PURPOSE: To improve electric characteristics and reliability, to increase the degree of freedom on the design of pattern, and to contrive improvement in miniaturization and the yield of production of the title semiconductor device by a method wherein the surface of the source, drain and gate electrode of a high breakdown voltage transistor is constituted by a metal or its silicide and the like.

CONSTITUTION: A logic part 130, consisting of the MOS transistor having relatively low drain breakdown voltage, and an output part 120 consisting of the MOS transistor having relatively high drain breakdown voltage are arranged on the same substrate 101. In the semiconductor device of this kind, a selective oxide film thicker than a gate oxide film 108 is buried in both ends of the channel part of the high breakdown voltage transistor, and impurity layers 105 and 106 of the same conductivity type, having the density lower than that of a drain region 113 to be used to lead out an electrode, are provided under the selective oxide film. Besides, the surface of a source region 112, a drain region 113 and a gate electrode 110 are constituted with a metal or silicides 125 and 126. A titanium disilicide or a polycide, for example, is used as the silicides 125 and 126 above-mentioned.