Fabrication of a pair of vertical fin field effect transistors having a merged top source/drain
A method of fabricating a vertical fin field effect transistor with a merged top source/drain, including, forming a source/drain layer at the surface of a substrate, forming a plurality of vertical fins on the source/drain layer; forming protective spacers on each of the plurality of vertical fins, forming a sacrificial plug between two protective spacers, forming a filler layer on the protective spacers not in contact with the sacrificial plug, and selectively removing the sacrificial plug to form an isolation region trench between the two protective spacers.
1. A method of fabricating a vertical fin field effect transistor with a merged top source/drain, comprising:
forming a plurality of vertical fins on a source/drain layer, wherein the source/drain layer is on a substrate, and a hardmask cap is on each of the plurality of vertical fins;
forming protective spacers on each of the plurality of vertical fins;
forming a sacrificial plug between two protective spacers;
forming a filler layer on the protective spacers and the sacrificial plug;
removing an upper portion of the filler layer, each of the hardmask caps, and the sacrificial plug using a chemical-mechanical polishing;
selectively removing the remaining portion of the sacrificial plug; and
forming an isolation region trench through the source/drain layer into the substrate, wherein the isolation region trench is offset from an adjacent vertical fin by a thickness of one of the protective spacers.
2. The method of claim 1 , wherein a first vertical fin and an adjacent second vertical fin of the plurality of vertical fins are separated by a distance, D 1 , and the first vertical fin and an adjacent third vertical fin are separated by a distance, D 2 , wherein D 2 is greater than D 1 .
3. The method of claim 2 , further comprising forming a trench fill layer in the isolation region trench.
4. The method of claim 3 , further comprising forming a gate structure on the first vertical fin and the adjacent third vertical fin of the plurality of vertical fins.
5. The method of claim 4 , further comprising removing the hardmask caps from the plurality of vertical fins prior to forming the trench fill layer, and forming a top source/drain on the first vertical fin, the adjacent second vertical fin, and the adjacent third vertical fin of the plurality of vertical fins.
6. The method of claim 5 , wherein the top source/drain on each of the first vertical fin, the adjacent second vertical fin, and the adjacent third vertical fin has a predetermined size greater than the distance, D 1 , to faun the merged top source/drain between the first vertical fin and the adjacent second vertical fin.
7. The method of claim 6 , wherein the distance between the first vertical fin and the adjacent second vertical fin is in the range of about 10 nm to about 40 nm.
8. The method of claim 7 , wherein, and the predetermined size of each of the first vertical fin and the adjacent second vertical fin is less than the distance, D 2 , between the first vertical fin and the adjacent third vertical fin.
9. The method of claim 7 , wherein the distance between the first vertical fin and the adjacent third vertical fin is in the range of about 30 nm to about 100 nm.