Nanoscale Metal Thin Film Dewetting Via Nanosecond Laser Melting: Understanding Instabilities and Materials Transport in Patterned Thin Films

Nanoscale metal thin film dewetting via laser treatment is studied in this dissertation. The purpose is to understand: 1) the spatial and temporal nature of intrinsic instabilities; and 2) mass transportation involved in dewetting pattern evolution in metal thin films as well as in lithographically patterned nanostructures; and finally 3) to explore advanced control of metallic nanostructure fabrication via the confluence of top down nanolithography and pulsed laser induced dewetting. This study includes three sections. In first section, thin film Cu-Ni alloys ranging from 2-8nm were synthesized and laser irradiated. The evolution of the spinodal dewetting process is investigated as a function of the thin film composition which ultimately dictates the size distribution and spacing of the nanoparticles, and the optical measurements of the copper rich alloy nanoparticles revealed characteristic plasmonic peaks. In section two, the dewetting behavior of nanolithographically patterned copper rings on Silicon substrate was studied. The self assembly of the rings into ordered nanoparticle/nanodrop arrays was accomplished via nanosecond pulsed laser heating. The resultant length scale of the 13nm and 7nm thick copper rings was correlated to the competition between transport and instabilities time scales during the liquid lifetime of the melted copper rings. To explore the influence of different substrates with different surface energy, the pulsed laser heated assembly of lithographically patterned copper rings on SiO2 substrate was studied in the last section. The correlated transport and instabilities show modified timescales. It is demonstrated again that the original geometry dictates the instability pathway, which for narrow rings obeys the Rayleigh-Plateau instability and for wider rings are influenced by the thin film instability.