Variable capacitance device and process for manufacturing the same

摘要

A variable capacitance device comprising, in a semiconductor layer formed on a substrate via an buried oxide film: an n- region 132 formed in the shape of a ring and containing an n-type dopant; an anode 133 adjoined to the outer periphery of the n- region 132, the anode 133 being formed in the shape of a ring and containing a p-type dopant; and a cathode 131 adjoined to the inner periphery of the n- region 132, the third region containing an n-type dopant, wherein the dopant concentration in the n- region 132 is lower than that in each of the anode 133 and the cathode 131.