Semiconductor structure and method of manufacturing the same

1. A method for manufacturing a semiconductor structure, comprising:

forming a fin on a substrate;

forming a nitridized capping layer covering the fin;

forming a nitridized oxide layer covering nitridized capping layer;

forming a dielectric layer over the nitridized oxide layer;

removing a portion of the dielectric layer, a portion of the nitridized oxide layer, and a portion of the nitridized capping layer to expose a portion of the fin, wherein a remained portion of the nitridized capping layer constitutes a bottom capping structure between the fin and a remained portion of the nitridized oxide layer; and

forming a top capping structure over the bottom capping structure and covering a sidewall of the exposed portion of the fin.

2. The method of claim 1 , wherein the bottom capping structure comprises a base and a fringe extending upwards from the base, and the fringe has a width less than a width of the base.

3. The method of claim 1 , wherein the bottom capping structure comprises nitrogen and the top capping structure is free of nitrogen.

4. The method of claim 1 , wherein removing the portion of the dielectric layer, the portion of the nitridized oxide layer, and the portion of the nitridized capping layer comprises:

etching away the portion of the dielectric layer to expose the portion of the nitridized oxide layer; and

removing the exposed portion of the nitridized oxide layer and the portion of the nitridized capping layer so to expose the portion of the fin.

5. The method of claim 1 , wherein forming the nitridized capping layer comprises:

depositing a capping material layer conformally covering the fin; and

nitridizing the capping material layer to form the nitridized capping layer.

6. A method for manufacturing a semiconductor structure, comprising:

providing a substrate having PMOS and NMOS regions;

forming first and second fins respectively in the PMOS and NMOS regions;

depositing a capping material layer conformally covering the first and second fins;

nitridizing the capping material layer to forma nitridized capping layer covering the first and second fins;

removing the nitridized capping layer to expose upper portions of the first and second fins;

forming a top capping structure that covers the upper portions of the first and second fins; and

forming an oxide layer covering the top capping structure.

7. The method of claim 6 , wherein nitridizing the capping material layer comprises doping the capping material layer with nitrogen.

8. The method of claim 6 , further comprising:

forming a nitridized oxide layer that covers the nitridized capping layer and the upper portions of the first and second fins; and

removing the nitridized oxide layer to expose the upper portions of the first and second fins.

9. The method of claim 6 , wherein forming the top capping structure is such that the top capping structure is free of nitrogen.

10. The method of claim 6 , wherein removing the nitridized capping layer is such that the nitridized capping layer comprises a base that surrounds lower portions of the first and second fins and a fringe that extends from the base and that has a width less than a width of the base.

11. The method of claim 10 , wherein removing the nitridized capping layer is such that the width of the fringe is about 20% to 80% of the width of the base.

12. The method of claim 8 , wherein removing the nitridized capping layer comprises etching a dielectric layer to expose the nitridized oxide layer.

13. A method for manufacturing a semiconductor structure, comprising:

forming a fin on a substrate;

forming a nitridized capping layer such that the nitridized capping layer includes a base that surrounds a lower portion of the fin and a fringe that extends from the base and that has a width less than a width of the base; and

forming a top capping structure covering a upper portion of the fin and the fringe of the nitridized capping layer.

14. The method of claim 13 , wherein forming the top capping structure is such that the top capping structure comprises a base that covers an upper portion of the fin and a fringe that extends from the base of the top capping structure and that covers the fringe of the nitridized capping layer and such that the sum of a width of the fringe of the nitridized capping layer and a width of the fringe of the top capping structure is equal to a width of the base of the top capping structure.

15. The method of claim 13 , wherein forming the top capping structure is such that the top capping structure is free of nitrogen.

16. The method of claim 13 , wherein forming the nitridized capping layer comprises doping a silicon layer with nitrogen.

17. The method of claim 13 , further comprising:

forming a nitridized oxide layer that covers the nitridized capping layer; and

removing the nitridized oxide layer and the nitridized capping layer to expose an upper portion of the fin.

18. The method of claim 13 , wherein forming the nitridized capping layer comprises:

depositing a capping material layer conformally; and

nitridizing the capping material layer.

19. The method of claim 13 , further comprising forming an oxide layer covering the top capping structure.

20. The method of claim 6 , wherein nitridizing the capping material layer comprises performing a rapid thermal nitridation process.