Laser direct -write microfabrication and patterning
The ability to generate small structures is central to modern science and technology. In this work, four laser direct-write microfabrication and micropatterning techniques were studied: (a) Laser micromachining of channels in PMMA using a CO2 laser was investigated experimentally and theoretically. Heat transfer models for the channel depth, channel profile, laser power and scanning speed were developed and applied in this work. These models, are in excellent agreement with experimental results, with a maximum deviation of approximately 5% for the range of experimental parameters (laser power, scanning speed) tested. (b) A sub-micrometer resolution laser direct-write polymerization system for 1 creating two-dimensional and three-dimensional structures was developed using a frequency-doubled Nd:YAG laser. Experimental studies and Monte Carlo simulations were conducted to understand the detailed microscale optical scattering, chemical reaction, polymerization, and their influence on critical fabrication parameters. The experimental data are in good agreement with the theoretical model. (c) Direct laser interference was developed for rapid and large area fabrication of two-dimensional and three dimensional periodic structures on photopolymerizable materials with 10ns pulses from a frequency-tripled Nd:YAG laser emitting at 355 nm. Three different photopolymerizable materials were investigated: pentaerythritol triacrylate (PETIA) with photoinitiator N-methyldiethanolamine (N-MDEA); SU-8 with absorber TINUVIN 384-2; and Shipley 1813. (d) A new approach to fabricating nanometer sized cavity arrays on Poly(3,4-ethylene dioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) thin films using laser-assisted near-field patterning was investigated. Periodic nano-cavity arrays were patterned by combining direct laser interference technology and laser induced near-field technology. An analytical model based on Mie theory was developed, the predicted intensity distributions on the substrate indicate a strong near-field enhancement confined to a very small area (nanometer scale).
0794: Materials science