JPS55120178A - Mis variable capacitance diode with plural electrode structures - Google Patents

Abstract

PURPOSE:To remarkably increase the reading capacitive change of a variable capacitance diode by independently forming a reverse bias applying electrode for controlling the width of a depletion layer and a reading electrode for picking up capacitive change. CONSTITUTION:Two p-type regions 12, 13 are diffused in the surface layer of an n-type semiconductor monocrystal bulk 11 to produce first and second pn junctions between the regions 12, 13 and the bulk 11, and control electrodes 14, 15 made of metal material are mounted on the regions 12, 13, respectively. Then, an insulator 16 is coated while crosslinking the regions 12, 13 on the surface of the bulk 11, a capacitance reading electrode 17 is mounted on the insulator 16 in a MIS structure, and an ohmic electrode 18 is coated on the back surface of the bulk 11 as a diode. When the reverse bias voltage is applied to the first and second pn junctions using the electrodes 14, 15 and 18 in this configuration thus formed, the width of the depletion layer 19 produced under the MIS structure is largely varied so as to pickup the capacitance largely varied from the electrode 17.