Semiconductor device and method of fabricating the same

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

• etching an insulation layer to form a trench therein, the insulation layer including a first region and a second region;
• conformally forming a first reaction layer along a surface of the insulation layer;
• forming a barrier layer by reacting an etching gas with the first reaction layer on a top surface of the first region, the first region being etched to a first thickness;
• and
• etching the second region to a second thickness greater than the first thickness by reacting the etching gas with the first reaction layer on a top surface of the second region.

A method for forming a trench of a semiconductor device, the method comprising:

• etching an insulation layer to form a trench therein, the insulation layer including a first region and a second region;
• conformally forming a first reaction layer along a surface of the trench;
• forming a barrier layer by reacting a first amount of etching gas at a first pressure with the first reaction layer on a top surface of the first region;
• and
• etching the insulation layer by reacting a second amount of etching gas at a second pressure with the first reaction layer on a top surface of the second region, the second pressure being less than the first pressure and the second amount of etching gas being greater than the first amount of etching gas.