Method for fabricating a semiconductor device

1. A method for fabricating a semiconductor device, comprising:

forming a deposition-type interface layer over a substrate;

converting the deposition-type interface layer into an oxidation-type interface layer;

forming a high-k layer over the oxidation-type interface layer;

forming a dipole interface on an interface between the high-k layer and the oxidation-type interface layer;

forming a conductive layer against the high-k layer; and

patterning the conductive layer, the high-k layer, the dipole interface, and the oxidation-type interface layer to form a gate stack over the substrate.

2. The method of claim 1 , wherein the forming of the deposition-type interface layer over the substrate is performed by an Atomic Layer Deposition (ALD) process or a Chemical Vapor Deposition (CVD) process.

3. The method of claim 1 , wherein the deposition-type interface layer includes a deposition-type silicon oxide.

4. The method of claim 1 , wherein the converting of the deposition-type interface layer into the oxidation-type interface layer includes:

exposing the deposition-type interface layer to a radical oxidation process.

5. The method of claim 1 , wherein the oxidation-type interface layer includes an oxidation-type silicon oxide.

6. The method of claim 1 , wherein the dipole interface includes dipole-inducing species.

7. The method of claim 6 , wherein the dipole-inducing species includes lanthanum.

8. The method of claim 1 , wherein the forming of the dipole interface on the interface between the high-k layer and the oxidation-type interface layer includes:

forming a sacrificial layer containing dipole-inducing species over the high-k layer;

exposing the sacrificial layer to a post-thermal treatment to diffuse the dipole-inducing species into the interface between the oxidation-type interface layer and the high-k layer; and

removing the sacrificial layer.

9. The method of claim 8 , wherein the sacrificial layer includes lanthanum oxide.

10. The method of claim 1 , wherein the gate stack includes a gate stack of an NMOSFET.

11. A method for fabricating a semiconductor device, comprising:

preparing a substrate including a first region and a second region;

forming a channel layer over the substrate of the second region;

forming a deposition-type interface layer over the substrate of the first region and the channel layer;

converting the deposition-type interface layer into an oxidation-type interface layer;

forming a high-k layer over the oxidation-type interface layer;

forming a dipole interface on an interface between the high-k layer and the oxidation-type interface layer in the first region;

forming a conductive layer against the high-k layer;

patterning the conductive layer, the high-k layer, the dipole interface, and the oxidation-type interface layer to form a first gate stack over the substrate of the first region; and

patterning the conductive layer, the high-k layer, and the oxidation-type interface layer to form a second gate stack over the substrate of the second region.

12. The method of claim 11 , wherein the deposition-type interface layer includes a deposition-type silicon oxide.

13. The method of claim 11 , wherein the forming of the deposition-type interface layer over the substrate of the first region and the channel layer is performed by an Atomic Layer Deposition (ALD) process or a Chemical Vapor Deposition (CVD) process.

14. The method of claim 11 , wherein the converting of the deposition-type interface layer into the oxidation-type interface layer includes:

exposing the deposition-type interface layer to a radical oxidation process.

15. The method of claim 11 , wherein the forming of the dipole interface on the interface between the high-k layer and the oxidation-type interface layer in the first region includes:

forming a sacrificial layer containing dipole-inducing species over the high-k layer;

exposing the sacrificial layer to a post-thermal treatment to diffuse the dipole-inducing species into the interface between the oxidation-type interface layer and the high-k layer; and

removing the sacrificial layer.

16. The method of claim 15 , wherein the sacrificial layer includes lanthanum oxide.

17. The method of claim 11 , wherein the channel layer includes crystalline silicon germanium.

18. The method of claim 11 , wherein the first region includes an NMOSFET region, and the second region includes a PMOSFET region.

19. A method for fabricating a semiconductor device, comprising:

preparing a substrate including a first NMOSFET region and a second NMOSFET region;

forming a thick deposition-type interface layer over the first NMOSFET region;

converting the thick deposition-type interface layer into a thick oxidation-type interface layer;

forming a thin oxidation-type interface layer over the second NMOSFET region;

forming a high-k layer over the thick oxidation-type interface layer and over the thin oxidation-type interface layer;

forming dipole interfaces at a first interface between the thin oxidation-type interface layer and the high-k layer and at a second interface between the thick oxidation-type interface layer and the high-k layer;

forming a gate conductive layer over the high-k layer where the dipole interfaces are formed; and

performing a gate patterning process to form respective gate stacks over the first NMOSFET region and the second NMOSFET region, respectively.

20. The method of claim 19 , wherein the forming of the dipole interfaces includes:

forming a sacrificial layer containing dipole-inducing species over the high-k layer;

exposing the sacrificial layer to a post-thermal treatment to diffuse the dipole-inducing species into the first interface and the second interface; and

removing the sacrificial layer.

21. The method of claim 19 , wherein the forming of the thick deposition-type interface layer over the substrate of the first NMOSFET region is performed by an Atomic Layer Deposition (ALD) process or a Chemical Vapor Deposition (CVD) process.

22. The method of claim 19 , wherein the converting of the thick deposition-type interface layer into the thick oxidation-type interface layer includes:

exposing the deposition-type interface layer to a radical oxidation process.

23. The method of claim 19 , wherein the thick oxidation-type interface layer is thicker than the thin oxidation-type interface layer.