Use of amorphous carbon film as a hardmask in the fabrication of optical waveguides

1. A method for forming a waveguide structure on a substrate surface, comprising:

forming a cladding layer on the substrate surface;

forming a core layer on the cladding layer;

depositing an amorphous carbon hardmask on the core layer, wherein depositing the amorphous carbon hardmask comprises introducing into a processing chamber one or more hydrocarbon compounds having the general formula C x H y , wherein x has a range of 2 to 4 and y has a range of 2 to 10, and generating a plasma of the one or more hydrocarbon compounds;

forming a patterned photoresist layer on the amorphous carbon hardmask;

etching exposed amorphous carbon hardmask; and

etching the exposed core layer.

2. The method of claim 1 , further comprising:

removing remaining portions of the amorphous carbon hardmask; and

depositing a cladding material on remaining portions of the core layer and exposed portions of the cladding layer.

3. The method of claim 1 , wherein the cladding layer has a refractive index lower than a refractive index of the core layer.

4. The method of claim 1 , wherein the cladding layer comprises a material selected from the group consisting of undoped silicon dioxide, thermal oxides, or silicon dioxide doped with boron, phosphorous, and combinations thereof.

5. The method of claim 1 , wherein the core layer comprises a material selected from the group consisting of germanium doped silicon dioxide, germanium boron doped silicon dioxide silicon-germanium compositions, phosphorous doped silicon dioxide, silicon oxynitride, silicon nitride, silicon, and combinations thereof.

6. The method of claim 1 , wherein the core layer comprises a light propagating channel.

7. The method of claim 1 , wherein the one or more hydrocarbon compounds are selected from the group consisting of propylene (C 3 H 6 ), propyne (C 3 H 4 ), propane (C 3 H 8 ), butane (C 4 H 10 ), butylene (C 4 H 8 ), butadiene (C 4 H 6 ), acetelyne (C 2 H 2 ), and combinations thereof.

8. The method of claim 1 , further comprising introducing an inert gas into the processing chamber.

9. The method of claim 1 , wherein the etch selectivity of amorphous carbon to the core layer is between about 1:8 and about 1:15.

10. A method for forming a waveguide structure on a substrate surface, comprising:

forming a first cladding layer on the substrate surface;

forming a core layer on the first cladding layer;

depositing an amorphous carbon hardmask on the core layer, wherein depositing the amorphous carbon hardmask comprises introducing into a processing chamber one or more hydrocarbon compounds having the general formula C x H y , wherein x has a range of 2 to 4 and y has a range of 2 to 10, and generating a plasma of the one or more hydrocarbon compounds;

forming a patterned photoresist layer on the amorphous carbon hardmask;

etching the amorphous carbon hardmask;

etching the core layer;

removing the amorphous carbon hardmask; and

forming a second cladding layer over the core layer.

11. The method of claim 10 , wherein the first cladding layer has a refractive index lower than a refractive index of the core layer.

12. The method of claim 10 , wherein the first cladding layer comprises a material selected from the group consisting of undoped silicon dioxide, thermal oxides, silicon dioxide doped with boron, phosphorous, and combinations thereof, and the core material comprises a material selected from the group consisting of germanium doped silicon dioxide, germanium boron doped silicon dioxide silicon-germanium compositions, phosphorous doped silicon dioxide, silicon oxynitride, silicon nitride, silicon, and combinations thereof.

13. The method of claim 10 , wherein the second cladding layer comprises the same material as the first cladding layer.

14. The method of claim 10 , wherein the second cladding layer comprises a material selected from the group consisting of quartz, silicon oxide, fused silicon oxide, and combinations thereof.

15. The method of claim 10 , further comprising:

depositing a layer of encapsulation material; and

planarizing the layer of encapsulation material to expose the core layer prior to forming a second cladding layer over the core layer.

16. The method of claim 10 , wherein the encapsulation material comprises a material having a refractive index lower than the refractive index of the core layer.

17. The method of claim 10 , wherein the core layer has a refractive index higher than the refractive index of the first and second cladding layers.

18. The method of claim 10 , wherein the one or more hydrocarbon compounds are selected from the group consisting of propylene (C 3 H 6 ), propyne (C 3 R 4 ), propane (C 3 H 8 ), butane (C4H10), butylene (C 4 H 8 ), butadiene (C 4 H6), acetelyne (C 2 H 2 ), and combinations thereof.

19. The method of claim 10 , further comprising introducing an inert gas into the processing chamber.

20. The method of claim 10 , wherein removing the amorphous carbon hardmask comprises exposing the amorphous carbon hardmask to a plasma of a hydrogen-containing gas or an oxygen containing gas.

21. A method for forming a waveguide structure on a substrate surface, comprising:

forming a cladding layer on the substrate surface;

forming a core layer on the cladding layer;

depositing an amorphous carbon hardmask on the core layer;

forming a patterned photoresist layer on the amorphous carbon hardmask;

etching exposed amorphous carbon hardmask: and

etching exposed core layer, wherein the etch selectivity of amorphous carbon to the core layer is between about 1:8 and about 1:15.

22. The method of claim 21 , further comprising:

removing remaining portions of the amorphous carbon hardmask; and

depositing a cladding material on remaining portions of the core layer and exposed portions of the cladding layer.