Trimming Silicon Refractive Index via Ion Implantation and Laser Annealing
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Solution Overview
Problem
Current methods for trimming the refractive index of silicon optical device structures, such as in Mach-Zehnder Interferometers, face limitations in achieving significant changes due to variations in processing techniques, leading to issues like incorrect chemical detection and cross-talk, and require methods that can be applied to pre-fabricated semiconductor devices with integrated electronic structures.
Innovation Solution
The method involves ion implantation to alter the crystal form and introduce lattice defects or amorphization, followed by local heat treatment, specifically using laser annealing, to adjust the refractive index of silicon materials, allowing for a greater change in refractive index and improved performance compared to polymer-based approaches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polymer-based trimming methods are used, then the refractive index can be adjusted, but the change in refractive index is limited to around 0.04
Solution Approach 1:
The patent changes the physical-chemical parameters of the silicon material by introducing lattice defects through ion implantation and controlling annealing conditions, enabling refractive index changes up to 0.4 - an order of magnitude greater than polymer-based methods. This transforms the material properties directly rather than using external polymer layers.
Solution Approach 2:
The patent utilizes phase transitions of silicon between crystalline and amorphous states through controlled ion implantation and thermal annealing. By manipulating these phase transitions, the refractive index can be precisely adjusted over a wide range, overcoming the limitations of polymer-based approaches.
2Productivity
If conventional processing techniques are used, then mass production is enabled, but variations at chip and wafer level cause device failure
Solution Approach 1:
The patent applies local quality by performing selective ion implantation and localized annealing on specific regions of the chip using masks and focused laser beams. This allows individual device trimming without affecting other components, enabling post-fabrication adjustment to compensate for manufacturing variations while maintaining mass production benefits.
Solution Approach 2:
The patent performs preliminary characterization of manufacturing variations during fabrication, then applies compensatory trimming adjustments in subsequent processing steps. This preliminary identification and correction approach ensures device reliability while maintaining production efficiency.
3Manufacturing precision
If ion implantation and oven annealing are used, then refractive index can be changed, but the method cannot be applied to pre-fabricated devices with integrated electronic structures
Solution Approach 1:
The patent segments the annealing process into localized regions using masks and focused laser beams, allowing selective heat treatment of specific device areas without affecting the entire chip or surrounding electronic structures. This enables application to pre-fabricated devices with integrated electronics.
Solution Approach 2:
The patent replaces the mechanical oven annealing system with a localized laser heating system. This substitution enables precise spatial control of the thermal process, allowing refractive index adjustment in specific regions without requiring removal of the device from its integrated electronic environment.
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 method enables a refractive index change of up to an order of magnitude greater than polymer-based methods, enhancing device performance and yield, while being applicable to pre-fabricated semiconductor devices with integrated electronic structures.
Implementation Method 1
implanting one or more first regions of material of one or more pre-fabricated devices, encompassing at least partially one or more device structures, with ions to alter the crystal form of the material within the one or more first regions
Implementation Method 2
heat treating one or more second regions of material of the one or more devices, encompassing at least partially the one or more first regions, to alter the crystal form of the material within the one or more first regions encompassed by the one or more second regions
Implementation Method 3
the step of heat treating the one or more second regions at least partially removes the introduced lattice defects within the material of the one or more first regions
Data Source
AI summary
A method of trimming the refractive index of material forming at least part of one or more structures integrated in one or more pre-fabricated devices, the method comprising: implanting one or more first regions of material of one or more pre-fabricated devices, encompassing at least partially one or more device structures, with ions to alter the crystal form of the material within the one or more first regions and change the refractive index of the material within the one or more first regions; and heat treating one or more second regions of material of the one or more devices, encompassing at least partially the one or more first regions, to alter the crystal form of the material within the one or more first regions encompassed by the one or more second regions and change the refractive index thereof, thereby trimming the refractive index of the material of at least part of the one or more device structures, such that the one or more device structures provide one or more predetermined device outputs.