Electronic devices having semiconductor elements and methods for fabricating such devices including, a method for fabricating an electronic device including a semiconductor memory, which includes: forming a sacrificial layer on a substrate including a first region and a second region; selectively etching the sacrificial layer and the substrate of the first region to form a trench; forming a first gate that fills a part of the trench in the first region; forming a gate protection layer on the first gate to fill the remaining part of the trench; removing the sacrificial layer of the first region to form a grooved portion surrounded by the gate protection layer; forming a conductive plug to cover the grooved portion; removing the sacrificial layer of the second region; and forming a second gate on the substrate of the second region.