Semiconductor device and method for fabricating the same

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

• forming a recess gate having sidewalls over a semiconductor substrate defining a landing plug contact region;
• forming a gate spacer on a sidewall of the recess gate;
• soft-etching the semiconductor substrate in the landing plug contact region to form a recess having a rounded bottom and a sidewall;
• forming a sidewall spacer only over the gate spacer and the sidewall of the recess, wherein the sidewall spacer is thicker than the gate spacer;
• forming an insulating film over the semiconductor substrate including the recess gate, the recess gate spacer, and the recess;
• performing a planarization process on the insulating film to expose the recess gate;
• selectively etching the insulating film to form a landing plug contact hole;
• and
• filling the landing plug contact hole with a conductive layer to form a landing plug.