Chip Scale Packaged, Stacked Imaging Sensor Functional Failure Analysis Through Chip Repackaging
Chip Scale Packaged, Stacked Imaging Sensor Functional Failure Analysis Through Chip Repackaging
Thursday, October 8, 2026: 12:00 PM
Summary:
Failure analysis for chip scale packaged stacked-die image sensors that exhibit functional failure become complicated when the failure is functional and the failure site is in the logic (bottom) die. A functional failure of this kind can only be duplicated on a dedicated application board. Such a setup allows fault isolation analysis only from top (pixel die) side. Optical access to the bottom die is blocked by the pixel die. And because functional failure resides at bottom die, there is a need to expose the silicon from the backside. This requires package material removal and re-packaging of the die to duplicate the failure, in this example a XSHUTDOWN IDD failure is observed at final test. During fault isolation analysis, XSHUTDOWN IDD failure cannot be reproduced by backside probing because multiple pins (>15 pins) need to be accessed simultaneously.
Failure analysis for chip scale packaged stacked-die image sensors that exhibit functional failure become complicated when the failure is functional and the failure site is in the logic (bottom) die. A functional failure of this kind can only be duplicated on a dedicated application board. Such a setup allows fault isolation analysis only from top (pixel die) side. Optical access to the bottom die is blocked by the pixel die. And because functional failure resides at bottom die, there is a need to expose the silicon from the backside. This requires package material removal and re-packaging of the die to duplicate the failure, in this example a XSHUTDOWN IDD failure is observed at final test. During fault isolation analysis, XSHUTDOWN IDD failure cannot be reproduced by backside probing because multiple pins (>15 pins) need to be accessed simultaneously.