Advanced packaging builds value at every step, so an undetected defect late in the process can threaten a costly assembly. At the same time, shrinking package features are pushing process control requirements closer to those traditionally seen in front-end fabrication. Manufacturers must therefore detect smaller defects and characterize more complex structures without slowing high-volume production.
Different layers demand different inspection approaches. High-sensitivity 2D inspection can spot surface particles and pattern anomalies, while high-speed infrared subsurface inspection can reveal voids and embedded defects. 3D metrology adds measurements of microbump height and surface profile. Combining these capabilities in a single workflow helps process engineers get actionable information at the point where a manufacturing decision is made.
One critical example is the chemical mechanical planarization step that prepares surfaces for hybrid bonding. Because those surfaces must meet stringent requirements, even small imperfections can become yield-limiting as bond pitches shrink. Greater sensitivity, however, creates more detections, and not all of them matter. Manufacturers need classification that separates likely yield-relevant defects from nuisance events, turning inspection results into decisions rather than simply generating larger defect maps.