Immersion Lithography Liquid Extraction Conduits
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Solution Overview
Problem
Existing immersion lithography systems face challenges in controlling the level of immersion liquid between the barrier member, projection system, and substrate, leading to undesirable variations in liquid level and potential errors or damage in the extraction process.
Innovation Solution
A lithographic apparatus with a liquid extraction system that uses a passage subjected to suction flow and a plurality of conduits arranged at different distances from the center of the image field to remove liquid, allowing for controlled liquid level management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a liquid supply system provides liquid on a localized area of the substrate using a liquid confinement system, then the liquid level can be maintained in the exposure area, but the extraction capacity becomes independent of the liquid level leading to undesirable variations
Solution Approach 1:
The extraction system is segmented into multiple independent conduits (first conduit and second conduit) positioned at different locations. This segmentation allows each conduit to independently respond to liquid level changes, enabling the extraction capacity to vary with liquid level while maintaining stable extraction through the combined effect of multiple conduits.
Solution Approach 2:
The invention adds a spatial dimension to the extraction system by positioning conduits at different heights or depths. The first conduit is positioned to extract liquid at a higher level while the second conduit extracts at a lower level, creating a multi-level extraction architecture that enables liquid level-dependent extraction capacity.
2Productivity
If the substrate is scanned beneath the projection system in immersion lithography, then pattern transfer is achieved, but turbulence in the liquid causes unpredictable effects
Solution Approach 1:
The invention extracts excess liquid from the system through dedicated extraction conduits positioned near the liquid supply inlet. By continuously removing excess liquid at the source, the system prevents turbulence generation while maintaining the necessary liquid flow for immersion lithography operation.
Solution Approach 2:
The extraction conduits act as intermediary elements between the liquid supply system and the exposure area. They mediate the liquid flow by providing a controlled extraction path that prevents direct turbulence in the exposure region while still allowing substrate scanning to proceed.
3Quantity of substance
If a barrier member confines liquid in the space between the projection system and substrate, then localized liquid supply is achieved, but liquid level variations cause extraction errors or damage
Solution Approach 1:
The invention implements a dynamic extraction system where the extraction capacity automatically adjusts with liquid level changes. As the liquid level rises or falls within the confined space, different conduits become active or inactive, dynamically adjusting the total extraction capacity to match the liquid volume and prevent over-extraction or under-extraction conditions.
Solution Approach 2:
The system provides inherent feedback through the liquid level-dependent activation of different conduits. When liquid level changes, the pressure differential across the conduits automatically adjusts, providing feedback-controlled extraction that responds to liquid level variations without requiring external sensing or control systems.
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 solution enables passive control of the liquid extraction capacity based on the immersion liquid level, minimizing variations and achieving a high extraction flow rate while reducing the risk of errors or damage.
Implementation Method 1
a passage configured to be subjected to an under pressure or suction flow, and a plurality of conduits connected between the passage and the space to remove liquid
Data Source
AI summary
A plurality of extraction conduits is provided to remove immersion liquid into a chamber. The extraction conduits are arranged at different distances from a target portion of the substrate. From the chamber, a passage is provided to which a suction force is applied. When all the conduits are filled with immersion liquid, the extraction capacity will be greater than when one or more of the conduits comprise gas.