Emerging techniques for 3-D integrated system-in-package failure diagnostics

Newly developed techniques suitable and adapted to the needs of physical failure analysis of highly integrated 3-D SiP (System-in-Package) devices are reviewed. Scanning acoustic microscopy (SAM) is a powerful tool for nondestructive investigation of internal structures in optically opaque materials and typically provides a spatial resolution on the order of >10 m. Lock-in thermography (LIT) is a novel technique for thermally based fault isolation to identify electrical defects such as resistive opens and electrical shorts. Combined FIB-SEM systems are widely used for physical failure analysis of CMOS devices because the FIB allows site-specific sample preparation, and the SEM analysis provides structural and chemical information with submicron resolution. An alternative approach for both precise and time-efficient cross sectioning is the combination of FIB with a preceding laser ablation process.