Warpage measurement comparison using shadow moire and projection moire methods

Microelectronic and photonic packaging are progressing toward integrating more devices with more functions into a smaller confined space, while requiring higher yield and superior reliability. New electronic components, materials, fabrication processes, and configurations are emerging to achieve these goals. As expected, surface flatness is playing a more crucial role in integrated circuits and integrated optics manufacturing. Out-of-plane displacement (warpage) is a global effect of interfacial stress and displacement. It is also the cause of mis-registration and non-contact between components and their substrates. Moire methods offer noncontact, full-field, high-resolution approaches for measuring warpage. In this paper, two types of moire methods are introduced and analyzed. They carry distinct features and grant more options to measure warpage under various scenarios. It has been shown through system analysis and experimental results that these systems are powerful tools for studying warpage mechanisms. Specifically, they can help to investigate the effects of materials, manufacturing processes, and packaging configurations on warpage.