Hybrid Organosilicate Low-k Dielectrics with Benzene Bridge Groups with Increased Mechanical Properties and Small Pore Size for Modern BEOL Metallization

In this work, the critical properties of a periodic mesoporous organosilicate dielectric with different ratios of benzene bridging and methyl groups are studied using various modern methods, such as ellipsometric porosimetry, surface acoustic wave spectroscopy, X-ray reflectometry, and others. It is shown that the pore size and surface roughness of the films decrease with an increase in the concentration of benzene groups, although at a concentration of >25 mol.%, the pore size sharply decreases and changes little with a further increase. With an increase in the concentration of benzene groups, the dielectric constant also increases and the mechanical properties improve. The increase in Young's modulus has a percolate behavior and increases sharply at a concentration close to 50 mol.%. It was found that the introduction of 30 wt.% porosity in films with benzene groups, in which there are no methyl groups, leads to an increase in Young's modulus. This behavior is associated with the formation of a crystal-like structure on the film framework. An increase in the dielectric constant is associated with the greater polarizability of benzene groups compared to methyl groups, as well as with their greater hydrophilicity and the presence of adsorbed water.