Lithographic Support Table Gas Flow Paths
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Solution Overview
Problem
The existing support tables for lithographic apparatuses face challenges in increasing throughput while maintaining thermal coupling between the substrate and the support table, as thermal rings or elongate raised protrusions can restrict gas flow, leading to slower clamping and loading times and potential substrate deformation due to non-uniform thermal expansion.
Innovation Solution
The support table design incorporates elongate raised protrusions arranged to form parallel gas flow paths, increasing the proportion of the base surface area covered by these paths to enhance gas evacuation efficiency without compromising thermal conductivity, thereby reducing substrate loading time and preventing deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If thermal rings or elongate raised protrusions are used to increase thermal coupling between substrate and support table, then thermal coupling is improved, but gas flow is restricted leading to slower clamping and loading times
Solution Approach 1:
The support table surface is segmented into multiple elongate raised protrusions distributed across the base surface. These protrusions create multiple discrete thermal contact points with the substrate while leaving gaps between them that form gas flow paths, thus segmenting the thermal conduction paths to maintain both thermal coupling and gas flow capability
Solution Approach 2:
The elongate raised protrusions are strategically positioned at specific locations on the support table base surface. By controlling the local distribution, height, and dimensions of these protrusions, the design achieves enhanced thermal coupling at contact points while preserving gas flow paths in the gaps between protrusions, resolving the contradiction between thermal performance and clamping speed
2Stability of the object's composition
If elongate raised protrusions are used to enhance thermal coupling, then thermal expansion uniformity is improved, but substrate deformation risk increases due to non-uniform thermal expansion
Solution Approach 1:
The design carefully controls parameters of the elongate raised protrusions including their height, width, spacing, and distribution pattern. By optimizing these parameters, the system achieves uniform thermal coupling across the substrate while minimizing localized thermal hotspots that could cause non-uniform thermal expansion and substrate deformation
3Productivity
If gas flow paths are increased to improve clamping speed, then loading time is reduced, but thermal coupling between substrate and support table is compromised
Solution Approach 1:
The solution moves from a two-dimensional flat support surface to a three-dimensional structure with elongate raised protrusions. This dimensional change creates vertical separation between thermal contact points (at the protrusion tops) and gas flow paths (in the gaps below), allowing both functions to operate simultaneously without interference
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 design improves the throughput of the lithographic apparatus by decreasing gas evacuation time and maintaining effective thermal coupling, reducing the risk of substrate deformation and ensuring uniform thermal expansion.
Implementation Method 1
maintaining effective thermal coupling
Implementation Method 2
enhance gas evacuation efficiency
Implementation Method 3
preventing deformation... ensuring uniform thermal expansion
Data Source
Figure 1
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Figure 5~6
AI summary
A support table having: a base surface configured to be substantially parallel to a lower surface of a substrate, a plurality of burls each having a respective distal end and a first height above the base surface, the burls arranged to support the substrate by the respective distal ends, and a plurality of elongate raised protrusions protruding above the base surface, each elongate raised protrusion having a second height above the base surface that is less than the first height. The base surface has a plurality of regions within each of which some of the elongate raised protrusions are located. All of the elongate raised protrusions located within each region have substantially the same direction of elongation such that they are substantially parallel to each other so as to form between the elongate raised protrusions at least one gas flow path substantially parallel to the elongate raised protrusions.