OPTICAL WAVEGUIDE PASSIVATION FOR MOISTURE PROTECTION
In part, in one aspect, the disclosure relates to a method for passivating a waveguide of an optical circuit. The method includes etching a suspended waveguide in the optical circuit; the suspended waveguide having a top surface, a bottom surface, and side surfaces; and covering the top surface and side surfaces of the suspended waveguide with a passivation coating having a thickness that ranges from between about 10 nm to about 20 nm. In one embodiment, the method further includes removing one or more coatings from a portion of the optical circuit. The disclosure also relates to various passivated optical silicon circuit embodiments.
1 . A method for passivating a waveguide of an optical circuit comprising:
etching a suspended waveguide in the optical circuit; the suspended waveguide having a top surface, a bottom surface, and side surfaces; and
covering the top surface and side surfaces of the suspended waveguide with a passivation coating.
2 . The method of claim 1 further comprising removing one or more coatings from a portion of the optical circuit.
3 . The method of claim 2 , wherein the passivation coating is Si 3 N 4 .
4 . The method of claim 3 wherein covering the top surface and side surfaces of the suspended waveguide with a passivation coating comprises applying a Si 3 N 4 coating having a thickness greater than 100 nm and removing a portion of the Si 3 N 4 coating.
5 . The method of claim 1 wherein the optical circuit comprises a stack of a plurality of layers, wherein one of the layers is silicon substrate having a top surface and a bottom surface.
6 . The method of claim 5 further comprising removing a portion of the top surface of the silicon substrate to define a cavity below the suspended waveguide, wherein the suspended waveguide comprises SiO 2 .
7 . The method of claim 5 further comprising removing a portion of the bottom surface of the silicon substrate to define a cavity.
8 . The method of claim 5 further comprising forming a metal heater relative to one or more layers of the suspended waveguide.
9 . The method of claim 5 wherein the passivation coating is a metal oxide, a metal nitride, or a silicon oxynitride.
10 . An optical silicon circuit comprising:
a substrate comprising silicon;
one or more regions of optical waveguide material disposed on the substrate; and
one or more regions of a passivation coating disposed on a top surface and a side surface of the one or more regions of optical waveguide material, wherein optical waveguide material.
11 . The optical silicon circuit of claim 10 wherein the passivation coating comprises Si 3 N 4 .
12 . The optical silicon circuit of claim 10 wherein the passivation coating comprises a silicon nitride, a metal oxide, a metal nitride, or a silicon oxynitride.
13 . The optical silicon circuit of claim 10 wherein optical waveguide material is etched to define one or more cavities.
14 . The optical silicon circuit of claim 10 wherein optical waveguide material is etched to define a suspended waveguide.
15 . The optical silicon circuit of claim 10 further comprising one or more silicon nitride waveguides disposed in the optical waveguide material.
16 . The optical silicon circuit of claim 10 wherein the substrate is silicon-on-insulator wafer having a top surface and a bottom surface.
17 . The optical silicon circuit of claim 16 wherein a portion of either the top surface or the bottom surface of the silicon-on-insulator wafer has been removed to define one or more cavities.
18 . A product made by the process comprising:
etching a suspended waveguide in the optical circuit; the suspended waveguide having a top, bottom and sides; and
covering the top and sides of the suspended waveguide with a passivation coating.
19 . The product made by the process of claim 18 further comprising removing a coating from a portion of the optical circuit.
20 . The product made by the process of claim 18 wherein the passivation coating comprises Si 3 N 4 .
21 . The product made by the process of claim 18 wherein the passivation coating comprises a silicon nitride, a metal oxide, a metal nitride, or a silicon oxynitride.