Micropatterning and crystallization of sol-gel-derived dielectric film by laser direct writing

Low temperature crystallization and the micropatterning of lead zirconate titanate (PZT) film were achieved by laser direct writing method using a sol-gel derived precursor film. After scanning of an Ar ion laser beam through an objective lens, the etching of the unirradiated area of the precursor film with an acidic solution gave micropatterns with a resolution of several im. The formation of crystalline micropatterns was confirmed by micro-Raman spectroscopy. The laser direct writing method provides a low-temperature processing of crystalline PZT film while the crystallization of PZT needs the heat treatment above 600 °C in the case of convenient methods. The influences of the power density of the laser beam were investigated. With increasing the laser power density, the change from tetragonal to rombohedral phase was observed. The micropattern with tetragonal phase showed residual carbon. The carbon contamination could be removed by heat treatment in air. The direct laser writing of crystalline barium titanate (BT) film was also successfully performed using sol-gel derived BT films containing BT nano-crystalline seeds. The dielectric constant of the crystalline BT micropatterns reached 76.2 at 100 kHz.