Lithographic Substrate Support Burls for Slip Reduction
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Solution Overview
Problem
In lithographic apparatuses, local slip between the mirror block and the substrate table during high acceleration movements can lead to incorrect substrate positioning and exposure errors, affecting the throughput and accuracy of the manufacturing process.
Innovation Solution
A substrate support system is introduced, featuring a substrate table and a support block with elongate elements and burls that are designed to maintain precise contact and alignment, minimizing slip by defining the distance between their surfaces based on the combined heights of these elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the substrate table is clamped to the chuck via vacuum or electrostatic forces, then the substrate can be held in position, but during high acceleration movements local slip may occur between the chuck and substrate table leading to positioning errors
Solution Approach 1:
The contact interface between the chuck and substrate table is segmented into multiple discrete contact points through the array of elongate elements. This segmentation distributes the clamping force across multiple locations, preventing localized slip while maintaining overall positional accuracy during high acceleration movements.
Solution Approach 2:
The elongate elements provide enhanced local contact quality at specific points along the interface between chuck and substrate table. By concentrating contact at these strategically positioned elements rather than across a continuous surface, the design optimizes friction and adhesion locally to prevent slip during acceleration while maintaining global positioning stability.
2Productivity
If higher accelerations are applied to move the substrate faster, then throughput is improved, but slip between chuck and substrate table increases causing exposure errors
Solution Approach 1:
The array of elongate elements is pre-configured on the chuck surface before substrate placement. This preliminary arrangement ensures that when the substrate table is clamped and subsequent high acceleration movements occur, the contact points are already optimally positioned to maintain grip and prevent slip, enabling both high throughput and precision.
Solution Approach 2:
The elongate elements act as intermediary contact structures between the chuck and substrate table. These intermediaries enhance the mechanical interface by providing dedicated contact points that mediate the transfer of forces during acceleration, preventing direct slip between the main surfaces while enabling high-speed operation.
3Stability of the object's composition
If the distance between chuck and substrate table surfaces is increased, then flexibility and accommodation of deformations are improved, but contact stability and positioning precision may be compromised
Solution Approach 1:
The contact interface is transitioned from a two-dimensional continuous surface contact to a one-dimensional array of discrete linear elements. This dimensional change allows the interface to accommodate deformations and flexibility needs while maintaining precise positioning through the defined distance relationship between the elongate elements and burls.
Solution Approach 2:
The distance parameter between the chuck and substrate table surfaces is explicitly defined and controlled based on the combined heights of the elongate elements and burls. By changing and controlling this critical parameter, the design achieves optimal balance between interface flexibility and alignment precision, ensuring both stability and measurement accuracy.
Data Source
AI summary
A substrate support is provided for a lithographic apparatus. The support comprises a substrate table constructed to hold a substrate and a chuck for the substrate table. In operation, the substrate table is supported by the chuck and clamped thereto. The substrate support comprises a first set of burls on a surface of the support block for abutting against the substrate table during the clamping and a second set of burls on a surface of the substrate table for abutting against the support block during the clamping.