FABRICATION OF SEMICONDUCTOR DEVICE

PURPOSE: To obtain a field effect transistor having double stage recess structure in which the interval between first and second stage recesses is controlled well. CONSTITUTION: Two openings 3a, 3b are made in a first insulation film 3 deposited on an active layer 2 formed on a substrate 1. The two openings 3a, 3b are filled with a second insulation film 4 and planarized. Subsequently, the first insulation film is removed only from the part 3-2 between two openings 3a, 3b and the active layer 2 is etched through the part 3-2. After removing the second insulation film 4 on the active layer, the active layer 2 is etched through a part from which the first and second insulation films 3, 4 are removed thus forming a two step recess.