Semiconductor device and method of fabricating a semiconductor device

A semiconductor device, comprises:

• a substrate;
• a plurality of fin structures arranged on the substrate;
• a dielectric fin structure disposed between a first fin structure of the fin structures and a second fin structure of the fin structures;
• and
• a shallow trench isolation isolating the dielectric fin structure from the substrate and the fin structures, wherein a material of the dielectric fin structure is different from the shallow trench isolation, the shallow trench isolation includes U-shape structures, and the dielectric fin structure is wrapped by one of the U-shape structures, and wherein a bottom surface of the one of the U-shape structures in contact with the substrate obliquely extends from the first fin structure at a first vertical level to the second fin structure at a second vertical level different from the first vertical level.

A semiconductor device, comprises:

• a substrate;
• a first fin structure disposed on the substrate and including a ridge portion and a bottom portion between the ridge portion and the substrate, wherein a critical dimension of the bottom portion in a cross-fin direction is gradually increased toward the substrate to be greater than a critical dimension of the ridge portion in the cross-fin direction;
• a second fin structure disposed on the substrate, and having a different conductive type from the first fin structure;
• a dielectric fin structure disposed between the first fin structure and the second fin structure in the cross-fin direction, a bottom portion of the dielectric fin structure having a dimension in the cross-fin direction being gradually reduced toward the substrate;
• and
• a shallow trench isolation isolating the dielectric fin structure from the substrate, the first fin structure and the second fin structure, wherein a material of the dielectric fin structure is different from the shallow trench isolation.