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 (IDDD1 etc) accessed? These results don’t appear to be displayed in the Module Analysis panel.
Wafer ID: V2AQMLH Analogue Test Digital 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
1 11 282 23.7 15 Yes Yes 98 163 2978 575.9
2 11 263 23 85.6 Yes Yes 222 25 4718 414.1
3 11 430 22 93 Yes Yes 26854 42 5277 243.4 Many pixels fail analogue test and threshold scan
4 11 254 23 82.5 Yes Yes 887 24 4073 537.7
5 9 101 23 107.5 Yes Yes 20977 2703 na na Many pixels fail analogue test. No meaningful threshold scan.
6 11 259 23 85 Yes Yes 216 941 4694 444.3
7 11 275 23 87 Yes Yes 1630 711 Many pixels fail threshold scan.
8 11 266 24 84 Yes No 3609 1331 5183 250.8
9 11 423 23 292 Yes Yes na na na na V high digital current during PR Test. Analogue & Digital Tests Empty
10 na na na na na na na na na na V high current on analogue and digital channels (>0.5A)
11 11 249 24 69.9 Yes Yes 17437 24 na na Many pixels fail analogue test
12 11 251 24 92 Yes Yes 26786 28 na na Many pixels fail analogue test
13 10.7 260 23.4 86 Yes Yes 326 248 4549 446.2
14
15
16
17
18 10.3 249 23.7 77.3 Yes Yes 888 2859 4599 336 Initial Measurement18 Yes Yes 762 2879 4551 322 Measurement after reprobing
19
20 11.3 218 23.4 78.2 Yes Yes 202 24 4046 461.2 Initial Measurement20 10.3 228.8 23.4 83.5 Yes Yes 188 24 4055 446 Measurement after reprobing
21
22
23
24 1596 1548 3801 391.9
60 244 24 4468 344.9
• Wafer results spreadsheet. • No pass/fail criteria set yet.
Repeatability Measurements
Die Bad Pixels (Analogue)
Bad Pixels (Digital)
Mean Threshold
Sigma Threshold
18 888 2859 4599 336
18 (Repeat) 762 2879 4551 322
20 202 24 4046 461
20 (Repeat) 188 24 4055 446
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)