Results on proton irradiation tests in Karlsruhe p do Bulk & Surface Damage Strip parameters after irrad. V FD for (300µm) and 500µm sensors after 10 years LHC Expectedpower for500 µm sensors after 10 years LHC Outlook F. Hartmann 1
Irradiation Facility 34 MeV protons 1000 na Beam spot: 2cm O T < -10 C Area: 20x40cm 2 Duration: 100cm 2 in 15min (1 sensor, 5e13p/cm 2 ) Compact Cyclotron at Forschungszentrum Karlsruhe 2
Cold Box Dry N 2 atmosphere at 10 C. Flexible box to hold sensors, teststructures and/or modules! Laser focus Simple power lines Temp. monitor 3
Simulate LHC bias conditions with respect to surface damage! During proton irrad.: Diode acts as a current source due to the p ionising effect SOLVE: 1V potential by applying V bias = 1V, But AC must also be on GND! DC diode Running @ LHC Rpoly CC AC readout (on GND) Current source Vbias Rpoly Here we need potentia like in LHC 1M Ω at 1µ A = 1V Strip current after irrad 4
Simulate LHC bias conditions with respect to surface damage! Bias ring --> GND Rpoly AC DC Short all AC to bias (GND) How to Realize? Backplane to +Vbias= 1V Conductive rubber V bias = 1V during irrad 5
Sensors before/after Irradiation 6
Fluences in the Tracker ~1.5e14 n/cm 2 for 320µm Upper limits: U FD <500V P(-10 C)<400mW ~0.5e14 n/cm 2 for 500µm 7
Irradiation Scheme 2 fluences chosen: Inner Tracker: 1.8e14 p/cm 2 (~3e14 n/cm 2 ): expected for low resisitivity silicon (300µm) * 1.8 18yLHC Outer Tracker: 0.5e14 p/cm 2 (~8e13 n/cm 2 ): expected for high resistivity silicon (500µm) *1.5 15yLHC Material (6, 500µm thick): 1 sensor W6b from Hamamatsu 1 sensor OB2 from ST Microelectronics 6 teststructures from Hamamatsu Biasing: 1V, 12V, 100V, non Notice: Inner Tracker fluence on Outer Tracker (500µm) sensors instead of 300µm, PRO: 1. resistivity almost right 2. No 320µm sensors present, 3. HPK will in future deliver inner 300µm sensors CON: unusual high V FD 8
Fluence Measurement 1.) Measurement by Ni-foil activation behind sensors: Calibration at 26 MeV Scaling with cross section to higher energies Fluence in [p/cm2] Hardness factor κ(e) scales to neutron equivalent 2.) I leak measurement: Temperature scaling to 20 C I(20 C)=I(T)*R(T); R(T)=(293K/T) 2 e (-E/k(1/293K-1/T)) ; E=1.4eV I/V=α*Φ α(t=20 C)=4e-17 A/cm Fluence in [n(1mev)/cm 2 ] 9
Karlsruhe probing equipment stencil/template Bias Measurements take ~1.5-2 hours Changing of sensor ~ 5 min Environment: 10 C, RH~1% 10
IV-Curve before/after Irrad. 2m 2m Sensor HPK Sensor ST Sensor HPK irradiated (1.8e14 p/cm 2 ) Sensor ST irradiated (0.5e14 p/cm 2 ) Current [A] 1m 500µ 10µ 8µ 6µ 4µ 2µ 0 0 200 400 600 800 1000 1200 Voltage [V] 11
Power Consumption 400.0µ 350.0µ I / V [A/cm 3 ] 300.0µ 250.0µ 200.0µ 150.0µ 100.0µ 50.0µ 0.0 Data (500µm sensors, ~5kΩcm) Linear Fit Extrapolated value for 500µm sensor at r=60cm α(t=-10 C) = 1.2 10-18 A/cm P ~ U FD I ~ d 2 d ~d 3 0.0 5.0x10 13 1.0x10 14 1.5x10 14 2.0x10 14 2.5x10 14 3.0x10 14 eq. Fluence [n/cm 2 ] 60µA/cm 3 => I leak (-10 C)=270µA (W6b) => P(500V, -10 C)=135mW/sensor Actual designed cooling power 400mW for each module (at least). 12
CV-Curve Curve before/after Irrad. 3,5x10 17 3,0x10 17 2,5x10 17 Capacitance -2 [F -2 ] 2,0x10 17 1,5x10 17 1,0x10 17 5,0x10 16 0,0 Sensor HPK Sensor ST Sensor HPK irradiated (1.8e14 p/cm 2 ) Sensor ST irradiated (0.5e14 p/cm 2 ) U FD ~ d 2 => U FD (320µm) = 410V 0 200 400 600 800 1000 1200 Voltage [V] ST and HPK sensors are stable up to V bias =1000V after irradiation! Even strip tests were done at V bias = 1000V! 13
Hamburg Model g a τ a (20 C) c g c 2.5x10 12 U FD (N eff )~d 2 g Y τ Y (20 C) 2.0x10 12 N [cm -3 ] 1.5x10 12 1.0x10 12 5.0x10 11 0.0 Beneficial Annealing Stable Damage Reverse Annealing PhD Thesis M. Moll: g a =(1.81±0.14)e-2 cm -1 τ a (20 C) =55h g c =(1.49±0.04)e-2 cm -1 c=(10.9±0.8)e-2 cm -1 /N eff g Y =(5.16±0.09)e-2 cm -1 τ Y (20 C)=475d Beneficial annealing Stable Damage Reverse Annealing 1 5 10 50 100 500 Time at RT [days] 14
Developement of U FD Full Depletion Voltage [V] 1100 1000 900 800 700 600 500 400 300 200 100 0 Data (FS sensors) Hamburg Model ST Hamamatsu 0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 eq. Fluence [10 14 n(1mev)/cm 2 ] Data is fully compatible with the Hamburg model fit! Predictions for different annealing scenarios possible! 15
Full depletion as function of annealing time and fluence Fluence given at once, then annealing. 16
Annealing scenario: 14 days at RT each year 600 Full Depletion Voltage [V] 500 400 300 200 100 0 500µm, 4.4kΩ, 5e13n/cm 2 " Fluence at once 320µm, 2.2kΩ, 16e13n/cm 2 0 14 28 42 56 70 84 98 112 126 140 154 Annealing Time at RT [days] Iterative calculation of full depletion voltage 17
Depletion voltages for diode minisensor and full sensor 3,0x10 20 ~600V 2,5x10 20 Capacitance -2 [F -2 ] 2,0x10 20 1,5x10 20 1,0x10 20 5,0x10 19 Diode 2.6e14 n/cm 2 Full sensor 3e14 n/cm 2 Mini sensor 2.6e14 n/cm 2 ~600V 0,0 0 200 400 600 800 1000 ~1000V values shifted in y for comparison to compensate for different sizes Voltage [V] Future: diode measurements as reference! 18
Strip Leakage Current Leakage Current @ 400V [na] 1000 100 10 1 0.1 0.01 Minisensor 41 Before Irradiation After Irradiation and Annealing (Measurement at -10 C) 0 5 10 15 20 25 30 35 40 45 50 Strip number As expected: Increase in leakage current! 19
Bias Resistance Poly Resistance [MΩ] 2,3 2,2 2,1 2,0 1,9 1,8 0 5 10 15 20 25 30 35 40 45 50 55 60 Strip number Minisensor H41 Before Irradiation Raw Data: After Irradiation and Annealing (Measurement at -10 C) Corrected values due to high I leak Measurement: Apply U=2V Measure I Calculate R=U/I Correction: Measure I leak (high after irrad Correct R c =U/(U/R+I leak ) No change in bias resistances! 20
Coupling Capacitance Coupling Capacitance [pf] 120 115 110 105 100 95 90 85 80 75 70 65 60 0 5 10 15 20 25 30 35 40 45 50 Strip number Minisensor H39 Before Irradiation After Irradiation and Annealing (Measurement at -10 C) No change in coupling capacitances! 21
Interstrip capacitance of HPK full sensor (1 neighbour) Wedgeshaped sensor: Longer strips on the sides but less neighbours! structure 100 ff 20 ff <Cint>=3.2 pf 22
Interstrip Capacitance Interstrip Capacitance [pf] 0.90 0.75 0.60 0.45 0.30 0.15 Non irradiated: 1 MHz 100 khz Irradiated: 1 MHz 100 khz 0 200 400 600 800 1000 Bias Voltage [V] Interstrip Capacitance [F] (2 neighbours) 1,7p 1,7p 1,6p 1,6p 1,5p 1,5p Before Irradiation After Irradiation 1,4p 70 72 74 76 78 80 82 84 86 88 90 Strip No. No change in interstrip capacitance before/after irrad.@ 1MH Homogeneous interstrip distribution before/after irrad. 23
Future CMS dedicated teststand at the Cyclotron Scan area: 20 x 50 [cm] Scan speed: 1.25x 2.5 [cm/s] Maximum load: 20kg (New dedicated beamline line) 24
Future: irradiation of a full module TEC outer, TEC inner,tob,tib Longterm with high voltage, current, power Test of S/N, CCE, (pedestal,noise,shape) Test of components: sensor, electronics, mechanics. First IEKP TEC module 25
Conclusion 1. Both: ST and HPK comply with the specification of irradiation hardness 2. Data fits Hamburg model well and shows a decent behavior after 10 years of LHC operation 3. No changes in the strip parameters observed 4. Future dedicated teststand promise easy access to the cyclotron 5. Further plans: 300µm sensors and full modules will be irradiated! 26
NEW: Ingot pre-qualification (june 2001) Hamamatsu proposed to produce a couple of additional sensors out of each new ingot for irradiation pre-qualification Special procedure in addition to the standard task. All measurements on diode and minisensor Save large sensors as spares! INGOT: IV & CV on diode To determine Vdepletion, fluence estimation and α-factor PROCESS: Cint, Rint, leakage current, Rpoly vs. Vbias upto Vdepletion + 50V (for ~10 strips) 27