Selective deposition of charged nanoparticles by self-electric focusing effect

A process for the selective deposition of nanoparticles by a self-electric focusing effect is discussed. The negatively charged Nickel nanoparticles were fabricated by a DC magnetron sputtering system, and were deposited on a photoresist-patterned silicon substrate. Because of the different conductance between silicon and photoresist, the charges were accumulated on the photoresist as the nanoparticles were deposited, which caused a focusing electric field to drive the nanoparticles towards the silicon substrate. We have demonstrated that the self-focusing effect of the charged nanoparticles is responsible for increasing the density of nanoparticles in the lines patterned on silicon substrate by two orders of magnitude with respect to that on photoresist. The width of the silicon line and the width ratio between photoresist line and silicon line are the two most important parameters that will affect the self-focusing effect. (C) 2008 Elsevier B.V. All rights reserved.