Noise study 6/May/’13 Kazuki Motohashi - Tokyo Tech

2  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 ⊿ Noise F ASSY

3  Only left chips on DC modules are included in the histograms to deal with all modules using one code Module list 13 CNM 13 FBK30 DC

4 Noise Evaluation Removed bad modules of SC ‘cut value’ of ⊿ Noise < 20 e is valid for ASSY As for FLEX, we must use also information of source scan ASSY : +10 ℃ FLEX : - 10 ℃ From disconnected bumps From modules with low breakdown voltage ~10% good pixels of FBK FLEX < 20 e !! Conclusion :

Backup

66 Noise Evaluation - CNM - FBK - DC Noise without HV of DC Some peaks are here Due to feature of s-curve fit of STControl?

7 Noise 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) ① Remove pixels with 0 noise ② Remove bad modules ② Cut bad modules to see the difference of the ‘flavors’ clearly We cannot set cut value on ⊿ Noise to count # disconnected bumps …make cut value list for each flavors individually?