Fin-last FinFET and methods of forming same

A method comprising:

• forming a semiconductor strip over a semiconductor substrate, the semiconductor strip being disposed in a dielectric layer;
• forming a first dummy gate over the semiconductor strip and the dielectric layer;
• forming a second dummy gate over the semiconductor strip and the dielectric layer;
• forming a first set of gate spacers on opposite sides of the first dummy gate;
• forming a second set of gate spacers on opposite sides of the second dummy gate;
• forming a first set of source/drain regions on opposite sides of the first dummy gate;
• forming a second set of source/drain regions on opposite sides of the second dummy gate;
• removing the first dummy gate to expose a first channel region in the semiconductor strip;
• removing the second dummy gate to expose a second channel region in the semiconductor strip;
• removing the first channel region from the semiconductor strip;
• removing the second channel region from the semiconductor strip;
• forming a first replacement channel region in the semiconductor strip;
• forming a second replacement channel region in the semiconductor strip;
• recessing the dielectric layer;
• forming a first active gate over the first replacement channel region;
• and
• forming a second active gate over the second replacement channel region.

A device comprising:

• a dielectric layer on a substrate;
• a fin extending from the substrate through the dielectric layer, the fin having a top surface over a top surface of the dielectric layer;
• a first source region and a first drain region in the fin;
• a first channel region in the fin, the first channel region being laterally between the first source region and the first drain region, the first channel region having a V-shaped bottom surface extending into the fin;
• and
• a first gate structure over the fin, the first gate structure being over the first channel region.