Known void size micro-bump, a novel standard of 3D X-ray computed tomography in-line metrology for accuracy assessment and monitoring

Three dimensional (3D) X-ray Computed Tomography (XCT) is used as an in-line metrology for silicon die and substrate packages to detect and quantify voids in micro bumps. Long term health monitoring of the 3D-XCT is important to ensure tool performance. The best means for evaluating tool performance is having a standard unit with a known void size embedded in micro a bump. However, this type of standard is not commercial available. In this study, a novel known void size micro-bump (KVSMB) standard for 3D-XCT in-line metrology is presented. A range of silicon oxide (SiO2) based glass beads with diameter of 42.8–76.2um is used to mimic the void and embedded in a micro bump on a coreless substrate packaging. Using this KVSMB, the accuracy and tool health monitoring through control chart is possible.