Morphology Evaluation of Microelectronic Packaging Substrates Using Shadow Moiré Technique

The surface quality and long-term reliability of packaging substrates in microelectronic packaging processes have become subjects of increasing concern as circuit board component density increases while the pitches of these components decrease. As a result, packaging substrate morphology inspection is becoming more crucial than ever before. This paper presents a noncontact measurement technology based on a shadow moiré technique to evaluate the surface quality and morphology of microelectronic packaging substrates. Fringe pattern images of packaging substrates are acquired through the noncontact measurement technology, and the resulting images are then analyzed using the phase-shifting technique to determine the morphology and surface quality (specifically, the flatness) of the microelectronic packaging substrates. A full-field morphology measurement system with adjustable sensitivity and measurement range was developed. The measurement system was tested using three typical types of microelectronic packaging substrate, a coin and a step made from two standard gauge blocks. The measurement system proved to be both feasible and effective by the test results.