Experimental and analytical study of submicrometer particle removal from deep trenches

Abstract

Particle removal from patterned wafers and trenches presents a tremendous challenge in semiconductor manufacturing. In this paper, the removal of 0.3 and 0.8 mu m polystyrene latex (PSL) particles from high-aspect-ratio 500 mu m deep trenches is investigated. An experimental, analytical, and computational study of the removal of submicrometer particles at different depths inside the trench is presented. Red fluorescent polystyrene latex (PSL) particles were used to verify particle removal. The particles are counted using scanning fluorescent microscopy. A single-wafer megasonic tank is used for the particle removal. The results show that once a particle is removed from the walls or the bottom of a trench, the vortices and circulation zones keep the particles in the trench for a few minutes before eventually moving the particle out of the trench. The experimental results show that the time required for complete removal of particles from the bottom of the trench takes a much longer time than particles on the surface. This has been also verified and explained by physical modeling of the cleaning process. The removal efficiency and cleaning time are reported at different trench depths. (c) 2006 The Electrochemical Society.