Abstract: A width of a circuit device isolation region and a width of a device region formed on a semiconductor substrate are determined in such a manner as to satisfy a condition which prevents the occurrence of dislocation due to thermal oxidation for forming the isolation region. A semiconductor device can be fabrication which includes a semiconductor substrate, a plurality of circuit regions formed on a device formation region in the semiconductor substrate and having a width of 0.1 to 125 &mgr;m and device isolation regions so formed on the semiconductor substrate as to isolate a plurality of circuit regions from one another and having a width of 0.05 to 2.5 &mgr;m, and wherein a ratio of the width of the device isolation region to the width of a plurality of circuit regions adjacent to the device isolation region is from 2 to 50.

Abstract: A semiconductor device includes a thermal oxide film for isolation, a semiconductor region that becomes an element forming region with the circumference thereof surrounded by the oxide film and diffused resistance layers in the semiconductor region and provides a structure for controlling resistance value variation of diffused resistors originated in a stress generated at time of forming the oxide film for isolation. A distance between an end portion on a longer side closest to a thermal oxide film of the diffused layer and an end of the thermal oxide film is apart from each other by a predetermined value determined by stress distribution in the semiconductor region or by at least 4 .mu.