Noise study6/May/’13

Kazuki Motohashi - Tokyo Tech

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Noise on pixel should decrease when bias voltage is applied• Because width of depletion zone changes with bias

If bump is disconnected, this effect cannot be seen We can get # disconnected bumps using information of

⊿Noise• ⊿Noise := |noise with HV – noise w/o HV|• Source scan not done in ASSY test

Current setting : If ⊿Noise is < 20 e, the bump is considered as disconnected

# disconnected bumps is estimated correctly with this procedure…?

To check, Made some distributions of ⊿Noise from 13 CNM, 13 FBK and 30 DC modules which tested in Genova

Introduction Introduction

⊿Noise

F12-02-02 ASSY

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Only left chips on DC modules are included in the histograms to deal with all modules using one code

Module list Module list 13 CNM 13 FBK 30 DC

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Noise EvaluationNoise Evaluation

Removedbad

modulesof SC

‘cut value’ of ⊿Noise < 20 e is valid for ASSYAs for FLEX, we must use also information of source scan

ASSY : +10 ℃FLEX : - 10 ℃

From disconnected bumpsFrom modules with low breakdown

voltage

~10% good pixels of FBK FLEX< 20 e !!

Conclusion :

Backup

666

Noise EvaluationNoise Evaluation

- CNM- FBK- DC Noise without HV of DC

Some peaks are hereDue to feature of s-curve fit of STControl?

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Noise EvaluationNoise Evaluation

- CNM (3D)- FBK (3D)- DC (Planar)

① Noise values of some pixels are 0 in results of noise scan without HV for DC

Strange bump appears at 120 e (=noise mean with HV for DC)

①Remove pixelswith 0 noise

②Remove

bad modules

② Cut bad modules to see the difference of the ‘flavors’ clearlyWe cannot set cut value on ⊿Noise to count # disconnected bumps

…make cut value list for each flavors individually?