The permittivity and dielectric loss of reaction-bonded silicon nitride

Abstract

Using recently developed coaxial line methods values of permittivity and dielectric loss have been determined over the frequency range 0.5 to 7 GHz for a series of reaction-bonded silicon nitride specimens in which the degree of nitridation has been varied. For fully nitrided material (having a weight gain of 62% and a volume porosity of 19%) the measured permittivity was 4.60 and was almost independent of frequency; fitting both the permittivity and loss data to the Universal Law of dielectric response confirmed that the limiting condition of lattice loss applied withn=0.98±0.02. Reduction of the degree of nitridation caused progressive increases in permittivity and loss, both of which closely approached the quoted values for pure silicon at weight gains below about 40%.