1. 1 Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory 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

2. 2 Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory Main vertex detector parameters: Excellent point resolution (3.5 μm), pixel size = 20 μm, close to IP Low material budget ( <0.1% X 0 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) Introduction and Conceptual Design 120 large sensors (e.g. CCDs) in 5 layers, 800 Mpixels (20 μm 20 μm)

3. 3 Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory Classic CCD Readout time N M/f out N M N Column Parallel CCD Readout time = N/f out M 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/cm 2 ) Optimised for low voltage clocks to reduce power dissipation The Column Parallel CCD

4. 4 Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory 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 by VTT (Finland) using solder bumps Hybrid assembly with Column-Parallel CCD (CPCCD) and CMOS ASIC Bump-bonded CPC1/CPR1 in a test PCB CPC1 Bump-bonded to CPR1

5. 5 Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory 5.9 keV X-ray hits, 1 MHz column-parallel readout Voltage outputs, non- inverting (negative signals) Noise 60 e- Charge outputs, inverting (positive signals) 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 Bump bonds on CPC1 under microscope CPC1/CPR1 Performance

6. 6 Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory CPR2 designed for CPC2 Results from CPR1 taken into account Numerous test features Size : 6 mm 9.5 mm 0.25 μm CMOS process (IBM) Manufactured and delivered February 2005 Bump bond pads Wire/Bump bond pads CPR1 CPR2 Voltage and charge amplifiers 125 channels each Analogue test I/O Digital test I/O 5-bit flash ADCs on 20 μm pitch Cluster finding logic (2 2 kernel) Sparse readout circuitry FIFO Next Generation CPCCD Readout Chip – CPR2 Steve Thomas, RAL

7. 7 Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory CPR2 Test Results Tim Woolliscroft, Liverpool U 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 Many of the findings have already been input into the CPR2A design Tim Woolliscroft, Liverpool U Parallel cluster finder with 2 2 kernel Global threshold Upon exceeding the threshold, 4 9 pixels around the cluster are flagged for readout Test clusters in Sparsified output

8. 8 Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory Next Generation CPCCD : CPC2 Three different chip sizes with common design: CPC2-70 : 92 mm 15 mm image area CPC2-40 : 53 mm long 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) Baseline design allows few MHz operation for the largest size CPC2

9. 9 Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory CPC2 + ISIS1 Wafer ISIS1 CPC2-70 CPC2-40 CPC2-10 5 wafers One CPC2-70 : 105 mm 17 mm total chip size Two CPC2-40 per wafer 6 CPC2-10 per wafer 14 In-situ Storage Image Sensors (ISIS1) 3 wafers delivered

10. 10 Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory Clock monitor pads CPR1/CPR2 pads CPC2-40 in MB4.0 Johan Fopma, Oxford U Transformer drive for CPC2 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 Transformer

11. 11 Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory Transformer Drive for CPC2 Requirements: 2 V pk-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. 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 mm 2 Brian Hawes, Oxford U

12. 12 Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory Radiation Damage Effects in CCDs: Simulations Simulation at 50 MHz Operating window L. Dehimi, K. Bekhouche (Biskra U); G. Davies, C. Bowdery, A.Sopczak (Lancaster U) Full 2D simulation based on ISE-TCAD developed Trapped signal electrons can be counted CPU-intensive and time consuming 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 Signal density of trapped electrons in 2D

13. 13 Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory 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;

14. 14 Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory In-situ Storage Image Sensor (ISIS) RG RD OD RSEL Column transistor 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 Development and design of ISIS is more ambitious goal than CPCCD Proof of principle device (ISIS1) designed and manufactured by e2V Technologies On-chip logicOn-chip switches Global Photogate and Transfer gate ROW 1: CCD clocks ROW 2: CCD clocks ROW 3: CCD clocks ROW 1: RSEL Global RG, RD, OD 5 μm

15. 15 Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory Output and reset transistors Photogate aperture (8 μm square) CCD (5 6.75 μm pixels) The ISIS1 Cell OG RG OD RSEL OUT Column transistor 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

16. 16 Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory 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

17. 17 Konstantin Stefanov, CCLRC Rutherford Appleton Laboratory 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/