Metal clusters in plasma polymerized matrices: Gold

Abstract

This paper describes how plasma processes can control the metal content, metal cluster dispersion, and metal cluster crystallography embedded in dielectric fluorocarbon film matrices. We will show that the metal volume fraction can be controlled over a wide range by superimposing varying degrees of physical sputtering onto the chemical plasma etching/polymerization process which inevitably takes place simultaneously in certain halocarbon plasmas using a capacitively coupled rf diode discharge system. The critical metal volume fraction Vc at which the metal cluster containing polymer suddenly becomes conducting is 0.4. Evidence is given to show that the crystallographic features of the Au clusters (particle size, nonuniform strain, unit cell dimensions) have quite a different functional behavior vis-a-vis the overall film conductivity at different metal volume fractions depending on the deposition temperature in the range -15 to 60 °C. Furthermore, crystallographic features of the clusters are independent of the metal volume fraction in the film but depend on surface migration during film growth in the Teflon-like matrix.