Method of fabricating semiconductor device including a recessed channel

A method of fabricating a semiconductor device, the method comprising:

• providing a substrate;
• removing a part of the substrate to form an isolation trench;
• forming a first liner on an inner surface of the isolation trench;
• forming an insulating material on the first liner until the isolation trench is filled to form an isolation region defining an active region in the substrate;
• forming a preliminary gate trench in the substrate, the preliminary gate trench including:
• a first region disposed across the isolation region to expose the first liner and the insulating material, and
• a second region disposed across the active region to expose a portion of the substrate, the first region having a first width, a central area of the second region having a second width greater than the first width, and the substrate having a pointed portion at an interface between the first region and the second region;
• increasing the first width of the first region to protrude the pointed portion;
• removing the pointed portion by performing a reflow process to convert the preliminary gate trench into a gate trench;
• and
• forming a gate insulating layer, a gate conductive pattern, and a gate capping pattern within the gate trench.

A method of fabricating a semiconductor device, the method comprising:

• providing a substrate;
• forming an isolation trench in the substrate;
• forming a first liner on an inner surface of the isolation trench;
• filling an insulating material in the isolation trench to form an isolation region such that the isolation region defines an active region in the substrate;
• forming a preliminary gate trench in the substrate, the preliminary gate trench including:
• a first region in the isolation region and exposing the first liner and the insulating material, and
• a second region in the active region and exposing a portion of the substrate, the first region having a first sidewall with a planar shape, and the second region having a second sidewall with a concave central area such that an interface between the first and second regions has a pointed portion;
• removing a portion of the first liner exposed by the first region to form a dent such that the dent has a first depth, the pointed portion protruding adjacent to the dent;
• removing the pointed portion by performing a reflow process such that the preliminary gate trench is converted into a gate trench;
• and
• forming a gate electrode within the gate trench such that the gate electrode includes a gate insulating layer, a gate conductive pattern, and a gate capping pattern.