Amorphous layers for reducing copper diffusion and method forming same
A method includes depositing an etch stop layer over a first conductive feature, performing a first treatment to amorphize the etch stop layer, depositing a dielectric layer over the etch stop layer, etching the dielectric layer to form an opening, etching-through the etch stop layer to extend the opening into the etch stop layer, and filling the opening with a conductive material to form a second conductive feature.
1. An integrated circuit structure comprising:
a dielectric layer;
a first conductive feature in the dielectric layer;
a metal cap over and contacting the first conductive feature, wherein the metal cap is amorphous, and wherein at least a lower part of the metal cap is lower than a top surface of the dielectric layer;
a first etch stop layer over the metal cap, wherein the first etch stop layer has a first amorphous structure;
a second etch stop layer over the first etch stop layer, wherein the second etch stop layer has a second amorphous structure or a polycrystalline structure, and the second etch stop layer comprises a material different from a material of the first etch stop layer;
a low-k dielectric layer over the second etch stop layer; and
a second conductive feature in the low-k dielectric layer, the first etch stop layer, and the second etch stop layer.
2. The integrated circuit structure of claim 1 , wherein the metal cap comprises a metal nitride.
3. The integrated circuit structure of claim 2 , wherein the metal nitride comprises a cobalt nitride.
4. The integrated circuit structure of claim 1 , wherein the first etch stop layer comprises an amorphous aluminum nitride layer.
5. The integrated circuit structure of claim 4 , wherein the amorphous aluminum nitride layer comprises hydrogen therein.
6. The integrated circuit structure of claim 1 , wherein the second etch stop layer is amorphous.
7. The integrated circuit structure of claim 1 , wherein the second etch stop layer is polycrystalline.
8. The integrated circuit structure of claim 1 further comprising:
a third etch stop layer over the second etch stop layer, wherein the third etch stop layer is amorphous.
9. The integrated circuit structure of claim 1 further comprising:
a third etch stop layer over the second etch stop layer, wherein the third etch stop layer is polycrystalline.
10. An integrated circuit structure comprising:
a first dielectric layer;
a first conductive feature in the first dielectric layer, wherein the first conductive feature comprises:
a diffusion barrier; and
a copper region in the diffusion barrier;
a cobalt nitride cap over and contacting the copper region;
an etch stop layer comprising:
a first sub layer over and contacting the cobalt nitride cap and the first dielectric layer;
a second sub layer over the first sub layer; and
a third sub layer over the second sub layer, wherein at least one of the first sub layer, the second sub layer, and the third sub layer has an amorphous structure;
a second dielectric layer over the etch stop layer; and
a conductive via in the second dielectric layer and the etch stop layer.
11. The integrated circuit structure of claim 10 , wherein the cobalt nitride cap is amorphous.
12. The integrated circuit structure of claim 10 , wherein the cobalt nitride cap has a thickness in a range between about 20 Å and about 40 Å.
13. The integrated circuit structure of claim 10 , wherein the first sub layer has the amorphous structure, and the second sub layer has a polycrystalline structure.
14. The integrated circuit structure of claim 13 , wherein the third sub layer has an additional amorphous structure.
15. The integrated circuit structure of claim 10 , wherein the first sub layer has the amorphous structure, and the third sub layer has a polycrystalline structure.
16. The integrated circuit structure of claim 15 , wherein the second sub layer has an additional amorphous structure.
17. The integrated circuit structure of claim 10 , wherein the first sub layer comprises aluminum nitride, and the second sub layer comprises silicon oxycarbide.
18. An integrated circuit structure comprising:
a first dielectric layer;
a copper feature in the first dielectric layer;
a cobalt nitride cap over and contacting the copper feature, wherein the cobalt nitride cap has an amorphous structure;
an etch stop layer comprising:
an aluminum nitride layer over the cobalt nitride cap and the first dielectric layer, wherein the aluminum nitride layer has an amorphous structure;
a silicon oxycarbide layer over the aluminum nitride layer; and
an aluminum oxide layer over the silicon oxycarbide layer, wherein the silicon oxycarbide layer and the aluminum oxide layer have a polycrystalline structure or an amorphous structure;
a low-k dielectric layer over the etch stop layer; and
a second conductive feature in the low-k dielectric layer and the etch stop layer.
19. The integrated circuit structure of claim 18 , wherein the silicon oxycarbide layer is polycrystalline.
20. The integrated circuit structure of claim 18 , wherein the aluminum oxide layer is polycrystalline.