Status of Indium Bumped FE-I4BRichard Bates, Craig Buttar, Kate Doonan, John Lipp, Thomas McMullen28/03/2014

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• Disconnected pixels• (criteria: Sigma > 0e and < 200e)

• This is the case for 6 out of 26880 pixels

Merged Bumps• Merged pixels• (criteria: Crosstalk occurs at 100V)

• This is the case for 106 out of 26880 pixels

Dead Pixels• As tuning was not ideal, this is

an approximate value by counting pixels with sigma value less than 1e from Threshold Scan @ 100V from long tuning attempt (see later)

• 21 pixels dead

Bump Yield• DISCONNECTED: 6 • MERGED: 106• DEAD: 21

• TOTAL: 133 out of 26880

• BUMP-YIELD: 99.505%

Tuning• The IBL tuning scheme

did not work fully as it uses FAST tunes and all parameter space was not scanned• 3000e threshold with

9ToT @ 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-3072-4-8

(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-3072-4-8

(250μm x 50μm) at 100V

• SIGMA: 119.6e

Tuning• TOT: This looks good!

Tuning• Compared to SC-3072-4-8

(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!

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