Transcript Konstantin Stefanov`s talk on LCFI at LCWS 2006

LCFI Status Report: Sensors for the ILC
Konstantin Stefanov
CCLRC Rutherford Appleton Laboratory
LCSW06, Bangalore, India
 Introduction
 Sensor Development for the ILC
 Column-Parallel CCDs
 Readout and Drive Electronics
 In-situ Storage Image Sensors
 Summary and Plans
Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory
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Introduction and Conceptual Design
Beam bunch structure at ILC
0.2 s
337 ns
2820x
0.95 ms
Multiple collisions
Main vertex detector parameters:
120 large sensors (e.g. CCDs) in 5 layers, 800
Mpixels (20 μm20 μm)
 Excellent point resolution (3.5 μm), pixel size = 20 μm, close to IP
 Low material budget ( <0.1% X0 per layer), low power dissipation
 Readout:
 Avoids excessive event overlap, occupancy << 1%
 Inner layer effectively read out at 50 μs intervals during the 1 ms pulse train (20
readouts) – information may leave the sensor or be stored in pixel
 Outer layers read out at 250 μs intervals
 Moderate radiation hardness ( 20 krad/year)
 Tolerates Electro-Magnetic Interference (EMI)
Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory
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The Column Parallel CCD
 Main detector work at LCFI
 Every column has its own amplifier and ADC – requires readout chip
 Readout time shortened by orders of magnitude
 All image area clocked (> 5 nF/cm2)
 Optimised for low voltage clocks to reduce power dissipation
M
M
N
N
“Classic CCD”
Readout time 
NM/fout
Column Parallel
CCD
Readout time = N/fout
Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory
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CPC1 Bump-bonded to CPR1
Hybrid assembly with Column-Parallel CCD (CPCCD) and CMOS ASIC
 CPC1 : Two phase CCD, 400 (V)  750 (H)
pixels, 20 μm square;
 CMOS readout chip (CPR1) designed by the
Microelectronics Group at RAL:
 0.25 μm process
 Charge and voltage amplifiers matching
the outputs of CPC1
 Correlated double sampling
 5-bit flash ADCs and 132-deep FIFO per
column
 Everything on 20 μm pitch
 Size : 6 mm  6.5 mm
 Manufactured by IBM
Bump-bonded CPC1/CPR1 in a test PCB
 Bump-bonded by VTT (Finland) using solder
bumps
Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory
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CPC1/CPR1 Performance
5.9 keV X-ray hits, 1 MHz column-parallel readout
Voltage outputs, noninverting (negative
signals)
Charge outputs,
inverting (positive
signals)
Noise 60 e-
Noise 100 e-
 First time e2V CCDs have been bump-bonded
 High quality bumps, but assembly yield only 30% : mechanical
damage during compression suspected
 Differential non-linearity in ADCs (100 mV full scale) : addressed
in CPR2
Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory
Bump bonds on CPC1
under microscope
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Next Generation CPCCD Readout Chip – CPR2
Bump bond pads
Voltage and charge amplifiers
125 channels each
Analogue test I/O
Digital test I/O
5-bit flash ADCs on 20 μm pitch
CPR1
Cluster finding logic (22
kernel)
CPR2
Sparse readout circuitry
FIFO
 CPR2 designed for CPC2
 Results from CPR1 taken into account
 Numerous test features
 Size : 6 mm  9.5 mm
Wire/Bump bond
pads
 0.25 μm CMOS process (IBM)
 Manufactured and delivered February 2005
Steve Thomas, RAL
Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory
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CPR2 Test Results
Sparsified output
Test clusters in
 Parallel cluster finder with 22
kernel
 Global threshold
 Upon exceeding the threshold,
49 pixels around the cluster are
flagged for readout
● Tests on the cluster finder: works!
● Several minor problems, but chip is usable
● Design occupancy is 1%
● Cluster separation studies:
 Errors as the distance between the
clusters decreases
 Reveal dead time
Tim Woolliscroft, Liverpool U
 Many of the findings have already been
input into the CPR2A design
Tim Woolliscroft, Liverpool U
Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory
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Next Generation CPCCD : CPC2
No
connections
this side
Clock bus
Charge
injection
 Three different chip sizes with
common design:
 CPC2-70 : 92 mm  15 mm
image area
 CPC2-40 : 53 mm long
Extra pads for clock
monitoring and
drive every 6.5 mm
Image area
Standard
Field-enhanced
Standard
Temperature
diode on
CCD
Four 2-stage SF in
adjacent columns
Four 1-stage and 2stage SF in adjacent
columns
Main clock
wire bonds
Main clock
wire bonds
CPR1
 CPC2-10 : 13 mm long
 Compatible with CPR1 and
CPR2
 Two charge transport sections
 Choice of epitaxial layers for
different depletion depth: 100
.cm (25 μm thick) and 1.5 k.cm
(50 μm thick)
CPR2
 Baseline design allows few MHz
operation for the largest size
CPC2
Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory
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CPC2 + ISIS1 Wafer
ISIS1
 5” wafers
 One CPC2-70 : 105 mm  17 mm
total chip size
 Two CPC2-40 per wafer
 6 CPC2-10 per wafer
CPC2-70
 14 In-situ Storage Image Sensors
(ISIS1)
CPC2-40
 3 wafers delivered
CPC2-10
Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory
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CPC2-40 in MB4.0
Transformer
CPR1/CPR2 pads
Clock monitor pads
 Transformer drive for CPC2
Johan Fopma, Oxford U
 “Busline-free” CCD: the whole image area serves as a distributed busline
 50 MHz achievable with suitable driver in CPC2-10 and CPC2-40 (L1 device)
 First clocking tests have been done
Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory
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Transformer Drive for CPC2
 Requirements: 2 Vpk-pk at 50 MHz over 40 nF (half
CPC2-40);
 Planar air core transformers on 10-layer PCB, 1
cm square
 Operation from 1 MHz to > 70 MHz unloaded;
 Parasitic inductance of bond wires is a major
effect – fully simulated;
 Work on the reduction of the CCD capacitance
and clock voltage is continuing – range of test
devices under development.
Brian Hawes, Oxford U
 Transformer is bulky;
 IC driver could be a better solution;
 Design of the first CPCCD driver chip (CPD1)
has started, manufacture in June
 CPD1: 2-phase CMOS driver chip for 20 Amp
current load at 25 MHz (L2-L5 CCDs)
 0.35 μm process, size 25 mm2
Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory
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Radiation Damage Effects in CCDs: Simulations
Signal density of trapped electrons in 2D
● Full 2D simulation based on ISE-TCAD
developed
● Trapped signal electrons can be
counted
● CPU-intensive and time consuming
Simulation at 50 MHz
Operating
window
● Simpler analytical model also used,
compares well with the full simulation
● Window of low Charge Transfer
Inefficiency (CTI) between -40 C and 0 C
● Will be verified by measurements on
CPC2
L. Dehimi, K. Bekhouche (Biskra U); G. Davies, C. Bowdery,
A.Sopczak (Lancaster U)
Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory
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In-situ Storage Image Sensor (ISIS)
 Beam-related RF pickup is a concern for all sensors converting charge into
voltage during the bunch train;
 The In-situ Storage Image Sensor (ISIS) eliminates this source of EMI:
 Charge collected under a photogate;
 Charge is transferred to 20-pixel storage CCD in situ, 20 times during the 1
ms-long train;
 Conversion to voltage and readout in the 200 ms-long quiet period after the
train, RF pickup is avoided;
 1 MHz column-parallel readout is sufficient;
Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory
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In-situ Storage Image Sensor (ISIS)
5 μm
Global Photogate and Transfer gate
ROW 3: CCD clocks
On-chip logic
ROW 2: CCD clocks
On-chip switches
ROW 1: CCD clocks
ROW 1: RSEL
 Additional ISIS advantages:
 ~100 times more radiation hard than
CCDs – less charge transfers
 Easier to drive because of the low clock
frequency: 20 kHz during capture, 1 MHz
during readout
 ISIS combines CCDs, active pixel transistors
and edge electronics in one device: specialised
process
Global RG, RD, OD
 Development and design of ISIS is more
ambitious goal than CPCCD
RG RD
 “Proof of principle” device (ISIS1) designed
and manufactured by e2V Technologies
OD RSEL
Column
transistor
Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory
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The ISIS1 Cell
 1616 array of ISIS cells with 5-pixel buried channel
CCD storage register each;
 Cell pitch 40 μm  160 μm, no edge logic (pure CCD
process)
 Chip size  6.5 mm  6.5 mm
Output and reset transistors
OG RG
OD
RSEL
Column
transistor
OUT
Photogate aperture (8 μm square)
CCD (56.75 μm pixels)
Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory
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Tests of ISIS1
Tests with Fe-55 source
 The top row and 2 side columns are not protected and collect diffusing charge
 The bottom row is protected by the output circuitry
 ISIS1 without p-well tested first and works OK
 ISIS1 with p-well has very large transistor thresholds, permanently off
Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory
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Conclusion and Plans
 CPCCD program well advanced:
 Main work at LCFI
 Hybrid assembly with CPCCD and CMOS chips works OK
 Detector-sized chips CPC2 have arrived, some tests have been done
 Started to develop CPCCD drive system, lots of challenges
 ISIS work will continue:
 First ISIS prototype on CCD technology manufactured, first tests promising
 Next-generation small pixel ISIS (CCD- or CMOS-based) will be actively
pursued
Immediate plans:
 Evaluate CPC2 and CPC2/CPR2 bump-bonded
 High speed external drive to CPC2-40 as demonstrator for the L1 vertex detector
Visit us at http://hepwww.rl.ac.uk/lcfi/
Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory
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