# Presentation: 473913

## Silicon sensors procurement and quality assuranceWBS 1.1.1

**Regina Demina**
***Kansas State University***

## Sensor procurement strategy

**Inner layers**
**High radiation – critical performance ******** Two vendors – Elma and HPK **
**Grade L1 prototypes**
**Electrical (done)**
**Irradiation (started – 2 points)**
**Mechanical**
**L0 vendor = L1 vendor**
**Outer layers**
**Large size, large quantity, less critical performance**
**One vendor – HPK – on 6” wafers**
**100 prototypes received ~ thanksgiving**
**First look at electrical quality**
**Start irradiation on 12/13**

## L1 Sensor quality: electrical grade

**ET1 grade: Vdepl from CV **
**If Vdepl < 300V ET1= 2, else ET1= 0 **
**ET2 grade: Vbreak from IV **
**If Vbreak > 700V ET2= 2, else ET2= 0 **
**If Vbreak<500V overall electric grade ET=0.**
**ET3 grade: Ileak @Vdepl+50V **
**If Ileak < 100 nA/cm****2**** ET3= 2, else ET3= 0**
**ET4 grade: N(bad channels) from AC, DC and Rpoly**
**If Nbad<=3 ET4= 2**
**If 3<Nbad<=8 ET4= 1 **
**Else ET4=0**
**ET5 grade: <Cint> on up to 5 strips @ Vdepl+50V.**
**If C_int < 1.2 pF/cm ET5=2 **
** ****if 1.2<C_int<1.4 pF/cm ET5= 1 point, **
**Else ET5=0  **
**ET=(ET1+ET2+ET3+ET4+ET5)/5**
**ET=0, if two or more individual grades are 0.**

## HPK and ELMA L1 electrical grades

- HPK: Rpoly too high on all strips – not a huge problem, but a document sent to HPK

## Irradiation at KSU JRM

**Facility: James R Macdonald lab at KSU**
**5-15 MeV proton beam **
**Beam swept by electrostatic deflector for uniform irradiation**
** ****can vary intensity to receive up to 1 Mrad/hour**
**Sensors are held in vacuum chamber**
**Flux is measured by a Faraday cup.**

**Target chamber**

## Irradiation plan

**2 points with 2 L1 (HKP and ELMA) and 2 L0 (ELMA) sensors**
**Installed chiller and cold chuck for reliable Vdepl determination at 0****o****C**
**Plan for L2-5 sensor irradiation **
**12/13 – 2.0 E12 1 MeV n equivalent**
**12/17 – 10.0 E12 1 MeV n equivalent**
**12/20 – 50.0 E12 1 MeV n equivalent**
**12/24 – 50.0 E12 1 MeV n equivalent**
**Total dose: – 1.12 E14 1 MeV n equivalent**
**Expected dose after 20 fb****-1**** 0.26 E14 1 MeV n equivalent**

## Testing schedule

**Before Xmas – irradiation **
**After New Year - Electrical testing on L2-5 **
**Full test on 10 sensors for evaluation **
**2 weeks of work**
**Results by 1/20**
**After L2-5 PRR resume L1 irradiation**

## Conclusions

**Use simple design, established technology, experienced vendors**
**Sensor design is essentially complete**
**all prototypes received**
**First L0 and L1 prototypes tested**
**Irradiation facility setup is essentially complete**
**Started ELMA and HPK L1 irradiation**
**Start HPK L2-5 irrad on Friday the 13****th**** **
**Expect all irrad and electrical results on L2 sensors by 1/20/03**

## Back up slidesdo not print

## Definition of bad strips

**Pinholes – current through capacitor >10 nA at 80 V and RT**
**Short – coupling capacitor >1.2 times the typical value**
**Open - coupling capacitor <0.8 times the typical value**
**Leaky channel if leakage current above 10 nA/strip at FDV and RT**
**Rpoly must be between 0.8********0.3 M********otherwise the channel is considered bad.**

## Requirements for silicon sensors

**Main challenge for silicon sensors - radiation**
**Depletion voltage (********) **
**Leakage current (********) ******** noise **
**Doses comparable to LHC – use their R&D**
**NB: Uncertainty in ********estimate– conservative approach**

**10 years of CMS at inner radius**

## Fluence estimations for Run IIb

**based on CDF silicon leakage current measurements in Run Ia+b**
**observed radial dependence ~1/r****1.7**
**measured CDF silicon sensor leakage currents are scaled to DØ sensor geometries and temperatures to give shot noise contributions of leakage currents**
**for depletion voltage calculations, a 1 MeV equivalent neutron fluence is assumed:**
******1Mev n****=2.19·10****13**** r[cm]****-1.7 ****[cm****-2****/fb-1]  (Matthew et al., CDF notes 3408 & 3937)**
**safety factor 1.5 applied**

## Depletion voltage

**Depletion voltage**

******fb******

**T=-10****o****C**
**with warm up periods**

**Specification on breakdown voltage derived based on depletion voltage evolution**

**Hamburg model**

## Signal to noise ratio

**Goal:  S/N> 10 **
**Possible if**
**T<-10****o****C for L0 and L1**
**T<-5****o****C for L2 – L5**
**Important to test I****leak**** after irradiation on prototype sensors  and on test structures during production**

**I****leak********cm****2**

**Noise contributions:**
**Capacitive load: 450+43C(pF)**
**Al strip resistance + analogue cables (L0)**
**Shot noise I****leak****=I****0****+********Ad (********=3E-17A/cm)**
**Thermal noise in R****bias**

## Performance extrapolations for Run IIb

**S/N extrapolations assume**
**noise in front end of SVX4: 450+43*C(pF)**
**total silicon strip capacitance: 1.4pF/cm**
**L0 analog cable assumed (and measured): 0.4pF/cm  **
**noise due to series resistance of metal traces in silicon ~210e-700e depending on module length**
**noise due to finite value of bias resistor: ~250e**
**shot noise due to increased leakage currents:**
**~1100e for L0 after 15fb****-1**** if T=-5C**
**~1000e for L2 (20cm long module) after 15fb****-1**** if T=0C****           **

## Radiation test results

**Radiation test results**

**Sensors of L0-type geometry from 4 vendors (ELMA, HPK, ST, Micron) irradiated by 8 GeV proton beam – Fermilab booster area**
**10Mrad = 1.8 E14 1MeV n/cm****2**** = 22 fb****-1**** at r=1.8cm**

**Micron**
**HPK**
**ELMA**
**ST**

**T=11****o****C**
**T=-12**** o****C**

**I****leak****=16uA/cm****2**** used **
**in S/N calculation**

**All sensors deplete at 300 V**
**Better than 600V used in estimations**

**Vdepl determined from Laser amplitude saturation**

## Preliminary results from JRM

**Preliminary results from JRM**

**4 ELMA L0 prototype sensors – 3 oxygenated, 1 non-oxygenated irradiated to 1.8E14 n/cm****2 **
**Vdepl determined from I****2 ****V behavior – could be systematically lower... need cold chuck**