Patent ID: 7929272

Claim:
A dielectric device comprising a dielectric layer and first to nth metal layers (where n is an integer of 2 or greater) in contact with the dielectric layer, wherein: at least one of the first to nth metal layers contains a base metal; interfaces between the first to nth metal layers and the dielectric layer have respective arithmetic mean roughnesses of Ra 1 to Ra n (nm); an average value Ram (nm) of the arithmetic mean roughnesses of Ra 1 to Ra n (nm) and a thickness T (nm) of the dielectric layer satisfy T/Ram ≧1.3, where Ram is equal to (Ra 1 +Ra 2 +. . . +Ra n )/n; the Ram (nm) is 53 nm or more; the dielectric layer is formed from barium strontium titanate; the thickness T (nm) of the dielectric layer is <200 nm; one of the first to nth metal layers is a metal foil supporting the dielectric layer; the metal foil has an upper main face polished by chemical mechanical polishing (CMP); and the dielectric device has a leak current density (A/cm 2 ) of equal to or less than 3.10×10 −4 .