Reduction of the feature size in microelectronics requires a reduction of the dielectric constant for the low-k barrier layers. Reduction of the dielectric constant is accomplished through two methods: varying the chemistry, and the creation of pores in the silica matrix. However, the porosity of the silica matrix is limited by the required mechanical strength of the films.

Here we show the synthesis of mesoporous organosilicate low dielectric constant films with increased hardness and modulus through the addition of polyhedral oligomeric silsesquioxane (POSS) in the silica matrix utilizing supercritical CO₂ as the reaction medium. The mesoporous organosilicate films are synthesized by selectively depositing organosilicate precursors inside sacrificial Pluronic block copolymer templates (PEO-b-PPO-b-PEO) with the addition of POSS molecules. The block copolymer templates are blended with copolymers of polyacrylic acid (PAA) and POSS functionalized acrylates to disperse the POSS uniformly in the template. The strong interaction between PAA and PEO facilitates the dispersion of POSS molecules, which tend to aggregate in the polymer matrix. The resulting films exhibit up to three times the hardness of the control films synthesized without the addition of POSS molecules for given porosities.