Phase Separator for Immersion Lithography Two-Phase Flow
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Solution Overview
Problem
In immersion lithography apparatuses, two-phase flows of liquid and gas can cause unstable conditions, leading to vibrations and evaporation issues, which complicate the design and operation of fluid handling systems.
Innovation Solution
A phase separator is used to separate two-phase flows into a liquid-rich flow and a gas-rich flow, with the liquid-rich flow flowing along a surface, stabilizing the meniscus and reducing vibrations by using a conduit with liquidphilic surfaces and structures that encourage liquid flow along specific paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a large body of liquid is used to fill the space between the projection system and substrate, then imaging of smaller features is enabled through increased effective numerical aperture, but additional powerful motors are required and turbulence in the liquid causes unpredictable effects
Solution Approach 1:
The liquid is segmented into a thin film configuration rather than a large body, confined to a narrow gap between the projection system and substrate. This segmentation maintains the optical benefits of liquid immersion while eliminating the need for powerful motors to accelerate large volumes of liquid during scanning.
Solution Approach 2:
The liquid is confined to a localized region - a thin film in the immediate vicinity of the projection system and substrate interface - rather than filling the entire space. This local confinement provides the necessary refractive index enhancement exactly where needed for imaging, while minimizing the total liquid volume to reduce motor power requirements and turbulence.
2Quantity of substance
If liquid is confined to a localized area between the projection system and substrate, then the required liquid volume is reduced, but fluid handling becomes more complex requiring barrier members and confinement structures
Solution Approach 1:
A barrier member is employed to confine the liquid in a thin film configuration. The barrier creates a controlled fluid handling environment that maintains liquid confinement while managing the complexity through a structured approach to fluid containment in the localized region between the projection system and substrate.
3Productivity
If two-phase flow of liquid and gas is used for liquid removal, then liquid can be extracted from the substrate, but unstable flow conditions cause vibrations and evaporation issues
Solution Approach 1:
Gas is extracted from the liquid phase to create a separate gas removal path. The gas extraction conduit removes gas independently from the liquid, preventing the formation of unstable two-phase flow. This separation eliminates vibrations and evaporation issues while maintaining effective liquid removal through the liquid extraction conduit.
Solution Approach 2:
The fluid removal system is segmented into separate liquid and gas removal pathways. By dividing the two-phase flow into distinct liquid extraction and gas extraction conduits, the system eliminates the instability inherent in mixed two-phase flow while maintaining the productivity benefits of efficient liquid and gas removal.
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 effectively stabilizes the meniscus and reduces vibrations, improving the efficiency and reliability of liquid removal and handling in immersion lithography systems.
Implementation Method 1
immerse the substrate in the lithographic projection apparatus in a liquid having a relatively high refractive index, e.g. water, so as to fill a space between the final element of the projection system and the substrate. The point of this is to enable imaging of smaller features since the exposure radiation will have a shorter wavelength in the liquid.
Implementation Method 2
a phase separator having a surface and arranged to separate the two-phase flow into a first flow and a second flow, the first flow having a higher ratio of liquid to gas than the two-phase flow and flowing along the surface, the second flow having a higher ratio of gas to liquid than the two-phase flow
Data Source
AI summary
An immersion lithographic apparatus is described in which a two-phase flow is separated into liquid-rich and gas-rich flows by causing the liquid-rich flow to preferentially flow along a surface.