Abstract: A method of fabricating semiconductor integrated circuit devices having a semiconductor region in a position separated by a predetermined distance from a dielectric isolating region provided on the surface of a semiconductor wafer, comprising the steps of forming a first mask to define the dielectric isolating region and semiconductor region, forming a second mask over the first mask so as to cover the region which is to become the semiconductor region, and removing the second mask after the dielectric isolating region has been formed by the first and second masks, to form the semiconductor region. The method thus permits the semiconductor region to be self-aligned with the dielectric isolating region.