Monolithic CMOS-Photonics Integration via Segmented Fabrication
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Solution Overview
Problem
The integration of CMOS structures with large-μm waveguide structures in photonics is challenging, limiting feature sizes, topologies, and materials, especially when using CMOS or Bi-CMOS fabrication processes, which restricts the development of high-density communications and increases power consumption and packaging costs.
Innovation Solution
A method for fabricating an integrated structure using both CMOS and photonics lines, where photonics components, such as waveguides, are fabricated in the photonics line and CMOS components are fabricated in the CMOS line, allowing for ultra-high integration densities and optical IO without high-speed electrical traces, using techniques like etching cavities, depositing oxide layers, and epitaxial growth to create inverted waveguides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If CMOS or Bi-CMOS fabrication processes are used to integrate photonics components, then manufacturing compatibility is improved, but waveguide feature sizes are limited and material selection is restricted
Solution Approach 1:
The fabrication process is segmented into two separate lines: a CMOS line for manufacturing CMOS components and a photonics line for manufacturing photonic components. This segmentation allows each line to be optimized independently, enabling the photonics line to produce large-μm waveguides with diverse materials while the CMOS line maintains its manufacturing advantages
Solution Approach 2:
A transfer mechanism serves as an intermediary between the photonics line and CMOS line, enabling the physical transfer of silicon wafers between the two fabrication lines. This intermediary allows the integration of components from both lines into a single integrated structure without compromising the specialized capabilities of either line
2Device complexity
If photonics components are fabricated using CMOS line equipment, then manufacturing simplicity is improved, but waveguide size and topology flexibility deteriorate
Solution Approach 1:
The fabrication system is divided into two independent lines with specialized equipment: the CMOS line for CMOS components and the photonics line for photonic components including large-μm waveguides. This segmentation eliminates the constraint of using limited CMOS equipment for all components, allowing the photonics line to manufacture waveguides with larger sizes and more diverse topologies
3Productivity
If monolithic integration of photonics and CMOS is achieved, then integration density is improved, but manufacturing flexibility deteriorates
Solution Approach 1:
The monolithic integration is achieved through a segmented approach where different components are manufactured in specialized lines before being combined. The photonics line manufactures photonic components with optimized features, the CMOS line manufactures CMOS components, and both are integrated onto a single silicon wafer, achieving high integration density while preserving manufacturing flexibility
Solution Approach 2:
The wafer transfer mechanism acts as an intermediary that enables the combination of components from separate fabrication lines into a single integrated structure. This allows the system to achieve monolithic integration benefits while maintaining the manufacturing flexibility of having separate specialized production lines
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
This approach enables the creation of larger, more stable waveguides with lower loss and broader bandwidth capabilities, reducing power consumption and packaging costs while enabling high-density communications and digital processing.
Implementation Method 1
epitaxial growth to create inverted waveguides
Implementation Method 2
depositing oxide layers
Data Source
AI summary
A method for fabricating an integrated structure, using a fabrication system having a CMOS line and a photonics line, includes the steps of: in the photonics line, fabricating a first photonics component in a silicon wafer; transferring the wafer from the photonics line to the CMOS line; and in the CMOS line, fabricating a CMOS component in the silicon wafer. Additionally, a monolithic integrated structure includes a silicon wafer with a waveguide and a CMOS component formed therein, wherein the waveguide structure includes a ridge extending away from the upper surface of the silicon wafer. A monolithic integrated structure is also provided which has a photonics component and a CMOS component formed therein, the photonics component including a waveguide having a width of 0.5 μm to 13 μm.