PURPOSE: To obtain a MOS capacitor whose dielectric breakdown strength against static electricity is made high without making the insulating film between a metallic electrode and a diffused electrode thick, by a method wherein two high-concentration N-type impurity diffused regions, whose depths are different from each other, are provided in an N-type epitaxial region of a P-type substrate.

CONSTITUTION: A MOS capacitor has a high-concentration N-type impurity buried region 6 and a high-concentration N-type impurity diffused region 4, which comes into contact with this buried region 6 and has a deep diffusion depth, in addition to a high-concentration N-type impurity diffused region 3 which is used as a diffused electrode. That is, the region 3 is connected to the region 6 through an N-type epitaxial region 5 and is connected to a metal film 1 through the region 4. In such a way, by preventing a charge concentration between the diffused electrode and a metallic electrode in the MOS capacitor, the dielectric breakdown strength of an insulating film against static electricity can be made high without increasing the film thickness of the insulating film between the diffused and metallic electrodes.