Twenty heads are better than one: scalable microAFM for highthroughput metrology and inspection

Abstract

With the increasing complexity of semiconductor manufacturing, process windows shrink and higher resolution measurement is required. Most measurement techniques face a trade-off between resolution and throughput, but scalable approaches can overcome this trade-off to maintain productivity. Atomic force microscopy (AFM) is an essential technique for high-resolution measurement, and one way to overcome the throughput-resolution trade-off is by operating multiple AFMs in parallel. Here, we demonstrate scalable microAFM technology for semiconductor metrology and inspection. Each microAFM device is a full MEMS AFM scan head, containing integrated XYZ scanners and sensors in a 1 mm² footprint. We demonstrate a system with twenty parallel microAFM scan heads capable of collecting data from multiple points per die (within die variation) and multiple dies (within wafer/die-to-die variation) simultaneously on a 300-mm wafer. To evaluate the system, the recess depth of fine-pitch copper pads for hybrid bonding were measured. This work highlights a path toward scaling AFM to full-die and full-wafer metrology and inspection with microAFM.