Nanostructure engineering using nanosecond pulsed laser and nanoimprint lithography.

摘要

This dissertation addresses the applications of an excimer laser in ultrafast nanoimprint lithography (NIL), self-perfection by liquefaction (SPEL), fabrication of metal nanoparticle monolayers, and fabrication of sub-10-nm nanofluidic channels.; Laser-assisted nanoimprint lithography (LAN) has been demonstrated. In LAN, the resist is melted by a laser pulse, and then imprinted with a fused silica mold. LAN has been used to pattern various polymer nanostructures on different substrates with high fidelity and uniformity. The imprint time is measured to be around 200 ns. Simulation indicates that the substrates and molds are exposed to negligible heat during LAN. A flash lamp facilitates LAN applications up to full wafer scale.; SPEL uses selective melting to remove fabrication defects in nanostructures post fabrication. In open space (O-SPEL), the line edge roughness (LER) of Si and Cr lines has been reduced as much as 5.6 fold in less than 200 ns. With a cap (C-SPEL), the nanostructures preserve the original geometries with LER removed. Under the guidance of a top plate (G-SPEL), the molten nanostructures rise up and reshape into new structures with vertical sidewalls and flat tops, but also with a higher aspect ratio. Applications of SPEL include making sub-25-nm smooth cylindrical NIL pillar molds and smoothing Si waveguides.; Metal nanoparticle monolayers are fabricated on various substrates (silicon, fused silica and plastics) by exposing thin metal films a single laser pulse. The particle size depends on the material and the film thickness. Regular nanoparticle arrays have been fabricated by fragmentation of metal grating lines. The periodicity of these nanoparticles can be regulated by wettability or surface topography differences.; 1D and 2D enclosed nanofluidic channel arrays have been fabricated using a self-sealing technique. A laser pulse melts the top portion of the nanostructures, and the molten silicon flows laterally and fuses with a neighboring nanostructure, forming enclosed channels. The channel size has been further reduced to 9 nm using thermal oxidation, which is found to be self-limiting. DNA stretching using 20 nm wide self-sealed channels is demonstrated.