EUV Projection Filtering for Zeroth-Order Suppression
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Solution Overview
Problem
Existing lithographic apparatuses face challenges in achieving high contrast and resolution for two-dimensional feature imaging due to the presence of zeroth diffraction order, which complicates interferometric printing, especially with extreme ultraviolet radiation.
Innovation Solution
The use of a projection system with a filter or phase shift mask to suppress the zeroth order portion of the radiation beam, enhancing the intensity of the first order portions for improved imaging by applying phase shifts and destructive interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithographic techniques are used for EUV interferometric printing, then the printing process can be performed with standard equipment, but the resolution and contrast for two-dimensional features are limited due to additional diffraction orders
Solution Approach 1:
The patent extracts and removes the zeroth order diffraction component from the radiation beam using a filter or phase shift mask. This separation allows the zeroth order to be suppressed while maintaining the first order portions that carry the useful imaging information, thereby improving contrast and resolution without adding complex additional systems
Solution Approach 2:
The patent changes the phase or intensity parameters of different diffraction orders through the use of phase shift masks or filters. By applying specific phase shifts (e.g., 180 degrees) or intensity modulation to the zeroth order portion, the system transforms the diffraction pattern to enhance contrast for 2D features while maintaining manufacturing feasibility
2Manufacturing precision
If the intensity of first order portions is increased to improve contrast and resolution, then the printing quality improves, but the overall power input would need to be increased
Solution Approach 1:
The patent applies local quality enhancement by selectively modifying only the zeroth order portion of the radiation beam while leaving the first order portions unchanged or enhanced. The filter or phase shift mask is positioned to affect only specific spatial or angular regions of the beam, allowing contrast improvement in the imaging regions without requiring increased overall power input to the system
3Manufacturing precision
If blocking elements are added to prevent interference between first order portions, then the imaging quality improves, but the device complexity increases
Solution Approach 1:
The patent merges multiple functions into a single integrated filter or phase shift mask structure. This single component simultaneously suppresses the zeroth order diffraction, blocks interference between first order portions, and maintains the desired imaging characteristics, thereby improving imaging quality without proportionally increasing device complexity through multiple separate blocking elements
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 increases the intensity of the first order portions, enabling high contrast, high depth of focus, and high resolution in two-dimensional interferometric printing without increasing overall power input, thereby improving the yield of IC output.
Implementation Method 1
The projection system may be configured to suppress at least a zeroth order portion of the shaped radiation beam
Implementation Method 2
Current lithographic techniques face challenges in achieving high resolution and contrast for two-dimensional features during extreme ultraviolet (EUV) interferometric printing, particularly due to the presence of additional diffraction orders
Implementation Method 3
The projection system may also be configured to direct an unsuppressed portion of the shaped radiation beam towards a substrate to form an image on the substrate according to the one or more 2D features
Data Source
AI summary
Apparatuses and techniques for suppressing a zeroth order portion of a configured radiation beam. In some embodiments, an extreme ultraviolet (EUV) lithographic apparatus for forming an image on a substrate by use of an EUV radiation beam that is configured by a patterning device comprising a pattern of reflective regions and partially reflective regions, wherein the partially reflective regions are configured to suppress and apply a phase shift to a portion of the EUV radiation beam, may include a projection system. The projection system may be configured to suppress a zeroth order portion of a configured EUV radiation beam, and direct an unsuppressed portion of a configured EUV radiation beam towards a substrate to form an image on the substrate.