A method of fabricating a semiconductor integrated circuit device includes: recessing a second surface portion of a semiconductor substrate; forming elements of a first circuit region at a first surface,forming elements of a second circuit region at a second surface, the elements of the first circuit region and those of the second circuit region having relatively small and large sizes as generally measured in a direction perpendicular to the surface portions of the semiconductor substrate, respectively; forming an insulating film to cover the first and second circuit regions, with a result that a level difference is caused between first and second portions of the insulating film ;effecting chemical-mechanical planarization of the insulating film to suppress the level difference; forming wiring conductors on the insulating film , enjoying the enhanced focus margin. |