Self-Aligned Spot Size Converter via Simultaneous Etching
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Solution Overview
Problem
Existing methods for fabricating optical waveguides and spot size converters often result in alignment errors between the waveguide and the spot size converter, leading to inefficiencies in fiber-optic communication systems due to separate fabrication processes.
Innovation Solution
A method involving simultaneous etching of crystalline and non-crystalline semiconductor regions using a shared etch mask to form both the waveguide and the spot size converter, ensuring alignment and allowing for early testing and defect detection in the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If separate fabrication processes are used for waveguide and spot size converter, then manufacturing flexibility is maintained, but alignment errors occur between the waveguide and spot size converter
Solution Approach 1:
The patent combines the fabrication of the waveguide and spot size converter into a single simultaneous etching process using a shared etch mask. This merging of previously separate fabrication steps eliminates alignment errors between the two components while maintaining process manageability through unified process control.
Solution Approach 2:
The patent performs the etching of both the waveguide and spot size converter structures in advance during the same fabrication stage, using a common etch mask that defines both structures. This preliminary simultaneous action ensures precise alignment is built into the structure from the outset rather than requiring subsequent alignment corrections.
2Reliability
If simultaneous etching is used to form waveguide and spot size converter, then alignment errors are reduced, but process complexity increases
Solution Approach 1:
The patent employs a universal etch mask that serves multiple functions: it defines both the waveguide structure and the spot size converter structure in a single mask layer. This multi-functional mask simplifies the overall process by eliminating the need for separate masks and multiple alignment steps, despite the simultaneous etching of multiple structures.
3Loss of time
If separate fabrication processes are used, then process flexibility is maintained, but defect detection is delayed
Solution Approach 1:
The patent performs defect detection early in the fabrication process, immediately after the simultaneous etching of both waveguide and spot size converter structures. This early detection approach allows identification of alignment or structural defects before subsequent fabrication steps, preventing waste of additional process steps on defective structures.
Data Source
AI summary
An optical device comprises a substrate, a waveguide disposed on the substrate, and a spot size converter (SSC) disposed on the substrate. The waveguide comprises a shoulder and a ridge. The SSC comprises a shoulder and a ridge. The ridge of the waveguide is aligned to a first stage of the ridge of the SSC. The waveguide is made of a first material. The shoulder and the ridge of the SSC are made of a second material. The second material is different from the first material.