Immersion Lithography Rinsing Liquid Flow for Contamination Control
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Solution Overview
Problem
Immersion type projection apparatuses face contamination issues due to the use of liquids in the lithographic process, leading to unpredictable effects and potential substrate contamination during exposure.
Innovation Solution
The method involves rinsing at least part of the immersion space with a rinsing liquid before projecting a patterned beam of radiation onto a substrate, utilizing an immersion system to fill the space with a liquid and moving components relative to each other to ensure thorough cleaning, and using a dummy substrate or patterning device during idle times to maintain cleanliness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the substrate is immersed in a liquid with high refractive index to improve imaging resolution, then the wavelength of exposure radiation decreases and imaging precision improves, but contamination of the immersion space and substrate occurs
Solution Approach 1:
The patent applies preliminary action by rinsing the immersion space with rinsing liquid before substrate exposure. This preventive measure removes potential contaminants from the immersion space before they can contaminate the substrate, thereby maintaining imaging precision while preventing contamination.
Solution Approach 2:
The patent extracts the harmful contaminants from the immersion space by introducing rinsing liquid that flows through the immersion space and carries contaminants away. This separation of contaminants from the imaging environment resolves the contradiction between maintaining clean immersion space and enabling continuous imaging.
2Manufacturing precision
If a large body of liquid is used to fill the immersion space, then the refractive index effect is maximized for better resolution, but turbulence and unpredictable effects occur during scanning exposure
Solution Approach 1:
The patent applies dynamics by implementing a controlled liquid flow system where rinsing liquid continuously moves through the immersion space. This dynamic flow prevents turbulence during scanning by maintaining stable liquid conditions while still providing contamination removal, thus resolving the contradiction between liquid volume for refractive index and liquid stability.
3Object-affected harmful factors
If the immersion space is rinsed before each substrate exposure, then contamination is reduced, but the process time increases
Solution Approach 1:
The patent applies continuity of useful action by implementing continuous rinsing of the immersion space during idle periods and between substrates. This continuous flow approach ensures contamination is constantly removed without requiring separate rinsing steps for each substrate, thereby reducing contamination levels while minimizing additional process time.
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 approach effectively reduces contamination, as demonstrated by lower particle counts and prevention of bacteria growth, maintaining a clean environment for subsequent substrate exposures and reducing the need for specialized cleaning devices.
Implementation Method 1
rinsing at least part of the immersion space with a rinsing liquid
Implementation Method 2
immerse the substrate in a lithographic projection apparatus in an immersion liquid having a relatively high refractive index... the exposure radiation will have a shorter wavelength in the liquid than in air or in a vacuum
Data Source
AI summary
A method for preventing or reducing contamination of an immersion type projection apparatus is provided. The apparatus includes at least one immersion space that is at least partially filled with a liquid when the apparatus projects a beam of radiation onto a substrate. The method includes rinsing at least part of the immersion space with a rinsing liquid before the apparatus is used to project the beam of radiation onto a substrate.