Status of Indium Bumped FE-I4B Richard Bates, Craig Buttar, Kate Doonan, John Lipp, Thomas McMullen 28/03/2014

Introduction 300μm CPII sensor Indium bump bonded to FE-I4B ROC Set up on probe station in GLADD to readout using USBPix RX Delay and Analog and Digital scans done to test module was working Tuning performed on the module to ascertain number of disconnected/merged bumps and dead pixels RX Delay Analog Digital

Disconnected pixels (criteria: Sigma > 0e and < 200e) This is the case for 6 out of pixels

Merged Bumps Merged pixels (criteria: Crosstalk occurs at 100V) This is the case for 106 out of pixels

Dead Pixels As tuning was not ideal, this is an approximate value by counting pixels with sigma value less than 1e from Threshold 100V from long tuning attempt (see later) 21 pixels dead

Bump Yield DISCONNECTED: 6 MERGED: 106 DEAD: 21 TOTAL: 133 out of BUMP-YIELD: %

Tuning The IBL tuning scheme did not work fully as it uses FAST tunes and all parameter space was not scanned 3000e threshold with 16ke THRESHOLD: Slightly high compared to target. White pixels here are not dead pixels, but pixels which are not reached using a fast tuning.

Tuning Compared to SC (250μm x 50μm) THRESHOLD: 2975e

Tuning Sigma on threshold with 0V bias shows very few pixels with values around 120e (disconnected) Next slide has log Y plot to show pixels with low values of sigma

Tuning Log Y Scale on sigma plot

Tuning Compared to SC (250μm x 50μm) at 100V SIGMA: 119.6e

Tuning TOT: This looks good!

Tuning Compared to SC (250μm x 50μm) TOT: 8.99

Tuning LONG tuning at 100V looked to be problematic: Threshold very high although note the pixels which were white in fast tune are occupied now Sigma very spread out Closer look at individual SCurves of pixels showed very poor fit giving both: HIGH THRESHOLD! LARGE SIGMA! HIGH THRESHOLD! SCurve is evident – fit has failed

Tuning LONG tuning at 100V looked to be problematic: Threshold very high Sigma very spread out Closer look at individual SCurves of pixels showed very poor fit giving both: HIGH THRESHOLD! LARGE SIGMA! Poor fit – sigma actually much smaller!

Tuning I am contacting Malte Beckhaus at CERN to see if there is a method of improving the fit for the SCurves With this issue, the threshold value and sigma value for each pixel is wrong in this case