1. 7. October 2013 13 th IPRD Siena W. Treberspurg, U. Bartl, T. Bergauer, M. Dragicevic, E. Frühwirth, S. Gamerith, J. Hacker, A. König, F. Kröner, E. Kucher, J. Moser, T. Neidhart, H.-J. Schulze, W. Schustereder, T. Wübben A new vendor for high volume production of silicon particle detectors

2. Outline Wolfgang Treberspurg (HEPHY Vienna)7. October 20131 1. Overview of the Project 2. The different Sensor Structures 3. Summary of the Electrical Characterization 4.Summary of Beam Tests 5.Outlook and Summary

3. Wolfgang Treberspurg (HEPHY Vienna)7. October 20132 1. Project Overview: Silicon Sensors  History:  Silicon is used for detectors since the 50ies  Silicon strip detectors have been first used in the CERN experiment NA11 in the 80ies  Today up to 200 m 2 (CMS) of silicon sensors are used  The same amount can be expected for the upgrades of CMS and ATLAS  Wafer Size:  NA11 started with 2” and 3”  Today 6” (150 mm) is standard  Introduced in the Industry in the 80ies

4. Wolfgang Treberspurg (HEPHY Vienna)7. October 20133 1. Project Overview: Different Vendors  Small scale R&D production:  Many institutes and companies are able to produce a few 10-100 wafers per year  6 inch is usually available at many sites  The sensors differ in a broad spectra of quality and price  Large scale commercial production:  Currently only one company is able to produce a few 1.000 – 10.000 high quality wafers per year  Possible new producer: Infineon  Production on thinned 8 inch wafers could be possible  Dual or multi-source strategy would be preferable

5. Wolfgang Treberspurg (HEPHY Vienna)7. October 20134 1. Project Overview: Infineon Austria  General: Infineon holds 26700 employers at different sites around the world  Villach (Austria): The Austrian site in Villach holds 2400 and produces 50.000 wafer per week  Villach is aimed for Frontend Production and R&D  The Clean room facilities just extended to over 10.000m 2  Pilot production lines are developed at Villach, E.g.: worlds first power devices on 12 inch wafer (Oct. 2011)

6. Wolfgang Treberspurg (HEPHY Vienna)7. October 20135 1. Project Overview: The Collaboration 1  End of 2009: Start of project (intense discussion on technical details)  Begin of 2011: Decision of baseline and milestones  Baseline:  Wafer Material: 6” n-type, 300 µm thickness, Approx. 1.2 kΩcm resistivity  Process Specifications: Standard p- on-n technology, AC coupled strips, SiO 2 /Si 3 N 4 sandwich dielectric, poly silicon resistor biasing  8 photo masks (one for patterning of Si 3 N 4 )

7. Wolfgang Treberspurg (HEPHY Vienna)7. October 20136 1. Project Overview: The Collaboration 2  August 2011: HEPHY finished the final mask design for the first produced batch  October 2011: Production of the first batch started  April 2012: The wafer have been characterized in Vienna  October 2012: Beam tests and irradiation studies  Beam tests at the SPS accelerator at CERN  Gamma irradiation at SCK-CEN Mol, Belgium  December 2012: Second batch with the same masks and other split groups is produced and delivered in February 2013  July 2013: Start of irradiation studies with protons (in Karlsruhe at KIT) and neutrons (in Vienna at ATI)  September 2013: Production of third batch with new (modified) masks CMS Track Trigger Prototype Module with 2 Infineon Baby Sensors

8. Wolfgang Treberspurg (HEPHY Vienna)7. October 20137 1. Project Overview: Comments  The production in the clean room was accompanied by our diploma students  The first batch was accompanied by Edwin Frühwirth  The third batch was accompanied by Axel König  We were discussing all technical details directly with the engineers and are involved in the process as far as possible  Since the beginning of 2010 we held weekly telephone conferences  We finally received every wafer from the production batch (except for one wafer, damage due mishandling)  no hidden losses In the cleanroom

9. Outline Wolfgang Treberspurg (HEPHY Vienna)7. October 20138 1. Overview of the Project 2. The different Sensor Structures 3. Summary of the Electrical Characterization 4.Summary of Beam Tests 5.Outlook and Summary

10. Wolfgang Treberspurg (HEPHY Vienna)7. October 20139 2. Wafer Structures: The STL Sensor  The large standard sensor (STL):  Size: 64 x 102 mm  Active size 61.5 x 99.6 mm  512 strips (4xAPV)  120 µm pitch  20 µm strip implant width  Motivation:  The large sensor has the same dimension as the current CMS sensors

11. Wolfgang Treberspurg (HEPHY Vienna)7. October 2013 2. Wafer Structures: The STS Sensor 10  The small standard sensor (STS):  Size: 23 x 50 mm  Active size 20.6 x 48.3 mm  256 strips (2xAPV)  80 µm pitch  20 µm strip implant width  Motivation:  The STS sensor is mainly dedicated for building modules  This sensors have been used at tests with a high energy beam

12. Wolfgang Treberspurg (HEPHY Vienna)7. October 2013 2. Wafer Structures: The STI Sensor 11  The standard irradiation sensor  Size: 7 x 42.5 mm  Active size 5.3 x 40.7 mm  64 strips (0.5xAPV)  80 micron pitch  20 strip implant width  Motivation:  This sensors have been designed for irradiations in the TRIGA Mark II reactor in Vienna with a narrow irradiation tube  The STI sensors have been used for R&D investigations

13. Wolfgang Treberspurg (HEPHY Vienna)7. October 201312 2. Wafer Structures: Split Groups Wafer No. Split1- Split2 Wafer No. Split1- Split2 01A-A14C-A 02A-A15C-A 03A-B16C-B 04A-B17C-B 05A-C18C-C 06A-C19C-C 07B-A20D-A 08B-A21D-A 09B-B22D-B 10B-B23D-B 11B-C24D-C 12B-C25D-C  First Batch:  25 wafers produced with photo masks designed by HEPHY  Wafer 13 not delivered because of mechanical damage  Wafer 04 not diced and used for presentation  Split Groups first Batch:  23 wafers split into 12 groups to test different process parameters  First split: Gate Oxide (4 groups A to D)  Second split: backside n+ implant diffusion (3 groups A to C)

14. Outline Wolfgang Treberspurg (HEPHY Vienna)7. October 20131 1. Overview of the Project 2. The different Sensor Structures 3. Summary of the Electrical Characterization 4.Summary of Beam Tests 5.Outlook and Summary

15. Wolfgang Treberspurg (HEPHY Vienna)7. October 201313 3. Electrical Characterization: Measurement Parameter  Global parameters:  IV-Curve: Dark Current, Breakdown Voltage  CV-Curve: Depletion Voltage, Total Capacitance  Strip Parameters:  Strip leakage current I strip  Poly-silicon resistor R poly  Coupling capacitance C ac  Dielectric current I diel

16. Wolfgang Treberspurg (HEPHY Vienna)7. October 201314 3. Electrical Characterization: Global Values  CV: The depletion voltage of structures on all wafer is around 240 V  IV: In general most sensors feature a low dark current (7 - 30 nA/cm 2 )  Many Sensors are stable up to 1000 V  Sensors of the X-C split group feature low current but early breakdown STL: ~65 cm 2 STS: ~11 cm 2 1/C 2 for all large sensors

17. Wolfgang Treberspurg (HEPHY Vienna)7. October 201315 3. Electrical Characterization: The STL Sensor Istrip/Istrip median Cac/Cac median Rpoly/Rpoly median  The plotted values are normalized the median strip value of each sensor  Homogenous values  Accumulation of anomalous strips around strip no. 500 (and 416 for I strip )  All split groups are affected

18. Wolfgang Treberspurg (HEPHY Vienna)7. October 201316 3. Electrical Characterization: The STS Sensor Istrip/Istrip median Cac/Cac median Rpoly/Rpoly median  Homogenous values  Accumulation of anomalous strips around strip no. 222- 248  Same behavior of anomalous strips as on other sensors  All split groups are affected

19. Wolfgang Treberspurg (HEPHY Vienna)7. October 201317 3. Electrical Characterization: The STI Sensor  Absolute values of measurement plotted  Accumulation of anomalous strips around strip no. 35-55  Same behavior.  Increasing I strip  Decreasing R poly  Decreasing C ac

20. STL: I strip STS: I strip Wolfgang Treberspurg (HEPHY Vienna)7. October 201318 3. Electrical Characterization: Summary Criteria: I strip > 50 nA (for STL) and I strip > 25 nA (for STS) I diel > 1 nA : short between dielectric and metal strip (Pinhole) C ac < 1.2 pF: Pinhole R poly : deviation is less than 20% from the median Results STL: 65 strips of 11776 faulty  5.5‰ 68% of the faulty strips from area around 500 Results STS: 418 strips of 5632 faulty  7% but 95.3% of the faulty strips from area around 235 only 22 (3.9‰) outside bad area remain

21. Wolfgang Treberspurg (HEPHY Vienna)7. October 201319 3. Electrical Characterization: Affected Strips 1  Inter strip measurements on STI sensors:  The inter strip resistance vanishes at affected strips  The inter strip capacitance decreases  A poor strip isolation at this area results in:  Increased I strip, as the leakage current of more than one strip is measured  The sum of all I strip currents exceeds the global dark current  Decreased R poly, as the bias resistors are some kind of shunted STI

22. Wolfgang Treberspurg (HEPHY Vienna)7. October 201320 3. Electrical Characterization: Affected Strips 2  The accumulation of affected strips is always placed in the same distance to the sensor edge and hence dicing line  STI Sensors of the seconded batch with the same behaviour have been measured  On the undiced wafer in Vienna  The wafer has been sent to Villach (Infineon) for dicing  And has been measured again  The bad area is generated during the dicing process STI

23. Wolfgang Treberspurg (HEPHY Vienna)7. October 201321 3. Electrical Characterization: An Explanation  All results indicate an accumulation of charge inside the silicon oxide  Based on that assumption tests with humidity could cure the affected strips  To simulate aging the STI sensor has been exposed 24 h to 180 degree  The sensor still stays cured  The different layer (Implant or Poly Silicon) show no problems SiO 2 Al Implant p+ Si n-type Implant n+ STI

24. Wolfgang Treberspurg (HEPHY Vienna)7. October 201322 3. Electrical Characterization: A possible Reason  Bare silicon exposed during later steps of the fabrication  At contact holes in the DC pads  Metal over etch was larger than expected  Bare silicon prone to contamination  Could be the reason for the appearance of charge accumulation  Redesign with corrected overlap of contact holes. The new batch is in production Remark: All layers have been remove by etching for this picture, only bare silicon is left

25. Outline Wolfgang Treberspurg (HEPHY Vienna)7. October 201323 1. Overview of the Project 2. The different Sensor Structures 3. Summary of the Electrical Characterization 4.Summary of Beam Test 5.Outlook and Summary

26. Wolfgang Treberspurg (HEPHY Vienna)7. October 201324 4. Results of Beam Test: The Setup  2 detector modules built with STS sensors  2 detector modules built with strixel sensors  Readout chips (APV25) same as in the CMS tracker  Readout system is a prototype for the Belle II experiment  Detector modules were  Tested at CERN  Gamma irradiated at CNK-CEN Mol  Tested again at CERN Setup at CERN North Area H6 beam line

27. Wolfgang Treberspurg (HEPHY Vienna)7. October 201325 4. Results of Beam Test: Sensor Sections  The bad strip area does not stand out clearly in beam profile and seems to be fully efficient  For a more detailed analysis the sensor has been divided into two sections:  One good section (green)  One bad section (red, strip no. 222 – 238)

28. Wolfgang Treberspurg (HEPHY Vienna)7. October 201326 4. Results of Beam Test: Different Sections  The results indicate problems with the strip isolation at the “bad area”  Clusters are wider in “bad section”  The eta distribution indicates an anomalous charge sharing between the strips

29. Wolfgang Treberspurg (HEPHY Vienna)7. October 201327 4. Results of Beam Test: Gamma Irradiation  The modules have been gamma irradiation and tested again  The gamma irradiation mainly effects the silicon oxide layer on the sensor surface  Gamma irradiation seems to cure the problem, which fits well to the assumption of accumulated charge inside the silicon oxide Gamma Irradiation Results just from “bad area”

30. Outline Wolfgang Treberspurg (HEPHY Vienna)7. October 201328 1. Overview of the Project 2. The different Sensor Structures 3. Summary of the Electrical Characterization 4. Summary of Beam Tests 5. Outlook and Summary

31. Wolfgang Treberspurg (HEPHY Vienna)7. October 201329 5. Summary: Beam Test and Characterization  A very first prototype batch of planar p-on-n sensors was produced at Infineon-Villach  The STS sensors show reasonable performance. They have very uniform noise and a standard cluster width- and eta distribution.  Electrical characterisation show promising quality  We found areas of strips which behave abnormal  A possible explanation for this effect has been suggested  The explanation will be tested with a new batch of sensors Noise of STS Cluster width of STS (including the “bad area”)

32. Wolfgang Treberspurg (HEPHY Vienna)7. October 201330 5. Summary: Outlook  Irradiation tests:  The reactor in Vienna (neutrons) became operational again  The irradiation at Karlsruhe (protons) is in progress  Producing a new batch:  Three masks have been redesigned with small corrections to prevent the “bad strip area”  The production is in progress and the sensors will be delivered in the next months  New run planned with CMS in 2014:  According to the CMS baseline n-on-p process on 200 µm FZ material  Production on 8 inch wafers is considered  Infineon could be a future supplier of high quality silicon sensors for large scale applications  ATLAS and CMS already show an interest in the possibilities offered by Infineon

33. THANKS FOR YOUR ATTENTION! 317. October 2013Wolfgang Treberspurg (HEPHY Vienna)

34. 7. October 201332 Backup Slides: Electrical Strip Parameter 1 Detector at a reverse bias of 300V Strip Leakage Current I strip  Electrometer connected to DC pad measures strip current for each strip Poly-silicon Resistor R poly  Resistance measurement between bias-ring and DC pad Coupling Capacitance C ac  Capacitance of dielectric between Al strip and strip implant Dielectric Current I diel  Current through dielectric at 10V between Al strip and implant

35. Wolfgang Treberspurg (HEPHY Vienna)7. October 201333 Backup Slides: Electrical Strip Parameter 2 STL Idiel/Idiel median STS Idiel/Idiel median STL STS Pinholes

36. Wolfgang Treberspurg (HEPHY Vienna)7. October 201334 Backup Slides: Strip Classification Criteria STL: Pinhole: short between dielectric and metal strip (I diel > 1nA) Coupling capacitance: C ac < 1.2pF Single strip current: I strip > 50nA Polysilicon resistor: more than 20% deviation from the median Criteria STS: Pinhole: short between dielectric and metal strip (I diel > 1nA) Coupling capacitance: C ac < 1.2pF Single strip current: I strip > 25nA Polysilicon resistor: more than 20% deviation from the median With “bad Area” Without “bad Area”

37. Wolfgang Treberspurg (HEPHY Vienna)7. October 201335 Backup Slides: Long term Stability V bias =300V, temperature ~19 °C, rel. humidity 6-50% Leakage Current stable for all sensors tested

38. Wolfgang Treberspurg (HEPHY Vienna)7. October 201336 Backup Slides: Additional Beam Test Results Cluster Signal Signal-to-Noise CW1: SNR 32 CW2: SNR 22 CW3: SNR 19 CW 1 CW 2 CW 3 CW 1 CW 2 CW 3 CW1: SNR 32 CW2: SNR 24 CW3: SNR 21 Results from „good“ strip area Results from „bad“ strip area