(478d) 3D Trajectories, Diffusion, and Interactions of Single Ceria Particles on a Glass Surface and Their Removal in Post-CMP Applications

A very important goal of dielectric chemical mechanical planarization (CMP) is to uniformly polish a dielectric material such as silicon dioxide in the IC manufacturing processes. Ceria-based slurries have been widely employed in such a dielectric CMP process, but the abrasive particles can remain attached to the oxide films after polishing and need to be removed completely during the subsequent cleaning process. As the minimum feature size of integrated circuit elements has shrunk below 7 nm, post-CMP cleaning technologies have become significantly more challenging. There has been increasing demand to understand various phenomena that occur during cleaning.

Recently, we proposed evanescent wave (EW)-based optical detection methods integrated with video microscopy to study various chemical and mechanical phenomena such as slurry chemistry, interfacial force measurement, surface adsorption, and surface characterization/ modification during polishing and cleaning. 3D trajectories, diffusion coefficients, and interactions of ceria particles near a glass surface in the slurry at the different pH values were investigated. How these results are related to the removal of ceria particles by repeated washing with DI water adjusted to pH 10 and 12 will be discussed. Here, the flat glass surface of the lens became our model for the SiO2 film surface of interest. In situ measurement data collected during cleaning are likely to provide more important insights into the underlying mechanisms of various complex reactions that occur at the particles/brush–wafer interface. As mentioned above, there is a strong need to understand various chemical and mechanical phenomena that occur in the brush cleaning systems used to remove the ceria particles adsorbed on the SiO2 film. This talk will also introduce our most recent EW microscopy coupled with a brushed set-up to monitor the real-time visualization of the removal of single ceria particles from the SiO2 film with PVA brush scrubbing.