Diamond Manufacturers for ATLAS Upgrades
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Transcript of Diamond Manufacturers for ATLAS Upgrades
Diamond Manufacturersfor ATLAS Upgrades
March 26, 2012 1R. Kass
Brief Overview: Next Upgrade (IBL): Diamond Beam Monitor (DBM)News from two diamond manufacturers
E6/DDLII-VI
News from diamond cutting & thinning companiesSummary
March 26, 2012
Diamond Beam Monitor
2
BCM
DBM: 3.2<η<3.5
R. Kass
Part of IBL upgrade– Bunch-by-bunch luminosity monitor (aim < 1 % per BC per LB)
• Finer segmentation & larger acceptance than BCM • Never saturates• Internal stability monitoring
– Bunch-by-bunch beam spot monitor• Need triple-module telescopes for (limited) tracking• Can distinguish hits from beam halo tracks• Unbiased sample, acceptance extends far along beam axis
– Baseline: 4 telescopes of 3 IBL modules per side → 24 total diamonds– Avoid IBL insertion volume and ID acceptance (η>2.5)– Place in pixel support structure close to detector and beam pipe
DBM Diamond Sensor Plan
Two diamond suppliers involved: DDL/E6 (UK based) II-VI (US based)
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Diamond Sensors for DBM: type: polycrystalline CVD diamond size: 21 x 18 mm2, 525 ± 25 m thickness number: 40-45 need for DBM modules 24 + spares 5 for Irradiation studies
21 x 18 mm2 pCVD diamond
Some parts already in hand that need cutting and/or thinning
Sensors from DDLTen Detectors ordered from DDL/E6
(thick E6 wafer – Wafer 9)– Plan was for wafer to be tested at
OSU → wafer characterization → device selection
– Wafer 9 received from E6 11-Jan-2012
• Rind still attached• Defect level looks ok
– Wafer 9 returned to E6 - rind removal– Wafer arrived at OSU, test grid
applied, being testing
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Wafer 9 from DDL
March 26, 2012 R. Kass
Growth side Substrate side
5
5 inches
Thickness of wafer 9 from DDL
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As grown thickness varies from ~1.24 to 1.48 mm
Collection Distance & Current Characterisation of DDL’s wafer 9
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We are almost finished measuring the CCD & I in all regions of the waferExpect to finish measuring the CCD & ship back to DDL/E6 mid-week
Good regions have I <5 nA at 1000V in airAll regions of wafer 9 look good
CCD (m) current (nA)
Electric Field Characterisation of DDL’s wafer 9
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Need to take into account the varying thickness of the waferScale previous CCD plot to E=0.66V/m
This information allows us to make a “cut map”
Cut Map Example
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Based on the CCD and thickness info we divide the wafer into “sensors”
wafer 8
Wafer 8 was cut into eleven 2 x 2 cm2 sensors
E6/DDL Production CapabilitiesGet 10-15 FE-I4 sensors per waferOrdered 10 DBM Sensors detectors from DDL’s
wafer 9 21 x 18 mm2 with CCD>200 m at 1000V Each piece will be thinned to 525 m Expect the pieces to arrive in June Processing takes 6-10 weeks after return of waferExpect to have access to 10-20 wafers/year determined by the orders we place
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Work with II-VI
• Can grow thick wafers - 2 mm thick– grown for another application
• Very good CCD results– 300 µm @ 0.5 V/µm
• Problems with N2 and growth rate• problems showed up at the edges 11
Wafer Results
5 inches
II-VI makes “optical grade” cvd diamondlaser windows..
II-VI is the“2nd Company”www.ii-vi.com
March 26, 2012 R. Kass
Sensors from II-VI
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Proceeding to develop additional supplier of detector grade material based on their samples
• Good CCD results– 300 µm @ 0.5 V/µm even though grown for
another application and problems with N2 – Modified growth process
• ATLAS committed to produce one detector grade wafer by June with option for second wafer
• Quote received 9-Feb: specified ccd >250 µm @500µm
thickness• ATLAS placed order for 10 parts with
option for 10 more
Cutting & Thinning Parts in HandHave tested part thinning (750μm→525μm)
– 1cm x 1cm part used, came back fineSent first 2cm x 2cm parts for thinning
returned with edge problemswe are looking into a laser trimming repair
looks do-ableSent: one 2x6 for cutting & thinning four 2x2’s for thinningExpect three weeks to get 2x2 parts backIf ok → send remainder of parts
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Summary
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Two manufacturers are in place: DDL, II-VIThree orders of sensors from two manufacturers: DDL: 11 (wafer 8) + 10 (wafer 9) wafer 9 being tested II-VI 10 (with an option of another 10) looking forward to receiving their pieces in MayCCD measurements on DDL’s wafer 9 just about finished will ship back to DDL/E6 shortlyProgress on wafer thinning working with 2 companies in the US
Can now get 100’s of sensors/yr
Extra Slides
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Introduction: Diamond as sensor material
Property Diamond SiliconBand gap [eV] Low leakage 5.5 1.12Breakdown field [V/cm] 107 3x105
Intrinsic resistivity @ R.T. [Ω cm] > 1011 2.3x105
Intrinsic carrier density [cm-3] < 103 1.5x1010
Electron mobility [cm2/Vs] 1900 1350Hole mobility [cm2/Vs] 2300 480Saturation velocity [cm/s] 0.9(e)-1.4(h)x 107 0.82x 107
Density [g/cm3] 3.52 2.33Atomic number - Z 6 14Dielectric constant – ε Low cap 5.7 11.9Displacement energy [eV/atom] Rad hard
43 13-20Thermal conductivity [W/m.K] Heat spreader
~2000 150
Energy to create e-h pair [eV] 13 3.61Radiation length [cm] 12.2 9.36Interaction length [cm] 24.5 45.5Spec. Ionization Loss [MeV/cm] 6.07 3.21Aver. Signal Created / 100 μm [e0] Low Noise, Low signal
3602 8892
Aver. Signal Created / 0.1 X0 [e0] 4401 8323
Single-crystal CVD & poly CVD fall along
the same damage curveProton damage well understoodAt all energies diamond is >3x
more radiation tolerant than silicon
kMFPMFP 0
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Radiation Studies
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Radiation Damage - Basics
Charge trapping the only relevant radiation damage effect NIEL scaling questionable a priori
Egap in diamond 5 times larger than in Si Many processes freeze out Typical emission times order of months
Like Si at 300/5 = 60 K – Boltzmann factor A rich source of effects and (experimental) surprises !
Radiation induced effect Diamond Operational
consequence Silicon Operational consequence
Leakage current
small &decreases none I/V = αΦ
α ~ 4x10-17 A/cm
HeatingThermal runaway
Space charge ~ none noneΔNeff ≈ -βΦ
β ~ 0.015 cm-1
Increase of full depletion
voltage
Charge trapping Yes Charge loss
Polarization
1/τeff = βΦβ ~ 5-7x10-16
cm2/ns
Charge lossPolarization
t
thttteff
vPN
)1(1
17OSU, Nov 9, 2011 R. Kass: DOE Review