Benzene bridged hybrid organosilicate films with improved stiffness and small pore size

Abstract

Critical properties of porous periodic mesoporous silica (PMO) low-k dielectric with a different ratio of benzene bridges and methyl terminal groups are studied by using various advanced instrumentations such as Ellipsometric Porosimetry (EP), Surface Acoustic Wave Spectroscopy (SAWS), Specular X-ray reflectivity and others. It is shown that the pore size and surface roughness of the films decrease with an increase in the concentration of the benzene bridge, although at a concentration of benzene bridges >25 mol %, the pore size sharply decreases and changes little with a further increase in the concentration of bridges. The concentration of the benzene bridge also increases dielectric constant and improves the mechanical properties. The increase in Young's modulus with the benzene bridge concentration has percolation type behavior and sharply increases at a concentration of the benzene bridge close to 50 mol %. It has also been found that introducing 30 wt % porosity into benzene-bridged films without methyl terminal groups increases the Young's modulus. It is assumed that this unusual behavior is associated with the formation of crystal-like structure on the film framework. The increase of dielectric constant is associated with the higher polarizability of the benzene bridges in comparison with methyl terminal groups, as well as with their higher hydrophilicity and presence of adsorbed water.