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Siviero F., Arcidiacono R., Cartiglia N., Costa M., Ferrero M., Mandurrino M., Milanesio M., Sola V. Staiano A., Tornago M.Borghi G., Boscardin M., Dalla Betta G-F., Ficorella F., Pancheri L., Paternoster G., Centis Vignali M.
Characterization with a β-source setup of the FBK UFSD3.2 & HPK2 LGAD productions
37th RD50 Online Workshop, 11.20.2020
Outline
Siviero F. 37th RD50 Online Workshop , 20.11.2020 2
➢ The FBK UFSD3.2 & HPK2 productions
➢ Torino β-source setup
➢ Measurements of sensors for the CMS Encap Timing Layer:
○ FBK + HPK non-irradiated
○ HPK irradiated
➢ Comparison of FBK sensors with different active thicknesses: 35, 45, 55 μm
Outline
Siviero F. 37th RD50 Online Workshop , 20.11.2020 3
➢ The FBK UFSD3.2 & HPK2 productions
➢ Torino β-source setup
➢ Measurements of sensors for the CMS Encap Timing Layer:
○ FBK + HPK non-irradiated
○ HPK irradiated
➢ Comparison of FBK sensors with different active thicknesses: 35, 45, 55 μm
FBK UFSD3.2
Siviero F. 37th RD50 Online Workshop , 20.11.20204
● 5 wafers for ETL measured so far:○ 2 thicknesses○ 3 carbon doses○ Shallow and deep gain layer (GL)
Latest R&D production of LGADs for CMS ETLWafer thickness GL depth Carbon
4 45 μm shallow 0.4*A
7 55 μm shallow A
10 45 μm deep 0.6*A
12 45 μm deep A
14 45 μm deep A
FBK UFSD3.2
Siviero F. 37th RD50 Online Workshop , 20.11.2020 5
● 5 wafers for ETL measured so far:○ 2 thicknesses○ 3 carbon doses○ Shallow and deep gain layer (GL)
Latest R&D production of LGADs for CMS ETLWafer thickness GL depth Carbon
4 45 μm shallow 0.4*A
7 55 μm shallow A
10 45 μm deep 0.6*A
12 45 μm deep A
14 45 μm deep A
FBK UFSD3.2
Siviero F. 37th RD50 Online Workshop , 20.11.2020 6
● 5 wafers for ETL measured so far:○ 2 thicknesses○ 3 carbon doses○ Shallow and deep gain layer (GL)
Latest R&D production of LGADs for CMS ETLWafer thickness GL depth Carbon
4 45 μm shallow 0.4*A
7 55 μm shallow A
10 45 μm deep 0.6*A
12 45 μm deep A
14 45 μm deep A
Explore different doses around the optimal “A” dose defined with the previous UFSD3 production
FBK UFSD3.2
Siviero F. 37th RD50 Online Workshop , 20.11.2020 7
● 5 wafers for ETL measured so far:○ 2 thicknesses○ 3 carbon doses○ Shallow and deep gain layer (GL)
Latest R&D production of LGADs for CMS ETLWafer thickness GL depth Carbon
4 45 μm shallow 0.4*A
7 55 μm shallow A
10 45 μm deep 0.6*A
12 45 μm deep A
14 45 μm deep A
Introduce deep gain layer implant to improve radiation resistance → interesting to compare performances with the standard shallow GL
FBK UFSD3.2
Siviero F. 37th RD50 Online Workshop , 20.11.2020 8
● 5 wafers for ETL measured so far:○ 2 thicknesses○ 3 carbon doses○ Shallow and deep gain layer (GL)
● All sensors are 2x2 arrays with “safe” interpad design strategy → interpad gap = 65 / 70 μm
Latest R&D production of LGADs for CMS ETLWafer thickness GL depth Carbon
4 45 μm shallow 0.4*A
7 55 μm shallow A
10 45 μm deep 0.6*A
12 45 μm deep A
14 45 μm deep A
Siviero F. 37th RD50 Online Workshop , 20.11.2020 9
FBK UFSD3.2
Wafer VBD
4 250
7 300
10 375
12 385
14 300
● charge [fC] = Area [pWb] / 4700○ 4700 = board transimpedance
● All sensors deliver 15 fC ○ target charge for electronics
deep GL
No significant differences between deep and shallow GL
preliminary
HPK2
Siviero F. 37th RD50 Online Workshop , 20.11.2020 10
● 4 gain split:○ split 1,2 highly doped ○ split 3,4 less doped
● All splits feature deep GL, no carbon, 45μm active thickness
● All measured devices are 2x2 arrays with interpad design strategy “IP5” or “IP7” → interpad gap = 100 / 120 μm
Gain split thickness GL depth Carbon
1 45 μm deep NO
2 45 μm deep NO
3 45 μm deep NO
4 45 μm deep NO
Siviero F. 37th RD50 Online Workshop , 20.11.2020 11
HPK2
Split VBD
1 160
2 180
3 220
4 240
● Splits 1,2 heavily doped → operate at very low V
○ Particularly interesting for ATLAS as they are the most rad-hard
● Splits 3,4 are less rad-hard but with better performances when new
preliminary
Siviero F. 37th RD50 Online Workshop , 20.11.2020 12
HPK2
Split VBD
1 160
2 180
3 220
4 240
We focused in particular on split 4, since it has the best performance when new (it might be the most suited for ETL) → remaining splits will be measured soon
● Splits 1,2 heavily doped → operate at very low V
○ Particularly interesting for ATLAS as they are the most rad-hard
● Splits 3,4 are less rad-hard but with better performances when new
preliminary
Outline
Siviero F. 37th RD50 Online Workshop , 20.11.2020 13
➢ The FBK UFSD3.2 & HPK2 productions
➢ Torino β-source setup
➢ Measurements of sensors for the CMS Encap Timing Layer:
○ FBK + HPK non-irradiated
○ HPK irradiated
➢ Comparison of FBK sensors with different active thicknesses: 35, 45, 55 μm
Torino β-source setup - 1
Siviero F. 37th RD50 Online Workshop , 20.11.2020 14
● DAQ and Analysis are fully automated○ Based on UCSC DAQ software○ works with pyVISA
● Compact, easy-to-use○ can be mounted in < 1h
● Dark box for measurements at room temp● Fridge + dry air for cold measurements
Lecroy 9404HD 40 Gs/s
Dark box
CAEN HV
LV
Torino β-source setup - 2
Siviero F. 37th RD50 Online Workshop , 20.11.2020 15
● Sr90 source, can work down to -40°C○ 3.6 kBq → max activity allowed in our lab
● Telescope formed by DUT + Trigger
● Trigger placed below the DUT ensures that we trigger only on MIPs
○ Trigger: HPK1 1x3 mm^2 single pad DUT
Trigger
Beta trajectory
3D-printed structure for sensors alignment
Torino β-source setup - 2
Siviero F. 37th RD50 Online Workshop , 20.11.2020 16
● Sr90 source, can work down to -40°C○ 3.6 kBq → max activity allowed in our lab
● Telescope formed by DUT + Trigger
● Trigger placed below the DUT ensures that we trigger only on MIPs
○ Trigger: HPK1 1x3 mm^2 single pad
● “Santa Cruz” Read-out board made by Artel○ single channel○ x10 amplification (+ 20dB Cividec
broadband external amplifier)
DUT
Trigger
Beta trajectory
3D-printed structure for sensors alignment
Torino β-source setup - 3
Siviero F. 37th RD50 Online Workshop , 20.11.2020 17
● Analysis code partially based on UCSC one and adapted to our setup
● Important parameters for time resolution: signal amplitude, area (charge), ToA○ Signal amplitude: gaussian fit around sampled point with maximum V○ Signal area: take 10% and 20% on both rising / falling edge → linear interpolation to find
start and end time of the signal → Integral of the signal using Simpson's rule○ Time of Arrival: once time corresponding to signal maximum (Tmax) has been determined,
take the two sampled points closest to the xx% of the signal → linear interpolation to find the time corresponding to xx%
● Temporal resolution defined as σDUT = √(σ 2measured - σ
2Trigger)
○ σ measured is the std. deviation of ToA DUT - ToA Trigger
○ 20% CFD usually provides the best result
Siviero F. 37th RD50 Online Workshop , 20.11.2020 18
Dry & Cold β setup● Commissioning of a cold setup started in September in
Torino● Commercial freezer that can work in the -10°C / -30°C range● Old setup:
○ Dry air provided by a commercial compressor → main issue: 30-50% humidity
○ Sensors can be measured, although it is not ideal○ Performed several measurements with no issue○ But, metal support of our beta source eventually rusted
because of the ice forming on it → we had to stop measurements and look for a better compressor
● New setup○ Same freezer but better compressor → <10% humidity
● Future setup○ Climate chamber (next year)
Outline
Siviero F. 37th RD50 Online Workshop , 20.11.2020 19
➢ The FBK UFSD3.2 & HPK2 productions
➢ Torino β-source setup
➢ Measurements of sensors for the CMS Encap Timing Layer:
○ FBK + HPK non-irradiated
○ HPK irradiated
➢ Comparison of FBK sensors with different active thicknesses: 35, 45, 55 μm
Resolution vs Bias
Siviero F. 37th RD50 Online Workshop , 20.11.2020 20
● All FBK sensors reached ~30ps● HPK split 1 and 2 cannot reach 30ps since bias voltage is too low: electrons drift velocity not yet saturated ● Noise is low for all sensors: 1.2 / 1.5 mV
All sensors are non irradiated and measured at room T (23°C)
deep GL
preliminary preliminary
Resolution vs Gain
Siviero F. 37th RD50 Online Workshop , 20.11.2020 21
deep GL
High gain in both productions
preliminary preliminary
Resolution vs Gain
Siviero F. 37th RD50 Online Workshop , 20.11.2020 22
● HPK needs higher gain to reach 30ps as they are operated at lower V
preliminary preliminary
deep GL
Resolution vs Gain
Siviero F. 37th RD50 Online Workshop , 20.11.2020 23
● HPK needs higher gain to reach 30ps as they are operated at lower V● Effect well visible comparing HPK split1 and split4: the gain required to reach a given resolution is higher
in sensors operated at lower V ( = lower E field → worse dV/dt )
increasing electric field
preliminary preliminary
deep GL
Resolution vs Gain
Siviero F. 37th RD50 Online Workshop , 20.11.2020 24
● HPK needs higher gain to reach 30ps as they are operated at lower V● Effect well visible comparing HPK split1 and split4: the gain required to reach a given resolution is higher
in sensors operated at lower V ( = lower E field → worse dV/dt )
increasing electric field
A good time resolution is given by the interplay of high gain and high electric field → GL doping must be chosen
to optimize these two aspects
preliminary preliminary
deep GL
Jitter
Siviero F. 37th RD50 Online Workshop , 20.11.2020 25
total resolution
● Estimated jitter = noise / (dV/dt)○ noise : RMS of the baseline○ dV/dt (slew rate): derivative of the signal rising edge, taken from 20% to 80%
jitter only
preliminary preliminary
Jitter
Siviero F. 37th RD50 Online Workshop , 20.11.2020 26
● Total resolution vs Gain flattens around 30ps because of the Landau term ( σLandau )
total resolution
jitter only
preliminary preliminary
Siviero F. 37th RD50 Online Workshop , 20.11.2020 27
Temperature scan
● We performed a temperature scan on both productions● For deep implants, the bias shift to reach 30ps is ~ 1V/1°C : ΔT = 55°C → ΔV = 55-60 V● We will measure a sensor with shallow GL soon
-10°C
- 30°C
23°C 23°C
- 30°C -10°C
ΔV = 55
preliminary preliminary
Outline
Siviero F. 37th RD50 Online Workshop , 20.11.2020 28
➢ The FBK UFSD3.2 & HPK2 productions
➢ Torino β-source setup
➢ Measurements of sensors for the CMS Encap Timing Layer:
○ FBK + HPK non-irradiated
○ HPK irradiated
➢ Comparison of FBK sensors with different active thicknesses: 35, 45, 55 μm
HPK2 split 4 irradiated
Siviero F. 37th RD50 Online Workshop , 20.11.2020 29
● Tested sensors (all 2x2 arrays):○ split4 IP5 non-irr
○ split4 IP7 1.5e15 neq/cm2 → max nominal fluence foreseen for the inner part of ETL
○ split4 IP7 2.5e15 neq/cm2 → max fluence considering a x1.5 safety margin
● Measurements performed at -30°C, relative humidity ~40%
Expected radiation levels @ ETL
HPK2 split4 irradiated
Siviero F. 37th RD50 Online Workshop , 20.11.2020 30
● 12fC delivered @ 1.5e15 neq/cm2
● 7fC @ 2.5e15 neq/cm2
non-irr
1.5e15
2.5e15
preliminary
HPK2 split4 irradiated
Siviero F. 37th RD50 Online Workshop , 20.11.2020 31
● Time resolution in the 30-40ps range up to a fluence of 2.5e15 neq/cm2
● Most irradiated device operated for many hours at 775V with no issues → good check of sensors stability
non-irr
1.5e15
2.5e15
non-irr1.5e15
2.5e15
preliminarypreliminary
HPK2 split4 irradiated
Siviero F. 37th RD50 Online Workshop , 20.11.2020 32
● Time resolution in the 30-40ps range up to a fluence of 2.5e15 neq/cm2
● Most irradiated device operated for many hours at 775V with no issues → good check of sensors stability
non-irr
1.5e15
2.5e15
non-irr1.5e15
2.5e15
best CFD non-irr, 1.5e15 : 20%
2.5e15 : 40%
preliminarypreliminary
HPK2 split4 irradiated
Siviero F. 37th RD50 Online Workshop , 20.11.2020 33
● Time resolution in the 30-40ps range up to a fluence of 2.5e15 neq/cm2
● Most irradiated device operated for many hours at 775V with no issues → good check of sensors stability
HPK2 split4 meets the ETL requirements!
non-irr
1.5e15
2.5e15
non-irr1.5e15
2.5e15
preliminarypreliminary
Outline
Siviero F. 37th RD50 Online Workshop , 20.11.2020 34
➢ The FBK UFSD3.2 & HPK2 productions
➢ Torino β-source setup
➢ Measurements of sensors for the CMS Encap Timing Layer:
○ FBK + HPK non-irradiated
○ HPK irradiated
➢ Comparison of FBK sensors with different active thicknesses: 35, 45, 55 μm
FBK UFSD3.2 → Thin sensors
Siviero F. 37th RD50 Online Workshop , 20.11.2020 35
● 2 additional wafers (not ETL) have been produced at FBK:
○ 25 / 35 μm active thickness○ only 35 μm considered here
Wafer thickness GL depth Carbon
4 45 μm shallow 0.4*A
6 35 μm shallow A
7 55 μm shallow A
FBK UFSD3.2 → Thin sensors
Siviero F. 37th RD50 Online Workshop , 20.11.2020 36
● 2 additional wafers (not ETL) have been produced at FBK:
○ 25 / 35 μm active thickness○ only 35 μm considered here
● Tested sensors:○ W4 & W7 2x2 arrays
Wafer thickness GL depth Carbon
4 45 μm shallow 0.4*A
6 35 μm shallow A
7 55 μm shallow A
FBK UFSD3.2 → Thin sensors
Siviero F. 37th RD50 Online Workshop , 20.11.2020 37
● 2 additional wafers (not ETL) have been produced at FBK:
○ 25 / 35 μm active thickness○ only 35 μm considered here
● Tested sensors:○ W4 & W7 2x2 arrays○ W6 single pad
Wafer thickness GL depth Carbon
4 45 μm shallow 0.4*A
6 35 μm shallow A
7 55 μm shallow A
FBK UFSD3.2 → Thin sensors
Siviero F. 37th RD50 Online Workshop , 20.11.2020 38
● 2 additional wafers (not ETL) have been produced at FBK:
○ 25 / 35 μm active thickness○ only 35 μm considered here
● Tested sensors:○ W4 & W7 2x2 arrays○ W6 single pad
● Comparison performed only on pre-rad devices at room T
Wafer thickness GL depth Carbon
4 45 μm shallow 0.4*A
6 35 μm shallow A
7 55 μm shallow A
Performance of thin sensors
Siviero F. 37th RD50 Online Workshop , 20.11.2020 39
35um
55um45um
W6 is the 1st wafer comprising thin sensors manufactured at FBK→ designed for tracking at extreme fluences (see V.Sola’s talk), not optimized for timing
35um
45um
55um
preliminarypreliminary
Performance of thin sensors
Siviero F. 37th RD50 Online Workshop , 20.11.2020 40
35um
55um45um 35um
45um
55um
Wafer VBD
4 (45um) 250
6 (35um) 230
7 (55um) 300
W6 is the 1st wafer comprising thin sensors manufactured at FBK→ designed for tracking at extreme fluences (see V.Sola’s talk), not optimized for timing
preliminarypreliminary
Lower collected charge and VBD because of the smaller volume
Performance of thin sensors
Siviero F. 37th RD50 Online Workshop , 20.11.2020 41
35um
55um45um
W6 is the 1st wafer comprising thin sensors manufactured at FBK→ designed for tracking at extreme fluences (see V.Sola’s talk), not optimized for timing
35um
45um
55um
low noise and good gain, regardless the active thickness
preliminarypreliminary
Siviero F. 37th RD50 Online Workshop , 20.11.2020 42
FBK thin sensors: time resolution
W6 (35μm) reaches 28ps:
● Smaller σLandau because it is thin
● but, worse dV/dt:○ risetime similar to thicker device○ smaller V because capacitance is
higher (approx. 4.5pF instead of 3pF) → worse jitter
35um 55um45um
preliminary
Siviero F. 37th RD50 Online Workshop , 20.11.2020 43
FBK thin sensors: jitter
35um
55um
45um
total resolution
jitter only
● Estimated jitter = noise / (dV/dt)preliminary
Measurements of gain on thin sensors are still very preliminary → need further studies for a precise determination
Siviero F. 37th RD50 Online Workshop , 20.11.2020 44
FBK thin sensors: jitter
35um
55um
45um
total resolution
jitter only
● Estimated jitter = noise / (dV/dt)
● Compare total resolution and jitter and get the Landau term:
○ σLandau (35μm) = 25 ps
○ σLandau (45μm) = 28.5 ps
○ σLandau (55μm) = 32 ps
preliminary
Siviero F. 37th RD50 Online Workshop , 20.11.2020 45
FBK thin sensors: the Landau term
35um
55um
45um
● Estimated jitter = noise / (dV/dt)
● Compare total resolution and jitter and get the Landau term:
○ σLandau (35μm) = 25 ps
○ σLandau (45μm) = 28.5 ps
○ σLandau (55μm) = 32 ps
→ go thin to minimize Landau fluctuations25um
Summary & outlook
Siviero F. 37th RD50 Online Workshop , 20.11.2020 46
● The FBK UFSD3.2 & HPK2 productions have been extensively measured in Torino with a β-source setup:
Summary & outlook
Siviero F. 37th RD50 Online Workshop , 20.11.2020 47
● The FBK UFSD3.2 & HPK2 productions have been extensively measured in Torino with a β-source setup:○ FBK UFSD3.2 features different level of carbon and either shallow and deep GL → all sensors have good gain and
low noise, reaching 30ps time resolution
Summary & outlook
Siviero F. 37th RD50 Online Workshop , 20.11.2020 48
● The FBK UFSD3.2 & HPK2 productions have been extensively measured in Torino with a β-source setup:○ FBK UFSD3.2 features different level of carbon and either shallow and deep GL → all sensors have good gain and
low noise, reaching 30ps time resolution ○ HPK2 features only deep-GL and no carbon: splits 3,4 work well when new, whereas splits 1 and 2 (heavily doped)
operate at too low V → GL doping must be carefully chosen to provide both high gain and high electric field
Summary & outlook
Siviero F. 37th RD50 Online Workshop , 20.11.2020 49
● The FBK UFSD3.2 & HPK2 productions have been extensively measured in Torino with a β-source setup:○ FBK UFSD3.2 features different level of carbon and either shallow and deep GL → all sensors have good gain and
low noise, reaching 30ps time resolution ○ HPK2 features only deep-GL and no carbon: splits 3,4 work well when new, whereas splits 1 and 2 (heavily doped)
operate at too low V → GL doping must be carefully chosen to provide both high gain and high electric field
● UFSD3.2 & HPK2 have been measured at different temperatures:○ In sensors with deep GL, the bias shift to reach 30ps is ~ 1V/1°C
Summary & outlook
Siviero F. 37th RD50 Online Workshop , 20.11.2020 50
● The FBK UFSD3.2 & HPK2 productions have been extensively measured in Torino with a β-source setup:○ FBK UFSD3.2 features different level of carbon and either shallow and deep GL → all sensors have good gain and
low noise, reaching 30ps time resolution ○ HPK2 features only deep-GL and no carbon: splits 3,4 work well when new, whereas splits 1 and 2 (heavily doped)
operate at too low V → GL doping must be carefully chosen to provide both high gain and high electric field
● UFSD3.2 & HPK2 have been measured at different temperatures:○ In sensors with deep GL, the bias shift to reach 30ps is ~ 1V/1°C
● HPK2 split4 irradiated up to a fluence of 2.5e15 neq/cm2 has been measured at -30°C○ It reached 40ps even at the largest fluence
Summary & outlook
Siviero F. 37th RD50 Online Workshop , 20.11.2020 51
● The FBK UFSD3.2 & HPK2 productions have been extensively measured in Torino with a β-source setup:○ FBK UFSD3.2 features different level of carbon and either shallow and deep GL → all sensors have good gain and
low noise, reaching 30ps time resolution ○ HPK2 features only deep-GL and no carbon: splits 3,4 work well when new, whereas splits 1 and 2 (heavily doped)
operate at too low V → GL doping must be carefully chosen to provide both high gain and high electric field
● UFSD3.2 & HPK2 have been measured at different temperatures:○ In sensors with deep GL, the bias shift to reach 30ps is ~ 1V/1°C
● HPK2 split4 irradiated up to a fluence of 2.5e15 neq/cm2 has been measured at -30°C○ It reached 40ps even at the largest fluence
● We measured 3 UFSD3.2 with different thicknesses (45, 35, 25 μm):○ First production of thin sensors by FBK → optimized for tracking, not for timing○ thin sensors reached 28ps, comparable with resolution of thicker sensors
Summary & outlook
Siviero F. 37th RD50 Online Workshop , 20.11.2020 52
● The FBK UFSD3.2 & HPK2 productions have been extensively measured in Torino with a β-source setup:○ FBK UFSD3.2 features different level of carbon and either shallow and deep GL → all sensors have good gain and
low noise, reaching 30ps time resolution ○ HPK2 features only deep-GL and no carbon: splits 3,4 work well when new, whereas splits 1 and 2 (heavily doped)
operate at too low V → GL doping must be carefully chosen to provide both high gain and high electric field
● UFSD3.2 & HPK2 have been measured at different temperatures:○ In sensors with deep GL, the bias shift to reach 30ps is ~ 1V/1°C
● HPK2 split4 irradiated up to a fluence of 2.5e15 neq/cm2 has been measured at -30°C○ It reached 40ps even at the largest fluence
● We measured 3 UFSD3.2 with different thicknesses (45, 35, 25 μm):○ First production of thin sensors by FBK → optimized for tracking, not for timing○ thin sensors reached 28ps, comparable with resolution of thicker sensors
● Measurement campaign will continue in the next months: irradiated FBK, remaining splits of irradiated HPK2, irradiated thin sensors
Thank You!
BACKUP
Siviero F. 37th RD50 Online Workshop , 20.11.2020 54
Siviero F. 37th RD50 Online Workshop , 20.11.2020 55
FBK + HPK Temperature scans: jitter
solid: total res
dashed: jitter only
23°C
23°C
-10°C
-10°C
- 30°C - 30°C
preliminary preliminary
Siviero F. 37th RD50 Online Workshop , 20.11.2020 56
FBK + HPK Temperature scans
● Tested sensors:○ FBK UFSD3.2 W12, W10 (deep GL, carbon, 45μm active thickness)○ HPK2 split4
-10°C
- 30°C
23°C
23°C
-10°C - 30°C
preliminary preliminary
Siviero F. 37th RD50 Online Workshop , 20.11.2020 57
FBK + HPK Temperature scans - 2
● Gain needed to reach 30ps is smaller at cold since the mobility is higher
-10°C
- 30°C
23°C
-10°C
- 30°C
23°C
preliminary preliminary
Siviero F. 37th RD50 Online Workshop , 20.11.2020 58
HPK2 split4 irradiated - 2
low noise even in the most irradiated sensor, between 1.2 and 1.7 mV
preliminary preliminary