C. Irmler, M. Friedl, M. Pernicka HEPHY Vienna

C. Irmler, M. Friedl, M. Pernicka HEPHY Vienna
Construction and Performance of a Double-Sided Silicon Detector Module using the Origami Concept C. Irmler, M. Friedl, M. Pernicka HEPHY Vienna

TWEPP 2009, Christian Irmler (HEPHY Vienna)
Contents Motivation “Origami” Chip-on-Sensor Concept Prototype Assembly Beam Test Performance Summary & Outlook 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

Motivation “Origami” Chip-on-Sensor Concept Prototype Assembly Beam Test Performance Summary & Outlook 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

KEKB and Belle @ KEK (Tsukuba, Japan)
Asymmetric machine: 8 GeV e- on 3.5 GeV e+ ~1 km in diameter Mt. Tsukuba KEKB Belle Belle KEKB Linac e+/e- linear accelerator + storage ring Center of mass energy: Y(4S) (10.58 GeV) High intensity beams (1.6 A & 1.3 A) 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

Belle-II KEKB factory upgrade until 2013 Target luminosity of 8 x 1035 cm-2s-1 40 times the present value Accordingly increase of background Limitations of current silicon vertex detector (SVD2): Occupancy  need faster shaping Trigger rate (dead time)  need faster readout and pipeline Replacement of the SVD and its readout is necessary APV25 readout chip would fit the needs 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

Comparison VA1TA – APV25 VA1TA (SVD2) Commercial product (IDEAS) Tp = 800 ns (300 ns – 1000 ns) no pipeline 5 MHz readout 20 Mrad radiation tolerance noise: ENC = 180 e e/pF time over threshold: ~2000 ns single sample per trigger APV25 (Belle-II SVD) Developed for CMS by IC London and RAL Tp = 50 ns (30 ns – 200 ns) 192 cells analog pipeline 40 MHz readout >100 Mrad radiation tolerance noise: ENC = 250 e + 36 e/pF time over threshold: ~160 ns multiple samples per trigger possible (Multi-Peak-Mode) Must minimize capacitive load !!! 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

Shaping Time and Occupancy
With hit time finding, we can cope with 40-fold increase in luminosity For details see poster by Markus Friedl 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

Consequences for SVD Ladder Design
up to 3 ganged sensors SVD2 ladders: Up to 3 ganged (concatenated) sensors are read out from the side Minimization of material budget, as hybrids are outside of acceptance SNR > 15 with VA1TA, but would be < 10 with APV25 Ganging of sensors does not work with APV25! 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

Origami – Chip-on-Sensor Concept
Prototype for 4” DSSD (later with 6” sensors) (readout connections not shown) Chip-on-sensor concept for double-sided readout Flex fan-out pieces wrapped to opposite side (hence “Origami“) All chips aligned on one side  single cooling pipe 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

Origami – Details Thinned readout chips (APV25) on sensor
Strips of bottom side are connected by flex fanouts wrapped around the edge All readout chips are aligned  single cooling pipe Shortest possible connections  high signal-to-noise ratio Total material budget: 0.72% X0 (cf. 0.48% for conventional readout) side view 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

Belle-II SVD Layout 4 layers of double-sided strip sensors Double-layer of DEPFET pixels Tentative geometry New central pixel double-layer using DEPFET 4 strip layers of 6” DSSDs Every sensor is read out individually to maintain high SNR red: Origami chip-on-sensor concept green: read out by conventional hybrid (from side) 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

Sketch of the Outermost Ladder (Layer 6)
Composed of 5 x 6” double-sided sensors Center sensors have Origami structure Edge sensors are conventionally read out from sides ca. 60cm Structural element (Zylon) Cooling pipe Electronics for border sensor Connector (Nanonics) Flex circuits Electronics for border sensor Cooling block (end ring) 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

APV25 Thinning One wafer (319 good dies) thinned down from 300 µm to 106 µm and diced by French company EDGETEK / WSI Received 314 good dies (5 lost = 98.4% yield) 16 thinned APVs mounted onto 4 hybrids Compared to 1 hybrid with 4 standard APVs Measurement Results: All APVs show similar signal and noise figure Proper calibration curve No measurable differences between normal and thinned chips  Thinning has no effects on APV functionality and signal quality! Thinned APV25 Standard APV25 APV25 Calibration Curve 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

Origami Hybrid – Final Layout
Connectors (on both sides) 2 p-side APV chips 2 p-side APV chips 4 n-side APV chips Animal farm (mascots of creators) 3-layer flex hybrid design p- and n-sides are separated by 80V bias n-side pitch adapter is integrated in hybrid 3 pcs. of each type produced at CERN PCB workshop Flex fanouts to be Wrapped around the sensor edge 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

Module Assembly 1 Hamamatsu 4” DSSD: top side: 152 µm pitch (z) bottom side: 50 µm pitch (rφ) Gluing fanouts onto bottom side: Custom jig (porous stone inlay) for gluing and wire bonding Two component epoxy paste adhesive Araldite® 2011 Aligning fanouts against sensor and hybrid Distance between flexes is important Wire bonding: Fully automated bonder F&K Delvotec 6400 Processing of bottom side is finished 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

Module Assembly 2 Attaching APV25 chips onto hybrid
bottom APV25 top APV25 APV25 calibration curves of Origami hybrid Attaching APV25 chips onto hybrid Two component conductive adhesive Alignment under microscope Gluing hybrid onto Rohacell foam There must be sufficient glue underneath the bond pads! Wire bonding of APV25 power and control lines Electrical test of hybrid some bad vias  mostly repaired with thin wires Hybrid PCB design is okay 7 of 8 APV chips are working well Excellent internal calibration results 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

Module Assembly 3 Flip sensor and fanouts Using another jig  jig2
Jigs are stuck together with 3 alignment pins Turning over Remove jig1 Further assembling has to be done on jig2 Gluing hybrid onto top side of sensor Aligning pitch adapter to strips on sensor and fanouts Wire bonding between sensor and integrated pitch adaptor 2 openings to protect bottom side bond wires 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

Module Assembly 4 Bending & Gluing of fanouts Using positioner equipped with a custom tool Easier than expected Allows precise positioning w/o damaging underlying wire bonds Wire bonding between APVs and pitch adaptors Attaching cooling pipe Thermal conductive paste Electrically isolating pad between APV and pipe 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

Final Origami Module Origami concept already presented at TWEPP 2008 Prototype completed beginning of August 2009 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

Beam Test Setup CERN SPS beam line Aug. 09 120 GeV π+ / p / K+ Cooling: 13 °C water beam Origami Module Together with different types of Belle DSSD prototype modules cooling system 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

Beam Test Results Origami Module has been tested for several hours Good performance w and w/o cooling (13 °C water) About 80 GB data recorded Analysis is in an early stage  results preliminary Benefit of cooling: ~ 10% higher SNR Preliminary 120 GeV/c π+/p/K+ w/o cooling cooling (13° water) p-side n-side Average cluster width 2.2 1.8 Cluster SNR 11.5 16.7 12.8 18.5 Cluster SNR = S strip_signal / ( sqrt(cluster_width) * noise_avg) ~10% higher noise compared to 2008 beam test for all modules (ground loop in the front-end and / or HV supply?) Hence SNR of all modules is slightly worse than expected 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

Beam Test Results 2 Time resolution achieved in beam tests with several different types of Belle DSSD prototype modules (covering a broad range of SNR) SPS 2009 data matches previous beam test. 2...3 ns RMS accuracy at typical cluster SNR ( ) Origami shows similar precision like other modules (TDC error subtracted) Origami Module 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

Summary & Outlook Motivated by KEKB upgrade and Belle II Concept for low-mass double-sided readout with cooling Thinning of APV25 chips does not affect its functionality Successfully built the first prototype of an Origami module Module showed excellent performance at beam test Beam test analysis is still ongoing Next goal: We want to build a prototype of the outermost layer of Belle-II SVD 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

 Thank you for your attention 
23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

BACKUP SLIDES 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

Origami Material Budget
X0 comparison between conventional and chip-on-sensor: +50% increase in material, but also huge improvement in SNR Trade-off between material budget and SNR According to simulation, additional material is prohibitive in innermost layer, but no problem for layers 4-6  OK with layout 23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

Origami Hybrid – Flexes
23 September 2009 TWEPP 2009, Christian Irmler (HEPHY Vienna)

C. Irmler, M. Friedl, M. Pernicka HEPHY Vienna

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