Grating Couplers with Multi-Layered Cladding
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Solution Overview
Problem
Grating couplers in semiconductor structures suffer from limited coupling efficiency due to additional reflection induced by nitride cladding, which reduces the overall performance of photonic devices.
Innovation Solution
The implementation of a multi-layered cladding structure with alternating materials or a single material layer with a grating pattern directly on the back end of line (BEOL) multilayer stack, optimizing the cladding configuration to minimize reflection and enhance constructive or destructive interference for improved light coupling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-layer SiN top cladding is used, then the structure is simple and easy to manufacture, but the coupling efficiency is limited due to additional reflection induced by the nitride cladding
Solution Approach 1:
The single-layer SiN cladding is segmented into multiple layers with different materials (e.g., SiN, SiO2, air gaps) arranged in a multilayer stack. This segmentation allows each layer to contribute differently to light management, reducing overall reflection while maintaining manufacturability through standard deposition processes.
Solution Approach 2:
The cladding structure transitions from a single material (SiN) to a composite multilayer stack comprising different materials with varying refractive indices. This composite structure enables tailored optical properties that minimize reflection across the operating bandwidth while preserving ease of manufacture using conventional semiconductor fabrication techniques.
2Adaptability or versatility
If grating couplers are designed for broad bandwidth operation, then versatility is improved, but coupling efficiency decreases due to the dispersive operating principle
Solution Approach 1:
The patent employs parameter changes in the cladding layer configuration (thickness, material composition, refractive index) to optimize the interference conditions across a broad wavelength range. By adjusting these parameters, the structure maintains high coupling efficiency while supporting broad bandwidth operation, resolving the trade-off between versatility and efficiency.
Solution Approach 2:
The grating structure utilizes periodic modulation combined with the multilayer cladding to create constructive interference conditions that are robust across different wavelengths. This periodic action, when combined with the optimized cladding stack, enables broad bandwidth operation without sacrificing coupling efficiency.
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 results in high-efficiency tunable grating couplers with reduced reflection, enhancing the coupling efficiency of photonic devices, including Si photonics and other technologies, by leveraging constructive and destructive interference.
Implementation Method 1
enhancing the coupling efficiency of photonic devices, including Si photonics and other technologies, by leveraging constructive and destructive interference
Implementation Method 2
optimizing the cladding configuration to minimize reflection and enhance constructive or destructive interference for improved light coupling efficiency
Implementation Method 3
Grating couplers are commonly used in integrated optics for coupling light between integrated on-chip photonic waveguide structures and optical fibers
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to grating couplers with structured cladding and methods of manufacture. A structure includes: a grating coupler in a dielectric material; a back end of line (BEOL) multilayer stack over the dielectric material; and a multi-layered cladding structure of alternating materials directly on the BEOL multilayer stack.