Scattering Bar Rule Selection for Lithography Resolution
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Solution Overview
Problem
Existing scattering bar rules for lithography are not adaptable to diverse layout patterns, leading to resolution differences between sparse and dense patterns, necessitating additional techniques like OPC to mitigate these differences, and risk enlarged defocus and loss of exposure latitude.
Innovation Solution
A method for automatically simulating aerial images using diverse scattering bar rules and selecting optimal rules for specific patterns by establishing image simulation models, generating simulation images, screening candidate layouts, and determining the corresponding scattering bar rule based on screening and selection criteria to ensure consistent printing results across varying process conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If scattering bar is applied to mask layouts sensitive to defocus variation, then focus latitude problem is resolved, but scattering bar risks printing out and exposure latitude is lost
Solution Approach 1:
The patent applies parameter changes by systematically varying scattering bar parameters (width, space, length) and evaluating their impact on aerial images through simulation. This allows optimization of scattering bar dimensions to prevent printing while maintaining focus latitude, resolving the contradiction between improving focus latitude and preserving exposure latitude.
2Ease of manufacture
If scattering bar rule is determined by collecting empirical data, then scattering bar rule is established, but it cannot be simply applied to diversified layout patterns and resolution differences remain
Solution Approach 1:
The patent implements local quality by creating layout-specific scattering bar rules through classification of different layout patterns (sparse, dense, isolated, connected). Each pattern type receives customized scattering bar parameters determined through aerial image simulation, ensuring optimal performance for each local layout context rather than applying a single global rule.
Solution Approach 2:
The patent applies dynamics by developing a flexible rule generation system that adapts scattering bar parameters based on the specific characteristics of each layout pattern. The system dynamically selects and generates appropriate scattering bar rules through automated classification and simulation, rather than using static empirical data for all patterns.
3Manufacturing precision
If scattering bar produces more dense proximity in sparse layout environments, then focus latitude is improved, but scattering bar risks printing out on the wafer
Solution Approach 1:
The patent applies preliminary action by performing aerial image simulation and evaluation before finalizing the scattering bar rule. The system predicts whether scattering bars will print out based on simulated aerial images and adjusts parameters in advance to prevent printing, while still achieving the desired focus latitude improvement.
Solution Approach 2:
The patent uses copying by creating virtual copies of the mask pattern with proposed scattering bars and simulating their aerial images. This allows evaluation of potential printing issues without actually fabricating the pattern, enabling safe optimization of scattering bar parameters.
Data Source
AI summary
A method for establishing a scattering bar rule for a mask pattern for fabricating a device is provided. The method is described as follows. First, at least one image simulation model is established according to the mask pattern and a process reference set used for fabricating the device based on the mask pattern. Next, a plurality of scattering bar reference sets is applied to the image simulation model so as to generate a plurality of simulation images, respectively. Further, a portion of the simulation images are selected to be a plurality of candidate layouts according to a screening criterion. Next, one of the candidate layouts is determined to be a pattern layout according to a selection rule, and the scattering bar reference set corresponding to the pattern layout is determined to be a scattering bar rule of the mask pattern.