Abstract: A capacitor is provided having a tough surface portion which prevents cracking that tends to occur when the capacitor is built-in or surface-mounted on a wiring board. A ceramic sintered body of the capacitor includes a capacitor forming layer portion, a cover layer portion and an interlayer portion. The capacitor forming layer portion has a laminated structure wherein ceramic dielectric layers and inner electrodes connected to a peripheral portion of capacitor via conductors, are alternately laminated. The cover layer portion is exposed at a surface portion of the ceramic body and has a laminated structure wherein ceramic dielectric layers and dummy electrodes not connected to the capacitor via conductors, are alternately laminated.

Abstract: A variable capacitance element includes a movable element provided above a substrate using supporting portions and support beams so as to be displaced from the substrate. An insulating film and a movable electrode are provided on a conductor facing surface of the movable element. A driving electrode is arranged to displace the movable element, between a signal cutoff position and a signal passage position, whereby a high frequency signal transmitted through a transmission line is cut off or allowed to pass. The insulating film uses compressive stress to warp the movable element and the movable electrode in a direction of warping in a convex form toward the transmission line, and maintains this warping direction.

Abstract: A variable capacitor element including: a buried electrode layer of a conductivity type different from a semiconductor substrate; a wiring layer connected to the lead portion of the buried electrode layer; a pair of capacitive insulating films that are formed as regions having mutually opposing adjacent sides in a plane shape on a portion of the buried electrode layer excluding the lead portion; an insulator layer formed on the border region of each outside of the pair of capacitive insulating films in a direction perpendicular to the adjacent sides; a pair of conductor layers formed both on the respective capacitive insulating films and on the respective insulator layers; and wiring layers that are connected respectively to lead portions of the pair of conductor layers above the insulator layer. The capacitance value between the buried electrode layer and each of the conductor layers can be changed by changing the voltage between the buried electrode layer and the conductor layers.