Epoxy/BaTiO/sub 3/ (SrTiO/sub 3/) composite films for high dielectric constant and low tolerance embedded capacitors fabrication in organic substrates

Abstract

Epoxy/BaTiO/sub 3/ composite embedded capacitor films (ECFs) were newly designed for high dielectric constant and low tolerance (less than /spl plusmn/5%) embedded capacitor fabrication in organic substrates. In terms of material formulation, ECFs were composed of specially formulated epoxy resin and latent curing agent. And in terms of coating process, a comma roll coating method was used for a uniform film thickness over large area. Dielectric constants of BaTiO/sub 3/ & SrTiO/sub 3/ composite ECFs were measured with MIM (metal-insulator-metal) capacitors at 100 kHz using LCR meter. Dielectric constants of BaTiO/sub 3/ ECFs were larger than these of SrTiO/sub 3/ ECFs, due to the difference of permittivity of BaTiO/sub 3/ and SrTiO/sub 3/ particles. Dielectric constants of BaTiO-, & SrTiO/sub 3/ ECFs at high frequency range (0.5/spl sim/10GHz) were measured using a cavity resonance method. For both powders, dielectric constants in high frequency range were about 3/4 of the dielectric constants at 1 MHz. This difference is mainly due to the decrease of dielectric constant of epoxy matrix. For BaTiO/sub 3/ ECFs, there was a dielectric relaxation at 5/spl sim/9GHz presumably due to the polarization mode change of BaTiO/sub 3/ powder. However in case of SrTiO/sub 3/ ECFs, there was no relaxation up to 10GHz.