Lithography Support Table Burls and Protrusions for Thermal Management
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Solution Overview
Problem
The use of immersion fluid in lithographic apparatuses introduces heat load issues, leading to non-uniform image formation and thermal expansion/contraction of substrates, which can result in overlay errors and reduced throughput due to the need for additional motors and turbulence in the liquid handling system.
Innovation Solution
A support table with a base surface and protrusions, including burls and elongate raised protrusions, is designed to enhance thermal coupling and gas flow, allowing for improved temperature conditioning and faster clamping/loading of substrates by aligning gaps to form straight gas flow paths, thereby reducing thermal variations and increasing throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If immersion fluid is used in lithographic apparatus, then imaging of smaller features is enabled, but heat load increases causing non-uniform image formation and thermal expansion/contraction of substrates
Solution Approach 1:
The support table is divided into multiple burls distributed across its surface, creating segmented contact points with the substrate. This segmentation allows localized thermal management at each burl contact point while maintaining overall substrate support, addressing the heat load issue without compromising imaging precision
Solution Approach 2:
The burls are positioned at specific locations on the support table to create non-uniform thermal coupling. By strategically placing contact points, the design achieves localized heat dissipation where needed while maintaining thermal stability in other regions, thereby managing the heat load from immersion fluid without affecting overall imaging quality
2Temperature
If substrate is supported by multiple burls, then thermal coupling is enhanced, but gas flow paths become blocked reducing clamping efficiency
Solution Approach 1:
The design incorporates elongate raised protrusions that extend vertically from the base surface between the burls. These protrusions create additional vertical pathways for gas flow while maintaining the horizontal arrangement of burls for thermal coupling, thus resolving the conflict between thermal management and clamping efficiency
Solution Approach 2:
The elongate raised protrusions act as intermediary structures that facilitate gas flow between the burls and the substrate. These protrusions create channels that allow gas to pass through the support table structure, enabling efficient clamping while the burls maintain thermal coupling with the substrate
3Productivity
If elongate raised protrusions are added between burls, then gas flow is improved, but structural complexity increases
Solution Approach 1:
The elongate raised protrusions are integrated into the existing support table structure as a continuation of the burl arrangement. By merging these protrusions with the base table structure rather than adding separate components, the design improves gas flow while minimizing increases in structural complexity
Solution Approach 2:
The elongate raised protrusions serve multiple functions: they provide structural support, create gas flow pathways, and maintain the thermal coupling architecture. This multi-functionality reduces the need for additional separate components, thereby improving gas flow efficiency without proportionally increasing structural complexity
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
The solution effectively reduces thermal expansion/contraction variations across the substrate, enhances heat transfer, and increases the speed of clamping/loading, thus improving the accuracy and efficiency of the lithographic process.
Implementation Method 1
The solution increases thermal coupling between the substrate and the support table, reducing temperature variations and enhancing the throughput of the lithographic apparatus by improving heat transfer
Implementation Method 2
a plurality of elongate raised protrusions separated by gaps, each of the plurality of elongate raised protrusions having a second height above the base surface, wherein the plurality of elongate raised protrusions protrude above the base surface between the burls
Data Source
AI summary
A support table to support a surface of a substrate, wherein the support table includes: a base surface substantially parallel to the surface of the substrate, a plurality of burls protruding above the base surface, each of the burls having a respective distal end and a first height above the base surface, the burls arranged such that, when the substrate is supported by the support table, the substrate is supported by the respective distal ends, and a plurality of elongate raised protrusions separated by gaps, each of the elongate raised protrusions having a second height above the base surface, wherein the elongate raised protrusions protrude above the base surface between the burls, and the second height is less than the first height; wherein the protrusions are arranged such that a plurality of the gaps are aligned to form a straight gas flow path towards an edge of the base surface.