Sidewall protection of low-K material during etching and ashing

1. A method for protecting an exposed low-k surface, comprising:

providing a substrate having a low-k insulation layer formed thereon and one or more mask layers overlying said low-k insulation layer with a pattern formed therein;

transferring said pattern in said one or more mask layers to said low-k insulation layer using one or more etching processes to form a structural feature in said low-k insulation layer;

forming an insulation protection layer on exposed surfaces of said structural feature following said one or more etching processes, and prior to mask removal, by exposing said substrate to a film forming process composition containing C, H, and N; and

removing at least a portion of said one or more mask layers using a mask removal process after forming the insulation protection layer.

2. The method of claim 1 , further comprising:

anisotropically removing said insulation protection layer from a top surface of said one or more mask layers and a bottom surface of said structural feature in said low-k insulation layer, while retaining a remaining portion of said insulation protection layer on sidewall surfaces of said structural feature.

3. The method of claim 1 , wherein said film forming process composition is a heterocyclic aromatic organic compound or an aromatic amine.

4. The method of claim 1 , wherein said film forming process composition is pyrrole (C 4 H 4 NH) or aniline (C 6 H 5 NH 2 ).

5. The method of claim 1 , wherein said forming said insulation protection layer comprises performing a plasma-assisted deposition process that includes generating plasma;

wherein said plasma-assisted deposition process excludes application of a radio frequency (RF) bias to a substrate holder upon which said substrate rests;

wherein a temperature of said substrate ranges from about 50 degrees C. to about 100 degrees C.; and

wherein a pressure ranges from about 200 mTorr to about 1000 mTorr.

6. The method of claim 5 , wherein said performing said plasma-assisted deposition process comprises adjusting at least one process parameter in said plasma-assisted deposition process to increase an etch resistance of said insulation protection layer to said mask removal process.

7. The method of claim 1 , wherein said one or more mask layers comprises one or more layers selected from the group consisting of a soft mask layer, a hard mask layer, a layer of radiation-sensitive material, an anti-reflective coating (ARC) layer, an organic planarization layer (OPL), or an organic dielectric layer (ODL); and

wherein said low-k insulation layer comprises a dielectric constant less than a value of 2.5.

8. The method of claim 7 , wherein said hard mask layer comprises a metal hard mask layer; and

wherein said structural feature is formed using a trench-first metal hard mask scheme or a via-first trench-last scheme.

9. The method of claim 8 , wherein said hard mask layer comprises TiN.

10. The method of claim 1 , wherein said insulation protection layer contains C and N.

11. The method of claim 1 , wherein said insulation protection layer contains C, N, and O.

12. The method of claim 1 , further comprising:

following said removing at least a portion of said one or more mask layers, selectively removing any remaining portion of said insulation protection layer from said exposed surfaces of said structural feature.

13. The method of claim 1 , wherein said transferring said pattern and said forming said insulation protection layer are alternatingly and sequentially performed multiple cycles until said pattern transfer is completed in said low-k insulation layer.

14. The method of claim 1 , wherein said transferring said pattern comprises:

receiving said substrate having said low-k insulation layer formed thereon, a first hard mask layer overlying said low-k insulation layer, and a second hard mask layer overlying said first hard mask layer, wherein said second hard mask layer contains a metal;

preparing a first lithographic mask layer with a trench pattern formed therein on said second hard mask layer;

transferring said trench pattern into said second hard mask layer and stopping on said first hard mask layer;

removing said first lithographic mask layer;

preparing a second lithographic mask layer with a via pattern formed therein on said second hard mask layer;

transferring said via pattern through said first hard mask layer and at least partially through said low-k insulation layer;

removing said second lithographic mask layer; and

transferring said trench pattern in said second hard mask layer through said first hard mask layer and into said low-k insulation layer to a pre-determined depth to form said structural feature, said structural feature being a trench-via structure.

15. A method for protecting an exposed low-k surface, comprising:

providing a substrate having a low-k insulation layer formed thereon and one or more mask layers overlying said low-k insulation layer with a pattern formed therein;

transferring said pattern in said one or more mask layers to said low-k insulation layer using one or more etching processes to form a structural feature in said low-k insulation layer;

forming an insulation protection layer on exposed surfaces of said structural feature during said one or more etching processes by exposing said substrate to a film forming process composition, the process composition having a compound containing C, H, and N, wherein said film forming process composition is pyrrole (C 4 H 4 NH), said forming said insulation protection layer comprises performing a plasma-assisted deposition process that includes generating plasma, wherein said insulation protection layer contains C, N, and O, and wherein said insulation protection layer does not contain silicon, wherein the insulation protection layer is formed prior to mask removal;

removing at least a portion of said one or more mask layers using a mask removal process; and

anisotropically removing said insulation protection layer from a top surface of said one or more mask layers and a bottom surface of said structural feature in said low-k insulation layer, while retaining a remaining portion of said insulation protection layer on sidewall surfaces of said structural feature.

16. The method of claim 15 , wherein said film forming process composition is aniline (C 6 H 5 NH 2 ).