CMOS Compatible Silicon Dielectric Optical Waveguide Coupler
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Solution Overview
Problem
Integrated semiconductor devices face challenges in coupling optical signals between optical fibers and silicon waveguides due to index and mode-profile mismatches, and fabricating polymer couplers for encapsulated photonic devices is complex, especially in CMOS-compatible processes.
Innovation Solution
The method involves depositing a silicon-based dielectric with a refractive index matching that of optical fibers into trenches on semiconductor dies, using chemical mechanical polishing to form efficient optical couplers that are compatible with CMOS processes, allowing for thermal treatment, electrical activation, and three-dimensional integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If polymer couplers are used to minimize coupling losses, then coupling efficiency is improved, but fabrication complexity increases
Solution Approach 1:
The patent changes the material parameter from polymer to silicon-based dielectric, which has a refractive index matching optical fibers. This material substitution maintains low coupling loss while enabling compatibility with standard CMOS fabrication processes, thereby reducing fabrication complexity
Solution Approach 2:
The patent uses silicon-based dielectric material that is homogeneous with the existing CMOS semiconductor substrate. This material homogeneity allows the coupler to be fabricated using the same CMOS process steps without requiring separate polymer deposition and processing, simplifying the overall fabrication
2Loss of energy
If polymer couplers are fabricated for encapsulated photonic devices, then coupling efficiency is improved, but process compatibility worsens
Solution Approach 1:
The patent changes the material composition parameter from organic polymer to inorganic silicon-based dielectric. This parameter change enables the coupler to withstand high-temperature encapsulation and annealing processes required in CMOS fabrication, achieving full process compatibility while maintaining low coupling loss
Solution Approach 2:
The silicon-based dielectric coupler serves multiple functions: it provides optical mode matching, withstands CMOS processing temperatures, and can be fabricated using standard CMOS deposition and etching tools. This multi-functionality eliminates the need for separate polymer processing steps
3Productivity
If conventional semiconductor fabrication techniques are used, then manufacturing efficiency is improved, but optical coupling performance worsens
Solution Approach 1:
The patent optimizes the refractive index parameter of the dielectric material to match that of optical fibers. By carefully controlling the silicon-based dielectric composition and deposition conditions, the coupler achieves optimal optical coupling performance while being fabricated using efficient conventional CMOS processes
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 reduces coupling losses, simplifies fabrication, and enables efficient integration of photonic devices with CMOS circuits, facilitating effective optical signal transfer and thermal management.
Implementation Method 1
depositing, into at least a portion of the trench, a silicon based dielectric that includes at least a portion with a refractive index substantially equal to a section of optical fiber
Implementation Method 2
The method also include etching the at least one layer to the chemical polishing stop layer, by a chemical mechanical polishing process after the depositing the silicon based dielectric
Data Source
AI summary
An optoelectronic circuit fabrication method and integrated circuit apparatus fabricated therewith. Integrated circuits are fabricated with an integral optical coupling transition to efficiently couple optical energy from an optical fiber to an integrated optical waveguide on the integrated circuit. Layers of specific materials are deposited onto a semiconductor circuit to support etching of a trench to receive an optical coupler that performs proper impedance matching between an optical fiber and an on-circuit optical waveguide that extends part way into the transition channel. A silicon based dielectric that includes at least a portion with a refractive index substantially equal to a section of the optical fiber is deposited into the etched trench to create the optical coupler. Silicon based dielectrics with graded indices are also able to be used. Chemical mechanical polishing is used finalize preparation of the optical transition and integrated circuit.