Skeleton Representation for Lithographic Mask Layouts
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Solution Overview
Problem
As integrated circuit designs become larger, denser, and more complex, the computational demands for lithographic mask development increase due to smaller, non-rectilinear features and more complex illumination sources, making traditional polygon-based representations less efficient and more computationally intensive.
Innovation Solution
The use of skeleton representations for mask layouts, which include nodes connected by edges with size parameters, provides a more compact and computationally efficient way to represent and manipulate mask layouts, reducing computation resources and speeding up processes like optical proximity correction and inverse lithography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional polygon-based representations are used for mask layouts, then manufacturing precision can be maintained, but computational complexity and processing time increase significantly
Solution Approach 1:
The patent segments the mask layout into discrete feature elements and represents them using skeleton structures rather than continuous polygon boundaries. Each feature is decomposed into skeleton nodes and edges with associated size parameters, enabling independent processing of individual features while maintaining overall layout precision. This segmentation reduces the computational burden by breaking down complex polygon representations into simpler, more manageable skeletal components.
Solution Approach 2:
The patent changes the representation parameters from traditional polygon vertex coordinates to skeleton-based parameters including node positions, edge lengths, and size parameters. This parameter transformation allows the same manufacturing precision to be achieved with fewer parameters and simpler mathematical operations, thereby reducing computational complexity while maintaining the ability to accurately represent curvilinear and non-rectilinear features.
2Productivity
If skeleton representations are used for mask layouts, then computational efficiency improves, but representation complexity increases
Solution Approach 1:
The patent transitions from two-dimensional polygon boundary representations to a hybrid representation that incorporates skeletal structures with explicit size parameters. This dimensional transformation allows the system to capture both the spatial arrangement (via skeleton nodes and edges) and the dimensional characteristics (via size parameters) of features, achieving computational efficiency without sacrificing representational completeness.
Solution Approach 2:
Instead of representing features by their outer boundaries (traditional approach), the patent inverts the representation by using skeleton structures that represent the core geometry and derive boundary information from size parameters. This inversion simplifies computational operations while maintaining the ability to reconstruct accurate feature boundaries when needed, thereby improving computational efficiency without significantly increasing representation complexity.
3Manufacturing precision
If more features are included on masks to increase circuit density, then manufacturing precision improves, but processing time and computational resources increase
Solution Approach 1:
The patent applies segmentation by representing each feature on the mask as an independent skeleton structure with its own nodes, edges, and size parameters. This allows features to be processed individually and in parallel, significantly reducing the time required to handle masks with large numbers of features. The segmented representation enables efficient computation of optical proximity effects and other lithographic simulations for each feature without the computational overhead of processing entire polygon layouts.
4Manufacturing precision
If curvilinear shapes are used on masks, then manufacturing precision improves, but simulation difficulty and computational intensity increase
Solution Approach 1:
The patent inverts the traditional approach by representing curvilinear features through skeleton structures that capture the essential geometry, rather than using detailed polygon approximations of curved boundaries. The size parameters associated with skeleton elements enable accurate representation of curvilinear shapes while simplifying the mathematical models required for simulation. This inversion reduces simulation complexity by replacing complex boundary-based calculations with simpler skeleton-based computations.
Data Source
AI summary
In certain embodiments, a method includes the following steps. A layout used in a lithographic mask development process is accessed. For example, the layout may be the layout of the mask itself, or it may be the layout of the resulting printed pattern on the wafer. The layout includes a number of disjoint shapes. Skeleton representations for at least some of the disjoint shapes in the layout are determined. The skeleton representation of an individual shape has elements of two or more nodes connected by edges. It also includes size parameters for at least some of the elements. The skeleton representations of the shapes are used in the mask development process.