Semiconductor device and method for fabricating the same

A semiconductor device comprising:

• a first active pattern extending along a first direction;
• a second active pattern extending along the first direction and spaced apart from the first active pattern in the first direction;
• a substrate;
• a field insulating film on the substrate and between the first active pattern and the second active pattern;
• and
• an element isolation structure in an isolation trench in the first active pattern and the field insulating film,
• wherein the isolation trench includes a first trench in the first active pattern and second trench in the field insulating film, and
• a first height from an upper surface of the substrate to a bottom surface of the first trench is different from a second height from the upper surface of the substrate to a bottom surface of the second trench.

A semiconductor device comprising:

• a first active pattern extending along a first direction;
• a second active pattern extending along the first direction and spaced apart from the first active pattern in the first direction;
• a field insulating film between the first active pattern and the second active pattern, an upper surface of the field insulating film being lower than or coplanar with upper surfaces of the first and second active patterns;
• and
• an element isolation structure on the first active pattern and the field insulating film, an upper surface of the element isolation structure being higher than the upper surfaces of the first and second active patterns, and a lower surface of the element isolation structure being lower than the upper surface of the field insulating film,
• wherein the element isolation structure includes a first side wall facing the first active pattern and a second side wall facing the field insulating film, and
• the first side wall and the second side wall are asymmetric about a plane including an interface between the first active pattern and the field insulating film.