Patterning Device Design Optimization for Lithography Overlay
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In lithographic processes, accurately positioning substrates relative to radiation beams and patterning devices is challenging due to substrate distortion and variations in overlay alignment between successive layers, which affects the consistency and quality of patterned layers on integrated circuits.
Innovation Solution
Determining topographic information and imaging error data to optimize the design of patterning devices and illumination parameters, allowing for precise placement of metrology targets and improving the accuracy of pattern projection onto substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If substrate distortion is monitored and compensated using grid models, then overlay alignment accuracy is improved, but measurement and modeling complexity increases
Solution Approach 1:
The patent applies preliminary action by determining topographic information of the substrate before lithographic exposure and using this information to adapt the patterning device design in advance. This allows imaging error information to be identified and compensated for before actual patterning, improving overlay alignment without requiring complex real-time measurement and adjustment systems during exposure.
Solution Approach 2:
The patent uses copying by creating a model of the substrate topography and using this model to predict and compensate for imaging errors. Instead of directly measuring and correcting each substrate during exposure, a representative topographic model is created and used to adapt the patterning device design, simplifying the overall measurement and control process.
2Measurement precision
If the patterning device design is adapted based on imaging error information, then imaging accuracy is improved, but design and manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by adapting the patterning device design specifically to compensate for imaging errors at different locations across the substrate. Instead of uniform compensation, the design is locally optimized based on position-specific topographic information, allowing high imaging accuracy without requiring complete redesign of the entire patterning device.
Solution Approach 2:
The patent uses parameter changes by modifying patterning device parameters such as illumination angles, focus settings, or pattern geometry based on determined imaging error information. These parameter adjustments compensate for topography-induced errors without requiring fundamental changes to the patterning device structure, balancing improved imaging accuracy with manageable design complexity.
Data Source
AI summary
A method includes determining topographic information of a substrate for use in a lithographic imaging system, determining or estimating, based on the topographic information, imaging error information for a plurality of points in an image field of the lithographic imaging system, adapting a design for a patterning device based on the imaging error information. In an embodiment, a plurality of locations for metrology targets is optimized based on imaging error information for a plurality of points in an image field of a lithographic imaging system, wherein the optimizing involves minimizing a cost function that describes the imaging error information. In an embodiment, locations are weighted based on differences in imaging requirements across the image field.