Slanted Nanostructure Lithography With Offset Alternating Layers
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Solution Overview
Problem
The existing methods for forming nanostructures on waveguides are challenging due to difficulties in accurately controlling the size and profile of slanted nanostructures, often requiring over-etching which can damage the substrate and result in inconsistent thickness or width.
Innovation Solution
A method involving multiple alternating layers of different materials on a transparent substrate, where each layer is offset from adjacent layers, allowing for precise control of nanostructure formation using lithography tools, enabling the creation of slanted nanostructures with controlled angles from 0° to 90°, and maintaining substrate integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If ion beams are used to etch nanostructures at a slanted angle, then the nanostructures can be formed with a slanted profile, but the angle is difficult to control and over-etching is required which may remove portions of the substrate
Solution Approach 1:
The patent divides the etching process into multiple sequential steps, each creating a portion of the final slanted profile. Instead of attempting to create the entire slanted structure in one etching step, the method segments the formation into multiple controlled etching operations with intermediate deposition steps, allowing precise control over the final angle and dimensions without requiring excessive material removal.
Solution Approach 2:
The patent performs preliminary deposition of sacrificial material layers before the final etching steps. These pre-deposited layers serve as temporary structures that guide the etching process and define the slanted profile. The sacrificial materials are strategically placed to control the etch front, enabling precise angle formation before the sacrificial materials are removed.
2Manufacturing precision
If over-etching is performed to ensure consistent nanostructure dimensions, then each nanostructure can have uniform thickness, but portions of the substrate may be inadvertently removed
Solution Approach 1:
The patent introduces sacrificial material layers as intermediary elements that mediate between the etching process and the substrate. These sacrificial materials act as protective intermediaries that define the etch boundaries and prevent the etching process from reaching the substrate. The sacrificial layers are removed after serving their protective function, leaving the desired nanostructure profile without substrate damage.
Solution Approach 2:
The patent deposits sacrificial material layers beforehand to cushion and protect the substrate during the etching process. These pre-positioned sacrificial layers absorb the excessive etching that would otherwise damage the substrate, allowing the etch process to proceed without risking substrate removal. The sacrificial materials are strategically placed to provide this protective cushioning effect.
3Ease of manufacture
If conventional single-layer deposition is used, then the process is simple, but it is difficult to accurately control the formation of nanostructures with consistent dimensions
Solution Approach 1:
The patent employs composite structures consisting of multiple alternating layers of different materials (sacrificial materials and structural materials) to achieve precise nanostructure formation. By combining materials with different etch selectivities and deposition properties, the method enables accurate control over nanostructure dimensions while maintaining a relatively straightforward sequential deposition process.
Solution Approach 2:
The patent transitions from conventional single-layer planar deposition to multi-layer stratified deposition, adding the dimension of vertical layering to the manufacturing process. This dimensional change allows precise control over nanostructure formation by utilizing the vertical stacking of sacrificial and structural materials, enabling accurate dimensional control that cannot be achieved with simple single-layer deposition.
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 allows for the accurate and efficient formation of slanted nanostructures with controlled angles and dimensions, reducing substrate damage and improving the consistency of nanostructure formation, enhancing the precision and reliability of waveguide fabrication.
Implementation Method 1
depositing a first layer of a first material on a first surface of a transparent substrate... and depositing a first layer of a second material in the one or more trenches
Implementation Method 2
A method involving multiple alternating layers of different materials is used, where each layer is deposited and etched to form slanted nanostructures with controlled angles using lithography tools
Implementation Method 3
etching sidewalls of each first remaining portion to smooth the sidewalls to form the plurality of slanted nanostructures
Data Source
AI summary
The present disclosure generally relates to methods of forming optical devices comprising nanostructures disposed on transparent substrates. A first process of forming the nanostructures comprises depositing a first layer of a first material on a glass substrate, forming one or more trenches in the first layer, and depositing a second layer of a second material in the one or more holes to trenches a first alternating layer of alternating first portions of the first material and second portions of the second material. The first process is repeated one or more times to form additional alternating layers over the first alternating layer. Each first portion of each alternating layer is disposed in contact with and offset a distance from an adjacent first portion in adjacent alternating layers. A second process comprises removing either the first or the second portions from each alternating layer to form the plurality of nanostructures.