Methods of fabricating semiconductor devices with enlarged recessed gate electrodes

A method of forming a semiconductor device, comprising:

• forming an insulation layer on a substrate;
• forming a sacrificial layer on the insulation layer;
• forming an opening through the sacrificial layer and the insulation layer to expose an active region of the substrate;
• removing a portion of the active region to form a recess therein that has a greater width than the opening through the sacrificial layer and the insulation layer;
• forming a gate insulator in the recess;
• forming a gate electrode extending through the sacrificial layer and the insulation layer and into the recess, the gate electrode comprising a first portion on the gate insulator in the recess and a second reduced-width portion extending from the first portion;
• removing the sacrificial layer to expose a sidewall of the gate electrode outside of the recess;
• forming an insulating spacer on the exposed sidewall of the gate electrode;
• and
• forming a source/drain region in the substrate adjacent the recess.