Automated Analysis of AFM Data of High-Density Cu Pad for Fine Pitch Wafer-to-Wafer (W2W) and Chip-to-Wafer (C2W) Hybrid Bonding

Abstract

With the advancement of 3D packaging, hybrid bonding is the most widely explored technology for heterogeneous integration and stacking of dies. For the hybrid bonding, prior measurement of the surface roughness, dielectric erosion, and dishing/protrusion of the copper bond pads is critical to check the quality of the fabricated wafers. Generally, atomic force microscopy (AFM) is used to collect the surface morphology of the wafers, and then the manual measurement is done for each scanned file which is quite time-consuming. Therefore, in this article, an automated method of analysis of AFM data was developed in Python to measure critical surface parameters on the wafers used in hybrid bonding. The Python code was used to measure the surface roughness, dishing/protrusion of bond pads with different shapes, i.e., circular and square. The use of the code provides a quick, efficient, first-order analysis methodology for evaluating the quality of the bonding surface, thereby, significantly reducing the manual time required in data crunching.