Semiconductor device and method for fabricating the same

Abstract

A semiconductor device in which the diffusion of copper from a wire is prevented and a method for fabricating such a semiconductor device. For example, a via groove and a wire groove are formed in a multilayer structure including a UDC diffusion barrier film, a porous silica film, a middle UDC stopper film, a porous silica film, a UDC diffusion barrier film, and the like, and the surfaces the UDC diffusion barrier film, the middle UDC stopper film, and the UDC diffusion barrier film that get exposed in the via groove and the wire groove are irradiated with hydrogen plasma, thereby making the surface of each exposed SiC film silicon-rich. After the plasma irradiation, a Ta film is formed in the via groove and the wire groove and copper is embedded in these grooves. By making the surface of each SiC film which is to touch the Ta film silicon-rich in advance, the crystal structure of the Ta film can be controlled so that copper cannot pierce through the Ta film. This prevents copper from diffusing from a wire.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view for describing a copper diffusion phenomenon.

FIG. 2 shows results obtained by measuring the sheet resistance of Ta films formed on SiC films.

FIG. 3 shows results obtained by analyzing the crystal structure of Ta films formed on SiC films.

FIG. 4 shows the relationship between the carbon content of the SiC films and the crystal structure of the Ta films.

FIG. 5 shows results obtained by measuring the sheet resistance of Ta films formed on SiC films on which hydrogen plasma treatment is performed.

FIG. 6 shows results obtained by analyzing the crystal structure of Ta films formed on SiC films on which hydrogen plasma treatment is performed.

FIG. 7 is a schematic sectional view showing an important part of a multilayer wiring structure.

Claims

1. A method for fabricating a semiconductor device having multilayer wiring, the method comprising the steps of: forming a multilayer structure including SiC films and insulating films;forming a groove in the multilayer structure;making a surface of an SiC film which gets exposed in the groove at the time of the groove being formed silicon-rich;forming a barrier metal film in the groove; andembedding a conductive material in the groove in which the barrier metal film is formed.

2. The method according to claim 1, wherein in the step of making the surface of the SiC film which gets exposed in the groove at the time of the groove being formed silicon-rich, the surface is irradiated with plasma which contains hydrogen to make the surface silicon-rich.

3. The method according to claim 1, wherein in the step of making the surface of the SiC film which gets exposed in the groove at the time of the groove being formed silicon-rich, the surface is irradiated with plasma which contains ammonia to make the surface silicon-rich.

4. The method according to claim 1, wherein in the step of making the surface of the SiC film which gets exposed in the groove at the time of the groove being formed silicon-rich, the surface is irradiated with plasma which contains nitrogen to make the surface silicon-rich.

5. The method according to claim 1, wherein in the step of making the surface of the SiC film which gets exposed in the groove at the time of the groove being formed silicon-rich, the surface is irradiated with ultraviolet rays to make the surface silicon-rich.

6. The method according to claim 1, wherein in the step of making the surface of the SiC film which gets exposed in the groove at the time of the groove being formed silicon-rich, an Si layer is formed on the surface to make the surface silicon-rich.

7. The method according to claim 1, wherein in the step of forming the multilayer structure including the SiC films and the insulating films, an SiC film is formed by performing chemical vapor deposition in an atmosphere in which oxygen concentration is low or which does not contain oxygen with organosilane as source gas.

8. The method according to claim 1, wherein the barrier metal film contains at least one of Ta, TaN, Ti, TiN, W, WN, Zr, ZrN, V, VN, TiZr, and TiZrN.

9. A method for fabricating a semiconductor device having multilayer wiring, the method comprising the steps of: forming a multilayer structure including SiC films in each of which a composition gradient is formed so that an upper portion will be silicon-rich and insulating films;forming a groove in which an SiC film is exposed in the multilayer structure;forming a barrier metal film in the groove; andembedding a conductive material in the groove in which the barrier metal film is formed.

10. The method according to claim 9, wherein in the step of forming the multilayer structure including the SiC films in each of which a composition gradient is formed so that an upper portion will be silicon-rich and the insulating films, source gas concentration is controlled during the formation of the SiC films to form the SiC films in each of which a composition gradient is formed so that a surface will be silicon-rich.

11. The method according to claim 10, wherein the SiC films are formed by performing chemical vapor deposition with organosilane as the source gas.

12. The method according to claim 9, further comprising, after the step of forming the groove in which the SiC film is exposed in the multilayer structure, the step of making a surface of the SiC film which gets exposed in the groove at the time of the groove being formed silicon-rich.

13. The method according to claim 9, wherein the barrier metal film contains at least one of Ta, TaN, Ti, TiN, W, WN, Zr, ZrN, V, VN, TiZr, and TiZrN.

14. A semiconductor device having multilayer wiring, the device comprising: a multilayer structure including SiC films and insulating films;a groove which is formed in the multilayer structure and in which an SiC film is exposed;a barrier metal film formed in the groove; anda conductive material embedded in the groove in which the barrier metal film is formed,wherein a surface of the SiC film which is touching the barrier metal film is silicon-rich.

15. The semiconductor device according to claim 14, wherein the barrier metal film contains at least one of Ta, TaN, Ti, TiN, W, WN, Zr, ZrN, V, VN, TiZr, and TiZrN.

16. The semiconductor device according to claim 14, wherein a composition gradient is formed in each of the SiC films so that an upper portion will be silicon-rich.

17. The semiconductor device according to claim 14, wherein dielectric constants of the SiC films are 2.5 to 4.5.