Real Time Nanoscale Cleaning Phenomenon Observation during PVA Brush Scrubbing by Evanescent Field

Abstract

Cleaning phenomenon is considered as nano-particle behaviors near the surface in nano-scale. The phenomenon concerns the removal of the nano-particle from the wafer surface to be cleaned, and the occasional reattachment of the nano-particle to surface in Post-CMP cleaning process. However, residual contamination on the wafer has been usually inspected only before and after cleaning process. Therefore, removal and reattachment mechanism of nano-particles on the surface have not already clearly known. Hence, we have been establishing dynamically visualization of cleaning phenomena on the surface applying localized light called evanescent light generated by internal reflection. In this article, we discuss the validity of our proposed optical method to observe nano-particle removal during PVA brush scrubbing in real time, by demonstrating removal of 100 nm fluorescent silica-nano-particles from a glass surface. Consequently, the mutual scrubbing behavior between nano-particles and PVA brush would be identified by fluorescent and non-fluorescent wavelength scattering light.

Inhibition of Silica Nanoparticle Adhesion to Poly(vinyl alcohol) Surfaces by Ammonia-Mediated Hydration: Implications for Effective Post-Chemical–Mechanical Planarization Cleaning

“…11,19,20,33 In addition, fluorescence microscopy has been employed for realtime observations of dynamic nanoparticle movements during the PVA brush scrubbing. 33,34 However, these methods do not allow us to directly measure the interaction forces acting between the nanoparticles and the PVA surfaces. Furthermore, PVA is known as a water-soluble polymer and, hence, the interface could present complicated three-dimensional (3D) mixtures of flexible polymer chains, water, and ammonia.…”

3D trajectories and diffusion of single ceria particles near a glass surface and their removal

“…While many studies have exploited EW microscopy to study particle interactions with various surfaces, very few studies have used EW microscopy to investigate the removal of ceria particles from surfaces [15,16]. Here, we show that this technique also enables the monitoring of the removal of ceria particles from a glass surface in real time.…”

“…Particle redeposition is determined by the diffusion and/or convective transport in the thin liquid film, where the 3D trajectories and diffusion coefficients matter, between the glass and the porous PVA brush surfaces. These processes are being imaged and analyzed now using EW spectroscopy [16].…”

3D trajectories and diffusion of single ceria particles near a glass surface and their removal

“…Particle redeposition is determined by the diffusion and/or convective transport in the thin liquid film, where the 3D trajectories and diffusion coefficients matter, between the glass and the porous PVA brush surfaces. These processes are being imaged and analyzed now using EW spectroscopy [16]. Furthermore, using our extended methodology and based on the techniques developed to study brush cleaning, it should be possible to image pad/wafer and pad/abrasive (ceria or silica)/wafer contact during polishing-something that has not been possible so far-using model wafer coupons and polishing pad pieces.…”