Passivation damage, a common failure mode in microelectronics circuitry, can be easily identified by optical inspection in the form of a local 'discoloration' after exposing the die to a chemical that would penetrate through the crack and attacks metal lines. Unfortunately, this process destroys evidence of what damaged the passivation, since it attacks the damaged region. As a result, in many cases, the mechanism by which the passivation damage occurred is unclear. This problem is addressed in this paper by a procedure to examine passivation damage by transmission electron microscopy (TEM) of a cross-section sample prepared from the backside and without exposing the die from the top side. The backside approach was successfully used to assign the root cause of the passivation damage to packaging process. A topside approach to characterize the passivation damaged region can result in destruction of evidence at the defect location.

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