Abstract: The influence of the distribution of nano-pores on the mechanical properties evaluation of porous low-k films by surface acoustic waves (SAW) is studied.A theoretical SAW propagation model is set up to characterize the periodic porous dielectrics by transversely isotropic symmetry.The theoretical deductions of SAW propagating in the low-k film/Si substrate layered structure are given in detail.The dispersive characteristics of SAW in different propagation directions and the effects of the Young’s moduli E,E′ and shear modulus G′ of the films on these dispersive curves are found.Computational results show that E′ and G′ cannot be measured along the propagation direction that is perpendicular to the nano-pores’ direction.

Key words: periodic porous materials, low-k dielectrics, transversely isotropic symmetry, mechanical property, SAW measurement