Assembling 100 nm Scale Particles by an Electrostatic Potential Field

The assembly of particles is one of the many methods for the fabrication of organized structures in the range of micro- to nanometer sizes. These structures have potential applications in the electronic, optical and biochemical fields. Recently, many papers have reported the patterning of particles using patterned SAM (self-assembly monolayer) films and micro molding methods. We have been developing a new technique to assemble particles using an electrostatic field. This paper describes a new technique to fabricate two-dimensional microstructures assembled from 100 nm particles. Spherical silica of 900 nm diameter and aluminum of 100 nm diameter were used as the model particles. An electrostatic image was formed on an insulating substrate by drawing a focused electron beam at 10 keV. Both types of particles were deposited on the electrostatic images. In this process, the dielectrophoretic (DEP) force plays an important role in depositing particles on the electrostatic images. The DEP forces for particles in a suspension were calculated using numerical analysis. The result showed that the DEP force above the electrified region on the substrate is larger than disturbing forces, such as Brownian motion.