Published online by Cambridge University Press: 01 February 2011
In ULSI circuit, interlayer thin film with low dielectric constant shall be used in order to reduce the interconnection RC delay. One promising material is methylsilesquioxane (MSQ) deposited by spin coating with controlled porosity. High porosity combined with matrix weakness result in low mechanical properties that could be detrimental to circuit reliability.
The aim of this study is to investigate the deformation behavior of mesoporous MSQ thin films by nanoindentation and by AFM analysis of residual indents. At first, proper measurement conditions were explored by modulating the film thickness from 100 nm up to 600nm for a fixed film density: the very low elastic modulus of the material on stiff substrate requires great care in the raw data analysis. Next, the density of these mesoporous films has been adjusted and the response to indentation is compared with dense bulk fused silica. AFM investigations lead to the sequence of fracture processes and to the sensitivity to hydrostatic pressure on the deformation of these materials.