Optical Interconnect Structure for FEOL-BEOL Waveguide Coupling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing BEOL-compatible integration approaches for optoelectronic devices are limited by device thicknesses of a few hundred nanometers, leading to high series resistances and modal losses, and require increased epitaxial effort, which are not suitable for advanced CMOS processing.
Innovation Solution
An integrated optoelectronic device with a substrate, FEOL and BEOL waveguides, and an optical interconnect structure comprising a vertical stack of optically coupled waveguide elements with higher refractive index than the embedding material, allowing efficient coupling over large vertical distances, up to 10 μm, and enabling integration of III-V semiconductor lasers with thicknesses of about 3 μm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If direct coupling between photonic components and silicon-on-insulator waveguides is used, then device thickness is limited, but integration of active photonic components is restricted and series resistances increase
Solution Approach 1:
The patent introduces an optical interconnect structure as an intermediary component between the silicon-on-insulator waveguide and the active photonic component (III-V semiconductor laser). This interconnect structure includes a vertical stack of dielectric waveguide elements that bridge the gap between the SOI waveguide and the laser, enabling coupling over distances exceeding 10 μm without requiring direct contact. The intermediary structure resolves the contradiction by allowing both thick active components and efficient optical coupling to coexist.
2Length of moving object
If direct coupling between photonic components and silicon-on-insulator waveguides is used, then device thickness is limited, but modal losses increase
Solution Approach 1:
The optical interconnect structure serves as a mediator that maintains low modal losses while enabling thick device design. The vertical stack of dielectric waveguide elements is designed to support supermodes that efficiently couple light from the SOI waveguide to the active photonic component, minimizing energy loss during transmission through the intermediate coupling region.
3Adaptability or versatility
If thicker photonic components are integrated, then design options expand, but series resistances and modal losses increase
Solution Approach 1:
The optical interconnect structure acts as an intermediary that enables thick photonic component integration without proportionally increasing losses. By distributing the coupling function across multiple dielectric waveguide elements in a vertical stack, the structure maintains efficient optical coupling while accommodating thicker active components with diverse design options.
Solution Approach 2:
The optical interconnect structure is segmented into multiple dielectric waveguide elements arranged in a vertical stack. This segmentation allows the coupling function to be distributed across several layers, reducing the burden on any single interface and enabling thicker overall device design while maintaining low modal losses through the segmented coupling path.
4Ease of manufacture
If direct coupling is used, then fabrication is simpler, but device thickness is limited to a few hundred nanometer
Solution Approach 1:
The optical interconnect structure serves as a manufacturable intermediary that bridges the SOI waveguide and active photonic component. The vertical stack of dielectric waveguide elements can be fabricated using standard semiconductor processing techniques, making the approach practical for industrial manufacturing while enabling device thicknesses of several micrometers rather than being limited to sub-micrometer scales.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design expands design options for photonic components, reduces series resistances, and minimizes modal losses, facilitating the integration of active and passive photonic components in BEOL processing without FEOL contamination risks.
Implementation Method 1
an optical interconnect structure that comprises a vertical stack of optically coupled waveguide elements
Implementation Method 2
forming and sustaining supermodes across the waveguide elements
Data Source
AI summary
An integrated optoelectronic device comprises a substrate with a silicon layer comprising one or more electronic components. An interconnect stack comprising a plurality of metal levels is arranged on the substrate. A front-end-of-line (FEOL) optical waveguide on the substrate has an optical FEOL coupling section. A photonic component is arranged in the interconnect stack at a distance from the substrate. A back-end-of-line (BEOL) optical waveguide in the interconnect stack is optically coupled to the photonic component and has an optical BEOL coupling section. An optical interconnect structure is configured for optically coupling radiation from the BEOL coupling section into the FEOL coupling section and vice versa. The optical interconnect structure comprises a stack of wave-guide elements made of a first dielectric material, which each are embedded in a second dielectric material and which in a desired wavelength range have an index of refraction higher than the second dielectric material.