(The) new method for producing metal nanoparticle arrays using plasma-induced dewetting

Abstract

A new method of producing metal nanoparticle arrays was developed with the help of plasma-induced dewetting. Various metal films (Cu, Ag, Au, Si, Ni, Co, Ti) were successfully turned into nanoparticle arrays at low operating temperatures. The mechanism of the plasma-induced dewetting was also discussed. TEM and SEM images showed that the dewetting proceeded through heterogeneous hole nucleation mechanism. The nanoparticles produced by plasma-induced dewetting were more uniformly distributed on the substrate than those produced by thermal annealing. It was revealed that low process temperature of the plasma treatment prevented coarsening of the nanoparticles, and uniformly distributed holes on the film surface, resulting in uniform nanoparticle arrays, were detected during plasma treatment. According to AES (auger electron spectroscopy), oxidation of the nanoparticles occurred less during plasma treatment because of the low operating temperature. Even at the low temperature, ion bombardment which transfers high energy to the substrate surface atoms made dewetting possible. The uniformity of nanoparticle arrays was controlled by varying plasma parameters. Plasma density and electron temperature were controlled by varying working pressure and applied RF power. Sheath voltage was also controlled directly using substrate bias. It was found that uniform nanoparticle arrays were produced when hole generation was increased by using high ion bombardment energy. When a low amount of energy was transferred to the substrate, small numbers of holes were generated on the film surface, resulting in non-uniformly distributed nanoparticles.