Binary Superimposed Grating Fabrication via Pitch Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional binary superimposed gratings suffer from distortion and inconsistent feature sizes due to minimum feature size constraints and aspect-ratio dependent etching, leading to spectral line shifts and broadening, compromising device performance.
Innovation Solution
Designing grating patterns with uniform feature widths or depths, where feature placement is determined by the positions of local minima or maxima of a superposition function, allowing for sub-nanometer precision in placement rather than relying on minimum feature size accuracy, and using advanced lithography tools like electron-beam lithography for precise feature formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional binary superimposed grating design is used with minimum feature size constraints, then fabrication is simplified, but spectral line accuracy deteriorates due to pattern distortion and feature size variation
Solution Approach 1:
The invention changes the design parameter from minimum feature size to feature pitch, allowing features to be spaced closer together while maintaining acceptable lithography resolution. This enables accurate spectral line positioning without requiring extremely small feature sizes, thus resolving the contradiction between fabrication simplicity and spectral accuracy.
Solution Approach 2:
Instead of designing gratings with uniform feature sizes and accepting pitch variation, the invention inverts the approach by specifying uniform pitch and allowing feature size to vary. This inversion enables precise spectral line positioning through controlled pitch while compensating for lithography limitations through adjusted feature dimensions.
2Manufacturing precision
If feature size is reduced to achieve higher spectral resolution, then spectral line accuracy improves, but lithography resolution requirements become more stringent and fabrication difficulty increases
Solution Approach 1:
The invention changes the critical design parameter from feature size to feature pitch. By controlling pitch rather than absolute feature size, the system achieves high spectral resolution without requiring lithography tools to resolve extremely small features, thus reducing device complexity while maintaining precision.
Solution Approach 2:
The invention moves the design constraint from one dimension (feature size) to another dimension (feature pitch). This dimensional shift allows the system to achieve the same spectral resolution goal through a different physical parameter that is more amenable to conventional lithography capabilities.
3Productivity
If aspect-ratio dependent etching is present in the fabrication process, then etching speed varies with feature width, but this causes variable etch depth and inconsistent effective index compromising device performance
Solution Approach 1:
The invention applies local quality by allowing feature size to vary locally while maintaining uniform pitch. Features in different locations can have different dimensions optimized for their specific position, compensating for aspect-ratio dependent etching effects and ensuring uniform etch depth and consistent effective index across the grating structure.
Data Source
AI summary
According to embodiments of the invention, the design and fabrication of a binary superimposed grating (BSG) results in better performing devices that may be fabricated using existing technology. The fabrication process includes forming grating features based upon repeating features of the desired superposition function. The design process also relaxes the processing requirement for equivalently performing devices.