Revisiting 3D X-ray for Board Level FA to In-line Metrology of Wafer Level Integration

While 3D X-ray Tools or X-ray Microscopes (XRM) have been the traditional nondestructive imaging tools in Failure Analysis (FA) labs, they normally involve smaller packages or small sections cut out of a package or PCB if high resolution better than 1 um is desired. They are seldom used for intact board level FA nor is a tool of choice for inline metrology for defect inspection in wafer level integration. As sample size increases to several cm, such as 2.5D/3D Packages, Multi Chiplet Modules (MCM), PCBs or a 300 mm wafer, high resolution (< 1 um) imaging is not practical nor in many cases achievable. The acquisition time takes too long (typically hours); images are noisy and are filled with beam hardening artifacts (with bands and streaks). In this paper we will revisit the use of X-rays for high resolution (sub-micron) board level FA and in line metrology for next generation wafer level integration using a novel 3D X-ray system that can achieve sub-micron resolution on large PCBs to 300 mm wafers in as little as a few minutes to evaluate failures or defects in 3D.