Ferroelectric Thin Film Stress Of X-ray Diffraction Study

Ferroelectric bulk ceramics have been widely used in many fields as sensor devices, and actuator devices because they can transfer the following information into each other: mechanical information, electronic information, thermal information, et al. Most of these devices are limited, however, by large relative dimensions, low fracture toughness, and small strains. Therefore, one needs its thin films, having the same properties as the bulk ferroelectric ceramics with the rapid development of the microelectronics and circuit integration in the new century. In general, thin films have higher energy densities, larger strain capabilities, and more rapid response times than their bulk counterparts. Thus, ferroelectric thin films have attracted great attentions all over the world.Due to the lattice mismatch and thermal mismatch between the thin film and the substrate and the process from high temperature to low temperature during the preparation of the thin films, residual stress will be inevitably induced between the thin film and the substrate. The residual stress in the thin films may lead the crack, hillock formation, or delamination or completely failure of the thin films. On the other hand, if the introduction of the residual stress is fully understood, one can make good use of the strain induced by the lattice mismatch between the film and the substrate to modulate and improve the properties of the ferroelectric thin films. Therefore, the study of the residual stress is very important.In the Introduction of this master thesis, the potential applications of the ferroelectric thin films, preparation methods and the current research on the residual stress in the ferroelectric thin films are reviewed. On the basis of the review, the investigation of the residual stress in the ferroelectric thin films by X-ray diffraction methods is proposed. Main content of the thesis are also given in the Introduction.The thesis presented three different of the residual stress based on X-ray diffraction--two-exposure method, sin2ψ, high-resolution reciprocal space mapping, which are applied to investigate the residual stress state of Pt/Ti bottom electrode stack, polycrystalline PZT ferroelectric thin films and epitaxial LaAlO3/BaTiO3 ferroelectric...