Asymmetric Single Pole Illumination for EUV Lithography
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Solution Overview
Problem
Extreme ultraviolet lithography (EUVL) processes face challenges in achieving high image contrast and accurate pattern placement due to the high absorption of EUV radiation by materials and the resulting 3D mask topography effects, which affect the reproducibility and fidelity of the pattern on semiconductor substrates.
Innovation Solution
The method involves selecting an asymmetric single pole illumination mode for EUV radiation, determining compensation parameters to mitigate disparities such as pattern shift, best focus shift, and defocused pattern shift, and applying these parameters to adjust the lithography process, including modifications to the IC design and photomask features like scattering bars, to enhance image contrast and pattern reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If symmetric illumination modes are used, then pattern placement is simpler to control, but image contrast is reduced and 3D mask topography effects increase
Solution Approach 1:
The patent applies asymmetric illumination modes (single pole, dipole, or higher-order asymmetric configurations) to the EUV lithography system. These asymmetric illumination patterns are specifically designed to counteract the 3D mask topography effects and improve image contrast by creating non-uniform intensity distributions that compensate for the asymmetric scattering and absorption characteristics of the mask structure.
Solution Approach 2:
The patent modifies illumination parameters including the angular distribution, intensity profile, and spatial configuration of the EUV beam. By changing these parameters to create asymmetric illumination patterns, the system achieves improved image contrast and reduced mask topography effects while maintaining control over pattern placement through computational optimization.
2Illumination intensity
If asymmetric illumination modes are used, then image contrast is improved, but pattern shift and focus shift disparities increase
Solution Approach 1:
The patent incorporates computational simulations and feedback mechanisms to predict and compensate for pattern shift and focus shift disparities caused by asymmetric illumination. The system uses simulated imaging data to determine compensation parameters that adjust the illumination pattern or mask design, thereby maintaining pattern placement accuracy while preserving the image contrast benefits of asymmetric illumination.
Solution Approach 2:
The patent performs preliminary computational analysis and simulation to pre-determine compensation parameters before the actual lithography process. By calculating and applying compensation parameters in advance, the system prepares for and mitigates potential pattern shift and focus shift issues, ensuring accurate pattern placement while using asymmetric illumination for improved contrast.
3Manufacturing precision
If compensation parameters are applied to mitigate disparities, then pattern reproducibility is improved, but process complexity increases
Solution Approach 1:
The patent performs preliminary computational simulations and analysis to pre-determine compensation parameters before the lithography process. By calculating optimal compensation values in advance based on simulated imaging data, the system simplifies the actual manufacturing process while achieving improved pattern reproducibility through automated parameter application.
Solution Approach 2:
The system uses self-service computational algorithms that automatically determine and apply compensation parameters based on the specific illumination mode and mask design. This automated approach reduces manual intervention and process complexity while maintaining high pattern reproducibility through consistent application of optimization algorithms.
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 improves image contrast and pattern reproducibility by optimizing the illumination mode and compensation parameters, leading to more accurate and efficient EUVL processes for semiconductor manufacturing.
Implementation Method 1
The EUVL employs scanners using light in the extreme ultraviolet (EUV) region
Implementation Method 2
reflective optics rather than refractive optics is used; a reflective mask is also used
Implementation Method 3
For EUV radiation, all materials are highly absorbing
Data Source
AI summary
A pattern of features of an integrated circuit is provided. A configuration of a pupil of an extreme ultraviolet wavelength radiation beam (also referred to as an illumination mode), is selected. The selected configuration is an asymmetric, single pole configuration. At least one disparity is determined between a simulated imaging using the selected configuration and a designed imaging for the pattern of features. A parameter (also referred to as a compensation parameter) is then modified to address the at least one disparity, wherein the parameter at least one a design feature, a mask feature, and a lithography process parameter. A substrate is then exposed to the pattern of features using the selected configuration and the modified parameter.