SiLC Silicon Sensors: Status of different activities Thomas Bergauer for the SiLC Collaboration April 25th, 2007 • Outline: • SiLC “Sensor Baseline” • DESY TPC • Synergies with SLHC • Status of companies
Linear Collider Constraints • Future Linear Collider Experiment will have a large number of silicon sensors • Few hundreds m2 (CMS has 200 m2) • Radiation damage will be no issue (e+e-) • Concept for strip tracker: • long strips (10-60cm) • low material budget • Light active cooling only due to power cycling of FE electronics(1/100ms duty cycle) • Time structureof beam:
SilC Silicon Sensor Baseline • SilC sensor baseline • FZ p-on-n sensors: n-bulk material, p+ implants for strips • high resistivity (5-10 kOhm cm) • Readout strip pitch of 50µm • Possibly intermediate strips in between (resulting 25µm pitch) • Smaller pitch becomes very complicated (Pitch adapter, bonding, charge sharing,…) • Thickness around 100-300µm • mostly limited by readout chip capabilities (S/N ratio) • Low current: <1nA per strip (Due to long integration time noise mostly defined by current and resistors) • Baseline for inner layers: • 6” inch, Double sided, AC coupled • Baseline for outer layers: • 8” (12”?) inch, Single sided, Preferably DC coupled (cheaper)
Sensor Baseline Details Biasing Possibilities: • bias resistor with poly-silicon(20 to 50 MOhm) • punch-through (upper picture) • or FOXFET biasing structure (lower picture) • Latter two have non-linear behavior • But are cheaper
Minimize material budget • Multiple scattering is crucial point for high-precision LC experiment • Minimize multiple scattering by reduction of material budget • avoid old-fashioned way (pitch adapter, FE hybrid, readout chip) • Integrate pitch adapter into sensor • Connectivity of strips to readout chip made by an additional oxide layer plus metal layer for signal routing • Readout chip bump-bonded to sensor like for pixels
Similar to SiD Concept: Slide taken from Timothy Nelson‘s Presentation of SiD detector concept at Bejing ILC GDE Meeting (Feb 6, 2007) …..very elegant!
“Inline pitch adapter” for SiLC UMC Chip IEKP Karsruhe • UMC 130nm chip successfully tested with long ladder out of 10 HPK GLAST sensors • Wire bonding • Next UMC chip version • 128 channels • Bump-bonding LPNHE Paris
Long ladder with 2 sensor types PA on sensor with bumpbonded chips Standard Wire Bonding F. Hartmann Chip to stip routing on sensor
SilC work program for sensor R&D • Step 1 (2007) • Use long strips (50 µm pitch) • Wafer thinning (100, 200, 300µm) • Test new readout chips (DC coupling, power cycling) • Improve standardized test structures and test setups • Step 2a (2008-) • Move from pitch adapter to in-sensor-routing • Test crosstalk, capacitive load of those sensors • Step 2b (2008-) • Test 6” double sided sensors • Step 2c (2008-) • 8” (12”) single sided DC wafer
Step 1 and 2a: • Bump-bondable 128-channel chip available end 2007 • HPK agreed to provide a sensor design • SiLC adapts strip to pad area • HPK will process the sensor • SiLC (Paris) provides chip • HPK could bump bond chip to sensor • HPK is very interested to strengthen inhouse bumpbonding • In Bump • Flipchip • Stud-bonding (Jean-Francois Genat) • Testing begins 2008
Silicon “Envelope” for TPC Ties Behnke, 4th SiLC Meeting Barcelona (Dec 2006):
Superconducting Magnet • Magnet already at DESY • TPC Support structure movable; Si modules should be mounted onto this structure • Timescale: • Construction of TPC Field Cage until autumn 2007 by commercial company • First beam test until end of the year
Silicon Envelope • Long ladder in z Direction • Stereo modules with two sensors • Resolution requirements still unclear: • R-Phi: 10-50 um • Z: 50-250 um • Stereo angle responsible for z resolution • Optimal z resolution when stereo sensor perpendicular to R-phi sensor • Crucial Point: Space between magnet and TPC: 2cm • Large stereo angle needs more space • Sensors perpendicular?
Resolution of stereo modules r-Phi resolution: z<100 um hard to archive CMS: angle 6 deg already a lot!
Next Steps • Sensor procurement from HPK • Details about HPK offer later • Sensors tests @ Vienna, Karlsruhe • Find material for module frame/support • Rohacell, Silicon foam • Carbon Fiber, Graphite • Define module/ladder geometry • Maximum number of daisy-chained sensors? • Depends on S/N ratio of chip (Jean-Francois?) • Layout of FE hybrid and Chip pitch needed (Jean-Francois?) • Everybody who is interested is welcome to join the phone/video meeting. Just send me a mail and I will take you on the list. • Plan to have a tour to the TPC magnet during LCWS07 in Hamburg (end of May)
Synergies with (S)LHC LHC Upgrade project is called “super” LHC
Synergies with (S)LHC Slide taken from Frank Hartmanns’ Talk in “CMS Sensor upgrade Workshop” (February, CERN)
Synergies with (S)LHC • Most interesting match between the projects: • Large areas (8”) • SLHC wants to use second metal layer to route signals from “large pixels” (a.k.a. “short” strips”) “stixels” • Many points which are not matching: (unfortunately) • search for other material which is more radiation tolerant: MCz, Oxygenated Si • Other “base” material: n-on-n; n-on-p • Double sided sensors • Long ladders (high capacitive load) vs. short integration time • Synergies would help both, SLHC and SiLC to convince companies about new developments
HPK • During Vienna Conference “VCI” (Feb 2007): Meeting with HPK’s European Sales representant and Japanese engineer. • We had several questions which have been answered by them (later by e-mail): • Double sided processing (6”)? Not possible • Cost difference AC-DC coupling: AC is 40-50% more expensive • Cost difference biasing (DC=100): PT: 115; FOXFET : 120; Poly-Si : 130 • Minimal sensor thickness? 200 micron (possible in 1 year from now) • Maximum dielectric layer? 1m with SiO2, maybe Polyimide in the future • Trace metallization: only Al with 0.9 m thickness and minimum width of 3 to 4 m; no other material for the time being (we asked for Copper) • Larger Sensors: 8-12” production possible via sub-contractor, but much more expensive; limited prototyping • bump bonding: Indium bump-bonding being developed within 1 year, 20 m pitch • We asked HPK for an offer for 30 pcs single sided detectors with 50um pitch during this meeting.
HPK offer from April 24th (yesterday): • Specification: • SSD type : single-sided DC type • SSDChip size : about 95 x 95 mm • Thickness : 320 um • Strip : 50 um pitch (with one intermediate strip) • Price quotation: • Delivery: • Lead time takes 5 months aro for first 30 pcs prototype. • They are now waiting for an official order.
VTT • After Proposal from Simo Eränen during December’s SiLC Meeting we (=Vienna) started to collaborate • Design almost ready • Two main sensors on wafer • One sensor DC coupled • Other AC coupled with PT or FOXFET bias because of lack of polySi processing line • Vienna provided CMS-like ‘half-moon’ TS • Now design verification • Begin of processing soon MAIN DETECTOR, 5 X 5 SQCM MEDIPIX2, 1.5 X 1.5 SQCM ALIGNMENT MARKS, 1 X 1 SQCM HALF MOON TEST STRUCTURE EDGELESS TEST STRUCTURES, 1.5 X 1.5 SQCM BABY DETECTORS, 1 X 1 SQCM
Meeting with Hwanbae Park (Korea), Jan 29th • Hwanbae showed results of the work of his group during December’s SiLC meeting • Frank, Manfred and I had a phone meeting asking him for larger detectors • Like it is shown on the right • Maximize size per wafer in a single sensor (approx. 10 x 10 cm2 ) • According to SiLC baseline • We agreed that we provide a modified CMS design (with TS) for full 6” wafer (timescale: several months) • Agreed to start in April 2007, when new financial year starts in Korea since more money will be available CMS OB2 sensor
IET Warsaw • Frank Hartmann established contact with Institute for Electron Technology (Jacek Marczewski) already three years ago • Karlsruhe and Vienna are both in loose contact with them to develop test structures • Based on CMS ‘half-moon’ • They have experience with SOI and chip production, but not with fully depleted devices yet. • Production of first batch has just started
Canberra ? (Aurore proposed to establish a contact with them)
ON Semiconductor • http://www.onsemi.cz • Former “Tesla” company • Located in Czech republic • Presumably high throughput • 4” production line running • 6” production line currently commissioned • “first contact” can be established with help of Vaclav Vrba from Czech Academy of Sciences hopefully soon.
Summary • Sensor baseline established: • FZ, p-on-n, high resistivity, 100-300um thick, 50um pitch • preferably DC coupled, otherwise biasing via PolySi, PT or FOXFET • DESY TPC project started • Sensor procurement with HPK ongoing, but takes longer than expected • Several design decision to be made: • Which stereo angle? (or perpendicular sensors; best resolution) • Material of Support: CF/Rohacell, CF legs like CMS, other material? • Next step: Module Construction • Layout of the FE hybrid unknown, need input from Jean-Francois • Discussion with several companies / institutes ongoing • VTT: design almost finished • Korea: 1st design has to come from us within next weeks • IET Warsaw: TS already in production • Canberra: unknown • ON Semiconductors: 1st visit next month?
The End. Backup Slides follow
Silicon sensor expertise within SiLC • Both, Vienna and Karlsruhe worked a long time already with silicon sensors • DELPHI @ LEP • CDF @ Fermilab • CMS @ LHC • We have experience in • Strip-by-strip characterization of Si strip sensor • Process monitoring with test structures • Proton irradiation facility in Karlsruhe • Post irradiation characterization • Examples of our experience on next few slides
Strip-by-Strip Characterization What do we test? • Global parameters: • IV-Curve:Dark current, Breakthrough • CV-Curve:Depletion voltage, Total Capacitance • Strip Parameters e.g. • strip leakage current Istrip • poly-silicon resistor Rpoly • coupling capacitance Cac • dielectric current Idiel
Process Monitoring on Test Structures TS-CAP baby diode MOS 2 GCD sheet CAP-TS-AC CAP-TS-AC MOS 1 • CMS “Standard Half moon” • 9 different structures • Use to determine one parameter per structure • Worked extremely well during CMS sensor production • Example of an identified problem can be seen in plot: low interstrip resistance • Improved version for SiLC • overall size reduction • Structure design improvements (e.g.better sheet structure) HEPHY Vienna
Strip-by-strip Test Setup • Sensor in Light-tight Box • Vacuum support jig is carrying the sensor • Mounted on freely movable table in X, Y and Z • Cold chuck in Karlsruhe available • Needles to contact sensor bias line • fixed relative to sensor • Needles to contact: • DC pad (p+ implant) • AC pad (Metal layer) • Can contact ever single strip while table with sensor is moving
TS-CAP: Coupling capacitance CAC to determine oxide thickness IV-Curve: breakthrough voltage of oxide Sheet: Aluminium resistivity p+-impantresistivity Polysilicon resistivity GCD: Gate Controlled Diode IV-Curve to determine surface current Isurface Characterize Si-SiO2 interface CAP-TS-AC: Inter-strip capacitance Cint Baby-Sensor: IV-Curve for dark current Breakthrough CAP-TS-DC: Inter-strip Resistance Rint Diode: CV-Curve to determine depletion voltage Vdepletion Calculate resistivity of silicon bulk MOS: CV-Curve to extract flatband voltage Vflatband to characterize fixed oxide charges For thick interstrip oxide (MOS1) For thin readout oxide (MOS2) Test Structures Description
Test structures Measurement Setup • Probe-card with 40 needles contacts all pads of test structures in parallel • Half moon fixed by vacuum • Micropositioner used for Alignment • In light-tight box with humidity and temperature control • Instruments • Source Measurement Unit (SMU) • Voltage Source • LCR-Meter (Capacitance) • Heart of the system: Crosspoint switching box, used to switch instruments to different needles • Labview and GPIB used to control instruments and switching system
Example of identified problems Inter strip resistance issue during CMS sensor production • Limit: Rint > 1GΩ to have a good separation of neighbouring strips • Each dot in the left plot shows one measurement • Value started to getting below limit • We reported this to the company • Due to the long production pipeline, a significant amount of ~1000 sensors were affected
Proton Irradiation @ Karlsruhe • 35 MeV protons with easy access to 10^15 1MeV Nequiv • Irradiation for design check • Later: Irradiation control during production • Standard pre- and post irradiation measurements Compact Cyclotron at Forschungszentrum Karlsruhe
UMC Technology parameters • 180 nm 130nm • 3.3V transistors yes yes • Logic supply 1.8V 1.2V • Metals layers 6 Al 8 Cu • MIM capacitors 1fF/mm² 1.5 fF/mm2 • TransistorsThree Vt options Low leakage option
SilC Readout Chip • SilC Collaboration is developing a new readout chip designed for the ILC needs: • DC coupled readout • Power cycling • UMC 130nm technology • Chip with 4 channels already available • Chip with 128 available early next year LPNHE Paris Picture
SiTR-130_1 tests results Gain OK: 30 mV/MIP OK Dynamics: 30 MIPs @ 5% OK Peaking time: 0.8 – 2ms 0.7 - 3 ms LPNHE Paris Power (Preamp+ Shaper) = 300 mW Noise comparative 130nm @ 0.8 ms : 850 + 14e-/pF 130nm @ 2 ms : 625 + 9e-/pF 180nm @ 3 ms : 360 + 10.5 e-/pF
NEW S/N measured with SiTR-180 (after t.b.)W. Da Silva, J. David, F. Kapusta, F. Rossel (LPNHE) VERY VERY PRELIMINARY GLAST module channels read by VA1 (top) or 180 (bottom)
UMC 130nm 4-channel test chip: SiTR-130 Channel n+1 Zero-suppression Can be used for a “trigger” S aiVi > th Time tag Ramp ADC Channel n-1 reset reset Analog samplers, (slow) Strip Preamp + Shaper DC servo implemented for DC coupled detectors Waveforms Clock 3-96 MHz Ch # Counter UMC CMOS 130nm: SiTR-130_1 Received in August 15 2006 Being tested: Analog OK, Digital under tests