Laser sintering of perovskite-oxide and metal coatings by the sol gel process

This paper presents a novel laser technique for the formation of metal Ag a nd perovskite-oxide LaxSr1-xCoO3 coatings. Metallic Ag and LaxSr1-xCoO3 are conductive materials with applications as resistors and as electrodes in t he microelectronics area. Suitable precursors in the form of sol gels are p laced on substrates and are subsequently sintered by high-power laser irrad iation. The Ag precursor is an aqueous sol of nanosized particles, while fo r the La0.8Sr0.2CoO3, a sol gel type precursor is used. Substrates (e.g., f used silica) are coated with the precursor solutions by spinning and are dr ied to stable solid layers. The coatings are cured and sintered to a define d pattern by means of a 3-kW CO2 laser beam scanned over the whole substrat e surface. The microstructure of the coatings was examined by the use of sc anning electron microscopy and X-ray diffraction, and the electrical proper ties were measured by the four-point resistivity method. The La0.8Sr0.2CoO3 coatings had a perovskite cubic structure with a lattice constant of 0.383 nm. The resistivity of the coatings was 30 m Omega cm, and the temperature dependence of the resistivity was 1.8 m Omega cm/degrees C. Metallic Ag co atings with a thickness of 100-170 nm were obtained with a resistivity of 2 0 mu Omega cm. This new technology is promising for the growth of three-dim ensional (3-D) structures and multilayers, especially because it can be int roduced in industrial scale production.