Direct Fabrication of Submicron-size Periodic Structures by Backside Irradiation

摘要

Toward adding specific functions to materials surface, submicron-size periodic structures were fabricated onto glass substrates by photochemical polymerization. A laser diode with continuous wave at 405 nm was used as a light source for the polymerization. Backside laser irradiation was utilized for inducing the photochemical polymerization in the close vicinity of a liquid-solid inter-face. Reactive liquid mixture composed of pentaerythritol triacrylate and 2-isopropylthioxanthone, those are used as an acrylic monomer and a photoinitiator, respectively, was set onto an aminosilane coated glass substrate. To confine the region where the polymerization occurs in the vicinity of the liquid-solid interface, reactive mixture containing high concentration of photoinitiator was em-ployed. Optical penetration depth was decreased to ca. 30 μm. This confinement is indispensable for the present method to fabricated submicron-size periodic structures. A laser beam was once divided into four beams. Then, two or four beams were used for backside irradiation with interference. Inci-dent angles of each divided beam were set to be 12 degrees in all experiments. Upon two beam irra-diation, fringe structures with a period of 0.9 μm could be fabricated. Meanwhile, upon four beam irradiation, two-dimensional array of dot structures with a diameter of 0.7 μm was successfully fab-ricated.