Periodic Grating Formation via Atomic Layer Deposition
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Solution Overview
Problem
Current methods for forming patterned structures, such as gratings, struggle to achieve small feature sizes and precise control over optical properties, particularly for optical devices that require manipulation of short-wavelength optical radiation, often resulting in significant diffraction and material inefficiencies.
Innovation Solution
A method involving sequential deposition and etching of layers, using atomic layer deposition and sacrificial layers to form periodic structures with reduced periods, allowing for the creation of small-scale, high-precision gratings without the need for additional sacrificial layers, and enabling the use of various materials for specific optical applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to form patterned structures, then the manufacturing process is simpler, but the feature size cannot be reduced below a certain limit and diffraction increases
Solution Approach 1:
The manufacturing process is divided into multiple sequential steps: forming sacrificial layers with first material, depositing second material layers, selectively removing portions, and repeating the process. This segmentation enables achievement of small feature sizes (periods less than 100 nm) by breaking down the complex task of direct patterning into manageable sequential operations, each contributing to the final high-precision structure.
Solution Approach 2:
Sacrificial layers of first material are formed in advance before the final pattern is created. These preliminary sacrificial structures serve as templates that guide subsequent material deposition and removal steps, enabling precise control over the final pattern geometry and period while reducing diffraction effects.
2Manufacturing precision
If additional sacrificial layers are used to achieve smaller periods, then the manufacturing precision improves, but the material usage and process complexity increase
Solution Approach 1:
The first material layers serve as sacrificial elements that are selectively removed after serving their templating function. This allows the second material to form the final pattern with high precision while the sacrificial material is discarded. The process recovers the benefit of using multiple layers for precision without permanently retaining the additional material, thus controlling material usage efficiency.
Solution Approach 2:
Portions of the first material sacrificial layers are selectively removed to create the final pattern. By extracting only the necessary portions and removing the sacrificial material, the process achieves high period control precision while minimizing the amount of material that remains in the final structure, thereby reducing overall material usage.
3Ease of manufacture
If larger period structures are formed, then the manufacturing is easier, but diffraction effects become significant for short-wavelength optical radiation
Solution Approach 1:
The process enables control of the period parameter to achieve dimensions less than 100 nm, which is sufficiently small to minimize diffraction effects for short-wavelength optical radiation. By changing the period parameter through sequential layer formation and selective removal, the structure achieves both manufacturability and reduced diffraction, resolving the contradiction between ease of manufacture and diffraction control.
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 formation of periodic structures with periods less than 100 nm, reducing diffraction and material usage, while providing precise control over optical properties, suitable for optical devices across different spectral regions.
Implementation Method 1
forming a first layer comprising a first material over a surface of a second layer, wherein forming the first layer includes sequentially forming a plurality of monolayers
Implementation Method 2
Removing portions of the first layer can include etching the first layer. In certain embodiments, the first layer is etched anisotropically.
Implementation Method 3
the rows of the second material are formed by exposing portions of a layer of a resist to radiation to produce an exposure pattern in the layer of the resist
Data Source
AI summary
In general, in a first aspect, the invention features a method that includes forming a first layer comprising a first material over a surface of a second layer, wherein forming the first layer includes sequentially forming a plurality of monolayers of the second material over the surface of the second layer, the second layer comprises a plurality of rows of a second material extending along a first direction and spaced from one another in a second direction orthogonal to the first direction, and the first layer conforms to the surface of the second layer. The method further includes removing portions of the first layer to produce a plurality of rows of the first material extending along the first direction and spaced from one another in the second direction and removing portions of a third layer comprising a third material, where the portions correspond to intervals between the second plurality of rows so that removing the portions forms a plurality of rows of the third material extending along the first direction and spaced apart from one another. The first and second materials are different.