PROJECTION MOIRE VS. SHADOW MOIR? FOR WARPAGE MEASUREMENT AND FAILURE ANALYSIS OF ADVANCED PACKAGES

摘要

There are three key industry trends that are driving the need for temperature-dependent warpage measurement: the trend toward finer-pitch devices, the emergence of lead-free processing, and changes in device form factors. Warpage measurement has become a key measurement for analysis, prevention and prediction of interconnect defects and has been employed in failure analysis labs and production sites worldwide. Over the past decade, the shadow moire technique has become the method of choice for temperature-dependent warpage measurement. It is estimated that there are over 200 such machines installed worldwide. However, as the above-mentioned industry trends began to emerge, certain limitations of shadow moire became apparent, such as camera resolution restrictions, schematic limitations on heating/cooling mechanisms, and data processing techniques that can affect accuracy. As a result of recent developments in projection moire technology, these issues have been addressed, and the technique is poised to meet the future requirements of the microelectronics industry. In this paper we discuss projection moire as a new technique for warpage measurement of advance packages, with applications in failure analysis, new product qualification and process control. Projection moire addresses many shadow moire limitations, including camera resolution, heating uniformity and noise.