Patent ID: 6683341
Filing Date: 2004-01-27
Classification: H01L

Abstract:
A parallel plate varactor comprising:a bottom electrode; a top electrode; a dielectric layer sandwiched between the bottom electrode and the top electrode, wherein a permittivity of the dielectric layer varies according to an electric field applied to the dielectric layer; the bottom electrode, dielectric layer, and top electrode are integrated on a substrate; and an overlap between the bottom electrode, dielectric layer, and top electrode defines an active region for the varactor; and wherein, for at least one of the electrodes: a resistance of said electrode is a significant portion of an overall resistance of the varactor; said electrode includes an electrode layer that includes the active region and extends laterally beyond the active region; a sheet resistance of the electrode layer is significantly higher than a sheet resistance of a bulk region of said electrode; the active region of said electrode has an area A, said electrode has a current conducting perimeter P for current flow between the active region and the bulk region; and a ratio R of the perimeter P to a square root of the area A is at least 2.0.