Noise study
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Transcript of Noise study
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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 :
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Backup
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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?