Optical Lithography Mask Design for Directed Self-Assembly
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Solution Overview
Problem
Current methods for designing optical lithography masks lack the necessary precision and optimization for directed self-assembly processes, limiting the ability to extend optical lithography beyond its resolution limits and achieve precise pattern formation in semiconductor fabrication.
Innovation Solution
A method involving computer-aided design to generate mask shapes that incorporate sub-resolution assist features and prepattern shapes, using directed self-assembly materials to form precise patterns on substrates, which includes evaluating the fidelity and lithographic exposure latitude of various prepattern shapes to select the most effective ones for achieving target design specifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional optical lithography is used for pattern formation, then the process is simple and widely applicable, but the resolution limit is reached at approximately 22 nm and cannot be extended further
Solution Approach 1:
The lithography process is segmented into two distinct stages: (1) forming a prepattern using conventional optical lithography, and (2) directing self-assembly to create the final high-resolution pattern. This segmentation allows each stage to operate within its own resolution limits, with the self-assembly stage achieving sub-22nm precision independently of optical diffraction constraints.
Solution Approach 2:
A prepattern serves as an intermediary structure that guides the self-assembly process. The prepattern is formed by conventional lithography and acts as a template or mediator that directs the self-assembling materials to form the final high-resolution pattern, thereby extending lithography's effective resolution beyond its physical limits.
2Manufacturing precision
If prepattern design is optimized for lithographic printing, then the printing process is straightforward, but the resulting patterns lack precision for sub-22nm features
Solution Approach 1:
The prepattern design parameters are specifically adjusted to account for the self-assembly process characteristics. This includes modifying features such as corner notches, line widths, and spacing to optimize the self-assembly outcome, thereby achieving precise sub-22nm pattern placement while maintaining manufacturability through systematic parameter optimization.
3Manufacturing precision
If existing mask design methods are used, then the design process is simple, but the patterns produced have high variation and poor fidelity to target designs
Solution Approach 1:
The mask design process incorporates feedback mechanisms where simulation results are used to iteratively refine the prepattern design. This feedback loop allows the design to be optimized based on predicted self-assembly outcomes, achieving high pattern fidelity while managing complexity through automated simulation and optimization tools.
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 precise via patterns with reduced variation and improved placement accuracy, extending the resolution of optical lithography and enhancing the printing capabilities of sub-resolution features in semiconductor fabrication.
Implementation Method 1
the photoresist layer and the prepattern opening are coated with a self-assembly material that undergoes directed self-assembly to form a directed self-assembly pattern
Data Source
AI summary
A method and a computer system for designing an optical photomask for forming a prepattern opening in a photoresist layer on a substrate wherein the photoresist layer and the prepattern opening are coated with a self-assembly material that undergoes directed self-assembly to form a directed self-assembly pattern. The methods includes: generating a mask design shape from a target design shape; generating a sub-resolution assist feature design shape based on the mask design shape; using a computer to generate a prepattern shape based on the sub-resolution assist feature design shape; and using a computer to evaluate if a directed self-assembly pattern of the self-assembly material based on the prepattern shape is within specified ranges of dimensional and positional targets of the target design shape on the substrate.