Back end of line process integrated optical device fabrication

1. A method of integrated optical device fabrication forming an optical device within a vertical span of a metal stack of an integrated semiconductor chip as part of a back end of line fabrication process, comprising:

providing a substrate with at least one semiconductor device thereon;

depositing a first layer comprising a dielectric over the semiconductor devices;

depositing a second layer comprising a first stop layer on the first layer;

depositing a third layer comprising a dielectric over the first stop layer;

etching a first portion of the third layer down to the first stop layer;

depositing metal in the first portion of the third layer for connection with external contacts;

connecting the metal to one of the at least one semiconductor device or other metal layer;

depositing a fourth layer comprising a second stop layer on the third layer; and

forming a second portion of the third layer into a first waveguide for coupling light to or from the at least one semiconductor device.

2. A method according to claim 1 , further comprising:

depositing a fifth layer comprising a dielectric over the second stop layer;

depositing a sixth layer comprising a third stop layer over the fifth layer;

depositing a seventh layer comprising a dielectric on the third stop layer;

etching a first portion of the seventh layer down to the third stop layer;

depositing metal in the first portion of the seventh layer for connection with external contacts;

connecting the second metal layer to one of the at least one semiconductor device; and

forming a second portion of the seventh layer into a second waveguide;

wherein forming the first and second waveguides comprises forming an edge coupler of a material having a first index of refraction greater than a second index of refraction of an oxide material in the third and seventh layers surrounding the input/output coupler.

3. A method according to claim 2 wherein forming the edge coupler comprises doping the oxide material to form a doped waveguide.

4. A method according to claim 3 wherein doping the oxide material to form the doped waveguide comprises doping utilizing at least one of ion implantation and diffusion and wherein the doping utilizes a material comprising at least one of B, F, Al, Ti, As, P, Er, Ni, Si, Cu, Zn, Ge, N, Zr, Nd, and Yb.

5. A method of integrated optical device fabrication forming an optical device within a vertical span of a metal stack of an integrated semiconductor chip as part of a back end of line fabrication process, comprising:

providing a substrate with at least one semiconductor device thereon;

depositing a first layer comprising a dielectric over the semiconductor devices;

depositing a second layer comprising a first stop layer on the first dielectric layer;

depositing a third layer comprising a dielectric over the first stop layer;

etching a first portion of the third layer down to the first stop layer;

depositing metal in the first portion of the third layer for connection with external contacts;

connecting the metal to one of the at least one semiconductor device or another metal layer;

depositing a fourth layer comprising a second stop layer on the third layer; and

forming a portion of one of the first stop layer and the second stop layer into a first waveguide for coupling light into or out of the at least one semiconductor device.

6. A method according to claim 5 , wherein forming the first stop layer comprises forming one of:

an etch stop layer; and

a chemical mechanical planarization stop layer.

7. A method according to claim 5 , wherein the first and second stop layers comprise at least one of silicon nitride, poly-silicon, and silicon oxynitride (SiON).

8. A method according to claim 5 , further comprising:

depositing a fifth layer comprising a dielectric over the second stop layer; and

depositing material within the fifth layer forming a third waveguide;

wherein at least one of the first and second waveguides form a vertical coupler with the third waveguide within the vertical span of the metal stack.

9. A method according to claim 8 wherein material deposition comprises deposition of at least one of silicon nitride, amorphous silicon, poly-silicon, silicon oxynitride, silicon-germanium (SiGe), SiO 2 , silicate glass, and germanium (Ge).

10. A method according to claim 9 wherein material deposition comprises deposition of a silicate glass comprising SiO 2 , and at least one of P 2 O 5 , B 2 O 3 , F, Al 2 O 3 , As 2 O 3 , GeO 2 , N 2 , TiO 2 , ZrO 2 , Nd 2 O 3 , Er 2 O 3 , and Yb 2 O 3 .

11. The method according to claim 5 , further comprising:

forming a portion of the other of the first stop layer and the second stop layer into a second waveguide for coupling light into or out of the at least one semiconductor device.

12. A method according to claim 11 , wherein the first and second waveguides comprise at least one of silicon nitride, poly-silicon, and silicon oxynitride (SiON), amorphous silicon, silicon-germanium (SiGe), SiO 2 , silicate glass, and germanium (Ge).

13. The method according to claim 11 , further comprising:

depositing a fifth layer comprising a dielectric over the second stop layer;

depositing a sixth layer comprising a third stop layer over the fifth layer; and

forming a third waveguide in a portion of the third stop layer;

wherein at least one of the first and second waveguides forms a vertical coupler with the third waveguide.

14. The method according to claim 13 , wherein the third waveguide comprises an arrayed waveguide grating (AWG).

15. The method according to claim 14 , wherein the AWG is more than 4 micrometers from the at least one semiconductor device.

16. The method according to claim 8 , wherein the third waveguide comprises a multimode interference coupler.

17. The method according to claim 5 , wherein at least one of the first and second waveguide comprises a tapered waveguide.

18. The method according to claim 5 , further comprising forming an edge coupler in another portion of the second stop layer.