Methods of forming recessed gate structures including blocking members, and methods of forming semiconductor devices having the recessed gate structures

A method of forming a recessed gate structure, comprising:

• forming a recess structure having an enlarged lower portion in a substrate;
• forming a gate insulation layer on surfaces of the recess structure and the substrate;
• forming a gate electrode partially buried in the recess structure on the gate insulation layer;
• and
• forming a blocking member in a buried portion of the gate electrode.

A method of manufacturing a semiconductor device, comprising:

• forming an isolation layer on a substrate to define an active region;
• forming a recess structure having an enlarged lower portion in the active region;
• forming a gate insulation layer from a surface of the recess structure onto the active region;
• forming a gate electrode partially buried in the recess structure on the gate insulation layer;
• forming a blocking member in a buried portion of the gate electrode;
• and
• forming source/drain regions at portions of the substrate adjacent to the gate electrode.