Method for forming cobalt nitride cap layers
A method is provided for integrating cobalt nitride cap layers into manufacturing of semiconductor devices to improve electromigration and stress migration in copper (Cu) metal. One embodiment includes providing a patterned substrate containing a recessed feature formed in a low-k material and a first metallization layer at the bottom of the feature, forming a cobalt nitride cap layer on the first metallization layer, depositing a barrier layer in the recessed feature, including on the low-k dielectric material and on the first cobalt metal cap layer, and filling the recessed feature with Cu metal. Another embodiment includes providing a patterned substrate having a substantially planar surface with Cu paths and low-k dielectric regions, and selectively forming a cobalt nitride cap layer on the Cu paths relative to the low-k dielectric regions.
1. A method of forming a semiconductor device, comprising:
providing a patterned substrate containing a recessed feature formed in a low-k dielectric material and a first metallization layer at the bottom of the recessed feature;
forming a first cobalt (Co) nitride cap layer on the first metallization layer by exposing the patterned substrate to a first deposition gas comprising a cobalt precursor that selectively deposits cobalt on the first metallization layer relative to on the low-k dielectric material;
depositing a barrier layer in the recessed feature, including on the low-k dielectric material and on the first cobalt nitride cap layer; and
filling the recessed feature with copper (Cu) metal.
2. The method of claim 1 , wherein the first deposition gas further comprises a thermally excited or plasma excited first nitriding gas selected from NH 3 , N 2 , N 2 +H 2 , NH(CH 3 ) 2 , N 2 H 4 , or N 2 H 3 CH 3 , or a combination thereof.
3. The method of claim 1 , wherein forming the first cobalt nitride cap layer comprises:
depositing a first cobalt metal layer on the first metallization layer; and
exposing the first cobalt metal layer to a first nitriding gas.
4. The method of claim 3 , wherein the first nitriding gas comprises a thermally excited or plasma excited first nitriding gas selected from NH 3 , N 2 , N 2 +H 2 , NH(CH 3 ) 2 , N 2 H 4 , or N 2 H 3 CH 3 , or a combination thereof.
5. The method of claim 1 , wherein the cobalt precursor comprises Co 2 (CO) 8 , Co 4 (CO) 12 , CoCp(CO) 2 , Co(CO) 3 (NO), Co 2 (CO) 6 (HCC t Bu), Co(acac) 2 , Co(Cp) 2 , Co(Me 5 Cp) 2 ), Co(EtCp) 2 , cobalt(II) hexafluoroacetylacetonate hydrate, cobalt tris(2,2,6,6-tetramethyl-3,5-heptanedionate), cobalt(III) acetylacetonate, bis(N,N′-diisopropylacetamidinato) cobalt, or tricarbonyl allyl cobalt, or a combination of two or more thereof.
6. The method of claim 1 , further comprising, prior to forming the first cobalt nitride cap layer, treating the patterned substrate with thermally excited or plasma excited first process gas comprising H 2 , NH 3 , N 2 , NH(CH 3 ) 2 , N 2 H 4 , N 2 H 3 CH 3 , or SiH 4 , or a combination thereof.
7. The method of claim 1 , further comprising:
following the filling, forming a substantially planar surface with Cu paths and low-k dielectric regions; and
forming a second cobalt nitride cap layer on the Cu paths by exposing the patterned substrate to a second deposition gas comprising a cobalt precursor that selectively deposits cobalt on the Cu paths relative to on the low-k dielectric regions.
8. The method of claim 7 , wherein the second deposition gas further comprises a thermally excited or plasma excited second nitriding gas selected from NH 3 , N 2 , N 2 +H 2 , NH(CH 3 ) 2 , N 2 H 4 , or N 2 H 3 CH 3 , or a combination thereof.
9. The method of claim 7 , wherein forming the second cobalt nitride cap layer comprises:
depositing a second cobalt metal layer on the Cu paths; and
exposing the second cobalt metal layer to a second nitriding gas.
10. The method of claim 9 , wherein the second nitriding gas comprises a thermally excited or plasma excited second nitriding gas selected from NH 3 , N 2 , N 2 +H 2 , NH(CH 3 ) 2 , N 2 H 4 , or N 2 H 3 CH 3 , or a combination thereof.
11. The method of claim 7 , wherein the cobalt precursor comprises Co 2 (CO) 8 , Co 4 (CO) 12 , CoCp(CO) 2 , Co(CO) 3 (NO), Co 2 (CO) 6 (HCC′Bu), Co(acac) 2 , Co(Cp) 2 , Co(Me 5 Cp) 2 ), Co(EtCp) 2 , cobalt(II) hexafluoroacetylacetonate hydrate, cobalt tris(2,2,6,6-tetramethyl-3,5-heptanedionate), cobalt(III) acetylacetonate, bis(N,N′-diisopropylacetamidinato) cobalt, or tricarbonyl allyl cobalt, or a combination of two or more thereof.
12. The method of claim 7 , further comprising, prior to forming the second cobalt nitride cap layer, treating the Cu paths and the low-k dielectric regions with thermally excited or plasma excited second process gas comprising H 2 , NH 3 , N 2 , N 2 +H 2 , NH(CH 3 ) 2 , N 2 H 4 , N 2 H 3 CH 3 , or SiH 4 , or a combination thereof.
13. A method of forming a semiconductor device, comprising:
providing a patterned substrate having a substantially planar surface with copper (Cu) paths and low-k dielectric regions; and
forming a cobalt (Co) nitride cap layer on the Cu paths by exposing the patterned substrate to a deposition gas comprising a cobalt precursor that selectively deposits cobalt on the Cu paths relative to on the low-k dielectric regions.
14. The method of claim 13 , wherein the deposition gas further comprises a thermally excited or plasma excited nitriding gas selected from NH 3 , N 2 , N 2 +H 2 , NH(CH 3 ) 2 , N 2 H 4 , or N 2 H 3 CH 3 , or a combination thereof.
15. The method of claim 13 , wherein forming the cobalt nitride cap layer comprises:
depositing a cobalt metal layer on the Cu paths; and
exposing the cobalt metal layer to a nitriding gas.
16. The method of claim 15 , wherein the nitriding gas comprises a thermally excited or plasma excited first nitriding gas selected from NH 3 , N 2 , N 2 +H 2 , NH(CH 3 ) 2 , N 2 H 4 , or N 2 H 3 CH 3 , or a combination thereof.
17. The method of claim 13 , wherein the cobalt precursor comprises Co 2 (CO) 8 , Co 4 (CO) 12 , CoCp(CO) 2 , Co(CO) 3 (NO), Co 2 (CO) 6 (HCC t Bu), Co(acac) 2 , Co(Cp) 2 , Co(Me 5 Cp) 2 ), Co(EtCp) 2 , cobalt(II) hexafluoroacetylacetonate hydrate, cobalt tris(2,2,6,6-tetramethyl-3,5-heptanedionate), cobalt(III) acetylacetonate, bis(N,N′-diisopropylacetamidinato) cobalt, or tricarbonyl allyl cobalt, or a combination of two or more thereof.
18. The method of claim 13 , further comprising, prior to forming the cobalt nitride cap layer, treating the patterned substrate with thermally excited or plasma excited process gas comprising H 2 , NH 3 , N 2 , NH(CH 3 ) 2 , N 2 H 4 , N 2 H 3 CH 3 , or SiH 4 , or a combination thereof.
19. A method of forming a semiconductor device, comprising:
providing a patterned substrate having a substantially planar surface with copper (Cu) paths and low-k dielectric regions;
treating the patterned substrate with thermally excited or plasma excited process gas comprising H 2 , NH 3 , N 2 , NH(CH 3 ) 2 , N 2 H 4 , N 2 H 3 CH 3 , or SiH 4 , or a combination thereof; and
forming a cobalt (Co) nitride cap layer on the Cu paths by
exposing the treated patterned substrate to a deposition gas comprising a cobalt precursor that selectively deposits a cobalt metal layer on the Cu paths relative to on the low-k dielectric regions; and
exposing the cobalt metal layer to a nitriding gas to form the cobalt nitride cap layer.
20. The method of claim 19 , wherein the nitriding gas comprises a thermally excited or plasma excited nitriding gas selected from NH 3 , N 2 , N 2 +H 2 , NH(CH 3 ) 2 , N 2 H 4 , or N 2 H 3 CH 3 , or a combination thereof.