Multi-Pass Lithography Using Non-Reflecting Radiation on Gratings
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Solution Overview
Problem
Current lithography techniques, such as EUV lithography, face challenges in achieving high fidelity and throughput for patterning small feature sizes due to low power sources and poor pattern fidelity, while multi-pass patterning using underlying gratings suffers from low pattern fidelity and a small process window, making it costly and difficult to achieve reliable manufacturing.
Innovation Solution
The use of non-reflecting radiation lithography on an underlying grating pattern, where a resist layer is exposed within the trenches of the grating pattern to form enhanced exposure portions, allowing for self-aligned pattern formation without the need for anti-reflective layers, thereby improving pattern fidelity and reducing processing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If EUV lithography is used to pattern structures, then higher photospeed and lower power requirements are achieved, but pattern fidelity deteriorates due to shot noise from low photon counts
Solution Approach 1:
The patent forms an underlying grating pattern before applying the resist layer to be exposed. This pre-formed grating structure serves as a template that guides the subsequent resist exposure, allowing the resist to be patterned with higher fidelity by conforming to the pre-established grating geometry rather than relying solely on direct lithographic exposure with limited photons.
Solution Approach 2:
The underlying grating pattern acts as an intermediary between the lithographic exposure and the final pattern formation. The grating structure mediates the patterning process by providing a physical template that enhances the fidelity of the resist pattern, bridging the gap between low-photon EUV exposure and high-fidelity pattern formation.
2Length of moving object
If multi-pass patterning techniques using underlying gratings are used to achieve smaller pattern structures, then feature size is reduced, but pattern fidelity and process window deteriorate
Solution Approach 1:
The patent segments the patterning process into distinct stages: first forming an underlying grating pattern, then applying and exposing a resist layer over it, and finally developing the resist to reveal the pattern. This segmentation allows each stage to be optimized independently, with the grating providing structural guidance and the resist providing fine pattern definition, thereby maintaining high fidelity at small feature sizes.
Solution Approach 2:
The patent adds a vertical dimension to the patterning approach by forming a three-dimensional structure where the resist layer is deposited over and conforms to the underlying grating pattern. This vertical stacking approach enables smaller feature sizes while maintaining pattern fidelity, as the vertical conformance to the grating template provides self-alignment and reduces lateral placement errors.
3Length of moving object
If multi-pass patterning techniques using underlying gratings are used, then smaller pattern structures are achieved, but device complexity and manufacturing cost increase due to scumming and planarization requirements
Solution Approach 1:
The patent extracts and eliminates the complex scumming and planarization steps from the multi-pass patterning process. By using a simplified approach where the resist layer is directly exposed and developed over the underlying grating without requiring additional scumming layers or planarization steps, the method reduces process complexity while still achieving smaller pattern structures with high fidelity.
4Ease of manufacture
If conventional lithography is used to achieve smaller feature sizes, then manufacturing simplicity is maintained, but resolution and depth of focus are insufficient
Solution Approach 1:
The underlying grating pattern provides self-alignment and self-definition for the resist layer, eliminating the need for complex alignment procedures and additional process steps. The resist layer automatically conforms to the grating structure during deposition and exposure, providing self-service alignment that maintains manufacturing simplicity while achieving higher resolution and depth of focus than conventional lithography alone.
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 enhances pattern fidelity, reduces defect density, and increases the depth of focus, providing broader process windows and improved resolution, enabling the creation of sub-resolution features that are not attainable with conventional methods, such as vias smaller than 20 nm or lines/trenches smaller than 11 nm half-pitch.
Implementation Method 1
exposing the resist layer with non-reflecting radiation to generate an enhanced exposure portion of the resist layer within at least one trench of the grating pattern
Data Source
AI summary
Techniques related to multi-pass patterning lithography, device structures, and devices formed using such techniques are discussed. Such techniques include exposing a resist layer disposed over a grating pattern with non-reflecting radiation to generate an enhanced exposure portion within a trench of the grating pattern and developing the resist layer to form a pattern layer having a pattern structure within the trench of the grating pattern.