Fluid Handling Structure for Immersion Lithography Disturbance Reduction
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Solution Overview
Problem
In immersion lithographic systems, disturbances such as vibrations are transmitted through the immersion liquid, affecting the accuracy and stability of the exposure process, leading to errors in positioning and focusing.
Innovation Solution
A fluid handling structure with a surface featuring a plurality of fluid extraction openings is used to define a meniscus by removing a mixture of immersion liquid and gas from the immersion space, with each opening having an area less than or equal to 0.1 mm² and a maximum dimension less than or equal to 0.4 mm, reducing disturbance forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If immersion liquid is used to fill the space between the projection system and substrate, then imaging resolution is improved, but disturbance forces and vibrations are transmitted through the liquid affecting positioning and focusing accuracy
Solution Approach 1:
The patent extracts the harmful disturbance forces from the immersion liquid by introducing a fluid handling structure with extraction openings. This structure selectively removes the liquid from regions where it generates harmful vibrations and disturbances, while maintaining the liquid in regions where it provides beneficial imaging resolution enhancement.
Solution Approach 2:
The immersion liquid space is segmented into different functional zones using the fluid handling structure. The extraction openings are strategically positioned to create distinct regions: one where liquid is present for high-resolution imaging and another where liquid is removed to minimize disturbance forces and vibrations.
2Productivity
If scan speed is increased to improve productivity, then throughput is improved, but turbulence and droplet formation in the immersion liquid increase causing defects
Solution Approach 1:
The fluid handling structure extracts excess immersion liquid that would otherwise form droplets and create turbulence during high-speed scanning. By continuously removing liquid through the extraction openings, the system maintains stable liquid levels and prevents droplet formation even at increased scan speeds.
3Productivity
If fluid extraction openings are made larger to improve fluid removal efficiency, then liquid extraction is improved, but disturbance forces and vibrations increase affecting exposure accuracy
Solution Approach 1:
The fluid extraction function is segmented into multiple small openings rather than one or few large openings. This segmentation allows efficient fluid removal through the collective effect of many small holes, while each individual small opening generates minimal disturbance forces and vibrations.
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 fluid handling structure significantly reduces disturbance forces, enhancing the accuracy and stability of the exposure process by maintaining a stable meniscus and allowing for increased scan speeds without droplet or bubble formation, thus improving the overall precision of the lithographic apparatus.
Implementation Method 1
fluid extraction openings configured to define, in use, a meniscus of an immersion liquid in an immersion space by removing a mixture of (i) immersion liquid from the immersion space and (ii) gas from an atmosphere outside the immersion liquid
Implementation Method 2
each have an area less than or equal to 0.1 mm²... significantly reduces disturbance forces, enhancing the accuracy and stability of the exposure process
Data Source
AI summary
A fluid handling structure is disclosed in which the size and arrangement of the fluid extraction openings is specified in order to reduce the vibrations which are transmitted to the fluid handling structure as a result of two-phase extraction. The area of each fluid extraction opening and/or the total area of all of the fluid extraction openings and/or the space in between neighboring fluid extraction openings may be controlled. The reduction in vibrations increases the accuracy of the exposure.