From PCB to BEOL: 3D X-Ray Microscopy for Advanced Semiconductor Packaging

X-ray imaging has been a key non-destructive analysis method for electronic packages and printed circuit boards (PCB) for over two decades. Applications such as artificial intelligence (AI), 5G, high-performance computing and internet-of-things (IOT) mandate higher IO density and 3D scaling at the device, package and system levels, thereby increasing the need for nondestructive imaging at high resolution and preferably in 3D. The first lab-based submicron X-ray microscopes (XRM) using focused-optics emerged in 2000 [1], based on components from synchrotron technology. This innovation enabled high-resolution 3D X-ray tomography on full packages. Since then a new type of XRM architecture in a lab-based instrument has emerged with spatial resolution in the tens of nanometers, when using a suitably prepared sample. When adopted in failure analysis (FA) workflows, submicron and nanoscale XRM enable successful failure analysis outcomes from PCB to die BEOL levels, even in complex samples. In addition, the unique capability to nondestructively acquire 3D images at high resolution is now driving the development of submicron XRM as a measurement solution offering rich 3D data and statistics to support advanced package development and manufacturing. XRM is continuing to grow in importance as the electronics industry develops more complex and integrated structures across all levels of the supply chain.