Immersion Lithography Liquid Supply Barrier and Flow Control
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Solution Overview
Problem
Existing lithographic apparatuses face issues with turbulent flow and overflow of immersion liquid, leading to imaging errors and refractive index changes, which affect the quality of pattern transfer onto substrates during the lithographic process.
Innovation Solution
A lithographic apparatus with a barrier member that surrounds the space between the projection system and the substrate, featuring a liquid inlet and outlet extending around a fraction of the inner circumference, and a control system to dynamically vary the liquid supply and extraction rates to maintain a stable liquid level, promoting laminar flow and minimizing overflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If liquid is supplied along the direction of movement of the substrate relative to the final element, then liquid can be provided to the space between the projection system and substrate, but turbulent flow occurs leading to imaging errors
Solution Approach 1:
The patent applies local quality by providing liquid supply inlets and outlets at specific localized positions around the final element rather than uniformly across the entire substrate surface. The inlets are positioned to supply liquid in a direction substantially parallel to the scanning direction, while outlets are positioned to remove liquid, creating localized flow control zones that prevent turbulence in the critical imaging area.
Solution Approach 2:
The patent implements dynamics by making the liquid supply and removal rates adjustable through control means. The system dynamically adapts the liquid flow rates based on operating conditions to maintain optimal liquid levels and flow patterns, preventing turbulence while ensuring adequate immersion liquid supply for high refractive index imaging.
2Quantity of substance
If liquid is supplied along the direction of movement of the substrate, then liquid can be provided to the space between the projection system and substrate, but liquid overflow occurs
Solution Approach 1:
The patent applies segmentation by dividing the liquid supply system into multiple discrete inlets and outlets positioned around the final element at specific locations. This segmented approach allows controlled distribution of liquid throughout the immersion space while preventing localized overflow, as each inlet/outlet pair manages liquid flow in its specific zone rather than providing uniform supply across the entire area.
3Quantity of substance
If liquid is supplied along the direction of movement of the substrate, then liquid can be provided to the space between the projection system and substrate, but refractive index changes occur
Solution Approach 1:
The patent implements feedback control through means for controlling the liquid supply and removal rates. The system monitors liquid levels and flow conditions, dynamically adjusting supply and removal rates to maintain stable liquid levels and prevent temperature changes that would cause refractive index variations. This feedback mechanism ensures consistent refractive index throughout the immersion liquid volume.
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 reduces turbulent flow and overflow, ensuring consistent refractive index and improving the accuracy of pattern transfer by maintaining a stable liquid level between predetermined minimum and maximum limits, thereby enhancing the quality of the lithographic process.
Implementation Method 1
promoting laminar flow and minimizing overflow
Implementation Method 2
turbulence in the liquid may lead to undesirable and unpredictable effects
Implementation Method 3
immerse the substrate in the lithographic projection apparatus in a liquid having a relatively high refractive index... so as to fill a space between the final element of the projection system and the substrate
Data Source
AI summary
A liquid supply system for an immersion lithographic apparatus provides a laminar flow of immersion liquid between a final element of the projection system and a substrate. A control system minimizes the chances of overflowing and an extractor includes an array of outlets configured to minimize vibrations.