Fin cut to prevent replacement gate collapse on STI
The present invention provides fin cut techniques in a replacement gate process for finFET fabrication. In one aspect, a method of forming a finFET employs a dummy gate material to pin a lattice constant of patterned fins prior to a fin cut thereby preventing strain relaxation. A dielectric fill in a region of the fin cut (below the dummy gates) reduces an aspect ratio of dummy gates formed from the dummy gate material in the fin cut region, thereby preventing collapse of the dummy gates. FinFETs formed using the present process are also provided.
1. A fin field-effect transistor (finFET), comprising:
at least one fin on a substrate, wherein a cut is present in the at least one fin that divides the at least one fin into multiple segments;
a first dielectric within the cut separating the multiple segments of the at least one fin, wherein the first dielectric has a rectangular cross-sectional shape;
gates over the at least one fin, wherein the gates comprise at least one first gate that is disposed on, and in direct contact with, only the first dielectric, at least one second gate that is disposed on, and in direct contact with, only the at least one fin, and at least two third gates that are disposed on, and in direct contact with, both the first dielectric and the at least one fin, wherein the at least one first gate has an aspect ratio and a height that are less than an aspect ratio and a height of the at least one second gate, and wherein the at least one first gate is present in between the at least two third gates; and
a second dielectric surrounding the gates.
2. The finFET of claim 1 , further comprising:
a recess in the substrate beneath the cut in the at least one fin.
3. The finFET of claim 2 , wherein the first dielectric is present within the recess.
4. The finFET of claim 2 , wherein the recess in the substrate has a depth d of from about 50 nanometers to about 300 nanometers, and ranges therebetween.
5. The finFET of claim 1 , wherein each of the gates comprises:
a gate dielectric;
a workfunction setting metal on the gate dielectric; and
a fill metal on the workfunction setting metal.
6. The finFET of claim 5 , wherein the gate dielectric comprises a high-κ dielectric.
7. The finFET of claim 6 , wherein the high-κ dielectric is selected from the group consisting of: hafnium oxide, aluminum oxide, and lanthanum oxide.
8. The finFET of claim 5 , wherein the workfunction setting metal comprises an n-type workfunction setting metal selected from the group consisting of: titanium nitride, tantalum nitride, titanium aluminide, titanium aluminum nitride, titanium aluminum carbide, tantalum aluminide, tantalum aluminum nitride, and tantalum aluminum carbide.
9. The finFET of claim 5 , wherein the workfunction setting metal comprises a p-type workfunction setting metal selected from the group consisting of: titanium nitride, tantalum nitride, and tungsten.
10. The finFET of claim 5 , wherein the fill metal is selected from the group consisting of: tungsten and aluminum.
11. The finFET of claim 1 , wherein the first dielectric and the second dielectric are each selected from the group consisting of: silicon dioxide and silicon nitride.
12. A finFET, comprising:
at least one fin on a substrate, wherein a cut is present in the at least one fin that divides the at least one fin into multiple segments;
a first dielectric within the cut separating the multiple segments of the at least one fin, wherein the first dielectric has a rectangular cross-sectional shape;
gates over the at least one fin, wherein the first dielectric is at a same height as the gates, and wherein the first dielectric is in direct contact with a gate dielectric along lateral surfaces of two of the gates; and
a second dielectric surrounding the gates.
13. The finFET of claim 12 , further comprising:
a recess in the substrate beneath the cut in the at least one fin, wherein the first dielectric is present within the recess.
14. The finFET of claim 12 , wherein each of the gates comprises:
a gate dielectric;
a workfunction setting metal on the gate dielectric; and
a fill metal on the workfunction setting metal.
15. The finFET of claim 14 , wherein the gate dielectric comprises a high-κ dielectric.
16. The finFET of claim 15 , wherein the high-κ dielectric is selected from the group consisting of: hafnium oxide, aluminum oxide, and lanthanum oxide.
17. The finFET of claim 14 , wherein the workfunction setting metal comprises an n-type workfunction setting metal selected from the group consisting of: titanium nitride, tantalum nitride, titanium aluminide, titanium aluminum nitride, titanium aluminum carbide, tantalum aluminide, tantalum aluminum nitride, and tantalum aluminum carbide.
18. The finFET of claim 14 , wherein the workfunction setting metal comprises a p-type workfunction setting metal selected from the group consisting of: titanium nitride, tantalum nitride, and tungsten.
19. The finFET of claim 14 , wherein the fill metal is selected from the group consisting of: tungsten and aluminum.
20. The finFET of claim 12 , wherein the first dielectric and the second dielectric are each selected from the group consisting of: silicon dioxide and silicon nitride.