Method and Structure for FinFET Isolation

A method of forming a semiconductor device, comprising:

• receiving a substrate having an active fin, an isolation structure over the substrate, a plurality of dummy gate stacks over a first surface of the isolation structure and engaging the fin, spacer features over the first surface and on sidewalls of the dummy gate stacks, and first dielectric features over the first surface and between the spacer features;
• removing the dummy gate stacks thereby forming first, second, and third trenches, wherein the second trench is between the first and third trenches, and the first, second, and third trenches expose first, second, and third portions of the active fin respectively;
• removing the second portion of the active fin;
• and
• forming gate stacks in the first and third trenches, the gate stacks engaging the first and third portions of the active fin.

A semiconductor device, comprising:

• a substrate having first and second active fins, wherein each of the first and second active fins has first and second ends, and the second end of the first active fin is adjacent to the first end of the second active fin;
• a first gate stack over the substrate and engaging the first active fin;
• a second gate stack over the substrate and engaging the second active fin;
• a first isolation structure over the first end of the first active fin from a top view;
• a second isolation structure over the second end of the second active fin from the top view;
• and
• a third isolation structure adjacent to both the second end of the first active fin and the first end of the second active fin from the top view.