High-K Nanocomposites with Core-Shell Structured Nanoparticles for Decoupling Applications

摘要

High-k materials with manufacturing processes capable of achieving continually high density for decoupling applications are believed to be one of the key issues to enable the extendibility of Cu/Low-k technology. Filled polymer nanocomposites are potentially one of such high-k materials because this approach can combine the low-temperature (<250degC) processibility of the organic polymer matrix with the desirable dielectric properties of the filler. In previous studies, we reported the development of a novel low-loss high-k composite by using self-passivated aluminum as the filler for polymer nanocomposites. A self-passivated aluminum particle has a core-shell structure. The core is metallic aluminum, and the shell is insulating aluminum oxide. Such core-shell structured aluminum particles give their composite a high dielectric constant but a low loss comparable with that of neat epoxy. Polymer/aluminum nanocomposites have the combined characteristics of polymer-ceramic (due to the ceramic shell) and polymer-metal (due to the metal core) systems. Because filler surface treatment is a vital factor to optimize the electrical and mechanical properties of polymer nanocomposites, to further enhance the dielectric properties and processibility of polymer/aluminum composites, an aluminum particle surface modification was performed with an epoxide-functionalized silane coupling agent. The nanoaluminum particle surface chemistry before/after coupling agent treatment was studied using a Fourier transformed infrared spectroscopy (FTIR). Thermogravimetric analyzer (TGA) was used to characterize the thermal degradation behavior of untreated/treated aluminum particles. From FTIR and TGA studies, it was found that the silane coupling agent was successfully grafted on the aluminum particle surface. Rheology properties of polymer/aluminum composites were studied with a stress rheometer. It was found that the coupling agent treatment could significantly reduce the viscosity of th--e aluminum composites, which indicates coupling agent treatment can improve the processibility of aluminum composites at high filler loading levels. Dielectric properties of the coupling agent treated aluminum composites were studied as well. At the same filler loading level, composites with coupling agent-treated aluminum particles showed a higher dielectric constant. The frequency responses and temperature coefficient of capacitance of the aluminum composites were studied with a dielectric analyzer (DEA). The microstructures of aluminum composites were studied with a scanning electron microscope (SEM)