The growing diffusion of personal computers and satellite communications systems turned out into an intensive research activity focused on the synthesis and on the study of new materials for the realization of next generation micro-devices. Zirconium titanate based ceramics are commonly used as dielectrics in microwave devices, owing to their high dielectric permittivity (?r ~38-40), very good thermal stability (TCC= ± 20 ppm °C-1) and low dielectric losses (tan? ~ 10-4). In view of these properties thin films of this material appear as very promising dielectric layers for the integration in MIM (metal-insulator-metal) and MIS (metal-insulator-semiconductor) structures. The real application of these materials is still connected to the development of a deposition technique able to produce ZT thin films possessing low dielectric losses and adequate values of permittivity. In this work we describe the metalorganic chemical vapour deposition of highly oriented Zirconium Titanate based materials (ZrxTiyO4) on Pt-covered and naked (100) Si substrates. The oxide films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The dielectric properties were evaluated by C-V and I-V measurements. The influence of the different substrates on films orientation, microstructure and chemical composition is discussed. Surface roughness, structural and microstructural features of ZrTiO4 thin films were controlled by varying the deposition conditions (i.e. substrate temperature, deposition pressure, flow gas rate) in order to achieve the most suitable dielectric properties. Single phased crystalline ZrTiO4 films were obtained in the 500 - 600 °C substrate temperature range. Pt induces (111) ZT film orientation, while temperature promotes (031) ZT texture. The realization of crystalline ZrTiO4 thin films having a high dense columnar structure, low surface roughness, and a clear interface film-substrate revealed to be the fundamental requirement to achieve low loss dielectric films.
Microstructure, phase formation and dielectric properties of highly oriented MO-CVD zirconium titanate thin films
2003
Abstract
The growing diffusion of personal computers and satellite communications systems turned out into an intensive research activity focused on the synthesis and on the study of new materials for the realization of next generation micro-devices. Zirconium titanate based ceramics are commonly used as dielectrics in microwave devices, owing to their high dielectric permittivity (?r ~38-40), very good thermal stability (TCC= ± 20 ppm °C-1) and low dielectric losses (tan? ~ 10-4). In view of these properties thin films of this material appear as very promising dielectric layers for the integration in MIM (metal-insulator-metal) and MIS (metal-insulator-semiconductor) structures. The real application of these materials is still connected to the development of a deposition technique able to produce ZT thin films possessing low dielectric losses and adequate values of permittivity. In this work we describe the metalorganic chemical vapour deposition of highly oriented Zirconium Titanate based materials (ZrxTiyO4) on Pt-covered and naked (100) Si substrates. The oxide films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The dielectric properties were evaluated by C-V and I-V measurements. The influence of the different substrates on films orientation, microstructure and chemical composition is discussed. Surface roughness, structural and microstructural features of ZrTiO4 thin films were controlled by varying the deposition conditions (i.e. substrate temperature, deposition pressure, flow gas rate) in order to achieve the most suitable dielectric properties. Single phased crystalline ZrTiO4 films were obtained in the 500 - 600 °C substrate temperature range. Pt induces (111) ZT film orientation, while temperature promotes (031) ZT texture. The realization of crystalline ZrTiO4 thin films having a high dense columnar structure, low surface roughness, and a clear interface film-substrate revealed to be the fundamental requirement to achieve low loss dielectric films.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
