Method to induce strain in finFET channels from an adjacent region
View Patent ↗Methods and structures for forming strained-channel finFETs are described. Fin structures for finFETs may be formed using two epitaxial layers of different lattice constants that are grown over a bulk substrate. A first thin, strained, epitaxial layer may be cut to form strain-relieved base structures for fins. The base structures may be constrained in a strained-relieved state. Fin structures may be epitaxially grown in a second layer over the base structures. The constrained base structures can cause higher amounts of strain to form in the epitaxially-grown fins than would occur for non-constrained base structures.
1. A device, comprising:
a substrate having a first surface and a second surface;
a base structure of a first material on the first surface of the substrate;
a fin structure of a second material on the base structure, the first material being different from the second material, the fin structure having a first surface on the base structure and a second surface opposite the first surface;
a constraining material having a first surface on the second surface of the substrate and a second surface opposite the first surface, the first surface and the second surface of the fin structure being between the first surface and the second surface of the constraining material; and
an insulating layer on the second surface of the substrate.
2. The device of claim 1 , wherein the first surface of the substrate is a raised portion that is spaced apart from the second surface of the substrate.
3. The device of claim 2 , wherein the substrate has a third surface that is transverse to the first surface of the substrate, and the constraining material is on the third surface of the substrate.
4. The device of claim 2 , wherein the base structure has a first surface on the first surface of the substrate and a second surface opposite the first surface, the first surface and the second surface of the base structure being between the first surface and the second surface of the constraining material.
5. The device of claim 1 , wherein the insulating layer has a first height and the constraining material has a second height, the first height being less than the second height.
6. The device of claim 5 , wherein the base structure has a third height, the third height being less than the first height.
7. A device, comprising:
a substrate having a first surface;
a base structure of a first material on the first surface of the substrate;
a fin structure of a second material that is different from the first material, the base structure being between the fin structure and the substrate, the fin structure extending to a first height; and
a constraining structure on the substrate, the constraining structure extending to a second height that is greater than the first height.
8. The device of claim 7 , further including an insulating layer on the substrate.
9. The device of claim 8 , wherein the insulating layer extends to a third height that is less than the second height.
10. The device of claim 9 , wherein the third height is less than the first height.
11. The device of claim 9 , wherein the base structure extends to a fourth height that is less than the third height.
12. The device of claim 7 , wherein the substrate has a second surface spaced apart from the first surface.
13. The device of claim 12 , wherein the constraining structure is on the second surface of the substrate.
14. The device of claim 12 , further including an insulating layer on the second surface of the substrate.
15. A method, comprising:
forming a base structure of a first material on a first surface of a substrate;
forming a fin structure of a second material on the base structure, the second material being different from the first material, the base structure being between the fin structure and the substrate, the fin structure extending to a first height; and
forming a constraining structure on the substrate, the constraining structure extending to a second height that is greater than the first height.
16. The method of claim 15 , further including forming an insulating layer on the substrate.
17. The method of claim 16 , wherein the insulating layer extends to a third height that is less than the first height.
18. The method of claim 17 , wherein the base structure extends to a fourth height that is less than the third height.
19. The method of claim 15 , further including forming a second surface of the substrate that is spaced apart from the first surface.
20. The method of claim 19 , wherein the constraining structure is on the second surface of the substrate.