Semiconductor device and method of manufacturing the same

A method of manufacturing a semiconductor device, the method comprising steps of:

• providing a semiconductor substrate having one or more trenches defined by a hard mask layer;
• forming a gate insulating layer on the semiconductor substrate inside the one or more trenches;
• and
• forming a buried gate electrode layer on the gate insulating layer to at least partially fill the one or more trenches,
• wherein the step of forming the buried gate electrode layer comprises steps of:
• repeating a unit cycle a plurality of times, the unit cycle comprising an atomic layer deposition (ALD) process for forming a conductive layer on the gate insulating layer and the hard mask layer to serve as the buried gate electrode layer, and an atomic layer etching (ALE) process for preferentially etching portions of the conductive layer formed near the one or more trenches and portions of the conductive layer formed on upper ends of the one or more trenches over other portions of the conductive layer inside the one or more trenches, and results in a lower portion of each trench being fully filled between opposite side walls and an upper end of each trench being only partially filled so that portions of the conductive layer remain on the opposite side walls and are spaced apart from each other at the upper ends of the one or more trenches;
• performing wet etching to etch the portions of the conductive layer remaining on the opposite side walls at the upper ends of the one or more trenches;
• and
• forming a polysilicon layer on the conductive layer remaining in the lower portion of each trench to fill the one or more trenches, and
• wherein the ALE process within the unit cycle comprises steps of:
• adsorbing an etchant onto the conductive layer;
• and
• removing portions of the conductive layer from the semiconductor substrate by activating portions of the etchant adsorbed onto the conductive layer by supplying ions onto the conductive layer in a direction perpendicular to the semiconductor substrate.