Nano-chemical characterization of SiO2 and Cu surfaces for Cu-Cu hybrid bonding

Infrared photo-induced force microscopy (IR PiFM), which combines non-contact atomic force microscopy and infrared spectroscopy (AFM IR), is applied to precisely characterize the surface chemical state of the silicon oxide and copper. Based on an AFM platform, the technique can monitor the topographical condition (flatness of the dielectric as well as the recession of the Cu pads) in addition to the surface chemistry (absence of unwanted molecules and the presence of desired surface termination), both with ~ 5 nm lateral resolution and monolayer sensitivity, to characterize the suitability of the samples for successful Cu-Cu hybrid bonding.