
196 Transforming One Industry at a Time
e example presented in Khade, R., Lin, J. and Patel, N., Finding Meaningful Contrast
Patterns for Quantitative Data, in Proceedings of the International Conference on Extending
Database Technology (EDBT), 444-455, Lisbon, Portugal (2019) shows that for the sample
of units that failed at nal test, the system was able to identify that the root cause could be
attributed to a specic placement head on the chip attach module that handles all units
going through the back lane of the reow oven. Furthermore, it also identied that there
were abnormalities in the temperature experienced by these parts that pointed to the need
to retune the oven temperature controllers. e eects were subtle enough that they did
not trigger any inline monitors to alarm.
Digitization of inline inspection
Over the past few years, there has been a tremendous interest in computer vision
techniques for the purpose of object recognition in images. Anywhere we look, there
are examples of successful outcomes when using these to identify objects in pictures.
Compared to manual inspection, where there is considerable operator fatigue resulting
in a large variation in the detected and classied defects, any computational solution will
provide consistent results.
From an inline inspection perspective, there are two aspects we need to address. First
is the ability to accurately detect defects, and second is the need to classify these for
the purposes of process improvement activities. In addition, there is also a need to
execute this inspection with high throughput. While we can get high-delity images
from standalone inspection tools, we cannot expect any solution that drives pervasive
inspection on processing tools to achieve this level of image delity. We should look
at the fab and packaging/test separately, the reason being that for the former, there are
dedicated inspection tools at multiple points in the manufacturing ow, and these take
high-delity images of the wafer. Intel has reported great success in applying ML to
classifying defects on wafers (https://www.intel.com/content/www/us/en/
it-management/intel-it-best-practices/faster-more-accurate-
defect-classification-using-machine-vision-paper.html).
Furthermore, the need to detect very ne defects and the variety of packages running
through the manufacturing line makes any solution based purely on deep learning
(DL) infeasible as the amount of data required for training would be formidable. In
the past, traditional image processing techniques were leveraged for defect detection
and classication—for example, Said, A. and Patel, N., Die Level Defect Detection in
Semiconductor Units, in Proceedings of the IEEE Advanced Semiconductor Manufacturing
Conference (ASMC), 130-133, NY (2013) present how, using a line scan camera imaging
tray of parts moving on a conveyor, we can develop very accurate defect detection and
classication algorithms for the die area.
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