FEI4A Wafer Probing Andrew Stewart 21 September 2012

Set-up of semi-automatic wafer probing of FE-I4A wafers near completion. – Cascade S300 probe station added to STControl software. – Reasonable success of achieving a good electrical contact. In a test of probing 6 consecutive die only 1 failed to return test data. – Measurement repeatability at different probe sites looks good (see slides 5 to 11). – Currently use USBpixTestI4 to conduct Global Register, Pixel Register & Sync Scan tests and STControl to conduct Analogue, Digital and Threshold scans. – Would like to use STControl wafer test panel for all tests and automated probing. However, I have encounted a number of issues establishing a full prim list of tests.

Issues with wafer panel prim list. – Regulators On: Does this turn on analogue and digital power supplies? Doesn’t appear to work. – How are the GR & PR tests and current readings (I DDD1 etc) accessed? These results don’t appear to be displayed in the Module Analysis panel.

Wafer ID:V2AQMLHAnalogue TestDigital Test Chip No. IDDA1 (mA) IDDA2 (mA) IDDD1 (mA) IDDD2 (mA) Global Register Test Pass Pixel Register Test Analogue Pixels with Occ ≠ 200 Digital Pixels with Occ ≠ 200 Mean Threshold Threshold Sigma Comments Yes Yes Yes Many pixels fail analogue test and threshold scan Yes Yes na Many pixels fail analogue test. No meaningful threshold scan Yes Yes Many pixels fail threshold scan YesNo Yes na V high digital current during PR Test. Analogue & Digital Tests Empty 10na V high current on analogue and digital channels (>0.5A) Yes na Many pixels fail analogue test Yes na Many pixels fail analogue test Yes Yes Initial Measurement 18 Yes Measurement after reprobing Yes Initial Measurement Yes Measurement after reprobing Wafer results spreadsheet. No pass/fail criteria set yet.

Repeatability Measurements

DieBad Pixels (Analogue) Bad Pixels (Digital) Mean Threshold Sigma Threshold (Repeat) (Repeat) Summary of Repeatability Measurements

Die 18: Initial Analogue Occupancy Plot (Left) and Analogue Occupancy after re-probing (Right)

Die 18: Initial Digital Occupancy Plot (Left) and Digial Occupancy after re-probing (Right)

Die 18: Initial Threshold Scan (Left) and Threshold Scan after re-probing (right)

Die 20: Initial Analogue Occupancy Plot (Left) and Analogue Occupancy after re-probing (right)

Die 20: Initial Digital Occupancy Plot (Left) and Digital Occupancy after re-probing (Right)

Die 20: Initial Threshold Scan(Left) and Threshold Scan after re-probing (Right)