An SiO2-Ta2O5Thin Film Capacitor

A capacitor has been developed which is superior to previously reported duplex capacitors. The dielectric consists of anodic tantalum oxide overlaid with silicon dioxide deposited by RF sputtering. This capacitor proved usefuI as a low-valued capacitor Of capacitance density ranging from 150 pF/mm²to 20 pF/mm², corresponding to a thickness range of a silicon dioxide film from 0.2 µ/m to 2.0µm. The capacitor can be produced with very high yield Of approximately 100%, due to the defect-free anodic oxide film diminishing the importance of defects inevitably induced in the RF sputtered silicon dioxide film. The silicon dioxide film can be deposited without causing any deterioration of the anodic film of tantalum oxide by Control of the RFsputtering conditions. The capacitor remained stable with no failures occurring when aged under various conditions of voltage, temperature, and humidity. The capacitor can be processed in a manner compatible with the manufacturing process of the TM or TMM capacitor.