Porous thin films are the main candidates to achieve Ultra Low K materials for interlayer dielectric (ILD) applications, but their mechanical properties remain low. Indeed, the introduction of porosity significantly decreases the dielectric constant k, but also affects the mechanical properties. However, both mechanical and dielectric performances are influenced by the pore arrangement and geometry that can thus be optimized for these two antagonist properties. A Finite Element study is conducted to quantify the influence of the arrangement and the geometry of the pores via a homogenization approach. The best architectures for ILD applications are deduced. Random arrangements as well as 3D cubic arrangements (simple, body-centered, face-centered) of monodisperse spherical pores have been considered. These arrangements are obtainable by sol-gel processing, a method that often induces a marked shrinkage of the films. This shrinkage modifies the original cubic arrangements which become orthorhombic and the pore shape which becomes ellipsoidal. The effect on the dielectric and elastic properties of these architectural changes due to the shrinkage has also been studied. (C) 2011 Elsevier B.V. All rights reserved.