Punch through protection of heavily irradiated ATLAS07 mini- sensors. Status report Jan Bohm, Institute of Physics ASCR, Prague Peter Kodys, Tomas Jindra, Zdenek Dolezal, Jan Scheirich, Charles University in Prague Petr Masek, Michael Solar, Institute of Experimental and Applied Physics of Czech Technical University in Prague 11/15/2012 J.Bohm, 21st RD50 Workshop, CERN 1
22
Embed
Punch through protection of heavily irradiated ATLAS07 mini- sensors. Status report Jan Bohm, Institute of Physics ASCR, Prague Peter Kodys, Tomas Jindra,
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
J.Bohm, 21st RD50 Workshop, CERN 1
Punch through protection of heavily irradiated ATLAS07 mini- sensors.
Status report
Jan Bohm, Institute of Physics ASCR, Prague
Peter Kodys, Tomas Jindra, Zdenek Dolezal, Jan Scheirich, Charles University in Prague
Petr Masek, Michael Solar, Institute of Experimental and Applied Physics of Czech Technical University in Prague
11/15/2012
J.Bohm, 21st RD50 Workshop, CERN 211/15/2012
The performance of the sample of 75 n-in-p 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 most suitable P-stop ion concentration and punch through structure as a protection against beam splashes – protection of coupling capacitorThis report is a preliminary compilation of measured characteristics.
-Irradiation of the sample of miniature sensors
-Bulk characteristics, IV & CV measurement
-Interstrip capacitance and Interstrip resistance
-Punch Through Protection and PT voltages
The micro-strip silicon miniature sensors of 1cmx1cm (strip length 0.8cm) are ATLAS07 Series fabricated by Hamamatsu Photonics (HPK) using 6” (150 mm) process technology . The baseline is p-type float zone silicon with crystal orientation <100> and having thickness of 320 μ. Sensors are single-sided with AC coupled readout n-type strips which are biased through polysilicon resistors. One hundred readout strips with pitch 74.5 μ are electrically isolated by a common and floating p-implant (‘p-stop’ isolation)
Outlook
J.Bohm, 21st RD50 Workshop, CERN 3
Sample of HPK miniature sensors
11/15/2012
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.
Wafer Isolation Ion/cm^2 Fluency neq/cm^2 Particles Where AnnealingW06 Pspr+Pstp 2E+12 4E+14 neutrons Ljubljana 80min/60degCW10 Pspr+Pstp 2E+12 2E+15 neutrons Ljubljana 80min/60degCW17 Pstop 2E+12 4E+14 neutrons Ljubljana 80min/60degCW19 Pstop 2E+12 2E+15 neutrons Ljubljana 80min/60degC
W04 AW04 B W04 C W04 D W05 A W05 C W05 D W06 A W06 B W06 C W06 D W10 A W10 B W10 C W10 D
Bias [V]
Curr
ent [
nA]
All sensors with p-stop isolation and with different ion concentrations were successfully operating up to 1000V, no onset of micro-discharges was observed.On other side, sensors with P-stop + P-spray isolation behaves differently and an onset of breakdowns are above already Vbias=900V.
J.Bohm, 21st RD50 Workshop, CERN 611/15/2012
-1000-800-600-400-20001
10
100
1000 IV characteristics of irradiated ATLAS07 sensorsWafer 91&93 Pstop=1E13 ion/cm^2 Rez near Prague
Wafer 278&281 Pstop=4E12 ion/cm^2 LjubljanaWafer 19&17 Pstop=2E12 ion/cm^2 Ljubljana
Current normalized to T=-10degC
W91 A 4E14
W91 B 4E14
W91 C 4E14
W91 D 4E14
W93 A 2E15
W93 B 2E15
W93 C 2E15
W93 D 2E15
W278A 4E14
W278B 4E14
W278C 4E14
W278D 4E14
W281A 2E15
W281B 2E15
W281C 2E15
W281D 2E15
W19A 2E15
W19B 2E15
W19D 2E15
W17B 4E14
Bias [V]
Leak
age
curr
ent [
µA]
An onset of micro –discharges is observed for irradiated sensors to fluency 4E14 neq/cm^2 contrary to fluency 2E15 neq/cm^2 where no breakdowns are visible.Higher current measured on wafers W91 and W93 is under study (irradiated in Rez).
J.Bohm, 21st RD50 Workshop, CERN
CV Characteristics
11/15/2012
-400-300-200-10000
0.0004
0.000800000000000001
0.0012
0.0016 ATLAS07 pre-series 3 Pstop 2E12 BZ4D
W14 DW17 DW19 DW31 D
Bias [V]
!/C^2
[1/p
F^2]
-400-300-200-10000
0.0004
0.000800000000000001
0.0012
0.0016ATLAS07 Series 3 Pstop 4E12
BZ4D P22
W264 DW278 DW281 D
Bias [V]
!/C^2
[1/
pF^2
]
-400-300-200-10000
0.0004
0.000800000000000001
0.0012
0.0016ATLAS series 2nd STD Pstop 1E13
BZ4D
W75 DW78 DW80 DW81 D
Bias [V]
1/C^
2 [1
/pF^
2]
-400-300-200-10000
0.0004
0.000800000000000001
0.0012
0.0016ATLAS07 series 2 HPKex Pstop 1E13
BZ4D
W89 D
Bias [V]1/C^
2 [1
/pF^
2]
Bulk capacitance has been measured on sensors BZ4D at each wafers.
Series Pre-Series3 Series 3 Series 2 STD Series2 HPK Pre-Series3
Concentration [ion/cm^2]
2E12 4E12 1E13 1E13 2E12 P stop2E12 P spray
V full depletion -183V -292V -186V -252V -204V
J.Bohm, 21st RD50 Workshop, CERN 8
CV Characteristics
11/15/2012
-400-20000
0.0004
0.000800000000000001
0.0012
0.0016ATLAS07 pre-Series 3
P stop 2E12 + P spray 2E12 BZ4D
W04 D
W05 D
W06 D
W10 D
Bias [V]
1/C^
2 [1
/Pf^
^]
0.1 1 10 100 100018
23
28
ATLAS07 series 2nd HPKex Pstop 1E13 BZ4D
Vbias=-240V
W89 D
W91 D
W93 D
W97 D
Freq [kHz]
Capa
cita
nce
[pF]
Series Pre-Series3 Series 3 Series 2 STD Series2 HPK Pre-Series3
Concentration [ion/cm^2]
2E12 4E12 1E13 1E13 2E12 P stop2E12 P spray
V full depletion -183V -292V -186V*)
-252V -204V
*) Sensors BZ4A-D from wafer W75 of Series 2 STD have higher full depletion voltage, Vfd=286V
Bulk capacitance does not depend on testing frequency in range of 200Hz up to 20kHz
C interstrip depends strongly on frequency.Capacitance is measured at 1MHz
For Vbias<Vfd the values of C interstrip depend on the P-stop & P-spray ion concentration . After irradiation Cinterstrip is a constant without any structure for low bias voltage.(J.B., RD50,Liverpool)There is narrow deep minimum of Cint at Vbias =-4V for P-stop+P-spray isolation.
J.Bohm, 21st RD50 Workshop, CERN 1011/15/2012
-600-400-20000.2
0.4
0.6
0.8
1
1.2Inter-strip Capacitance
ATLAS07 Series2, pre-Series3 & Series3W89 A
W89 B
W89 C
W89 D
W14 A
W14 B
W14 C
W14 D
W04 A
W04 B
W04 C
W04 D
W264 A
W264 B
W264 C
W264 D
W78 A
W78 B
W78 C
W78 DReverse Bias [V]
Cint
er [p
F]
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 andthe punch through protection structures within ±20fF.Possible time dependence of Cint and an influence of relative humidity is in progress.
J.Bohm, 21st RD50 Workshop, CERN 11
Interstrip Resistance - non-irradiated
11/15/2012
0E+00 2E+12 4E+12 6E+12 8E+12 1E+130
200
400
600
800BZ4A 300V
BZ4B 300V
BZ4C 300V
BZ4D 300V
BZ4A 100V
BZ4B 100V
BZ4C 100V
BZ4D 100V
BZ4A 50V
BZ4B 50V
BZ4C 50V
BZ4D 50V
P-stop ion concentration/cm^2
Resi
stan
ce [G
Ω]
Rbias
Bias ring
AC pad
DC pad
VV
I
Rint = 2*dV/dI measured at Vbias=-50V, -100V and -300V
Interstrip resistance increases with P-stop ion concentration from 4E12ion/cm^2 up to 1E13 ion/cm^2
Interstrip resistance is decreasing with increasing fluencyK.Hara et al: Nucl.Instrum.Meth. A636 (2011) S83-S89
PT structures
J.Bohm, 21st RD50 Workshop, CERN 12
Punch Through Protection Structures
11/15/2012
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 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.
Punch Through Protection Structures
Reff=dVtest/dItest, where Vtest is an applied voltage (Uappl) to DC pad and Itest is an current between DC pad and the bias ring. Rpt is supposed to be parallel to Rbias: 1/Reff=1/Rbias+1/Rpt.
BiasRing
Itest
Punch-Through Voltage is the Test Voltage for Rbias=Rpt, i.e. for Reff=Rbias/2.PT voltage is evaluated at bias voltages 100, 300, 500, 700 and 900V for PT structures Z4A-D
R implant
DC pad NEAR END Vtest
DC pad FAR END
n+ implant
PT structure Rpt
RbiasDC method S.Lindgren et.al NIM A636(2011)S111-S11&
-50 -30 -10 100
0.4
0.8
1.2
ATLAS07 Series 3 P-stop 4E12 ion/cm^2W264 BZ4B P10
Vb -100V
Vb -300V
Vb -500V
Vb -700V
Vb -900V
Vtest [V]
Reff
[MΩ
]
-70 -50 -30 -10 100
0.4
0.8
1.2
1.6
ATLAS07 Series 2HPK P-stop 1E13 ion/cm^2W89 BZ4A P04
Vb -100V
Vb -300V
Vb -500V
Vb -700V
Vb -900V
Vtest [V]
Reff
[MΩ
]
11/15/2012
J.Bohm, 21st RD50 Workshop, CERN 14
Punch Through Protection Structures - Rpt
11/15/2012
-70 -50 -30 -100
0.4
0.8
1.2
1.6 ATLAS07 Series 2 P-stop 1E13 ion/cm^2W89 BZ4A-D NEAR END
BZ4ABZ4BBZ4DBZ4C
Vtest [V]
Reff
[MΩ
]
-800000 -600000 -400000 -200000 00.01
0.1
1
10 Rpt vs ItestW89 Series 2 P-stop 1E13 ion/cm^2
Vbias=-300V
BZ4DBZ4CBZ4BBZ4A
Itest [nA]
Rpt [
MΩ
]
-50 -30 -10 100
0.4
0.8
1.2
ATLAS07 Series3 Pstop 4E12W264 BZ4C P16
NEAR END
Vb -100VVb -300VVb -500VVb -700VVb -900V
Vtest [V]
Reff
[MΩ
]
Calculated Rpt‘s as a function of Itest for the same structure, BZ4C, and different bias voltages are the same contrary to Rpt’s evaluated for different PT structures but for the same bias voltagewhich show different dependences. Structure BZ4A is very effective at high current.
Vbias=-300V
-400000 -200000 00.01
0.1
1
10W264 Series3 BZ4C 4E12 ion/cm^2
Vb -100VVb -500VVb -900VW264 CVb -700V
Itest [nA]PT
res
ista
nce
Rpt
[mΩ
]
J.Bohm, 21st RD50 Workshop, CERN 15
Punch Through Protection Structures - Rpt
11/15/2012
-600000 -400000 -200000 00.01
0.1
1
10 Rpt vs ItestPre-Series3 P-stop 2E12
ion/cm^2
W14 BZ4A
W14 BZ4B
W14 BZ4C
W14 BZ4D
Itest [nA]
Rpt
[MΩ
]
-800000 -600000 -400000 -200000 00.01
0.1
1
10 Rpt vs ItestW89 Series 2 P-stop 1E13 ion/cm^2
Vbias=-300V
BZ4D
BZ4C
BZ4B
BZ4A
Itest [nA]
Rpt [
MΩ
]
-800000 -600000 -400000 -200000 00.01
0.1
1
10 Rpt vs ItestSeries3 P-stop 4E12 ion/cm^2
W281 A
W264 B
W281 D
W264 C
Itest [nA]
Rpt [
MΩ
]
Structure BZ4A seems to be the most effective short at low currents : -8µA, --18µA and -26µA for all P-stop ion concentrations: 2E12, 4E12 and 1E13 ion/cm^2 , respectively.
-Punch through voltage dominantly depends on P-stop ion concentration for all punch through structures.-PT voltage for P-stop+P-spray isolation is considerable higher than for P-stop isolation at same p-dose 2E12 ion/cm^2-Differences among PT voltages for each structure BZ4A-D are small for all concentrations, several volts only-PT voltage increases with applied bias, for concentration 1E13 ion/cm^2 is observed nearly saturation for Vb>500V.-PT voltages are smaller than 50V, i.e. they are significantly below the hold-off voltages of the coupling capacitor which are typically tested to 100V.There is practically no difference (1-2 V only) of PT voltages measured on FAR END and NEAR END.
J.Bohm, 21st RD50 Workshop, CERN 1811/15/2012
-1000-800-600-400-2000
-60
-40
-20
0
Punch-Through VoltageATLAS07 Pstop 4E12 ion/cm^2 W281 A 2E15
W281 B 2E15W281 C 2E15W281 D 2E15W278 A 4E14W278 B 4E14W278 C 4E14W278 D 4E14W281A nonirrW264B nonirrW264C nonirrW281D nonirr
Bias [V]
PT V
olta
ge [V
]
-1000-800-600-400-2000
-60
-40
-20
Punch-Through VoltageATLAS07 Pstop 1E13 ion/cm^2
W93 A 2E15W93 B 2E15W93 C 2E15W93 D 2E15W91 A 4E14W91 B 4E14W91 C 4E14W91 D 4E14W89 A nonirrBias [V]
-PT voltage increases with fluency and ion concentration
-At high fluency 2E15 neq/cm^2 and all tested ion concentrations the superiority belongs to the structure BZ4A with suppressed PTV with respect to structures BZ4B and BZ4C. BZ4D without any special structure reaches highest PT voltages.
-PT voltages for P-stop ion concentration 1E13 ion/cm^2 exceeds safety level of 50V even for BZ4A and fluency 4E14 neq/cm^2 and therefore concentration 1E13 ion/cm^2 is not suited to the protection against beam splashes
Punch Through Voltage irradiated
-At fluency about 4E14 neq/cm^2 and lower, an efficiency of special structures diminishes
J.Bohm, 21st RD50 Workshop, CERN 1911/15/2012
-1000-5000
-70
-50
-30
Punch-Through VoltageATLAS07 PTP BZ4A and BZ4D fluence 2E15
neq/cm^2
W93 A Pst 1E13
W93 D Pst 1E13
W281A Pst 4E12
W281D Pst 4E12
W19 A Pst 2E12
W19 D Pst 2E12
Bias [V]
PT V
olta
ge [V
]
0E+00 2E+12 4E+12 6E+12 8E+12 1E+13 1E+13
-60
-40
-20
PT Voltage vs P-stop concentrationBZ4A 4E14
BZ4B 4E14
BZ4C 4E14
BZ4D 4E14
BZ4A 2E15
BZ4B 2E15
BZ4C 2E15
BZ4D 2E15
P-stop concentration [ion/cm^2]
PT V
olta
ge [V
]
A comparison of PT voltages measured onspecial structure BZ4A with “no structure” BZ4D for various ion concentration at fluency 2E15 neq/cm^2.
PT voltage dependence on the P-stop ion concentration has shown a small differencebetween 2E12 and 4E12 ion/cm^2 and alsofor some structures (A and D) the PTV hasminimum at 4E12ion/cm^2.
Since one can expect for higher p-stop dose the higher inter-strip resistance,the 4E12 ion concentration is preferable.(Rint will be measured soon).
J.Bohm, 21st RD50 Workshop, CERN 20
Summary
11/15/2012
Non-irradiated sensors ATLAS07 with p-stop isolation and with different ion concentrations were successfully operating up to 1000V, no onset of micro-discharges was observed.On other side, irradiated sensors to fluency 4E14 neq/cm^2 behave differently and an onset of breakdowns is observed above already Vbias ~800V. For higher fluency, 2E15 neq/cm^2, no micro-discharges were found.
Punch through voltage dominantly depends on the P-stop ion concentration for all punch through structures, irradiated and non-irradiated samples and PTV increases with fluency, p-dose and applied bias.
PT voltages for P-stop ion concentration 1E13 ion/cm^2 exceeds safety level of 50V even for BZ4A and fluency 4E14 neq/cm^2 and therefore concentration 1E13 ion/cm^2 is not suited to the protection against beam splashes
At high fluency 2E15 neq/cm^2 and all tested ion concentrations the superiority belongs to the structure BZ4A with suppressed PTV with respect to structures BZ4B and BZ4C. The BZ4D without any special structure reaches highest PT voltages.
Protection structure BZ4A made with P-stop concentration of 4E12ion/cm^2 ensures that PTV will be smaller than 50V, (i.e. significantly below the hold-off voltage of the coupling capacitor -typically ~100V), for fluency up to 2E15neq/cm^2.
J.Bohm, 21st RD50 Workshop, CERN 21
Interstrip Capacitance - Method of measurement
11/15/2012
0 100 200 300 400 500 6000.600000000000001
0.800000000000001
1
1.2
1.4
1.6
1.8
2
2.2
Cinter CpRp 100kHz Sensor W37
Vbias [-V]
Cin
t [p
F]
2 probes
5 probes GND
3 probes
5probes2-probes
3-probes
5-probes
LCR High
DC pad
LCR Low
Isolated strips to GND
Cint(5-pr)/Cint(3-pr)=0.939 and 0.913 for 100kHz and 1MHz, respect.Cint(2-pr)/Cint(5-pr)=0.57
AC pad
J.Bohm, M.Mikestikova et.al, NIM A636 (2011)S104-S110
J.Bohm, 21st RD50 Workshop, CERN 22
Interstrip Capacitancenon-irradiated
11/15/2012
Wafer W14 W264 W78 W89 W04
Series Pre-Ser3 Series3 Series2 STD Series2 HPK Pstop Pspray
Ion/cm^2 2E12 4E12 1E13 1E13 2E12
Vfd [V] -183 -292 -186 -252 -186
Cint BZ4A pF 0.69 0.66 0.68 0.69 0.71
Cint BZ4B pF 0.68 0.67 0.68 0.68 0.71
Cint BZ4C pF 0.68 0.67 0.68 0.68 0.71
Cint BZ4D pF 0.71 0.66 0.68 0.69 0.70
Interstrip capacitance in this table was evaluated for Vbias=Vfd+10V
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 andthe punch through protection structures within ±20fF.Possible time dependence of Cint and an influence of relative humidity is in progress.