v488 (40MHz 12bit)
• VME I2C controller
• VME embedded PC mounting Linux
• SEQSI
• Agilent E3631A power supply
• 1 KHz Pulse Generator.

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X-Ray Irradiation Setup

• Tube placement X,Y (motorized) and Z (manual).
• Max Voltage 50 kV. Max Current 50 mA
• Tube with W anode (7.4-12.06 KeV L-lines)
• 10 hours to reach 10Mrad(SiO2)
• Irradiation uniformity on chips dimension within
  10

X-Ray Tube
Y Motor
Laser pointer
Semi-automatic probestation
Z
Y
X
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X Ray spectra for W anode (simulation)
1.0
7.6-12.06 KeV
0.8
0.6
Photons/(mA?s?mm2) at 750 mm normalized to maximum
50kV, 0.1 mm Al filtration
0.4
0.2
0.0
0
5
10
15
20
25
30
35
40
45
50
Photon energy (keV)
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Experimental Results
These results refer to chips operating in peak
mode and with the charge injected by an external
pulse generator.
The Isha parameter distribution, does not
significantly change before irradiation, after
irradiation and after annealing
The Vfs values decrease after irradiation and do
not change after the annealing
Until Now 85 (79) 29 samples from the first
five production lots have been electrically
characterized before irradiation (after
irradiation) after annealing.
15
Experimental Results
The APV25 gain remains close to the expected
value of 25000 electrons/m.i.p.
The noise after does not significantly change
after irradiation in both short- and long-term
operation, respectively.
16
Conclusions

• The radiation hardness qualification of the
  APV25, which is now in production phase, shows,
  for what concerns the ionising radiation levels
  expected at CMS
• The circuit parameters can be easily retuned to
  optimise the 50 ns shaping after irradiation in
  short- and long-term operation.
• Radiation effects on power consumption, gain,
  linearity and noise are minimal.
• Consequently, minimal changes in system
  performance are expected during the APV25
  operation at CMS.