Fin field-effect transistor and method of forming the same

A semiconductor device, comprising:

• a substrate;
• a semiconductor fin structure disposed over the substrate, wherein the semiconductor fin structure extend along a first lateral direction;
• a gate structure that straddles a semiconductor fin structure, wherein the gate structure extends along a second lateral direction, the first lateral direction perpendicular to the second lateral direction;
• a dielectric fin structure that extends along the first lateral direction and is disposed next to the semiconductor structure fin structure;
• and
• a gate isolation structure disposed above the dielectric fin structure,
• wherein the gate isolation structure contacts an upper portion of the gate structure at a first tilted interface.

A method for making a semiconductor device, comprising:

• forming a first semiconductor fin structure and a second semiconductor fin structure over a substrate that both extend along a first direction;
• forming a dummy gate structure that extends along a second direction perpendicular to the first direction and straddles the first and second semiconductor fin structures;
• removing a portion of the dummy gate structure between the first and second semiconductor fin structures to form a trench, wherein a width of the trench along the second direction decrease with increasing depth toward the substrate;
• filling the trench with a dielectric material;
• and
• removing the second semiconductor fin structure and a portion of the dielectric material.