Structural and dielectric properties of ZrTiO4 and Zr0.8Sn0.2TiO4 deposited by pulsed laser deposition

Zirconium titanate based ceramics are commonly used as dielectrics in microwave devices. The basic compound, ZrTiO4, has long been known to have a low temperature coefficient of the dielectric permittivity, while the compound Zr0.8Sn0.2TiO4 has optimal properties at microwave frequencies (ɛr ∼ 38, Tcc = 0 ppm °C−1 and tan δ ≈ 1 × 10−4). Thin films of these materials appear as very promising dielectric layers for the integration in MIM and MIS structures. In this work we describe the pulsed laser deposition of zirconium titanate based materials on Pt/TiO2/SiO2/(1 0 0)Si substrates. The influence of the different processing parameters on film orientation, microstructure and chemical composition is discussed. Surface roughness, chemical composition and microstructural features of the films were optimised to achieve the most suitable dielectric properties. A laser fluence J ≈ 4.5 J/cm2, a substrate temperature Ts ≈ 550-600 °C and 5 × 10−2 mbar of oxygen atmosphere are required to achieve highly oriented and crystalline films. The departure from these optima deposition conditions causes variations on the film composition, microstructure and residual strains. The permittivity of the films is affected by the presence of foreign crystalline phases. Crystalline and single phase thin films having a dense columnar structure is a fundamental requirement to achieve low loss dielectric films.