Defect analysis using scanning acoustic microscopy for bonded microelectronic components with extended resolution and defect sensitivity

Ongoing trends in microelectronics aim at continuously increasing the integration rate and complexity of microelectronic systems and devices. Novel integration technologies that arise from these demands need to be addressed from a reliability and quality assurance perspective. As a consequence, novel and adapted inspection techniques are strongly required, including non- or semi-destructive testing during development and manufacturing. Within this context non-destructively operating scanning acoustic microscopy is an already widely used and established inspection method that provides even more potential if the corresponding performance parameters can be further improved. Currently, conventional scanning acoustic imaging is performed based on pure amplitude imaging thereby neglecting most of the information contained in the acoustic signals. The current paper exemplarily presents novel and extended approaches for addressing current limitations in conventional acoustic microscopy, including the detection and evaluation of void defects in small electrical interconnects, increasing detectability of delaminations in bonded wafers, but also the use of acoustic GHz-microscopy for increasing the spatial resolution and sub-surface sensitivity. An improved detectability and sensitivity for crack assessment using shear and mixed acoustic mode inspection is presented