Mechanism of Particle Deposition on Silicon Surface during Dilute HF Cleans

Abstract

The mechanism of particle deposition onto silicon wafer surfaces during dilute HF cleans is discussed. Direct surface force measurement using an atomic force microscope showed that particle redeposition on a silicon surface is due to the dominant van der Waals interaction between the particle and the wafer surface. The addition of surfactants can affect the clean effectiveness of a dilute HF solution by changing the surface interaction forces between a particle and a wafer. We show that there is a simple correlation between particle deposition and the product of the zeta-potentials of the wafer and particle. This correlation can be explained by introducing the linear superposition approximation to the derivation of electrical double-layer interactions. The addition of surfactant will also decrease dispersion attraction, introduce steric repulsion, and eliminate adhesion force, as indicated by the results of surface force measurements.