Semiconductor device and fabricating method thereof

A method of fabricating a semiconductor device, comprising:

• providing a semiconductor substrate;
• depositing a surface oxide layer, a first silicon nitride layer and a hard mask on the semiconductor substrate;
• patterning, by performing a patterning process, the hard mask to form a patterned hard mask;
• patterning the surface oxide layer to form a patterned liner oxide layer;
• patterning the first silicon nitride layer to form a patterned silicon nitride layer;
• forming alternately arranged island patterns and trenches in the semiconductor substrate, a portion of an upper surface of each island pattern close to a corresponding one of the trenches being a corner area, the patterned hard mask covering the patterned silicon nitride layer, the patterned silicon nitride layer covering the patterned liner oxide layer, and the patterned liner oxide layer covering the island patterns;
• etching the patterned liner oxide layer and the patterned silicon nitride layer to expose the corner area;
• forming a protective layer on a sidewall and a bottom surface of each of the trenches, the corner area, a surface of the patterned liner oxide layer, and an etched side surface of the patterned silicon nitride layer, wherein the protective layer extends from the sidewall of each of the trenches to the upper surface of a corresponding one of the island patterns to form a corner;
• and
• forming an isolation structure in the corresponding one of trenches.

A semiconductor device, comprising:

• a semiconductor substrate comprising alternately arranged island patterns and trenches, a portion of an upper surface of each island pattern close to a corresponding one of the trenches being a corner area;
• a patterned liner oxide layer covering an area of the upper surface of each island pattern except the corner area;
• a protective layer covering a sidewall and a bottom surface of each of the trenches, the corner area, and a side surface of the patterned liner oxide layer, wherein the protective layer extends from the sidewall of each of the trenches to the corner area to form a corner;
• and
• an isolation structure in the corresponding one of trenches.