Mixed Silicon-Silicon Nitride Waveguide Layer for Dense Photonic Integration
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Solution Overview
Problem
Current methods for manufacturing photonic components with silicon and silicon nitride waveguides require stacking multiple layers, which is complex and limits integration density, as there is no efficient process for creating a mixed layer with both waveguide types in a single layer.
Innovation Solution
A method involving chemical mechanical polishing and selective etching to create a mixed layer with silicon and silicon nitride waveguides in a single layer, allowing for the production of III-V semiconductor photonic components with improved integration density and simplified manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If three different layers are stacked to manufacture silicon and silicon nitride waveguides, then the waveguides can be produced, but the manufacturing process becomes complex and integration density is limited
Solution Approach 1:
The patent merges the production of silicon waveguides and silicon nitride waveguides into a single mixed layer instead of using separate stacked layers. This is achieved by depositing a silicon nitride layer over a silicon layer, then selectively removing portions to create waveguides of both materials in the same layer, thereby simplifying the manufacturing process and improving integration density
Solution Approach 2:
The patent segments the mixed layer into different regions: areas where silicon waveguides are formed by removing the silicon nitride layer, areas where silicon nitride waveguides are formed by removing the silicon layer, and areas where both materials coexist. This segmentation allows both waveguide types to be produced in a single layer while maintaining their distinct structures
2Manufacturing precision
If chemical mechanical polishing is used on a thick silicon nitride layer, then planarization can be achieved, but the process cannot be stopped precisely when the underlying silicon oxide layer is exposed
Solution Approach 1:
The patent applies a thin silicon nitride etch stop coating to the silicon layer before depositing the thick silicon nitride layer. This preliminary action creates a protective layer that prevents the chemical mechanical polishing process from removing the underlying silicon oxide, allowing precise control of the polishing depth and enabling the polishing to stop exactly when the etch stop coating is reached
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 simplifies the manufacturing process and enhances integration density by enabling the simultaneous production of silicon and silicon nitride waveguides in a single layer, improving the performance and integration of photonic components.
Implementation Method 1
there is no simple method for chemical-mechanical polishing a thick layer of silicon nitride covering the majority of the outer face of a substrate
Implementation Method 2
A method involving chemical mechanical polishing and selective etching to create a mixed layer with silicon and silicon nitride waveguides
Data Source
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AI summary
This manufacturing method comprises: - producing (144) a trench, in an encapsulated silicon layer, at the location where a silicon nitride core of the waveguide should be produced, then - depositing (150) a layer of silicon nitride on the encapsulated silicon layer, the thickness of the deposited silicon nitride layer being sufficient to completely fill the trench, then - removing (160) the silicon nitride located outside the trench in order to expose an upper face with which the trench filled with silicon nitride is flush, then - depositing (170) a layer of dielectric material which covers the exposed upper face in order to finalise the encapsulation of the silicon nitride core and thus obtain a mixed layer containing both silicon and silicon nitride cores encapsulated in the dielectric material.