Electrophoresis-driven agglomeration enables filtration-based removal of sub-100 nm silica nanoparticles from...

Trace sub-100 nm impurities in processing chemicals represent a major yield-limiting challenge for sub-10 nm semiconductor manufacturing because they are difficult to remove using conventional purification methods. Mechanical filtration is ineffective for capturing nanoparticles smaller than 100 nm, while dielectrophoresis (DEP) exhibits limited performance for low-permittivity nanoparticles such as silica because the dielectrophoretic force is proportional to the particle volume and the Clausius-Mossotti factor. Here, we report a scalable purification strategy that integrates electrophoresis (EP) with standard centrifugal filtration to overcome these limitations. Unlike DEP, EP directly couples to the intrinsic surface charge of nanoparticles, enabling effective manipulation regardless of the particle size, permittivity, or electrode geometry. Under a DC bias, localized pH gradients generated by water electrolysis protonate silanol groups near the anode, thereby neutralizing the surface charge and inducing nanoparticle agglomeration into clusters exceeding 1 µm. These agglomerates are readily removed using conventional polyvinylidene fluoride membrane filtration, achieving a silica removal efficiency of 92.9% in deionized water. The proposed process was further validated for silica-, silicate-, and silicon-based impurities under neutral, acidic, and basic conditions, demonstrating broad chemical compatibility and operational versatility. These findings establish EP-assisted agglomeration and filtration as a promising and industrially compatible strategy for achieving the ultra-high chemical purity required for next-generation semiconductor manufacturing.