Photonic semiconductor device and method of manufacture

1 . A method comprising:

forming a first redistribution structure on a first substrate;

forming a waveguide structure on a second substrate, wherein the waveguide structure comprises a plurality of waveguides in a plurality of dielectric layers, wherein the waveguide structure is free of metal features;

bonding the waveguide structure to the first redistribution structure using dielectric-to-dielectric bonding;

removing the second substrate;

after removing the second substrate, forming a plurality of metal features in the waveguide structure;

forming a second redistribution structure on the waveguide structure; and

connecting a photonic package to the second redistribution structure, wherein the photonic package is optically coupled to the plurality of waveguides.

2 . The method of claim 1 further comprising performing a thermal treatment process on the waveguide structure before bonding the waveguide structure to the first redistribution structure.

3 . The method of claim 2 , wherein the thermal treatment comprises an anneal temperature greater than 1000° C.

4 . The method of claim 1 , wherein the plurality of waveguides are silicon nitride waveguides.

5 . The method of claim 1 , wherein the second redistribution structure is electrically connected to the waveguide structure.

6 . The method of claim 1 , wherein forming the plurality of metal features comprises forming through vias in the first substrate, wherein the through vias are electrically connected to the first redistribution structure.

7 . The method of claim 6 further comprising connecting the first substrate to an interconnect substrate, wherein the through vias are electrically connected to the interconnect substrate.

8 . The method of claim 1 , wherein the photonic package is connected to the second redistribution structure by solder bumps.

9 . A method comprising:

forming a first interposer, comprising:

forming a plurality of first waveguides over a first substrate;

forming a first dielectric layer over the plurality of first waveguides;

after forming the first dielectric layer, annealing the plurality of first waveguides; and

bonding the first dielectric layer to a first redistribution structure; and

connecting a die to the first interposer, wherein the die is electrically coupled to the first redistribution structure and optically coupled to the plurality of first waveguides.

10 . The method of claim 9 , wherein forming the first interposer further comprises forming a second redistribution structure over the plurality of first waveguides.

11 . The method of claim 9 , wherein the first redistribution structure comprises a plurality of second waveguides.

12 . The method of claim 11 , wherein the plurality of first waveguides has a smaller optical transmission loss than the plurality of second waveguides.

13 . The method of claim 9 , wherein the plurality of first waveguides comprise silicon nitride.

14 . The method of claim 9 , wherein connecting the die to the first interposer comprises bonding the die to the interposer using dielectric-to-dielectric bonding and metal-to-metal bonding.

15 . The method of claim 9 further comprising connecting the first interposer to an organic core substrate, wherein the first interposer is electrically connected to the organic core substrate.

16 . The method of claim 15 further comprising connecting a second interposer to the organic core substrate, wherein the second interposer is electrically connected to the organic core substrate, wherein the second interposer is laterally adjacent the first interposer.

17 . A package comprising:

an interconnect structure, wherein the interconnect structure comprises:

a first metallization layer on a substrate, the first metallization layer comprising at least one first conductive line;

a first bonding layer over the first metallization layer;

a second bonding layer bonded to the first bonding layer;

a waveguide layer on the second bonding layer, the waveguide layer comprising at least one waveguide, wherein at least one waveguide of the waveguide layer overlaps at least one first conductive line of the first metallization layer; and

a second metallization layer over the waveguide layer, wherein the second metallization layer is electrically connected to the first metallization layer through the first bonding layer and the second bonding layer;

and

a first device over the second metallization layer, wherein the first device comprises a photonic component that is optically coupled to the waveguide layer, wherein the first device is electrically connected to the second metallization layer.

18 . The package of claim 17 further comprising a second device over the second metallization layer and adjacent the first device, wherein the second device is electrically connected to the second metallization layer.

19 . The package of claim 17 , wherein the waveguide layer and the substrate have coplanar sidewalls.

20 . The package of claim 17 , wherein the first metallization layer is within a first dielectric layer, wherein the first dielectric layer and the first bonding layer are different materials.