US 7,118,682 B2 · Low loss SOI/CMOS compatible silicon waveguide and method of making the same

Abstract

A method and structure for reducing optical signal loss in a silicon waveguide formed within a silicon-on-insulator (SOI) structure uses CMOS processing techniques to round the edges/corners of the silicon material along the extent of the waveguiding region. One exemplary set of processes utilizes an additional, sacrificial silicon layer that is subsequently etched to form silicon sidewall fillets along the optical waveguide, the fillets thus “rounding” the edges of the waveguide. Alternatively, the sacrificial silicon layer can be oxidized to consume a portion of the underlying silicon waveguide layer, also rounding the edges. Instead of using a sacrificial silicon layer, an oxidation-resistant layer may be patterned over a blanket silicon layer, the pattern defined to protect the optical waveguiding region. A thermal oxidation process is then used to convert the exposed portion of the silicon layer into silicon dioxide, forming a bird's beak structure at the edges of the silicon layer, thus defining the “rounded” edges of the silicon waveguiding structure.

Claims34

Dependent claims

A method of making a low loss optical waveguiding structure disposed on a top surface of a silicon-on-insulator (SOI) wafer comprising a silicon substrate, a buried dielectric layer and a silicon surface waveguiding layer disposed over the buried dielectric layer, the method comprising the steps of:

forming a dielectric layer over at least a portion of the silicon surface waveguiding layer;
forming a silicon waveguiding structure over at least a portion of the dielectric layer, the combination of the contiguous portions of the silicon surface waveguiding layer, the dielectric layer and the silicon waveguiding structure forming an optical waveguiding region, at least one of both the silicon surface waveguiding layer and the silicon waveguiding structure defined as exhibiting at least one right-angled edge in the waveguiding region;
and
rounding the at least one right-angled edge in the optical waveguiding region to reduce optical loss in the optical waveguiding structure by forming a sacrificial silicon layer over the silicon waveguiding structure and processing the sacrificial silicon layer to form rounded edges along the borders of the optical waveguiding region.

1 more element

Dependencies are inferred from the claim text.

Low loss SOI/CMOS compatible silicon waveguide and method of making the same

Life of this patent

Low loss SOI/CMOS compatible silicon waveguide and method of making the same

Life of this patent

Abstract

Claims34