Buried Alignment Fiducials for Automated Waveguide Mounting
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Solution Overview
Problem
Traditional methods for mounting waveguides to substrates in optical packages are not well-suited for automated processes due to tight alignment tolerances (+/−5 μm) and require manual alignment using microscopes, which can lead to misalignment issues in high-volume manufacturing.
Innovation Solution
The use of buried alignment fiducials on the substrate, which are formed in the substrate's metal layer and made visible through a dielectric layer, allows for precise alignment of waveguides with optoelectronic chips using machine vision systems, enabling optimal alignment without relying on adjacent substrate features like solder pads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manual alignment using microscope and micropositioner is used, then alignment precision can be achieved, but productivity decreases and the process cannot be automated
Solution Approach 1:
The patent replaces the manual mechanical alignment system (microscope and micropositioner) with an automated machine vision system that uses optical fields and image processing to detect and align waveguides, enabling high-speed automated manufacturing while maintaining precision
Solution Approach 2:
The patent creates a digital copy of the waveguide position through machine vision imaging, allowing the system to detect and measure waveguide locations automatically without requiring manual visual inspection and physical adjustment
2Ease of operation
If adjacent substrate features like solder pads are used for alignment, then alignment can be performed, but alignment accuracy deteriorates due to limited microscope viewing range
Solution Approach 1:
The patent extracts the alignment function from adjacent substrate features (solder pads) and implements dedicated alignment fiducial markers that are specifically designed for machine vision detection, providing superior alignment accuracy
Solution Approach 2:
The patent introduces alignment fiducial markers as intermediary reference features between the substrate and waveguide, which are optimized for machine vision detection and provide more accurate alignment references than solder pads
3Manufacturing precision
If multiple substrate features are selected for alignment in X and Y directions, then alignment can be achieved, but process complexity increases due to requiring movement of viewing area
Solution Approach 1:
The patent merges the alignment reference features into a single integrated fiducial marker structure that provides both X and Y direction alignment references simultaneously, eliminating the need to move the viewing area between directions
Data Source
AI summary
Methods and apparatus to mount an optical waveguide to a substrate are disclosed. A disclosed method involves providing a substrate having a first layer and a second layer. The first layer includes at least one alignment fiducial and the second layer covers the at least one fiducial. At least a portion of the second layer is removed to render the fiducial visible and a waveguide is automatically aligned with the first fiducial. The waveguide is then fixed to the substrate.