基于取向平均方法多晶铁电薄膜残余应力的测量材料科学与工程专业论文.docxVIP

II II Abstract For the specific physical properties, such as pyroelectric properties, ferroelectric properties, piezoelectric properties, electrostrictive properties, nonlinear optical properties and electro-optical properties in the ferroelectric thin film, it has been more and more widely used in many areas of technology and science, and drawn a lot of attention to the research of the ferroelectric thin film. The mechanical properties present important influence in the delamination, brittle fracture, and fatigue degradation of the ferroelectric thin film/substrate structures, which may cause poor reliability that is one of the major problems in MEMS design. Residual stress is inevitable for the structural misfit, thermal misfit and the process from high temperature to low temperature during deposition of thin film. In this case, the investigation of the residual stress is very important for the fabrication of the ferroelectric thin film and ferroelectric thin film device. In the paper, we discuss several commonly used methods for residual stress measurement in thin films, and then focus on the use of the non-destructive X-ray diffraction (XRD) method on the measurement of residual stresses for ferroelectric thin film. Moreover, two methods based on XRD were proposed to evaluate the residual stress in ferroelectric thin film, taking account of the intrinsic properties of ferroelectric thin films, such as isotropy or transversely isotropy, piezoelectricity and grain orientation. Investigations are presented on the evaluation and analysis of residual stresses in (Pb(Zr0.52Ti0.48)O3 (PZT)) and (Na1-xKx)0.5Bi0.5TiO3 (NBT-KBT-100x) thin films by XRD. The main contents are presented as follow: The transversely isotropy, piezoelectricity and grain orientations of the thin film are taken account in the orientation average method, it’s a comprehensive method. The method’s validity is verified by comparing the residual stresses in three kinds of the previous PZT thin films e