ATLAS SCT BARREL MODULE PAR COMPONENTS AND PRODUCTION

ATLAS SCT BARREL MODULE PAR COMPONENTS AND PRODUCTION OVERVIEW Janet Carter, Cambridge TOPICS: 1. 2. 3. 4. 5. 6. 7. Barrel Module Requirements Module Component Production Module Assembly Clusters Module Specifications and Categories Module QA Steps and Common Issues Production Schedule Summary 14 th May 2003 SCT Barrel Module PAR - Overview J. R. Carter 1

The Barrel Module n 2112 Identical Barrel Modules required for SCT mounted on 4 Barrels (B 3, B 4, B 5, B 6) 4 single-sided p-in-n ac-coupled silicon microstrip sensors, 80 µm pitch, mounted back-to-back, 40 mrad stereo rotation angle Thermo-mechanical baseboard encapsulated thermalised pyrolitic graphite with fused Be. O facings 14 th May 2003 12 128 -channel ABCD 3 TA binary readout ASICs Bridged wrap-around hybrid – copper-polyimide flex glued on carbon-carbon substrate SCT Barrel Module PAR - Overview J. R. Carter 2

Module Requirements n Detailed in Barrel Module FDR, May 2001: SCT-BM-FDR-4 (http: //atlas. web. cern. ch/Atlas/GROUPS/INNER_DETECTOR/SCT/module/SCTbarrelmod. html) n Summary of Principal Module Requirements: u. MIP Detection efficiency >99% with noise occupancy ≤ 5× 10 -4 u. Intrinsic r-φ point resolution per single-side measurement of 23 µm (80 µm pitch sensor strip) i. Giving 17 µm precision in r-φ co-ordinate and 500 µm in z from back-toback sensor pair with stereo rotation angle of 40 mrad u. Precise mechanical assembly to simplify digitisation and alignment in ATLAS u. Low mass - <1. 2% X 0 per module, averaged over sensor area i 1. 17% X 0 achieved u. Electrical performance maintained up to radiation levels of 2× 1014 neqcm-2 (barrel 3 with safety factor) i. Verified through proton (CERN PS) and neutron (Llublyana) irradiation and lab and test beam studies (sensors, ASICs, modules) 14 th May 2003 SCT Barrel Module PAR - Overview J. R. Carter 3

n Summary of Principal Module Requirements (continued): u. Cold operation in ATLAS (cooling pipes ~ -20 o. C) – module must routinely withstand thermal cycling between -25 o. C and +30 o. C i. Tested by thermal cycling in module QA u. Module safe against thermal runaway of sensors after irradiation in ATLAS i. Thermal designs of baseboard, hybrid and cooling block – thermal simulations and tests with irradiated modules 14 th May 2003 SCT Barrel Module PAR - Overview J. R. Carter 4

Module Component Production n n Hybrids – in production in Japanese industry – talk by S. Terada Baseboards – in production by collaboration at CERN – talk by A. Carter Glues – purchased centrally and distributed to module assembly sites Silicon Sensors and ASICs – status briefly summarised here: Silicon Microstrip Sensors n All SCT barrel sensors manufactured by Hamamatsu Photonics, Japan u. Identical detectors for all modules: 64 mm× 63. 6 mm× 285 µm thick u. Single-sided, ac-coupled, 768 readout strips at 80 µm pitch n Milestones – all achieved, on schedule: u. Sensor FDR: April 1999 u. Sensor PRR following evaluation of pre-series: August 2000 u. Start of series deliveries: January 2001 u. Delivery (including purchase options) completed: May 2003 n QA completed by collaboration (pre-irradiation and sampling after 3× 1014 p. cm-2 24 Ge. V/c proton irradiation at CERN PS) n Sensor quality is excellent 14 th May 2003 SCT Barrel Module PAR - Overview J. R. Carter 5

Series Deliveries (Barrel + Endcap) Barrel 99% Complete on 1 st May 2003 Purchase options added Contract Ordered (including purchase options) Delivered Japan 6000 5913 Norway 1950 UK 2750 Total 10, 700 10, 613 n Pre-Irradiation: u. All quantities within specification u. Very low leakage currents Typically <200 n. A at 500 V bias at 20 o. C u>99. 9% good readout strips 14 th May 2003 SCT Barrel Module PAR - Overview Initial current at 350 V bias (20 o. C) Number of Strip defects J. R. Carter 6

n Post-Irradiation: u. Within specification for operation at ~400 V bias after 10 years of LHC n Points to note for module construction concerning high bias voltages: u. The edges of the sensors are at the back-plane voltage i. Great care must be taken to avoid conducting debris shorting to grounded areas – eg bond wires, openings in sensor passivation in guard rings, bond pads etc i. Module production and assembly to barrels must be a clean process u. On Barrels 3 and 4, modules must be tested to 500 V bias during assembly and commissioning at CERN to ensure there are no HV shorts that would prevent final post-irradiation HV operation i. So I-V of modules are tested up to 500 V in assembly QA (even though initial modules will operate at <200 V bias) 14 th May 2003 SCT Barrel Module PAR - Overview J. R. Carter 7

n Pre-irradiation sensor ‘microdischarge’ u. A small fraction ( ≤ 2%) of sensors show ‘microdischarge’ (impact ionisation) preirradiation between 350 V and 500 V bias i. Rapid current rise with bias voltage, but falls to normal levels with short timeconstant (~30 mins) if bias maintained u. Not a problem for module operation in ATLAS: i. Disappears after irradiation and type-inversion - field configuration changed: Example of smooth, normal I-V curves of ‘microdischarge’ detectors up to 500 V bias after irradiation to 3× 1014 p cm-2 u. But will not use ‘mirodischarge’ modules for the inner barrels 3 and 4 as they complicate initial HV tests up to 500 V during macro-assembly and commissioning 14 th May 2003 SCT Barrel Module PAR - Overview J. R. Carter 8

Front-End ASICs n ABCD 3 TA ASIC u. DMILL technology, fabricated by Atmel u. Single-strip threshold binary readout u. Threshold trimming for each channel n Performance meets requirements both pre- and post-irradiation, with ~1 f. C binary threshold n Series production released in July 2001 following PRR u~87% of SCT requirement for perfect ASICs now delivered and die identified after wafer testing u. But Atmel may not deliver any more before the DMILL line is stopped n The SCT will use an ASIC with 1 bad channel on each module as necessary to make up the shortfall u. Should have a negligible effect on barrel performance Deliveries stopped ASIC Statistics Lots delivered 50 Accepted wafers 795 Accepted wafer yield 25. 9% Tested wafers rejected 24. 0% Accepted perfect chips 52, 695 % of total requirement 87. 5% Wafers left to test 14 th May 2003 SCT Barrel Module PAR - Overview 0 J. R. Carter 9

Module Assembly Clusters n 4 Barrel Clusters for module assembly: u. Japan, Scandinavia, UK, US – reports from each on progress to-date n Clusters have developed different jigging and assembly techniques u. Each builds to the same module specification u. Site qualification process following FDR/PRR in May 2001 with documented requirements and module exchange before series module assembly can get fully underway 14 th May 2003 Cluster Site Qualification Date Number of modules to deliver to macroassembly sites (Oxford, KEK) Japan December 2001 800 Scandinavia Not yet 400 UK June 2002 550 US April 2003 480 SCT Barrel Module PAR - Overview J. R. Carter 10

Module Specifications and Categories n Summary of Principal Module Build Specifications: n Detailed in Barrel Module FDR, May 2001: SCT-BM-FDR-7 (http: //atlas. web. cern. ch/Atlas/GROUPS/INNER_DETECTOR/SCT/module/SCTbarrelmod. html) n Electrical Performance u <1% bad readout strips at 1 f. C binary threshold (noisy, dead, part-bonded, untrimmed, pipeline errors etc). i. Verified through a Characterisation Sequence test using custom SCT VME readout, prototype SCT voltage supplies and standardised DAQ and analysis code (SCTDAQ) u. Module sensor leakage current < (sum of individual sensors + 4 µA) up to 500 V bias at 20 o. C u. Stable performance during 24 hour cold operation (hybrid at ~0 o. C) n All Modules classed for use in ATLAS satisfy the full electrical specification 14 th May 2003 SCT Barrel Module PAR - Overview J. R. Carter 11

n Mechanical Specifications n Principal in-plane parameters (further parameters define the hybrid position and angle) (y is perpendicular to the sensor strips to within half the stereo angle) Design Value ‘Good’ Module Tolerance ‘Pass’ Module Tolerance Baseboard dowel mounting hole in x, mhx [µm] -6500 ± 30 ± 40 Baseboard dowel mounting hole in y, mhy [µm] -37500 ± 30 ± 40 Baseboard dowel mounting slot in x, msx [µm] 38500 ± 140 Baseboard dowel mounting slot in y, msy [µm] -37500 ± 30 ± 40 Mid-point of pair of front sensors in x, midxf [µm] 0 ± 10 Mid-point of pair of back sensors in y, midyf [µm] 0 ± 5 ± 8 64090 ± 10 ± 20 0 ± 0. 13 -20 ± 0. 13 In-Plane Parameter Separation of centres of sensors; front pair, sepf; back pair sepb [µm] Rotation angles of the 4 sensors, a 1, a 3, a 4 [mrad] Half stereo angle between the front and back sensor pairs, stereo [mrad] n The category ‘Good’ satisfies the agreed specification n The category ‘Pass’ is an extension to cover measurement error and the tails of the observed distributions n Both ‘Good’ and ‘Pass’ modules will be used in ATLAS 14 th May 2003 SCT Barrel Module PAR - Overview J. R. Carter 12

n Principal out-of-plane Parameters u Detector surfaces compared with a standard shape u ‘Good’ and ‘Pass’ categories again defined Design Value ‘Good’ Module Tolerance ‘Pass’ Module Tolerance 0 0 1. 15 -0. 2 ± 0. 1 Maximum deviation of lower sensor from common module profile, optimalmax. Zerrorlower [mm] Maximum deviation of upper sensor from common module profile, optimalmax. Zerrorupper [mm] RMS deviation of lower sensor from common module profile, optimal. RMSZerrorlower [mm] 0 0. 05 0. 07 0 0. 025 RMS deviation of upper sensor from common module profile, optimal. RMSZerrorupper [mm] Lower Be. O cooling facing angle perpendicular to mounting line, b [mrad] (module cooling contact issue) Lower Be. O cooling facing angle parallel to mounting line, a [mrad] Lower Be. O cooling facing concavity along the mounting line, lo. Cooling. Facing. Concavity [mm] Maximum thickness of module at surface of large capacitors on hybrid, cap. Max. Thickness [mm] (clearance issue) 0 0. 025 0 ± 3 ± 5 0 0 ± 0. 5 ± 0. 03 5. 78 6. 44 Out-of-Plane Parameter Maximum deviation of lower sensor from module plane, max. Zlower [mm] Maximum deviation of upper sensor from module plane, max. Zupper [mm] Module thickness [mm] 14 th May 2003 SCT Barrel Module PAR - Overview J. R. Carter 13

n Barrel Module Categories u. Each produced module is assigned to one of the following categories: Category Description Good Satisfies all electrical and ‘good’ mechanical specifications. Pass In ‘pass’ grade for 1 or more mechanical parameters. Satisfies all electrical specifications. Hold Outside ‘pass’ grade for 1 or more mechanical parameters and/or does not satisfy all electrical specifications. Such a module is stopped in production and stored. Fail Could never be used in ATLAS (damage, gross errors). Rework is needed before the module could be usable. u. From component availability and schedule requirements, ~90% of modules started in assembly need to be suitable for use in ATLAS 14 th May 2003 SCT Barrel Module PAR - Overview J. R. Carter 14

Module QA Steps and Common Issues n Basic steps in module assembly (with small variations between Clusters): Step QA after step 1. Load 12 ASICs on hybrid §Electrical tests warm and cold 2. Glue 4 sensors to baseboard §In-plane metrology 3. Wrap hybrid around and glue to baseboard-sensor sandwich 4. Wire-bond module 14 th May 2003 §Metrology (in-plane and out-of-plane) following thermal cycling §Electrical characterisation warm §Long-term (24 hr) electrical test cold §Visual inspection SCT Barrel Module PAR - Overview J. R. Carter 15

A Common Electrical Issue: s-curves n Noise-occupancy s-curves are part of module electrical characterisation u. These are occupancy vs threshold for no injected charge n Normally they are smooth curves: picture here 14 th May 2003 SCT Barrel Module PAR - Overview J. R. Carter 16

n But coherent effects can build up between ASICs when digital activity is high and produce s-curve distortions at thresholds << 1 f. C u. A severe example: picture here 14 th May 2003 SCT Barrel Module PAR - Overview J. R. Carter 17

n Barrel Clusters have recently been studying all their available data because a high fraction (of the small number) of series modules completed by Scandinavia have severely distorted s-curves u. Has caused a delay in Scand site qualification, in case of any association with the hybrid mounting technique used by Scand – they are now proceeding cautiously with a new method n But s-curve distortions are seen in varying degrees by all Clusters u. An on-going study to look for correlations and differences between Clusters n Does it matter? u. We think not, provided the distortions are well below (<0. 3 f. C) the operating threshold of 1 f. C – which they are i Noise Occupancy of module at 1 f. C is not affected i Effect reduces with irradiation i Has not to-date caused problems in system test operation u. The properties after irradiation and system operation will be further tested this summer using modules with the most severely distorted s-curves 14 th May 2003 SCT Barrel Module PAR - Overview J. R. Carter 18

Production Schedule n SCT Schedule requirements for macro-assembly imply: Barrel Number of Modules to deliver From Clusters Delivery to be completed by B 3 404 All December 2003 B 6 706 All March 2004 B 5 605 All May 2004 B 4 504 Japan June 2004 n ******I have made up these dates, which are later than the schedule******* n There are further constraints on selecting the modules with the most robust high bias voltage characteristics for barrels 3 and 4 n Nevertheless, sufficient modules should be available in time for the required completion of the first barrel - B 3 14 th May 2003 SCT Barrel Module PAR - Overview J. R. Carter 19

Summary n Sensors are in-hand of very good quality n Problems with the end of ASIC delivery, but 1 -bad channel chips can be used to make up the difference n Module assembly underway – now x% of total ‘Good’ + ‘ Pass’ requirement completed n Site qualification of the Scandinavian cluster is an urgent priority n Integrated assembly yield is still lower than the 90% target for all but the Japanese cluster (to be seen from the Cluster presentations) n Overall quality of modules is good – s-curves need careful monitoring and some more study 14 th May 2003 SCT Barrel Module PAR - Overview J. R. Carter 20