X-ray scattering methods for porosity metrology of low-k thin films

Abstract

X-ray scattering is a non-destructive analytical technique capable of detecting electron density fluctuations in mesoporous and nanoporous structures. X-ray methods have the potential to provide fully quantitative porosity analyses of open and closed pore structures. Specular x-ray reflectivity (XRR) offers accurate measurement of thickness, density, and roughness of uniformly deposited thin films. Diffuse scattering techniques are also studied by manipulation of the scattering geometry and approximation of the average pore size and pore size distribution. Effects of refraction and reflection from the surface and buried interface are corrected via the Distorted Wave Born Approximation (DWBA). Distortion of the scattering profile due to slit smearing is also taken into account to obtain an accurate interpretation of diffuse scattering phenomena. Preliminary results for average pore size and pore size distribution of PECVD-prepared SiCOH thin films with both open and closed pore structures are reported, and show good agreement with positron annihilation lifetime spectroscopy (PALS) data. © 2009 American Institute of Physics.