Double patterning method using metallic compound mask layer

1. A method of forming a double patterning structure, the method comprising:

forming a hard mask layer over a substrate;

forming a developable bottom anti-reflective coating (dBARC) layer above the hard mask layer;

forming a first photosensitive layer above the dBARC layer;

exposing the first photosensitive layer;

developing the first photosensitive layer to form a first pattern and developing the dBARC layer; and

etching the first pattern into the hard mask layer to form a first pattern of openings in the hard mask layer, the hard mask layer being etched with a mild acid solution.

2. The method of claim 1 , wherein the hard mask layer comprises a material selected from the group consisting of silicon nitride (SiN), silicon carbide (SiC), hafnium dioxide (HfO2), zirconium dioxide (ZrO2), titanium dioxide (TiO2), alkyl derivatives cross-linked with a transition metal compound, and combinations thereof.

3. The method of claim 1 , wherein the forming the hard mask layer includes forming the hard mask layer by physical vapor deposition (PVD).

4. The method of claim 1 , wherein the hard mask layer is etched by wet chemistry etching.

5. The method of claim 1 , wherein the mild acid solution comprises a solution selected from the group consisting of acetic acid, formic acid, citric acid, hydrochloric acid, phosphoric acid, and sulfuric acid.

6. The method of claim 1 , wherein the etching of the hard mask layer comprises implementing an etchant selected from the group consisting of an organic acid group, an inorganic acid group, and combinations thereof.

7. The method of claim 1 , further comprising:

removing the first photosensitive layer;

forming a second photosensitive layer over the dBARC layer and within the first pattern of openings in the hard mask layer;

exposing the second photosensitive layer; and

developing the second photosensitive layer to form a second pattern and developing the dBARC layer.

8. The method of claim 7 , further comprising etching the second pattern into the hard mask layer to form a second pattern of openings in the hard mask layer, the hard mask layer being etched with a mild acid solution.

9. The method of claim 8 , wherein the mild acid solution for etching the second pattern into the hard mask layer comprises a solution selected from the group consisting of acetic acid, formic acid, citric acid, hydrochloric acid, phosphoric acid, and sulfuric acid.

10. The method of claim 8 , further comprising removing the second photosensitive layer and the dBARC layer and etching the first pattern and the second pattern into the dielectric layer.

11. The method of claim 1 , further comprising forming an etch stop layer (ESL) over the substrate before the forming of the hard mask layer.

12. The method of claim 11 , further comprising forming a dielectric layer above the etch stop layer before the forming of the hard mask layer.

13. The method of claim 12 , further comprising forming an inorganic anti-reflective coating (ARC) layer over the dielectric layer before the forming of the hard mask layer.

14. A method of forming a double patterning structure, the method comprising:

providing a substrate with an etch stop layer formed thereabove;

forming a dielectric layer above the etch stop layer;

forming a hard mask layer above the dielectric layer;

forming a developable bottom anti-reflective coating (dBARC) layer above the hard mask layer;

forming a first photosensitive layer above the dBARC layer;

exposing the first photosensitive layer;

developing the first photosensitive layer to form a first pattern and developing the dBARC layer; and

etching the first pattern into the hard mask layer to form a first pattern of openings in the hard mask layer, the hard mask layer being etched with a mild acid solution.

15. The method of claim 14 , wherein the hard mask layer comprises a material selected from the group consisting of silicon nitride (SiN), silicon carbide (SiC), hafnium dioxide (HfO 2 ), zirconium dioxide (ZrO 2 ), titanium dioxide (TiO 2 ), alkyl derivatives cross-linked with a transition metal compound, and combinations thereof.

16. The method of claim 14 , wherein the hard mask layer is etched by wet chemistry etching.

17. The method of claim 14 , wherein the mild acid solution comprises a solution selected from the group consisting of acetic acid, formic acid, citric acid, hydrochloric acid, phosphoric acid, and sulfuric acid.

18. The method of claim 14 , further comprising forming an inorganic anti-reflective coating (ARC) layer over the dielectric layer before the forming of the hard mask layer.

19. The method of claim 14 , further comprising:

removing the first photosensitive layer; forming a second photosensitive layer over the dBARC layer and within the first pattern of openings in the hard mask layer;

exposing the second photosensitive layer;

developing the second photosensitive layer to form a second pattern and developing the dBARC layer;

removing the second photosensitive layer and the dBARC layer; and

etching the first pattern and the second pattern into the dielectric layer.

20. The method of claim 19 , wherein the mild acid solution for etching the second pattern into the hard mask layer comprises a solution selected from the group consisting of acetic acid, formic acid, citric acid, hydrochloric acid, phosphoric acid, and sulfuric acid.