This paper evaluates the use of nanomilling and STEM imaging to analyze failure mechanisms in sub-50 nm InP HEMTS. The devices were life tested at elevated temperatures and biases and their electrical characteristics were measured at each stress interval. Devices that were damaged were investigated further to assess the underlying failure mechanism. Advanced microscopy with sub-nm resolution was employed to examine the physical characteristics of the failed HEMT devices at the atomic scale. As the paper explains, the examination was conducted using a focused ion beam/scanning electron microscope (FIB/SEM), an Ar gas ion nanomill, and STEM imaging.

Temperature and humidity dependent reliability analysis was performed based on a case study involving an indicator printed-circuit board with surface-mounted multiple-die red, green and blue light-emitting diode chips. Reported intermittent failures were investigated and the root cause was attributed to a non-optimized reflow process that resulted in micro-cracks and delaminations within the molding resin of the chips.

Thermal fatigue cracking of lead-free solder joints within flipchip packages was investigated in this study by using scanning acoustic microscope (SAM) and SEM. The distribution of substrate delaminations was mapped with SAM of high depth resolution and observed in cross-section with SEM to find the mechanism of crack growth during thermal reliability tests. The study revealed that the interfacial crack always initiated from the pad edge. This is attributed to the coefficient of thermal expansion (CTE) mismatch between underfill and the PCB substrate. The propagation of fatigue crack within solder joint is closely related to the morphology of interfacial/intergranular intermetallic compound (IMC) formed at the elevated temperature of thermal cycle.