Direct Writing Shot Count Reduction via Elementary Shape Removal
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Solution Overview
Problem
Current direct-writing lithography techniques, such as electron beam lithography, face challenges in reducing the number of elementary shapes required for pattern transfer, leading to long and expensive writing operations due to fragmented patterns and sub-resolution features, especially in advanced photolithography masks.
Innovation Solution
A method that identifies and removes selected elementary shapes based on predetermined rules and compensates for their removal, ensuring changes to the pattern remain within a tolerance envelope, thereby reducing the number of shots needed for pattern transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pattern is fractured into elementary shapes for direct writing, then the pattern transfer can be performed, but the number of shots increases significantly leading to long and expensive writing operations
Solution Approach 1:
The patent extracts and removes selected elementary shapes from the fractured pattern that contribute minimally to the final pattern fidelity. By identifying and eliminating redundant shapes based on proximity effects and pattern criticality, the shot count is reduced without significantly compromising pattern accuracy, thereby decreasing writing time while maintaining productivity.
Solution Approach 2:
The patent applies different treatment strategies to different regions of the pattern based on local characteristics. Critical regions with tight tolerances retain all necessary elementary shapes, while non-critical regions undergo aggressive shape removal. This localized quality control allows shot count reduction in less sensitive areas without affecting overall pattern fidelity, thus reducing writing time while preserving essential pattern features.
2Manufacturing precision
If OPC treatments are applied to advanced photolithography masks, then pattern accuracy is improved, but the patterns become highly fragmented increasing the number of shots required
Solution Approach 1:
After OPC treatment creates highly fragmented patterns, the patent applies a second stage of elementary shape removal that specifically targets shapes generated by OPC that are below critical dimensions or in non-critical regions. This extracts redundant complexity introduced by OPC while preserving the essential correction features, thereby maintaining pattern accuracy while reducing shot count to improve writing speed.
Solution Approach 2:
The patent performs preliminary analysis of the OPC-treated pattern to identify regions where elementary shapes can be removed before actual writing. By pre-processing the pattern data to eliminate obviously redundant shapes created by OPC fragmentation, the system prepares an optimized pattern set that maintains OPC benefits for accuracy while reducing the shot count burden on the writing system.
3Loss of time
If the number of elementary shapes is reduced to decrease writing time, then writing cost is reduced, but pattern accuracy may be compromised
Solution Approach 1:
The patent implements a feedback mechanism where the impact of removing each elementary shape is evaluated based on proximity effects, pattern criticality, and local feature density. The system uses this feedback to make intelligent decisions about which shapes can be safely removed without compromising pattern accuracy. This feedback-driven approach ensures that shot count reduction does not come at the expense of manufacturing precision.
Solution Approach 2:
The patent dynamically adjusts the criteria for elementary shape retention based on local pattern parameters such as feature size, spacing, and critical dimension requirements. In regions with tight tolerances, the system maintains stricter shape retention criteria, while in less critical regions, it applies more aggressive reduction. This parameter-based adaptive approach balances writing time reduction with pattern accuracy maintenance.
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 simplifies the pattern transfer process, achieving a more precise and cost-effective shot-count reduction by focusing on the physics of direct writing and allowing for easier integration with existing techniques, while maintaining accuracy within defined tolerances.
Implementation Method 1
reference 20 to an electron beam source, reference 21 to an electron beam generated by said source and impinging onto the resist layer
Implementation Method 2
the forward- and back-scattering resulting from the interactions of the electrons with the resist and the substrate
Data Source
Figure 1~3
Figure 2
Figure 4
AI summary
A method for transferring a fractured pattern (210, 310), decomposed into elementary shapes, onto a substrate by direct writing by means of a particle or photon beam, comprising a step of identifying at least one elementary shape (2000) of the fractured pattern, called removable elementary shape, whose removal induces modifications of the transferred pattern within a preset tolerance envelope; - a step of removing said removable shape or shapes from the fractured pattern, to obtain a modified fractured pattern (220, 230) ; and - an exposure step, comprising exposing the substrate to a plurality of shots of a shaped particle or photon beam, each shot corresponding to an elementary shape of said modified fractured pattern. A computer program product for carrying out such a method.