Semiconductor devices having a trench isolation layer and methods of fabricating the same

A semiconductor device including a trench isolation layer, the semiconductor device comprising:

• a substrate having a first trench and a second trench wider than the first trench;
• a liner insulation layer filling the first trench, covering a bottom surface and sidewalls of the second trench, and including micro trenches located at bottom inner sidewall corners of the liner insulation layer in the second trench, the liner insulation layer on sidewalls of an upper region of the second trench having a thickness that gradually increases toward a bottom surface of the second trench and the liner insulation layer on sidewalls of a lower region of the second trench having a thickness that is uniform;
• a first isolating insulation layer completely filling the micro trenches located in the sidewall corner of the liner insulation layer and the lower region of the second trench that are surrounded by the liner insulation layer;
• and
• a second isolating insulation layer filling the second trench on the first isolating insulation layer.