Uniform fin dimensions using fin cut hardmask

1. A method for forming fins, comprising:

patterning a fin cut mask over a fin etch mask to protect the fin etch mask in a fin region;

etching a substrate using the fin cut mask to form fin cut regions;

forming first dielectric fill material in the fin cut regions;

after forming the first dielectric fill material in the fin cut regions, exposing the fin etch mask by removing the fin cut mask; and

after exposing the fin etch mask, etching fins in the substrate using the fin etch mask.

2. The method as recited in claim 1 , further comprising:

forming a fin liner on the first dielectric fill material and exposed portions of the substrate.

3. The method as recited in claim 2 , further comprising:

filling spaces between the fins by depositing a second dielectric fill over the fin liner;

planarizing the second dielectric fill down to the fin etch mask; and

recessing the first dielectric fill and the second dielectric fill to form a shallow trench isolation region in the fin cut regions and the fin region.

4. The method as recited in claim 3 , further comprising removing the fin etch mask.

5. The method as recited in claim 1 , further comprising:

removing the first dielectric fill; and

forming a fin liner on exposed portions of the substrate including the fins.

6. The method as recited in claim 5 , further comprising:

filling spaces between the fins by depositing a second dielectric fill; and

recessing the second dielectric fill to form a shallow trench isolation region in the fin cut regions and the fin region.

7. The method as recited in claim 1 , wherein etching the fins in the substrate using the fin etch mask includes etching the substrate in the fin region to a different depth than the fin cut regions.

8. A method for forming fins, comprising:

forming a fin etch mask on a substrate;

patterning a fin cut mask over a fin region of the fin etch mask to protect the fin etch mask in the fin region;

etching the substrate using the fin cut mask to form fin cut regions outside of the fin region;

forming first dielectric fill material in the fin cut regions;

planarizing the first dielectric fill and the fin cut mask to a height of the fin etch mask;

after planarizing the first dielectric fill material and the fin cut mask to the height of the fin etch mask, exposing the fin etch mask by removing the fin cut mask;

after exposing the fin etch mask, etching fins in the substrate using the fin etch mask; and

forming a shallow trench isolation region in the fin cut regions and the fin region.

9. The method as recited in claim 8 , further comprising:

forming a fin liner on the first dielectric fill material and exposed portions of the substrate before forming the shallow trench isolation region.

10. The method as recited in claim 9 , wherein forming the shallow trench isolation region includes:

filling spaces between the fins by depositing a second dielectric fill over the fin liner;

planarizing the second dielectric fill down to the fin etch mask; and

recessing the first dielectric fill and the second dielectric fill to form a shallow trench isolation region in the fin cut regions and the fin region.

11. The method as recited in claim 10 , further comprising removing the fin etch mask.

12. The method as recited in claim 8 , further comprising:

removing the first dielectric fill; and

forming a fin liner on exposed portions of the substrate including the fins before forming the shallow trench isolation region.

13. The method as recited in claim 12 , wherein forming the shallow trench isolation region includes:

filling spaces between the fins by depositing a second dielectric fill; and

recessing the second dielectric fill to form the shallow trench isolation region in the fin cut regions and the fin region.

14. The method as recited in claim 8 , wherein etching the fins in the substrate using the fin etch mask includes etching the substrate in the fin region to a different depth than the fin cut regions.