Rad-Hard Active Pixel Sensors for HL-LHC Detector Upgrades based on HV-CMOS

1. Rad-Hard Active Pixel Sensors for HL-LHC Detector Upgrades based on HV-CMOS Marlon Barbero – Centre de Physique des Particules de Marseille barbero@cppm.in2p3.fr Genova visit / December 16th 2013

2. ATLAS tracker upgrade plan • New insertable b-layer • (IBL) • New Al beam pipe • New pixel services • New insertable b-layer • (IBL) • New Al beam pipe • New pixel services • All new tracker (baseline: • long strips /short strips / • pixels) • Possible level1 tracker • Fast TracKing (FTK) • for level2 trigger IBL: On-going construction phase!

3. HL-LHC environment challenge • HL-LHC targets: • 14TeV; Luminosity: 5.1034 cm-2.s-1 / 3000 fb-1 in ~7 years • Consequences for trackers: • High radiation for the innermost layers (~5cm): • ~1.1016 neq.cm-2 / ~1GRad  rad-hardness! (note: ~50-100MRad at 25cm) • High occupancy: • cope with of order <140> pile-up events / bunch-crossing  high granularity! fast! • Huge surface to cover: • of order 200m2 reduction in costs!

4. Using Hybrid Detectors • Hybrid detectors: • n-in-n or n-in-p with reduced drift distance (3D or thin silicon). • DSM rad-hard IC (a la IBL FE-I4 -130nm- or reduced feature size 65nm?). • Valid option: should work (after development). • Drawback: 1- Price of hybridization / of non-standard sensors (yield?) and for a large area. 2- Will stay rather thick. 3- High bias voltage. 4- Deep charge collection leads to difficult 2-trackseparation in boosted jets.

5. Principle of HV-CMOS process • An n-well in p-substrate diode, populated with CMOS (first stage amplifier or more complex). CMOS! e.g. 1st stage amplifier n-well in p-substrate diode n-well biasing depletion zone around nwell: charge collected by drift resist~10Ω.cm

6. ATLAS HV-CMOS Collaboration • Bonn University: M. Backhaus, L.Gonella, T. Hemperek, F. Hügging, H. Krüger, T. Obermann, N. Wermes. • CERN: M. Capeans, S. Feigl, M. Nessi, H. Pernegger, B. Ristic. • CPPM: M. Barbero, F. Bompard, P. Breugnon, JC. Clemens, D. Fougeron, J. Liu, P.Pangaud, A. Rozanov. • Geneva University: D. Ferrere, S. Gonzalez-Sevilla, G. Iacobucci, A. Miucci, D. Muenstermann. • Goettingen University: M. George, J. Grosse-Knetter, A. Quadt, J. Rieger, J. Weingarten. • Glasgow University: R. Bates, A. Blue, C. Butter, D. Hynds. • Heidelberg University: I. Peric (original idea). • LBNL: M. Garcia-Sciveres.

7. Process Main Characteristics • CMOS electronics inside deep n-well. • Negatively biased substrate leads to ~8-10μm depletion zone  charge collection by drift. • Small feature size + relatively low complexity of in-pixel logic  small pixel. • 1st stage signal amplification on-sensor (low capacitance  low noise). • Featuring: 1- electronics rad-hard (DSM technology). 2- sensor rad-hard (small depletion depth, small ΔNeff). 3- low price (standard CMOS process). 4- low material budget (can be thinned down). 5- low maximum bias voltage (moderate substrate resistivity). 6- fast (electronics on sensor). 7- good granularity(1st prototype 33×125μm2, can go down). • HV2FEI4p1/-p2 in AMS180nm HV-CMOS.

8. HV2FEI4 series • -p1: Proof of principle. • -p2: Rad-hardness enhanced. • 2.2×4.4 mm2. • 60columns×24rows. • pixels: 33×125μm2. • pads to realize various operation modes: • Standalone measurement possible. • CCPD: Capacitively coupled to pixel IC. • Bonded to strip readout IC. IO for CCPD strip pads pixel array w. transmission pads IO for strips

9. Readout -a la strips- • Readout: use HV-CMOS sensor in combination with existing powerful IC by connecting HV-CMOS pixels in various ways. • e.g. pixels can be summed up as “virtual strips”, with hit position encoded as pulse height. Pixel hit map from strip information (note the shadow of a wire)

10. Readout -with larger pixels- • Combine 3 pixels together to fit one FE-I4pixel (50×250μm2), with HVCMOS pixels encoded by pulse height. • Capacitive coupling OK: gluing! (perspective toavoid bump-bonding?) The tiny HV2FEI4p1 prototype glued on the large FE-I4

11. HV2FEI4p1 on FEI4 • 90Sr-source. • Readout through FE-I4. • kHz rate recorded!

12. Sub-pixel encoding principle unirradiated sensor Sub-pixel 2 • Works on single pixel cells. • Sub-addresses well separated in ToT histo. 3 sub-pixels on Sub-pixel 3 Sub-pixel 1 Three values for the addresses decoded by the FE-I4 pixel

13. HV2FEI4p1 • Recorded routinely 90Sr and 55Fe spectra. • Degradation at 80MRad proton irradiation (dead at 200MRad!) Discri

14. Bulk damage • Small depletion depth + Neff > 1014.cm-3 bulk rad-hard? • Non-ionizing radiation at neutron source (Ljubljana) to 1.1016 neq.cm-2. occupancy in 10 minutes No source With 90Sr leakage current increase (as expected) sensor works at room T after 1016 neq.cm-2. (scintillator trigger used) Note: 30 days annealing at room temp

15. TID issue HV2FEI4p2 • Few pixel flavors with enhanced rad-hardness: guard rings, circular transistors… (different pixel types lead to different gains -expected-). 55Fe spectra, unirradiated “normal” “rad-hard” different gains

16. TID issue HV2FEI4p2 • After 862 MRad Xray (annealing included 2h at 70C each 100MRad), after parameter retuning, amplifier gain loss recovered to 90% of initial value Relative preampli amplitude variation as function of dose Recovery at 862 MRad (NOT 900MRad)

17. Conclusion • Principle: Firmly established. Various types of readout demonstrated, among which capacitive coupling through gluing to FE-I4. • Prospects for: Small pixels, less material, cheaper, large area… • Need further studies on radiation hardness, but positive indications of radiation tolerance. • Need efficiency / spatial resolution studies test beam. • Needoptimization to establish geometry & architecture. • Discussion on new larger size prototype to realize currently on-going.

18. Outlook Back Side Metal • Hybrid solution vs monolithic for future trackers? 65nm vs HVCMOS? • Our collaboration has started to look into other processes: sensor Super Contact Tier 1 (thinned wafer) M1 M2 M3 M4 M5 Bond Interface M6 M6 M5 M4 M3 M2 M1 Tier 2 Super Contact T3-MAPS (LBNL) IBM 130nm 1640 electrons (assuming collected by one pixel) DMAPS (Bonn) ESPROS 150nm GFMAPS (CPPM) GF 130nm

19. BACKUP • BACKUP

20. New monolithic sensors on a fully isolated substrate Spectrum of Fe55 (X-ray) and Sr90 (e-), obtained from a 10mX10m single pixel. We have exploited a new CMOS substrate isolation implant to implement a monolithic radiation detector. Because the substrate is completely junction-isolated from the active wells, it can be biased at larger negative voltages than would be possible in a standard process. This not only permits true 100% fill factor but also improves the sensor performance. Preliminary results will be shown.

21. Outlook another 3D approach Back Side Metal • We submitted on June 2013 a new HV2FEI4 version in GlobalFoundries 0.13µm BCDLite technology. The chip is 100% compatible with the HV2FEI4 chip, and could be easily tested. Despite some small failures, the chip works at -30V • The HV2FEI4 could be use on a complex and advanced monolithic 3D chip, including analog sensor and digital post-processing parts Super Contact sensor Tier 1 (thinned wafer) M1 M2 M3 M4 M5 M6 M6 Bond Interface M5 M4 M3 M2 M1 Tier 2 Super Contact

22. EPCB01 – Depleted monolithic pixel chip • Features: • Technology: ESPROS • Feature size: CMOS 150 nm • High resistive N-type bulk (~ 2 kΩ cm) • High voltage at sensor domain possible (~ 10 V) • P-type well to integrate CMOS electronics • 6 metal layers • Chip is thinned down to 50 µm Full depletion can be achieved New Physicist’s dream??

23. Source scan Fe55 • Fe55 used for calibration of Sr90 plot • Sr90 MPV ~2400 electrons • (~ 4200 electrons expected for • ~ 50 µm silicon) • → rest of the charge is collected by • other pixels (clustering)