Upgrade Silicon Strip Detectors (SSD) Hartmut F.-W. Sadrozinski SCIPP, UC Santa Cruz

1. Upgrade Silicon Strip Detectors (SSD) Hartmut F.-W. SadrozinskiSCIPP, UC Santa Cruz Status Pre-Rad Testing Post-rad Testing Protons Neutrons Gammas Preparation for Modules/Staves Work shared by UCSC, BNL, SUNY, NYU, KEK, Tsukuba, Liverpool, Cambridge, Lancaster, Ljubljana

2. KEK Tsukuba Liverpool Lancaster Glasgow Sheffield Cambridge QML Freiburg MPI Ljubljana Prague Barcelona Valencia Santa Cruz BNL PTI SSD Development for ATLAS Upgrade Tracker Share expertise and cost within the ATLAS groups Leverage rad-hard experience with p-type SSD (RD50, KEK) Sensor fabrication with the only viable large-volume and high-quality manufacturer (HPK) Produce proto-type test structures (radiation damage, isolation, ..) Produce full-size sensors to support module/stave program (stereo, bonding, gluing, thermal management, ..)

3. Purpose Full square for Modules/Stave Use in 2008 Delivery target Pre-series Feb. 2008 2nd Pre-series Sep. 2008 Production Dec 2008 Wafer 150 mm p-FZ(100) 320 µm thick n-strip isolation Individual p-stop P-spray P-spray + p-stop Stereo 40 mrad Integrated in half area Dead area: 2 mm Strip segments 4 for SS (but still true for 4% limit?) LS: segments wire-bonded Strip segments 4 for SS (but still true for 4% limit?) LS: segments wire-bonded ATLAS07

4. After testing of pre-series: ATLAS07M - with modified masks Edges of the bias ring of the stereo strips Zone4 PTP structures: 4 types Zone2 mistake corrected Fabrication in process 2nd Pre-series Delivery: Mid Sep. Study of p-spray dose by HPK Order of "Al-metal" dummy sensors Limited number of “mechanical samples” Status of ATLAS07

5. ATLAS07 p-type mini-SSD • 6-inch (150 mm) wafer • Maximum size sensor (~10 cm x ~10 cm) • Prototyping simultaneously both short and long strips • Prototyping simultaneously both axial and stereo strips • R&D 24 Test structures (“Zones”) • Candidate isolation structures • "Punch-thru Protection" structures • Wide/Narrow metal effect • Wide/Narrow pitch effect • P-spray vs. P-stop vs. combined 26 Monitor Diodes 4mm x 4 mm 3 Isolation schemes on wafers with and without p-spray Wafers 1-17 with p-spray, 20 – 30 no p-spray

6. ATLAS07 Specification

7. ATLAS07 Order: 132 Wafers

8. ATLAS07 Pre-Series Verify Masks Verify Specifications Chose Isolation schemes? Initial Verification of Radiation Hardness Start Module/ Stave construction

9. Pre-rad Breakdown Voltage Specs >600V Baseline (common narrow p-stop) Shows good behavior BUT: no punch-through protection Zone 4 has punch-through. Zone 3 with p-spray is acceptable

10. Pre-rad Isolation: Interstrip Resistance R int = 2* DV2/Di1 Interstrip Resistance: “no Bias Dependence” 100’s of GW lessfor Zone 1 & 5? RBias = 1.22 MW

11. Pre-rad Isolation: Interstrip Capacitance Interstrip capacitance to next neighbor pair (total ~30% higher): Close to 1 pF/cm. Same value for p-spray with and without implants “No” bias dependence for Zone 1 and Zone 3

12. Pre-rad Full-size Sensors (p-spray) : i-V Average current before breakdown i(400V) = 0.83 uA = 8 nA/cm^2 Average breakdown: 530V

13. All four segments (of all wafers) probed found less faulty channels than indicated by HPK (?) Testing (& retesting) 15360 channels takes quite some time Full wafer (W9) strip test (Brad Hommels, Cambridge)SUNY Story Brook is working on this

14. i-V post KEK Protons & Ljubljana Neutrons Post-rad no breakdown, in contrast to pre-rad

15. Charge Collection KEK Proton Irradiation Collected Charge up to ~ 1000V

16. Efficiency post KEK Proton Irradiation Efficiency @ 1fC Threshold saturates at ~ 600V

17. Charge Collection post KEK Proton Irradiation: Affolder et al (Liverpool) , Compares well will Micron p and n irradiations

18. Surface: Gamma Irradiation at BNL: Gamma Irradiation (1 Mrad, biased + 0.5V on Al) at BNL: check Isolation, Interstrip Capacitance, MD p-stop, zone 3 W26-BZ3-P13 p-stop, zone 4 W29-BZ4-P4 p-spray, zone1 W02-BZ1-P7 p-spray, zone3 W06-BZ3-P6 p-spray, zone4 W06-BZ4-P22 All Al readout traces are bonded out together During irradiation bias the metal strips to +0.5 V wrt to bias ring. Bias back plane to 200V. RT annealing for about 10 days. Take i-V with the Al either “grounded” or “floating”

19. i-V post Gamma Irradiation Breakdown Behavior not fully understood

20. i-V post Gamma Irradiation: N2 flow prevents breakdown

21. Isolation post Gamma Irradiation Interstrip Resistance much reduced, ok ?

22. Gamma Irradiation / Glue tests on-going Observations after Irradiation with gamma’s and gluing to surface: Breakdown voltage much reduced ( to 100-200V) Improvement observed after cleaning and/or flushing with N2 gas Short term annealing (~10 min @ 60 deg) does not help Things to test: origin of breakdown effect of passivation effect of guard rings effect of accumulated surface charge Comparison with other manufacturers helps

23. n-in-p p-type microstrip sensors have been fabricated in p-FZ and p-MCZ wafers, for several years by now at HPK. Latest submission, ATLAS07, within the ATLAS R&D collaboration of "Development of non-inverting Silicon strip detectors for the ATLAS ID upgrade" Number of isolation structures are being investigated in mini-SSD test structures A full size microstrip sensor has been prototyped for module/stave work. Pre-series of ~9 wafers with many test structures received Total of 132 wafers contracted, 2 different FZ wafer types Full testing by HPK Modification of masks required after first pre-series HPK will investigate optimization of p-spray Proton irradiations, 70 MeV, 800 MeV, 24GeV, neutron irradiations (1 MeV) and gamma irradiation have been performed on the test structures Good charge collection and low noise after hadron irradiations to 1e15 confirmed by several groups: bulk as expected Apparent sensitivity to moisture can be overcome with N2 flow, more testing needed Program to investigate top-side gluing in full swing. Concentrate on surface properties Summary ATLAS07