EUV Lithography Mask Shadowing Correction via DDM
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Solution Overview
Problem
EUV lithography systems face challenges in correcting the mask shadowing effect due to non-telecentricity and mask topography, leading to asymmetric pattern widening and critical area bias, which conventional rule-based methods fail to address effectively, especially for complex geometric patterns.
Innovation Solution
The domain decomposition method (DDM) is employed to simulate and correct the mask shadowing effect by determining DDM signals for various azimuthal angles of illumination, processing layout designs to obtain aerial image intensities, edge placement errors, and mask displacement, using edge-based DDM signals and interpolation techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional rule-based compensation methods are used, then the correction process is simple and fast, but the correction accuracy is insufficient for complex geometric patterns and does not account for azimuthal angle dependence
Solution Approach 1:
The patent transforms the mask shadowing correction problem from a spatial domain problem to a frequency domain problem by using Fourier transforms. The DDM signals are computed in the frequency domain, allowing for efficient calculation of aerial image intensities while accurately capturing the azimuthal angle dependence of the shadowing effect across different spatial frequencies.
Solution Approach 2:
The patent replaces the traditional spatial-domain rigorous modeling approach with a frequency-domain computational method. By using Fourier transforms and computing in the frequency domain, the system achieves both computational efficiency and high accuracy for complex geometric patterns, substituting the mechanical calculation approach with a mathematical transformation approach.
2Manufacturing precision
If rigorous modeling methods are used, then the correction accuracy is high, but the computational cost is expensive and impractical for many applications
Solution Approach 1:
The patent replaces the computationally intensive spatial-domain rigorous modeling with a frequency-domain computational approach using Fourier transforms. This substitution maintains high correction accuracy for complex geometric patterns while dramatically reducing computational cost, making the method practical for production environments.
Solution Approach 2:
The patent changes the computational domain from spatial to frequency domain, transforming the problem parameters. By computing DDM signals and aerial image intensities in the frequency domain, the system achieves rigorous modeling accuracy with significantly improved computational efficiency, as frequency-domain operations are more efficient for this type of periodic illumination problem.
Data Source
AI summary
Disclosed are techniques for simulating and correcting the mask shadowing effect using the domain decomposition method (DDM). According to various implementations of the invention, DDM signals for an extreme ultraviolet (EUV) lithography mask are determined for a plurality of azimuthal angles of illumination. Base on the DDM signals, one or more layout designs for making the mask may be analyzed and/or modified.