Nondestructive Inspection Method for Detecting Open Failures btween a Si Chip and metalic bumps in Flip Chip Assembly Structures by Measurement of Local Deformation of a Si Chip

Abstract

In the three-dimensionally assembled structures of electronic systems, the thickness of each LSI chip has been thinned to less than 100 micron. This thinning of LSI chips, however, increases the local thermal deformation of each chip because of decrease of bending elasticity of the chip. The magnitude of the local deformation was calculated using a three-dimensional finite element analysis, and it exceeds 200 nm easily. Thus, it is possible to find out the position where a bump does not exist by comparing the deformation pattern of a regular structure with that of an irregular or defect structure. To confirm that the estimated local deformation of an LSI chip thinner than 100 micron is detectable, we applied a scanning blue laser microscope to measure the local deformation.