Development of high-k inorganic/organic composite material for embedded capacitors

The particle size distribution control and the dispersion agent were investigated, and a higher than 79 vol.% BaTiO₃ filler loading to epoxy resin was implemented by suppressing the porosity increment. The dielectric constant of a 10 μm thick film at 1 MHz was 115, which corresponded to a capacitance density of larger than 10 nF/cm². The dielectric constant was 100 at 10 GHz when evaluated from 45 MHz -10 GHz. The chemical state evaluation of the surface of the filler, which was performed by FT-IR spectroscopic analysis, revealed that the water surface absorption of the filler increased the dielectric loss. After the dispersant was added and the composition of the resin and cure condition was optimized, the dielectric loss of the composite was 0.02 at 1 MHz. The temperature dependence of the dielectric constant was evaluated and was shown to be small. A laser via formation process using the composite material was also examined. It was confirmed that a 100 μm diameter via hole into a 10 μm thick layer could be formed. The inplane CTE of the composite material was 17 ppm/°C, obtained by stress measurement of the film. This value is coincident with the CTE of Cu. The elastic modulus was measured and found to be 18 GPa at 75 vol.% of the filler.