Study on particle removal during the Co post-CMP cleaning process

The cleaning process of a cobalt surface after the chemical mechanical polishing (CMP) process is indispensable for removing a large amount of residue. In this work, the particle removal efficiency of three target solutions was first characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Then, based on the mechanism of particle removal on the Co surface, the reasons for different cleaning effects of the three cleaning solutions were investigated by zeta potential measurements, wettability characterization and X-ray photoelectron spectroscopy (XPS). The results show that the Si-O-Co chemical bond formed during the CMP process can be broken by citric acid (CA). Moreover, fatty alcohol polyethylene ether (JFCE) can greatly improve the wetting and spreading properties of the cleaning solution and increase the electrostatic repulsion between particles and Co surface to accelerate the particle removal. In the wettability characterization process, a new microspreading edge height measurement method is proposed, which lays a foundation for characterizing the dynamic wettability of droplets on solid surfaces in mechanics, biology, materials and other disciplines.