Semiconductor structure and fabrication method thereof

1. A method for fabricating a semiconductor structure,

comprising:

providing a substrate;

forming an ultra-low-dielectric-constant (ULK) dielectric layer on a surface of the substrate;

etching the ultra-low-dielectric-constant dielectric layer to form a trench in the ultra-low-dielectric constant material layer;

performing an inert plasma treatment process on a side surface of the trench;

performing a carbonization process on the side surface of the trench; and

after performing the carbonization process, performing a nitridation process on the side surface of the trench to form a carbonized-nitridized layer on the side surface of the trench.

2. The method according to claim 1 , wherein:

a plasma of the inert plasma treatment process is one of a He plasma, an Ne plasma and an Ar plasma and is configured to break Si—OH bond.

3. The method according to claim 2 , wherein:

the inert plasma of the inert plasms treatment process is the Ar plasma;

a gas of the inert plasma is Ar;

a flow rate of Ar is in a range of approximately 200 sccm˜2000 sccm;

a high-frequency radio-frequency power of the Ar plasma is in a range of approximately 0˜200 W;

a low-frequency radio-frequency power of the Ar plasma is in a range of approximately 200 W˜2000 W;

a pressure of a plasma chamber is in a range of approximately 5 Torr˜10 Torr; and

a temperature of the inert gas treatment process is in a range of approximately 250° C.˜400° C.

4. The method according to claim 1 , wherein:

the carbonization process is a carbon and hydrogen containing plasma treatment process;

a gas of the carbonization process includes one of trimethylsilane and tetramethylsilane;

a flow rate of the gas is in a range of approximately 200 sccm˜2000 sccm;

a high-frequency radio-frequency power of the plasma is in a range of approximately 0˜200 W;

a low-frequency radio-frequency power of the plasma is in a range of approximately 200 W˜2000 W;

a pressure of a plasma chamber is in a range of approximately 5 Torr˜10 Torr; and

a temperature of the carbonization process is in a range of approximately 250° C.˜400° C.

5. The method according to claim 1 , wherein:

the nitridation process is a nitrogen-containing plasma treatment process;

a gas for the nitrogen-containing plasma treatment process includes one or more of NH 3 and N 2 ;

a flow rate of the gas is in a range of approximately 200 sccm˜2000 sccm;

a high-frequency radio-frequency power of the plasma is in a range of approximately 0˜200 W;

a low-frequency radio-frequency power of the plasma is in a range of approximately 200 W˜2000 W;

a pressure of a plasma chamber is in a range of approximately 5 Torr˜10 Torr; and

a temperature of the nitridation process is in a range of approximately 250° C.˜400° C.

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

providing a substrate;

forming an ultra-low-dielectric-constant (ULK) dielectric layer on a surface of the substrate;

etching the ultra-low-dielectric-constant dielectric layer to form a trench in the ultra-low-dielectric constant material layer;

performing an inert plasma treatment process on a side surface of the trench;

performing a carbonization process on the side surface of the trench;

performing a nitridation process on the side surface of the trench to form a SiCNH layer on the side surface of the trench; and

sequentially repeating performing the inert plasma treatment process, performing the carbonization process, and performing the nitridation process for a predetermined number of cycles.

7. The method according to claim 6 , wherein:

a number of the cycles is in a range of approximately 2˜10.

8. The method according to claim 1 , further comprising:

forming a diffusion barrier layer on side and bottom surfaces of the trench; and

forming a metal layer on the diffusion barrier layer in the trench.

9. The method according to claim 8 , wherein:

the diffusion barrier layer is formed by a sputtering process.

10. The method according to claim 1 , wherein;

the trench is one of a rectangular trench and a Damascene trench.

11. The method according to claim 1 , wherein forming the ultra-low-dielectric-constant dielectric layer further comprises:

forming an ultra-low-dielectric-constant dielectric film by a reaction of a precursor, a pore-making agent and oxygen introduced into a chamber; and

performing an UV treatment process on the ultra-low-dielectric-constant dielectric film to remove the pore-making agent and form pores.

12. The method according to claim 11 , wherein:

the precursor includes one of tetraethylorthosilicate, methyldiethoxysilane, dirthoxydimethylsilan, and methyltriethoxysilane.

13. The method according to claim 11 , wherein:

the pore-making agent includes one of α-terpinene and dicycloheptadiene.

14. A semiconductor structure, comprising:

a substrate;

a first metal interconnect structure formed on a surface the substrate;

an ultra-low-dielectric-constant dielectric layer formed on the surface of the substrate;

a metal layer formed in the ultra-low-dielectric-constant dielectric layer and on the first metal interconnect structure;

a diffusion barrier layer formed on surfaces of sidewalls and bottom of the metal layer, in the ultra-low-dielectric-constant dielectric layer, and on the first metal interconnect structure; and

a carbonized-nitridized layer of the ultra-low-dielectric-constant dielectric layer, on sidewall surfaces of the diffusion barrier layer and on the first metal interconnect structure.

15. The semiconductor structure according to claim 14 ,

wherein the carbonized-nitridized layer includes a SiCNH layer formed by:

etching the ultra-low-dielectric-constant dielectric layer to form a trench in the ultra-low-dielectric-constant dielectric layer;

performing an inert plasma treatment process on a side surface of the trench;

performing a carbonization process on the side surface of the trench; and

performing a nitridation process on the side surface of the trench.

16. The semiconductor structure according to claim 14 ,

wherein:

the ultra-low-dielectric-constant dielectric layer includes silicon, carbon, hydrogen and oxygen.

17. The semiconductor structure according to claim 14 , wherein:

a dielectric constant of the ultra-low-dielectric-constant dielectric layer is smaller than three.

18. The semiconductor structure according to claim 14 , wherein:

the diffusion barrier layer is made of one or more of Ti, Ta, TiN, and TaN.

19. The semiconductor structure according to claim 14 , wherein:

the metal layer is made of one of Cu, Al, and W.

20. The semiconductor structure according to claim 14 , wherein the substrate further comprises:

a semiconductor substrate; and

a dielectric layer formed on a surface of the semiconductor substrate.