Structure and formation method of semiconductor device structure

1. A method for forming a semiconductor device, the method comprising:

forming a dummy gate stack over a fin structure, the fin structure being interposed between isolation regions;

forming spacers along sidewalls of the dummy gate stack;

forming a dielectric layer alongside the spacers, the spacers being interposed between the dielectric layer and the dummy gate stack;

removing the dummy gate stack to form a recess, the fin structure being exposed in the recess;

forming a gate dielectric layer over sidewalls and a bottom of the recess, the gate dielectric layer extending over the fin structure;

forming a work function layer over the gate dielectric layer along the sidewalls and the bottom of the recess, the work function layer extending over the fin structure;

removing a portion of the work function layer along the sidewalls of the recess, the gate dielectric layer on the sidewalls of the recess being free of the work function layer; and

forming a conductive gate electrode in the recess, wherein the gate dielectric layer is interposed between the conductive gate electrode and the spacers, wherein a distance between the work function layer and a vertical portion of the gate dielectric layer is between about 0.5 nm and 50 nm.

2. The method of claim 1 , wherein the conductive gate electrode extends to a bottom of the work function layer.

3. The method of claim 1 , wherein the dummy gate stack comprises a dummy gate electrode overlying a dummy gate dielectric, wherein forming the spacers comprises forming the spacers over the dummy gate dielectric.

4. The method of claim 3 , wherein after forming the conductive gate electrode, the spacers are separated from the isolation regions by the dummy gate dielectric.

5. The method of claim 4 , wherein the dummy gate dielectric and the gate dielectric layer are formed of different materials.

6. The method of claim 1 , wherein forming the spacers comprises forming the spacers directly on the isolation regions.

7. The method of claim 1 , wherein the conductive gate electrode contacts the dielectric layer.

8. A method for forming a semiconductor device, the method comprising:

forming a dummy gate stack over a fin structure, the fin structure being interposed between isolation regions;

forming spacers along sidewalls of the dummy gate stack;

forming a dielectric layer alongside the spacers, the spacers being interposed between the dielectric layer and the dummy gate stack;

removing the dummy gate stack to form a recess, sidewalls of the spacers and the fin structure being exposed in the recess;

forming a gate dielectric layer in the recess over sidewalls of the spacers and the fin structure, the gate dielectric layer contacting an entirety of a first sidewall of the dielectric layer, the first sidewall being substantially parallel to a longest sidewall of the fin structure;

forming a work function layer over the gate dielectric layer;

removing a portion of the work function layer along the sidewalls of the recess; and

forming a conductive gate electrode in the recess, wherein a shortest distance between the spacers and the work function layer is greater than a shortest distance between the spacers and the conductive gate electrode along a same line.

9. The method of claim 8 , wherein forming the dummy gate stack and forming the spacers comprises:

forming a dummy gate dielectric;

forming a dummy gate electrode over the dummy gate dielectric;

forming a spacer layer over the dummy gate electrode;

etching the spacer layer to form the spacers, wherein etching the spacer layer exposing portions of the dummy gate dielectric; and

removing the portions of the dummy gate dielectric exposed by etching the spacer layer.

10. The method of claim 9 , wherein after forming the conductive gate electrode, the spacers are separated from the isolation regions by remaining portions of the dummy gate dielectric.

11. The method of claim 10 , wherein the dummy gate dielectric and the gate dielectric layer are formed of different materials.

12. The method of claim 8 , wherein forming the dummy gate stack and forming the spacers comprises:

forming a dummy gate dielectric;

forming a dummy gate electrode over the dummy gate dielectric;

removing exposed portions of the dummy gate dielectric; and

after removing exposed portions of the dummy gate dielectric, forming the spacers alongside the dummy gate dielectric and the dummy gate electrode, wherein the spacers are directly over the isolation regions.

13. The method of claim 8 , wherein the gate dielectric layer extends to an upper surface of the dielectric layer.

14. The method of claim 8 , wherein the gate dielectric layer is only partially removed from a sidewall of the recess.

15. A semiconductor device structure, comprising:

a fin structure over a semiconductor substrate;

isolation regions on opposing sides of the fin structure;

a gate stack covering a portion of the fin structure, wherein the gate stack comprises a gate dielectric layer, a work function layer, and a conductive gate electrode over the work function layer;

a spacer along sidewalls of the gate stack, wherein the spacer is over the isolation regions;

a dummy gate dielectric interposed between the isolation regions and the spacer; and

a dielectric layer adjacent the spacer, the spacer being interposed between the dielectric layer and the gate stack, wherein a shortest distance along a line orthogonal to a lengthwise direction of the fin structure between the dielectric layer and the work function layer is greater than a shortest distance along the line orthogonal to the lengthwise direction of the fin structure between the spacer and the conductive gate electrode.

16. The semiconductor device structure of claim 15 , further comprising an isolation regions adjacent the fin structure, wherein the work function layer terminates over the isolation region.

17. The semiconductor device structure of claim 15 , wherein the conductive gate electrode is in direct contact with the gate dielectric layer.

18. The semiconductor device structure of claim 15 , wherein an uppermost surface of the gate dielectric layer is level with an uppermost surface of the dielectric layer.

19. The semiconductor device structure of claim 15 , wherein the conductive gate electrode directly contacts the dielectric layer.

20. The semiconductor device structure of claim 15 , wherein the gate dielectric layer completely separates the conductive gate electrode from the dielectric layer.