Devices and methods of forming higher tunability FinFET varactor

A method comprising:

• obtaining an intermediate semiconductor device, comprising:
• a substrate;
• a dielectric layer over the substrate;
• and
• a plurality of mandrels formed on the dielectric layer;
• applying a spacer layer over the intermediate semiconductor device;
• etching the intermediate semiconductor device to remove a horizontal portion of the spacer layer to form at least one vertical portion of the spacer layer and to expose a top surface of the plurality of mandrels, the at least one vertical portion of the spacer layer comprising:
• a first set of spacers with a first width;
• and
• a second set of spacers with a second width, wherein the first width is about twice the size as the second width;
• removing the plurality of mandrels;
• etching the intermediate semiconductor device to remove at least a portion of the dielectric layer to form a first set of masks under the first set of spacers and a second set of masks under the second set of spacers;
• forming at least one first fin and at least one second fin, wherein the intermediate semiconductor device now comprises:
• a portion of the substrate;
• the at least one first fin extending above the portion of the substrate, the at least one first fin having a first fin width;
• the at least one second fin extending above the portion of the substrate, the at least one second fin having a second fin width and wherein the first fin width is about twice the size of the second fin width;
• the first set of masks positioned on the at least one first fin;
• the second set of masks positioned on the at least one second fin;
• the first set of spacers positioned on the first set of masks;
• and
• the second set of spacers positioned on the second set of masks;
• and
• removing the at least one vertical portion of the spacer layer and the dielectric layer.