Low loss silicon waveguide and method of fabrication thereof
First Claim
1. A method of fabricating a silicon rib waveguide for a micro-optical device, comprising the steps of:
- providing a silicon-on-insulator structure having a single crystal silicon wafer surface thereof being bonded to a surface of a silicon wafer with a layer of insulative bonding material;
patterning a surface of the single crystal silicon wafer opposite said surface bonded to the surface of the silicon wafer to form at least one silicon rib waveguide, the at least one silicon rib waveguide having a top surface and opposing side walls and end walls; and
forming a silicon nitride cladding layer on said top surface and said opposing side walls and end walls of the at least one silicon rib, said silicon nitride cladding layer having a predetermined thickness.
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Abstract
A silicon rib waveguide that has a silicon nitride cladding layer of predetermined thickness to reduce optical loss of light propagating therethrough. An exemplary embodiment of the waveguide is fabricated by using a silicon-on-insulator structure having a single crystal silicon layer bonded to a silicon wafer with a layer of insulative material. An etch resistant masking layer is deposited on the outer surface of the single crystal silicon layer and patterned to produce vias therein. A RIE etching process is used through the vias in the masking layer to form at least one rib bounded by a pair of parallel trenches. The masking layer is removed and a silicon nitride cladding layer is deposited on the rib side and end walls and on the trenches.
33 Citations
11 Claims
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1. A method of fabricating a silicon rib waveguide for a micro-optical device, comprising the steps of:
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providing a silicon-on-insulator structure having a single crystal silicon wafer surface thereof being bonded to a surface of a silicon wafer with a layer of insulative bonding material;
patterning a surface of the single crystal silicon wafer opposite said surface bonded to the surface of the silicon wafer to form at least one silicon rib waveguide, the at least one silicon rib waveguide having a top surface and opposing side walls and end walls; and
forming a silicon nitride cladding layer on said top surface and said opposing side walls and end walls of the at least one silicon rib, said silicon nitride cladding layer having a predetermined thickness. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A silicon rib waveguide for a micro-optical device, comprising:
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a silicon-on-insulator structure having a single crystal silicon substrate with opposing surfaces, one of said single silicon substrate surfaces being bonded to a silicon wafer by a layer of insulative bonding material;
a rib waveguide formed in the surface of the single crystal silicon substrate opposite the one bonded to the silicon wafer by a Reactive Ion Etching (RIE) process, said rib waveguide having opposing side walls and opposing end walls that serve as facets, said rib waveguide being bounded by a pair of parallel trenches, one trench on each side of the rib waveguide, so that one side wall of each of the trenches is also a respective one of the opposing side walls of the rib waveguide, said rib waveguide side walls and end walls formed by the RIE etching process having a surface roughness; and
a silicon nitride cladding layer deposited on the surfaces of the rib waveguide and trenches, the silicon nitride cladding layer being of the type having a low film stress to minimize strain on said rib waveguide and having a predetermined thickness to reduce the optical loss caused by the roughness of the rib waveguide rib side walls and end walls, the silicon nitride cladding on the rib waveguide end walls that serve as facets provide an anti-reflection coating at said facets.
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Specification