Large-Area Processable High k Nanocomposite-Based Embedded Capacitors

Abstract

In this study, we have developed high dielectric constant (k>50) embedded capacitor dielectrics with a moderate volume fraction of tiller that show good adhesion, good thermal stress reliability and good large area processibility at low processing temperature (<200/spl deg/C). Material design and processing are critical to obtain a high dielectric constant composite at a moderate filler loading. The material formulations were systematically studied, and by using the combination of a chelating agent, a dispersing agent, and bimodal fillers, dielectric constants above 50 were obtained. However, theses high k formulations had low peel strength and poor thermal stress reliability. It was found that filler pretreatment, which led to the chemical bonding of dispersing agent on filler particle surface, can effectively improve the peel strength and thereby the thermal stress reliability of embedded capacitor components. Meanwhile, to reduce the large moduli of high k composites and thereby reduce the high thermal stress in the embedded capacitor components, the epoxy varnish was modified with a rubberized polymer. The optimized, rubberized nanocomposite formulations had a high dielectric constant above 50 and successfully passed the stringent thermal stress reliability test. A low leakage current (/spl sim/10/sup -11/A/cm/sup 2/) and a high breakdown voltage (/spl sim/90 MV/m) were measured in the large area thin film capacitors.