# Presentation: 485459

## Silicon sensors procurement and quality assuranceWBS 1.1.1

**Regina Demina**
***Kansas State University***
***Frank Lehner ***
***University of Zurich***

## Outline

**Silicon sensor for Run IIb**
**Radiation environment and silicon sensor specs**
**Procurement strategy**
**Quality assurance**
**Irradiation studies and plans**
**Conclusions**

## Silicon sensors for DØ IIb

**Very tight schedule ******** Simple, robust design**
**Single sided sensors**
**3 sensor types – L0, L1, L2-5**
**L0, L1 **
**Inner radii ******** small sensors, high radiation**
**Essential for impact parameter resolution ******** fine pitch, intermediate strip**
**L2-L5**
**Essential for efficient tracking ******** larger pitch, robust design**
**Large quantity ******** uniform design – one sensor type**

**144 L1 sensors**
**7.94x2.50 cm****2**
**29/58 um pitch**

**144 L0 sensors**
**7.94x1.55 cm****2**
**25/50 um strip/readout pitch**

**1900 L2 sensors**
**10.0x4.11 cm****2**
**30/60 um pitch**

## 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**

## 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**

## 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**

**Based on preliminary irradiation studies we expect our sensors to survive >22 fb****-1**

## Silicon sensors (L0, L1)

**single sided n+p **
**robust, simple, # of dead channels <1%  **
**pitch: 25 & 29 ********m, every 2****nd**** strip read out**
**improve single hit resolution**** **
**integrated AC coupling and polysilicon bias resistor**
**both features work well after irradiation**** **
**guard ring structure design for necessary radiation resistance:**
**either multi-guard ring structure **
**or single guard ring design with peripheral n-well (Hamamatsu development)**
**overhanging metal on readout strips**
**significantly reduced risk of HV breakdown**
**  **

**ELMA**

**HPK**

## Silicon sensors (L2-5)

**wafer: **
**6’’-wafer, n-type silicon, crystal orientation <100>**
**thickness 320********20********m**
**wafer warp less than 50********m**
**depletion voltage: full depletion (FDV)<300V**
**leakage currents:**
**<100nA/cm2 at FDV and RT**
**total <16********A at 350V**
**junction breakdown > 350V**
**implant width 8********m with 2-3********m Al-overhang on R/O strips**
**coupling capacitance > 10pF/cm**
**interstrip capacitance <1.2pF/cm**
**Polysilicon resistor 0.8********0.3 M******
**bad strips: <1% **

## Silicon sensor procurement strategy

**L0 and L1 sensors**
**critical for radiation ******** Qualify two vendors – HPK and ELMA**
**prototypes received from ELMA, **
**undergoing tests**
**2 L1 sensors used in full module prototype**
**Choose vendor after irradiation of L1 ELMA and HPK sensors**
**L2-L5 sensors**
**large sensors, large quantity, more straight forward design ******** benefit from 6” technology  One vendor – HPK**
**Cost and schedule drivers**
**Very conservative design, experienced vendor ******** ****low to moderate risk**** **

**Sensor design is essentially complete (FNAL, U Zurich, Moscow, KSU)**
**Prototypes ordered for all sensor types**

## Silicon sensor quality assurance program (QA)

**QA measurements **
**Key tests **
**leakage currents, depletion voltage and visual inspections **
**100% on all prototypes and L0,L1 production, 10% on L2 production**
**Sensor subset tests**
**Leakage current stability over time, AC- and DC-scans, Rpoly**
**100% on all prototypes, 10% on all production**
**Sensor diagnostic tests**
**detailed evaluation of sensors (e.g. interstrip C, R)**
**routinely done on small sample and on sensors missing specs to provide detailed feedback to vendor**
**Mechanical tests (on OGP at FNAL)**
**sensor thickness, warp and cut dimensions/accuracy**
**Irradiation tests on small subset of prototypes and test structures.**

## QA sites

**Probing sites:**** **
**KSU – setup complete, work on L0 and L1 prototypes underway**
**SUNY at Stony Brook – setup in progress**
**CINVESTAV in Mexico – setup in progress**
**Fermilab – receiving, distributing, equipment exists**
**Two back up sites – U of Zurich and Moscow State**
**Equipment**** **
**Vibration-free table**
**R61 Alessi probe station**
**Keithley 237 ammeter/voltage source**
**HP4284 LCR meter GPIB interface**
**Dark box (not shown)**
**Guard box**
**Lab view based software**

## QA schedule and manpower

**QA schedule and manpower**

**BOE – experience with Run 2b prototypes, Run 2a and CMS sensors**
**~1 technician FTE/institution for 3 years, 3 tasks – setup, maintenance, probing**
**Manpower for QA is identified at all sites**

**Source: MRI**

**Source: institutional contribution**

**Source: MRI matching**

## 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**

**Target chamber**

**Goals: **
**Irradiation of prototype sensors to ensure sound technology and vendor choice**
**Irradiation of test structures during production to ensure high quality of delivered sensors**
**Possibly do a joint study of the “CDF” effect**

## 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 **
**Preliminary results from JRM agree with earlier tests. Sensors are expected to last >20fb****-1**

## Conclusions

**Use simple design, established technology, experienced vendors**
**Sensor design is essentially complete**
**Orders placed for all prototypes**
**First L0 and L1 prototypes received and are tested**
**Irradiation facility setup is essentially complete**
**Based on irradiation tests at Fermilab and at KSU sensors are expected to survive >20fb****-1**** of luminosity**
**QA procedures are defined, one QA site setup is complete, two others in progress **
**Manpower for QA and irradiation is estimated using prior experience, personnel is identified**
**Silicon sensor schedule risk is low to moderate**