PTP and the inter-strip capacitance and resistance for irradiated ATLAS07 mini-sensors . Jan Bohm, Institute of Physics ASCR, Prague Peter Kodys, Zdenek Dolezal, Jan Scheirich, Charles University in Prague Petr Masek, Michael Solar, Institute of Experimental and Applied Physics of Czech Technical University in Prague 18/02/2013 J.Bohm, 8th Trento Workshop, Trento, Italy 1
The performance of the sample of 75 n -in- p ATLAS07 HPK miniature 1cm*1cm sensors developed by ATLAS Collaboration for LHC upgrade [ Y. Unno, et.al., Nucl. Inst. Meth. A636 (2011) S24-30 ] with different punch through structures, BZ4A-D, and with three different ion concentrations of 2E12, 4E12 and 1E13 ion/cm^2 of the P-stop and P-stop + P-spray separation is studied before and after irradiation with the aim to select the P-stop ion concentration and punch through structure as the most effective protection against beam splashes 1. Introduction 2. IV characteristics of heavily irradiated sensors 3. Interstrip capacitance and bias dependence 4. Time evolution of interstrip and bulk capacitances 5. Interstrip resistance 6. Characteristics of punch through structures 7. Summary and conclusions 18/02/2013 J.Bohm, 8th Trento Workshop, Trento, Italy 2
Sample of HPK miniature sensors From Hamburg we received next 12 sensors BZ4A-D of Series 3 (wafers 264,278 and 281) with P-stop ion concentration 4E12 ion/cm^2 . Many thanks to colleagues from DESY . Irradiation of sensors BZ4A, B, C and D for each wafer Wafer Isolation Ion/cm^2 Fluency neq/cm^2 Particles Where Annealing W06 Pspr+Pstp 2E+12 4E+14 neutrons Ljubljana 80min/60degC W10 Pspr+Pstp 2E+12 2E+15 neutrons Ljubljana 80minn/60degC W17 Pstop 2E+12 4E+14 neutrons Ljubljana 80min/60degC W19 Pstop 2E+12 2E+15 neutrons Ljubljana 80min/60degC W278 Pstop 4E+12 4E+14 neutrons Ljubljana 80min/60degC W281 Pstop 4E+12 2E+15 neutrons Ljubljana 80min/60degC W31 Pstop 2E+12 4E+14 p 23GeV/c CERN 80min/60degC W91 Pstop 1E+13 4E+14 neutrons Rez Prague 80min/60degC W93 Pstop 1E+13 2E+15 neutrons Rez Prague 80min/60degC W97 Pstop 1E+13 1E+16 neutrons Rez Prague 80min/60degC Many thanks to Vlado Cindro , Morris Glaser and Jan Kucera for irradiation 18/02/2013 J.Bohm, 8th Trento Workshop, Trento, Italy 3
Punch Through Protection Structures for ATLAS07 A protection of AC coupling capacitors against the beam splashes should ensure special structures, BZ4A,B,C on the HPK ATLAS07 mini-sensors. A beam splash generates a spike of voltage across the AC coupling insulator. When the distance between the bias rail BZ4A BZ4B and the n-strip implants is appropriate, this voltage between the bias rail and the n-strip implant ends can be limited. This distance is 20 µ and is used in all special structures BZ4A,B,C and sensor BZ4D Sensor BZ4D has no special structure and it is used for comparison with structures BZ4A, B and C. BZ4C BZ4D 18/02/2013 J.Bohm, 8th Trento Workshop, Trento, Italy 4
IV characteristics of non-irradiated ATLAS07 sensors W14 A -4 -4 W75 A W14 B ATLAS07 pre-series3 P-stop 2E12 ATLAS07 series 2nd STD P-stop 1E13 W75 B -3.5 -3.5 W14 C W75 C BZ4A-D W14 D BZ4A-D W75 D -3 -3 W17 A W78 A W17 B W78 B -2.5 -2.5 Current [nA] W17 C W78 C Current [nA ] W17 D -2 W78 D -2 W19 A W80 A -1.5 W80 B W19 B -1.5 W80 C W19 C -1 W80 D -1 W19 D W81 A W31 A -0.5 W81 B -0.5 W31 B W81 C W31 C 0 0 W81 D W31 D 0 -200 -400 -600 -800 -1000 0 -200 -400 -600 -800 -1,000 Bias [V] Bias [V ] -4 -4 W264 A ATLAS07 Series3 P-stop 4E12 ATLAS07 series 2nd HPK P-stop 1E13 W89 A W89 B W264 B -3.5 -3.5 BZ4A-D BZ4A-D W89 C W264 C -3 W89 D -3 Current [nA] W264 D W91 A -2.5 -2.5 W91 B W278 A W91 C -2 W278 B Current [nA] -2 W91 D W278 C W93 A -1.5 -1.5 W93 B W278 D -1 W93 C -1 W281 A W93 D -0.5 W281 B -0.5 W97 A W281 C W97 B 0 0 W97 C W281 D 0 -200 -400 -600 -800 -1000 0 -200 -400 -600 -800 -1000 W97 D Bias [V ] Bias [V] Measured sensors were placed on the table without vacuum chuck jig to avoid possible strong stresses which could cause breakdowns. 18/02/2013 J.Bohm, 8th Trento Workshop, Trento, Italy 5
IV Characteristics of irradiated ATLAS07 sensors 1000 W91 A 4E14 W91 B 4E14 1E16n/cm2 W91 C 4E14 W91 D 4E14 W93 A 2E15 W93 B 2E15 2E15n/cm2 W93 C 2E15 W93 D 2E15 100 W278A 4E14 Leakage Current [µ Ω ] W278B 4E14 W278C 4E14 W278D 4E14 W281A 2E15 W281B 2E15 W281C 2E15 4E14n/cm2 10 W281D 2E15 W19A 2E15 W19B 2E15 W19D 2E15 W17B 4E14 Proton irradiation at CERN W97 A 1E16 W97 B 1E16 1 W97 C 1E16 W97 D 1E16 0 -200 -400 -600 -800 -1000 W31 A p 4E14 W31 B p 4E14 Bias [V] W31 C p 4E14 W31 D p 4E14 The heavily irradiated sensors (≥ 2E15n/cm2) with p-stop isolation of different ion concentrations were successfully operating up to 1000V with the exception of fluency 4E14n/cm2 where an onset of micro-discharges was observed above ~700V 18/02/2013 J.Bohm, 8th Trento Workshop, Trento, Italy 6
Interstrip Capacitance - Method of measurement 5-probes Cinter CpRp 100kHz 3-probes Sensor W37 2.2 2-probes 5probes – outer strips to LCR Low 2 3 probes DC pad 1.8 5 probes 1.6 Cint [pF] GND AC pad 1.4 1.2 1 2 probes LCR High 0.8 LCR Low 0.6 0 100 200 300 400 500 600 Vbias [-V] V] Cint(5-pr)/Cint(3-pr)=0.939 and 0.913 for 100kHz and 1MHz, respect. Cint(2-pr)/Cint(5-pr)=0.57 Outer strips to GND J.Bohm, M.Mikestikova et.al, NIM A636 (2011)S104-S110 18/02/2013 J.Bohm, 8th Trento Workshop, Trento, Italy 7
Interstrip Capacitance – non-irradiated Interstrip Capacitance Cinterstrip vs Frequency 0.8 p-stop 1E13 ion/cm^2, Series 2 STD & HPK 0.8 W78-STD Pstop 1E13; W89-HPK Pstop 1E13; Vfd W14-Pstop 2E12; W04-PstopSpray 2E12 W78 A W264-Pstop 4E12 W78 B 0.6 0.7 W78 C Cinter [pF] W78 B Cinterstrip [pF] W78 D 0.4 W89 B W89 A W14 B 0.6 W89 B 0.2 W04 B W89 C W89 D W264 B 0 0.5 0.1 1 10 100 1000 Bias [V] 0 -200 -400 -600 Frequency [kHz] Interstrip capacitance is measured by 3 probes 1.2 Interstrip Capacitance at 1 MHz and CpRp ATLAS07 pre-Series3 p-stop&spray W14 A C interstrip for frequency above 100kHz is slowly 1 2E12ion/cm^2 W14 B increasing up to 1MHz. Vfd W14 C 0.8 For Vbias<Vfd the values of C interstrip depend W14 D Cinter [pF] on the P-stop & P-spray ion concentration but W04 A 0.6 W04 B above Vfd the Cinter is constant and the same W04 C 0.4 for all p-stop doses. W04 D 0.2 Bias [V] There is narrow deep minimum of Cint at 0 -200 -400 -600 Vbias =-4V for P-stop+P-spray isolation. 18/02/2013 J.Bohm, 8th Trento Workshop, Trento, Italy 8
Interstrip Capacitance Dependence on Frequency 0.8 Irradiated ATLAS07 sensors 0.6 1.E+13 W97 D 1E16 1.E+13 W97 A 1E16 Cinter [pF] 4.E+12 W281A 2E15 0.4 4.E+12 W281B 2E15 2.E+12 W19 A 2E15 2.E+12 W10 A 2E15 PstSpr 2.E+12 W10 B 2E15 PstSpr 0.2 2.E+12 W19 B 2E15 1.E+13 W91 A 4E14 1.E+13 W91 C 4E14 Frequency [kHz] 0 0.1 1 10 100 1000 0.8 Non-irradiated ATLAS07 sensors W78-STD Pstop 1E13; W89-HPK Pstop 1E13; W14-Pstop 2E12; W04-PstopSpray 2E12 0.6 W78 B Cinter [pF] W89 B 0.4 W14 B W04 B 0.2 W264 B 0 0.1 1 10 100 1000 18/02/2013 J.Bohm, 8th Trento Workshop, Trento, Italy 9 Frequency [kHz]
Interstrip Capacitance – non-irradiated 1.2 Inter-strip Capacitance W89 A W89 B ATLAS07 Series2, pre-Series3 & Series3 W89 C W89 D 1 W14 A W14 B W14 C W14 D 0.8 W04 A Cinter [pF] W04 B W04 C W04 D 0.6 W264 A W264 B W264 C W264 D 0.4 W78 A W78 B W78 C Reverse Bias [V] W78 D 0.2 0 -200 -400 -600 The inter-strip capacitance, Cint, is constant for bias voltages higher than respective full depletion voltages and Cint does not depend in this region on an ion concentration and the punch through protection structures within measuring error of ±0.02pF. 18/02/2013 J.Bohm, 8th Trento Workshop, Trento, Italy 10
Interstrip Capacitance of Heavily Irradiated Sensors ATLAS07 Pstop 1E13 ion/cm2 W91 A 4E14 0.74 W91 B 4E14 W91 C 4E14 W91D 4E14 W93 A 2E15 0.7 W93 B 2E15 W93 C 2E15 Cinter [pF] 0.04pF W93 D 2E15 W97 A 1E16 0.66 W97 B 1E16 W97C 1E16 W97 D 1E16 W89 A nonirrad 0.62 W89 B nonirrad W89 C nonirrad W89 D nonirrad 0.58 0 -100 -200 -300 -400 -500 Bias [V] Cinter before irradiation for p-stop dose 1E13ion/cm2 is also shown. Cinter is not changed by irradiation up to 1E16n/cm2. A slow decrease is observed with growing bias voltage which is more pronounced for fluency 4E14n/cm2 than for higher doses. 18/02/2013 J.Bohm, 8th Trento Workshop, Trento, Italy 11
Interstrip Capacity and p-stop ion concentration 0.76 2.E+12 W10 A 2E15 PstSpr 2.E+12 W10 B 2E15 PstSpr 0.72 2.E+12 W10 C 2E15 PstSpr 2.E+12 W19A 2E15 2.E+12 W19 B 2E15 Cinter [pF] 0.68 2.E+12 W19 C 2E15 4.E+12 W281A 2E15 4.E+12 W281B 2E15 0.64 4.E+12 W281C 2E15 1.E+13 W93 A 2E15 Fluency 2E15n/cm2 1.E+13 W93 B 2E15 0.6 1.E+13 W93 C 2E15 0 -100 -200 -300 -400 -500 Bias [V] Interstrip capacitance does not depend on ion concentration of p-stop implant within measuring error of ~0.02pF. A decrease of Cinter with bias voltage is the same for all p-stop and p-stop+p-spray implant doses. It is supposed that this decrease of Cinter is due to small contribution of Cg, capacitance between strip and the backplane. Cg is decreasing function of bias voltage. 18/02/2013 J.Bohm, 8th Trento Workshop, Trento, Italy 12
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