Patent ID: 6900976
Filing Date: 2005-05-31
Classification: H01L

Abstract:
1. A variable capacitor element comprising: a buried electrode layer formed in a surface region of a semiconductor substrate with a semiconductor layer of a conductivity type different from the semiconductor substrate; a wiring layer that is formed above the buried electrode layer and is connected to a 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, wherein a capacitance value between the buried electrode layer and each of the pair of conductor layers can be changed by changing a voltage between the buried electrode layer and each of the pair of conductor layers.