LASER TRIANGULATION PROVIDES ESSENTIAL METROLOGY AND DEFECT INSPECTION FOR MICROBUMPS IN 3DIC MANUFACTURING

摘要

Continuous miniaturization and the advent of TSV packages are pushing solder bump sizes smaller and smaller. Micro bumps and pillar bumps are the main bump geometries leading this advance. 3D packages are expected to require hundreds of thousands of bumps at pitch values down to 10μm and lower. The small bump size, small pitch and high number of bumps are challenging inspection technologies, requiring inspection at higher accuracies and higher throughput. Laser triangulation has been used successfully to inspect bumps of many different shapes and sizes over the past several years. This study will analyze the performance and extendibility of laser triangulation technology in 3D inspection of micro solder and pillar bumps. The laser triangulation technique examined in this study is a line scan laser with the ability to collect hundreds of 3D data points along one scan line in a fraction of a second. These data points can then be used to build a 3D model of the top of the bump and surface of the wafer for local height inspection. The specific challenge with smaller bumps is the ability to have enough data points on top of the bump, as the surface area decreases. Results of an application study of a 10μm bump height as well as a 20um pitch bump are reviewed.