# Presentation: 806085

## Pixel 2000 Genova – june 5-8, 2000http://www.ge.infn.it/Pix2000/slides.html Internal report 

- Pixel meeting  June 12, 2000_  _
**G. Chiodini – Fermilab**

- Overview
- Rad-hard Sensors (Marina)
- Rad-hard electronics
- Hybridization
- Pixel Module
- Mechanics and cooling
- Test beam results
- Monolithic pixels and 3D pixels
- X-ray imaging (..., HPD)
- Miscellanea

## Rad-hard electronics

- All speakers and experimental results validate the Abder’s conclusion: “Deep SubMicron CMOS process is the right way to go”
- ALICE2Test chip irradiated with X, , and p survives up to 30 Mrad: W. Snoeys (ALICE beam test) and F.Meddi (ALICE review talk)
- Review talks of P.F. Manfredi (FE) and P. Jarron (RH-FE) discussed about DSM:
- Likely high yield and low cost.
- Total Irradiated Dose Effect: outstanding performance with enclosed geometry and guard ring for n-channel Mosfets.
- Single Event Latch-up: good immunity (DMILL is immune to it)
- Single Event Gate Rupture: no evidence in ALICE2Test chip up to 91014 p/cm2.
- Single Event Upset: is an issue (true for all technologies) solved only by circuit design techniques and became worse going to 0.18 or 0.15 micron.
- Electrostatic Discharge Sensitive worse going to 0.18 or 0.15 micron.

- G. Chiodini - Fermilab

## Slide 3

- G. Chiodini - Fermilab

## Hybridizations (1/3)

- Talk review given by M. Caccia
- Delphi experience
- 106 pixels and 150 module
- Final yield 36 % (not acceptable for ATLAS)
- Real solutions are:
- Indium bump-bonding (industrial standard, room temperature, UBM is not complicate).
- Solder -above all flux less- (not industrial standard, UBM  is complicate).
- R. Horisberg: Development of indium bumping at PSI  (some secret recipes)
- Mass production (400 modules 2004-2005)
- UBM made by companies
- Reflow oven (for indium!) and Flip-chip for ATLAS pixel module
- Spherical 20 m diameter bumps after reflow
- Bumps deposited only on the read out chip (for indium!)
- Larger strength achieved
- In (273psi) , In-Ag (800psi) , and In-Sn(1720psi)

- G. Chiodini - Fermilab

## Hybridizations (2/3)

- Round table discussion on bump-bonding
- Industrial partners
- AMS (Rome, indium)
- IZM (Berlin, MCM-D module, solder, electroplating, reflow, 120minute/wafer all bumps inspection)
- VTT electronics (Finland, solder, electroplating, reflow, no flux)
- AIT (Usa) sent out an email (I am trying to have it)
- Discussed topics
- 8” wafer for 50 m pitch (A. Mekkaui’s question)
- Needed for DSM
- No one is ready now
- Module reworkability (M. Caccia’s question)
- Homogeneous detachment and re-bonding
- Cleaning the surfaces
- Not a problem for indium but for solder (thermal shock at high T for the chip)
- Mechanical stress of the sensor (M. Caccia’s talk: no problem for the indium)
- Companies don’t like that: a reworkability line parallel to the production line
- Large dead area probability (P. Delpierre’s question)
- Opposite to random 10-5 failure rate quoted up to now
- Impact on final yield

- G. Chiodini - Fermilab

## Hybridizations (3/3)

- Alenia Marconi System (Rome)
- Very simple process
- T<500 C and no reflow for indium
- Thinner chip bonded (lower T and lower P is enough to succeed)
- Same evaporation system for every step
- Wafer protected by photo resist in every step
- High yield, but problems with dies
- Wafer up to 6”
- They are thinking about to go to 8’’ wafers
- Investment in the deposition chamber to increase the size (several hundreds K$)
- Other equipments are ready
- C. Gemme: Study of indium bumping for the ATLAS pixel detector
- 2pixels/Fechip failure rare
- Threshold from 2000e to 4000e after bonding (7m+7m=8m)

- G. Chiodini - Fermilab

## Slide 7

- G. Chiodini - Fermilab

## Slide 8

- G. Chiodini - Fermilab

## Pixel module (1/2)

- P.Netchaeva: results on 0.7% X0 thick pixel modules for the Atlas detector
- 0.7% X0 Material budget (Two metal layer?)
- Silicon glue, thermo-camera test of  T uniformity
- One tested module from Boeing (150 m thinned ROC by GDSI after bumping)
- Two test module from AMS (156 m thinned ROC by Okamoto after bumping)
- P.Skubic: Flex Circuit designs for the Atlas pixel detector
- Design rules, simulation with Maxwell-Spice link, and comparison with test bench
- Wire bonding experience
- Vendor experience
- a lot of companies, only one produced non working sample
- Cleo III experience with GE (General Electric Corporate Research and Development NY)
- Flex hybrid Atlas module (LBL) beam test at CERN in May ’99 (SnPb bumps, good results)
- C.Grah: Pixel-detector modules using MCM-D technology
- Good bench test and beam test results presented
- Personal informal discussion suggest to me that it is not reliable up to now

- G. Chiodini - Fermilab

## Pixel module (2/2)

- I. Gregor: Optical links for the ATLAS SCT and Pixel detector
- Test on Rad-Hardness for SCT optical link (for Pixel optical link in the near future)
- SEU can be fixed sending more light

- G. Chiodini - Fermilab

## Slide 11

- G. Chiodini - Fermilab

## Slide 12

- G. Chiodini - Fermilab

## Slide 13

- G. Chiodini - Fermilab

## Slide 14

- G. Chiodini - Fermilab

## Beam Test

- L.Perera: Diamond pixel detectors
- W. Snoeys: OMEGA3 (ALICE+LHCb) chip in DSM process
- irradiated with 91014 p/cm2
- the threshold is changed but not dramatically
- M.Aleppo: A measurement of Lorentz angle of rad-hard pixel sensors
- Model
- Agreement test beam results and model
- T. lari: A measurement of spatial resolution of Atlas pixel sensors
- 6 m telescope resolution
- Large multiple scattering
- Error prediction subtracted from the residual distribution gaussian sigma
- Pixel module beam test already discussed

- G. Chiodini - Fermilab

## Slide 16

- G. Chiodini - Fermilab

## Slide 17

- G. Chiodini - Fermilab

## Slide 18

- G. Chiodini - Fermilab

## Mechanics and cooling

- M. Olcese: Mechanics and cooling for pixel detectors
- Fluorocarbon coolants are the best choice for pixel (stable, good thermal properties, relatively low viscosity at low temperature)
- Glue chip-support is an issue
- Phone conversation about BTeV design

- G. Chiodini - Fermilab

## Miscellanea

- G. Bolla: Measurements of prototype pixel sensors for CMS
- Analog data optical driver
- Readout architecture bypassing bad chip or bad column or bad pixel in the token readout.
- Controlling the single chip average rate to see if there are runaway in the system
- The reset must be local
- SEU about 1Hz
- S. Seidel: Capacitance of Silicon pixels
- Test bench for Atlas sensors
- Cback plane = 10-20 fF about 15% total C
- Cpspray =128 fF and  Cpstop = 80 fF
- CSeiko <  CCiS (Why?)
- Contribution to total C from first neighbors 11%, from after first neighbors 7%

- G. Chiodini - Fermilab