Light High Precision CMOS Pixel Devices Providing 0(µs) Timestamping for Future Vertex Detectors

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1 Light High Precision CMOS Pixel Devices Providing 0(µs) Timestamping for Future Vertex Detectors M. Winter, on behalf of PICSEL team of IPHC-Strasbourg IEEE/NSS-MIC - Anaheim(CA) Novembre 2012 Contents Reminder: main features of CMOS sensors Architecture developped - state of the art MIMOSA-28 (STAR-PXL, AIDA) Extension towards more demanding experiments speed, radiation tolerance ALICE-ITS (& -MFT) CBM-MVD ILD-VXD SuperB-SVT First test results of a 0.18 µm CMOS technology charged particle detection perfo. for deep P-well & elongated pixels radiation load & T dependence Summary 1

CMOS Pixel Sensors: Main Features Prominent features of CMOS pixel sensors: high granularity excellent (micronic) spatial resolution very thin (signal generated in 10-20 µm thin epitaxial layer)

integration ( cost) CMOS pixel sensor technology has the highest potential R&D largely consists in trying to exploit potential at best with accessible industrial processes manufaturing param.

2 CMOS Pixel Sensors: Main Features Prominent features of CMOS pixel sensors: high granularity excellent (micronic) spatial resolution very thin (signal generated in µm thin epitaxial layer) signal processing µ-circuits integrated on sensor substrate impact on downstream electronics and syst. integration ( cost) CMOS pixel sensor technology has the highest potential R&D largely consists in trying to exploit potential at best with accessible industrial processes manufaturing param. not optimised for part. detection: epitaxy characteristics, feature size, N(ML),... Organisation of MIMOSA sensors: manufactured in 0.35 µm OPTO process (until recently) signal sensing and analog processing in pixel array mixed and digital circuitry integrated in chip periphery read-out in rolling shutter mode (pixels grouped in columns read out in //) impact on power consumption 2

State-of-the-Art: MIMOSA-28 for the STAR-PXL Main characteristics of ULTIMATE ( MIMOSA-28): 0.

discrimination & binary charge encoding on-chip zero-suppression active area: 960 colums of 928 pixels (19.9 19.2 mm 2 ) pitch: 20.

/cm 2 /s 2 outputs at 160 MHz 150 mw/cm 2 power consumption Sensors fully evaluated : (50 µm thin) N 15 e ENC at 30-35 C (as

3 State-of-the-Art: MIMOSA-28 for the STAR-PXL Main characteristics of ULTIMATE ( MIMOSA-28): 0.35 µm process with high-resistivity epitaxial layer column // architecture with in-pixel cds & amplification end-of-column discrimination & binary charge encoding on-chip zero-suppression active area: 960 colums of 928 pixels ( mm 2 ) pitch: 20.7 µm 0.9 million pixels charge sharing σ sp 3.5 µm JTAG programmable t r.o. 200 µs ( frames/s) suited to >10 6 part./cm 2 /s 2 outputs at 160 MHz 150 mw/cm 2 power consumption Sensors fully evaluated : (50 µm thin) N 15 e ENC at C (as MIMOSA-22AHR) ǫ det, fake & σ sp as expected Rad. tol. validated ( n eq /cm 2 & 150 krad at 30 C) All specifications are met 40 ladders under construction Start of data taking early

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Towards Higher Read-Out Speed and Radiation Tolerance Next generation of experiments calls for improved sensor performances : Expt-System σ t σ sp TID Fluence T op STAR-PXL 200 µs 5 µm 150 krad 3 10

5 Towards Higher Read-Out Speed and Radiation Tolerance Next generation of experiments calls for improved sensor performances : Expt-System σ t σ sp TID Fluence T op STAR-PXL 200 µs 5 µm 150 krad n eq /cm 2 30 C??? ALICE-ITS µs 5 µm 700 krad n eq /cm 2 30 C CBM-MVD µs 5 µm 10 MRad n eq /cm 2 0 C ILD-VXD 10 µs 3 µm O(100) krad O(10 11 ) n eq /cm 2 30 C SuperB-SVT 2 µs 10 µm 5 MRad/yr SF n eq /cm 2 /yr SF 10 C Main improvements required to comply with forthcoming experiments specifications : aim for higher epitaxial layer resistivity reduce nb(pixels) / read-out unit (column) aim for smaller feature size process & more parallelised read-out How to accelerate the pixel read-out elongated pixels less pixels /col. & in-pixel discri. 3-8 faster r.o. read out simultaneously 2 or 4 rows 2-4 faster r.o./side subdivide pixel area in 4-8 sub-arrays read out in // 2-4 faster r.o./side conservative step: 2 discri./col. end (22 µm wide) simult. 2 row r.o. remain inside virtuous circle: spatial resol., power, flex mat. budget, µm process needed instead of currently used 0.35 µm process 5

Prototype sub-divided in several blocks : Sensing elements and in-pixel amplifiers : pixel dimensions : 20 20/40/80 µm 2 2 different types of sensing elements : diodes of 9 15 µm 2

6 MIMOSA-32 : Prototyping a 0.18 µm Process 0.18 µm imaging technology options used : Epitaxial layer: High-Resistivity (1-5 kω cm) & 18 µm thick SNR, rad. tol.,... Quadruple well: deep P-type skin embedding N-well hosting P-MOS transistors compactness, power,... MIM capacitors 6 Metal Layers etc. Prototype sub-divided in several blocks : Sensing elements and in-pixel amplifiers : pixel dimensions : 20 20/40/80 µm 2 2 different types of sensing elements : diodes of 9 15 µm 2 N-MOS and P-MOS transistor based amplifiers Discriminators : Col. // pixel array ended with 1 discriminator/col. (2 variants) Pixel array with in-pixel discriminator (16 80 µm 2 pixels) Total surface 43 mm 2 Mimosa-32 fabricated in Q4/2011 tests since April 12 6

7 MIMOSA-32 Tests Prominent test purposes : Validate epitaxial layer characteristics (behaviour) Study charge collection properties of sensing node 2T Validate technology radiation tol. for ALICE-ITS (T=30 C) Study sensing performances of elongated vs square pixels Study sensing performances of deep P-well pixels Estimate necessity of ELT design Beam tests at CERN-SPS in Summer 2012 : MIMOSA-32 chips mounted on beam telescope beams of GeV charged particles 3T test results based on 50,000 tracks reconstructed in BT and DUT effect of combined radiation load: 1 MRad n eq /cm 2 T coolant = 15 C & 30 C RESULTS ARE STILL PRELIMINARY! 7

8 Observed Charge Sensing Properties MIMOSA-32 lab tests ( 55 Fe source) of pixel matrix with analog output Read-out time of each sub-matrix = 32 µs Observed CCE (20 20 µm 2 pixels) : seed pixel : % 2 2 pixel cluster : nearly 100 % confirms Epi. layer 1-5 kω cm No parasitic charge coll. seen with Deep P-well CCE of µm 2 pixels seed 30 %; with 1st crown % Noise 20e ENC at 20 C, unchanged at 35 C Irradiation: 0.4/1/3 MRad no effect up to 35 C (tbc!) Beam tests : Deep P-well Rect. 1D Cluster multiplicity for 60 & 120 GeV charged particles Radiation 20 20µm µm 2 Load 2T 3T Deep P 1D-3T 2D-3T (1.4) (1.3) (1.2) (1.9) (1.2) 1 MRad and n eq /cm 2 (1.2) (1.1) (1.1) (1.5) (1.2) High resistivity of epitaxial layer confirmed 8 Cluster multiplicity S/N> hmult_sn_5 Entries 2639 Mean RMS Cluster multiplicity S/N> hmult_sn_5 Entries 3211 Mean RMS 1.798

9 Beam Tests of 20x20 µm 2 Deep P-Well (3T) Pixel Pros and cons of deep P-well: Pros: allows use of P-mos transistors reduced in-pixel µcircuit footprint and/or more in-pixel functionnalities Cons: potential parasitic charge collection (esp. after ionising irradiation) and increased noise Signal/Noise ratio for P9 Signal/Noise ratio for P9 Events MPV=19.29± MPV=22.6±0.4 Events Mrad+10 - MPV=19.29± MPV=22.6±0.4 REF@30C - MPV=29.7±0.4 REF@15C - MPV=30.85± REF@30C - MPV=29.7± REF@15C - MPV=30.85± Signal/Noise Signal/Noise SNR (MPV) and detection efficiency (stat. uncertainty only): Radiation SNR (MPV) Detection efficiency [%] Load 15 C 30 C 15 C 30 C ± ± ± ± MRad & n eq /cm ± ± ± ±

10 Beam tests of 20x40 µm 2 (1 Sensing Diode) Pixel Trade-off to be found for each application: read-out time reduction spatial resolution degradation NI radiation tolerance degradation (SNR ց) depends on t int, T, epitaxy, diodes (size, Nb),... Signal/Noise ratio for L4_1 Signal/Noise ratio for L4_1 Events Mrad+10 - MPV=10.94± MPV=13.34±0.31 Events MPV=10.94± MPV=13.34±0.31 REF@30C - MPV=21.76± REF@30C - MPV=21.76±0.25 REF@15C - MPV=22.6± REF@15C - MPV=22.6± Signal/Noise Signal/Noise SNR (MPV) and detection efficiency (stat. uncertainty only): Radiation SNR (MPV) Detection efficiency [%] Load 15 C 30 C 15 C 30 C ± ± ± ± MRad & n eq /cm ± ± ± ±

11 Spatial Resolution Beam test (analog) data used to simulate binary charge encoding : Apply common SNR cut on all pixels using <N> simulate effect of final sensor discriminators Evaluate single point resolution (charge sharing) and detection efficiency vs discriminator threshold for 20x20 µm 2 pixels and 20x40 µm 2 staggered pixels (1 sensing diode) Comparison of 0.18 µm technology (> 1 kω cm) with 0.35 µm technology (< 1 kω cm) (pitch values: 20.0 µm and 20.7 µm) σ bin sp 3.2 ± 0.1 µm (20X20 µm 2 ) AND 5.4 ± 0.1 µm (20X40 µm 2 ) Mimosa 28 - epi 20 um - 30 C Efficiency (%) MIMOSA 28 - epi 20 um MIMOSA 32 - REF - 15C 20x20 um^2 MIMOSA 32 - REF - 15C 20x40 um^2 PRELIMINARY Threshold / noise Resolution (µm) 11

12 SUMMARY CPS have a very high potential for high precision/low power tracking and vertexing devices 1st vertex detector based on CPS (STAR-PXL) close to commissionning CMOS industry fabrication parametres make it difficult to fully exploit this potential e.g µm technology far from optimal A newly available 0.18 µm imaging technology with thick high-resitivity epitaxial layer is being explored, which pushes the limits of state-of-the-art sensors : - match the requirements of ALICE-ITS (up to 10 m 2 pixellated tracker) Next steps : - opens possibilities for other applications: CBM-MVD, ILC-1TeV, SuperB-SVT, submission: pixel array with peripheral discri. and 2-row simultaneous r.o. zero-suppression circuitry prototype 2013 submission: Q1/Q2: pixel array with in-pixel discriminators 2-4 faster r.o. Q4: complete 1 cm 2 sensor with peripheral discri. (30 µs) full scale proto. (MISTRAL) subm. in 2014 Final goal: ASTRAL ( 10 µs) 12

Next Steps of 0.18µm Architecture Prototyping 1st step : MISTRAL MIMOSA FOR THE INNER SILICON TRACKER OF ALICE MIMOSA-22THR ( Upstream part of sensor) : Col.

Pixel array sub-divided in sub-arrays featuring different pixel designs (22 22/33 µm 2 ) 2 options submission in Decembre 12 : sgle end of column discriminator translation of MIMOSA-22AHR (0.

13 Next Steps of 0.18µm Architecture Prototyping 1st step : MISTRAL MIMOSA FOR THE INNER SILICON TRACKER OF ALICE MIMOSA-22THR ( Upstream part of sensor) : Col. // pixel array with in-pixel ampli + pedestral subtraction (cds) Each of 128 columns ended with discriminator + 8 columns without discri. Pixel array sub-divided in sub-arrays featuring different pixel designs (22 22/33 µm 2 ) 2 options submission in Decembre 12 : sgle end of column discriminator translation of MIMOSA-22AHR (0.35 techno.) simultaneous 2-row encoding & 2 discriminators/column twice faster AROM-1 (Accelerated Read-Out Mimosa) ASTRAL (2nd step) in-pixel discri. & simultaneous 4-row encoding 8 times faster than MIMOSA-22THR submission of 1st prototype in Q1-Q2/2013 SUZE-02 ( Downstream part of sensor) : Ø µ-circuits & output buffers (extension of SUZE-01 with 4 rows simult. encoding) encode windows of 4 rows 5 columns signal transmission at 320 MHz/cm submission in Decembre 12 13

R&D Plans towards Final Sensor FSBB (Full Scale Basic Block) : combining upstream and downstream chain elements Composition: Pixel array with final pixel design ( 1 cm 2 )

Q4/2013 ALICE fast sensor (ASTRAL): 15 µs (can be < 4 µs), same pixels, subm. Q4/2015 AIDA-BT:??? Final sensors for ALICE, CBM, AIDA,.

14 R&D Plans towards Final Sensor FSBB (Full Scale Basic Block) : combining upstream and downstream chain elements Composition: Pixel array with final pixel design ( 1 cm 2 ) Final r.o. circuitry (Ø, filtering, data transmission,...) Variants: ALICE baseline (MISTRAL): 30 µs, µm 2 pixels, subm. Q4/2013 ALICE fast sensor (ASTRAL): 15 µs (can be < 4 µs), same pixels, subm. Q4/2015 AIDA-BT:??? Final sensors for ALICE, CBM, AIDA,...: Composition : 3 adjacent FSBB (1-sided read-out) or 2 rows of 3 FSBB (stitching, 2-sided r.o.) Complemented with serial r.o. circuitry Submissions: MISTRAL: 30 µs (15µs possible), subm. Q4/2014 ASTRAL: 15 µs ( 2 µs possible) subm. Q4/2016 AIDA-BT: subm (?) 14

Development of CMOS pixel sensors for tracking and vertexing in high energy physics experiments

PICSEL group Development of CMOS pixel sensors for tracking and vertexing in high energy physics experiments Serhiy Senyukov (IPHC-CNRS Strasbourg) on behalf of the PICSEL group 7th October 2013 IPRD13,