Fractographic analysis on the die surface crack of a LOC packaged DRAM

Abstract

This paper describes the surface crack on the Silicon die of a LOC packaged DRAM device. Surface crack was found to occur on the die at one edge, after reliability tests. The root cause was found to be the interaction of the LOC tape that exceed the die area covered by the protective PIX, and the scribe structures at the saw street due to thermal stress on the tape. This paper presents the fractographical analysis done on a failed unit to find the root cause, sample preparation needed, and the micrographs of the nature of the crack and the striations observed in the crack site using the optical microscope, SEM and the Laser Scan Microscope (LSM) confocal imaging.