Multilayer Aluminum Oxynitride Capacitors for Higher Energy Density, Wide Temperature Applications (Preprint)

摘要

Capacitors are a pervasive technology in every military and commercial application. Increased performance and smaller size in capacitor devices have been the main focus of our research in the development of new dielectrics. A multilayer stacked rigid aluminum oxnynitride (AlaN) capacitor design concept has been developed to improve the energy density and high temperature capability of AlaN capacitors. This method consists of depositing alternating layers of dielectric and metal on a rigid substrate. A rigid substrate can withstand the stresses of the dielectric being coated on only a single side which eliminates the wrinkling problem of depositing AlaN on thin metal foil and metallized polymer substrates. The inherent surface roughness issue associated with commercially available polymers is no longer a concern as the surface finish of the substrate can be more easily controlled. Amorphous aluminum oxynitride films possess unique properties of high dielectric strength, high resistivity, low loss, high decomposition temperature, chemical inertness and good thermal conductivity. Dual DC pulsed magnetron reactive sputtering was employed to synthesize amorphous AlaN films on various substrates. Dielectric properties were compared for films developed with different process conditions. The properties were optimized with respect to the following input parameters: DC power, pulse frequency, total pressure, substrate temperature and reactive gas ratio. The effects on the dielectric constant, frequency dependence of capacitance, dissipation factor, resistivity, and breakdown strength of these films were measured using simple parallel plate capacitor test structures. Temperature dependent dielectric properties were evaluated from -200 degrees C to 400 degrees C.