Apparatus and method for FinFETs

1. A method comprising:

forming a first isolation region in a substrate;

forming a second isolation region in the substrate;

forming a cloak-shaped recess between the first isolation region and the second isolation region, wherein the cloak-shaped recess extends into the first isolation region and the second isolation region; and

forming a cloak-shaped active region through an epitaxial growth.

2. The method of claim 1 , wherein the forming the cloak-shaped recess comprises:

etching a portion of the substrate between the first isolation region and the second isolation region to form a recess;

expanding the recess into the first isolation region and the second isolation region to form the cloak-shaped recess.

3. The method of claim 2 , wherein the expanding the recess comprises performing a treatment using an oxygen-containing gas and an etching gas.

4. The method of claim 3 , wherein the oxygen-containing gas comprises oxygen (O 2 ) or ozone (O 3 ), and the etching gas comprises a fluorine-containing gas.

5. The method of claim 1 further comprising:

forming a gate electrode over a first portion of the cloak-shaped active region; and

forming a drain/source region in a second portion of the cloak-shaped active region through an ion implantation process.

6. The method of claim 1 , wherein the forming the cloak-shaped active region comprises epitaxially growing a silicon germanium epitaxial region in the cloak-shaped recess.

7. The method of claim 1 further comprising:

applying an etching process to form a trench in the substrate; and

filling a dielectric material in the trench to form the first isolation region.

8. A method comprising:

forming a first isolation region in a substrate;

forming a second isolation region in the substrate;

etching the first isolation region and the second isolation region to form a recess extending into the first isolation region and the second isolation region; and

epitaxially growing a semiconductor region from the recess, wherein the semiconductor region has a substantially V-shaped bottom in a cross-sectional view of the substrate, and the substantially V-shaped bottom extends into the first isolation region and the second isolation region.

9. The method of claim 8 , wherein the forming the recess comprises:

etching a portion of the substrate between the first isolation region and the second isolation region to form an initial recess; and

performing the etching the first isolation region and the second isolation region to expand the initial recess into the first isolation region and the second isolation region to form the recess.

10. The method of claim 9 , wherein the initial recess is substantially limited in the substrate.

11. The method of claim 8 further comprising:

forming a gate electrode over a first portion of semiconductor region; and

forming a drain/source region in a second portion of the semiconductor region through an ion implantation process.

12. The method of claim 8 further comprising:

applying a chemical mechanical polishing process on the semiconductor region to form a planar surface;

recessing the first isolation region and the second isolation region, with a top portion of the semiconductor region protruding higher than remaining portions of the first isolation region and the second isolation region to form a semiconductor fin;

depositing a gate dielectric on a top surface of the semiconductor fin; and

forming a gate electrode over the gate dielectric.

13. The method of claim 12 , wherein the gate dielectric is further formed on sidewalls of a top portion of the semiconductor region.

14. The method of claim 8 , wherein the epitaxially growing the semiconductor region comprises epitaxially growing a silicon germanium region.

15. The method of claim 8 further comprising:

applying an etching process to form a trench in the substrate; and

filling a dielectric material in the trench to form the first isolation region.

16. A method comprising:

forming a first isolation region and a second isolation region extending into a semiconductor substrate;

removing a portion of the semiconductor substrate between the first isolation region and the second isolation region to form a recess, with the recess has a substantially V-shaped bottom;

performing a treatment to extend the substantially V-shaped bottom into the first isolation region and the second isolation region; and

forming a cloak-shaped active region in the recess through an epitaxial growth.

17. The method of claim 16 , wherein the treatment is performed using an oxygen-containing gas and an etching gas.

18. The method of claim 17 , wherein the oxygen-containing gas comprises oxygen (O 2 ) or ozone (O 3 ), and the etching gas comprises a fluorine-containing gas.

19. The method of claim 18 , wherein the fluorine-containing gas comprises CF 4 .

20. The method of claim 16 further comprising:

forming a gate electrode over a first portion of the cloak-shaped active region; and

forming a drain/source region in a second portion of the cloak-shaped active region through an ion implantation process.