Method to improve finFET cut overlay
View Patent ↗A patterned photoresist having an overlay tolerance of (x+y)/2 is formed over preselected hard mask portions or semiconductor fin portions, wherein x is a width of a semiconductor fin and y is a distance between a neighboring pair of semiconductor fins. Hard mask portions or semiconductor fin portions not protected by the patterned photoresist are then removed by an isotropic etching process. The patterned photoresist is removed. In some embodiments, the remaining hard mask portions are employed as fin forming etch masks.
1. A method of forming a semiconductor structure, said method comprising:
providing a plurality of hard mask portions on a semiconductor substrate, wherein said providing said plurality of hard mask portions comprises forming a blanket layer of hard mask material on said semiconductor substrate, and patterning said blanket layer of hard mask material;
forming a patterned photoresist having an overlay tolerance of (x+y)/2 over preselected hard mask portions, wherein x is a width of a semiconductor fin and y is a distance between a neighboring pair of semiconductor fins;
removing hard mask portions not protected by said patterned photoresist by an isotropic etching process;
removing said patterned photoresist; and
forming semiconductor fins in an upper semiconductor material portion of said semiconductor substrate, wherein said remaining hard mask portions are employed as fin forming etch masks.
2. The method of claim 1 , wherein said patterning said blanket layer of hard mask material comprises lithography and etching.
3. The method of claim 1 , wherein said patterning said blanket layer of hard mask material comprises a sidewall image transfer process.
4. The method of claim 1 , further comprising cutting each hard mask portion to provide a plurality of first hard mask portions located over one area of said semiconductor substrate, and a plurality of second hard mask portions located over another area of said semiconductor substrate.
5. The method of claim 4 , wherein said cutting comprises an anisotropic etching process.
6. The method of claim 1 , wherein each hard mask portion has a width from 5 nm to 30 nm.
7. The method of claim 1 , wherein said isotropic etching process comprising contacting said exposed hard mask portions with a chemical wet etchant.
8. The method of claim 1 , wherein said removing said patterned photoresist comprises a resist stripping process.
9. The method of claim 1 , wherein said forming semiconductor fins in said upper semiconductor material portion of said semiconductor substrate comprises an anisotropic etch process.
10. The method of claim 1 , further comprising removing each remaining hard mask portion utilizing a planarization process.
11. The method of claim 1 , further comprising forming a functional gate structure straddling each semiconductor fin.
12. The method of claim 11 , wherein said forming said functional gate structure comprises:
forming a sacrificial gate structure straddling each semiconductor fin; and
replacing said sacrificial gate structure with said functional gate structure.
13. The method of claim 1 , wherein said semiconductor substrate is a bulk semiconductor substrate.
14. The method of claim 1 , wherein said semiconductor substrate is a semiconductor-on-insulator, and said upper semiconductor material portion of said semiconductor substrate is a top semiconductor layer of said semiconductor-on-insulator substrate.
15. The method of claim 14 , wherein an insulator layer is located beneath each semiconductor fin.
16. A method of forming a semiconductor structure, said method comprising:
forming a blanket layer of hard mask material on said semiconductor substrate, and patterning said blanket layer hard mask material to provide a plurality of first hard mask portions located over one area of a semiconductor substrate, and a plurality of second hard mask portions located over another area of said semiconductor substrate;
forming a patterned photoresist having an overlay tolerance of (x+y)/2 over preselected first and second hard mask portions, wherein x is a width of a semiconductor fin and y is a distance between a neighboring pair of semiconductor fins;
removing first and second hard mask portions not protected by said patterned photoresist by an isotropic etching process;
removing said patterned photoresist; and
forming first semiconductor fins in an upper semiconductor material portion of, and in a first region of, said semiconductor substrate and forming second semiconductor in said upper semiconductor material portion of, and in a second region of, said semiconductor substrate, wherein said remaining first hard mask portions are employed as first semiconductor fin forming etch masks and said second hard mask portions are employed as second semiconductor fin forming etch masks.