Dielectric and Thermal Properties of Diamond Film/Alumina Composite

The feasibility of diamond film coated alumina ceramics used as the packaging substrate of integrated circuits with ultra high speed and high power was studied. The measurement results of dielectric properties of the diamond film/alumina composites show that CVD diamond films can effectively reduce the dielectric constant of the composite. Carbon ions implantated into alumina substrates prior to the diamond deposition can reduce the dielectric loss of the composite from 5×10-3 to 2×10-3, and make the composite have better frequency stability. The thermal conductivity of the composite can obviously increase by CVD diamond film. With increasing the thickness of diamond film, the thermal conductivity of the composite will monotonously increase. The composite has a dielectric coefficient of 6.5 and a thermal conductivity of 3.98W/cm·K when the thickness of diamond film is up to 100/μm.