Semiconductor Optical Waveguide Dummy Pattern Symmetry
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Solution Overview
Problem
The production of silicon optical waveguides requires high processing accuracy due to their high refractive index, leading to sensitive propagation mode changes with core shape variations, making it difficult to achieve desired properties using semiconductor electronic circuit process technology.
Innovation Solution
A semiconductor optical waveguide with a substrate, a semiconductor optical waveguide structure, and a planar region surrounded by dummy patterns arranged symmetrically with respect to a symmetry axis, allowing for precise core width control and phase accuracy through a manufacturing method involving photolithography and etching with a mask featuring periodically arranged dummy patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If silicon optical waveguide is used with high refractive index, then waveguide downsizing is facilitated, but processing accuracy requirement increases significantly
Solution Approach 1:
The patent applies preliminary action by forming dummy patterns in regions where they are not strictly necessary before the main waveguide formation process. These dummy patterns are created during the photolithography step and are subsequently removed in the etching process. This preliminary formation of dummy patterns helps control stress distribution and etching uniformity, thereby achieving the required high processing accuracy for the waveguide core width while maintaining the downsized compact structure enabled by high refractive index materials.
2Stability of the object's composition
If high processing accuracy is required for core width, then propagation mode stability is improved, but device complexity increases
Solution Approach 1:
The patent applies the taking out principle by extracting and removing dummy patterns from the final waveguide structure. These dummy patterns are formed during manufacturing but are not part of the functional waveguide structure. They are removed through selective etching processes, leaving only the necessary waveguide core and cladding regions. This extraction approach simplifies the final device structure while the dummy patterns during formation helped control manufacturing variations for propagation mode stability.
Solution Approach 2:
The patent applies local quality by placing dummy patterns only in specific regions where they provide beneficial stress distribution and etching uniformity control, rather than throughout the entire structure. The dummy patterns are strategically positioned in regions where local stress control is most critical for maintaining propagation mode stability, while being omitted from regions where they would add unnecessary complexity or interfere with the waveguide function.
3Manufacturing precision
If dummy patterns are arranged symmetrically, then core width deviation is suppressed, but manufacturing steps increase
Solution Approach 1:
The patent applies asymmetry in the sense of deliberately creating symmetric dummy pattern arrangements to achieve a specific manufacturing goal. By arranging dummy patterns symmetrically with respect to the waveguide core, the patent creates balanced stress distribution and uniform etching conditions that suppress core width deviations. This symmetric arrangement, while seemingly complex, actually simplifies the manufacturing process by ensuring uniform processing conditions across the wafer, thereby achieving high core width accuracy without requiring complex post-processing adjustments.
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 suppression of deviations in optical waveguide core width, achieving high accuracy in waveguide formation and desired properties, even in regions requiring precise phase control, thus addressing the challenges of high processing accuracy and phase control in silicon optical waveguides.
Implementation Method 1
a core pattern is formed by subjecting the core layer to photolithography and etching using a predetermined mask
Implementation Method 2
a core pattern is formed by subjecting the core layer to photolithography and etching using a predetermined mask
Data Source
AI summary
It is difficult to actualize a semiconductor optical waveguide having desired properties that reflect design even when process technology for a semiconductor electronic circuit is applied as is to the production of a semiconductor optical waveguide.The present invention includes: a substrate; a semiconductor optical waveguide structure arranged on the substrate; a planar region formed around the semiconductor optical waveguide structure on the substrate; and a semiconductor dummy structure that is arranged around the planar region on the substrate and is formed of a plurality of dummy patterns, wherein the semiconductor optical waveguide structure includes a line-symmetric pattern on a plane that is parallel to the substrate; and the plurality of dummy patterns are arranged symmetrically with respect to the symmetry axis of the line-symmetric pattern.