EUV Debris Filter With Localized Buffer Gas Injection
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Solution Overview
Problem
Existing debris filters for EUV radiation sources are ineffective in suppressing all types of debris particles, particularly fast, high-energy particles, and often result in excessive attenuation of the desired EUV radiation due to high pressures and gas discharges.
Innovation Solution
A debris filter with a buffer gas injection system that creates a defined volume layer with increased gas pressure within the filter structure, using inlet nozzles to inject buffer gas laterally, and vacuum pumps to manage pressure, combined with a blade structure and constricted channels to enhance flow resistance and decelerate debris particles without increasing the gas load in the vacuum chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high pressure buffer gas is used throughout the vacuum chamber to suppress debris particles, then debris suppression effectiveness is improved, but EUV radiation attenuation increases significantly
Solution Approach 1:
The patent applies different gas pressures in different spatial zones: high buffer gas pressure is confined to the debris filter region where debris suppression is needed, while the rest of the vacuum chamber maintains low pressure to minimize EUV radiation attenuation. This local differentiation resolves the contradiction by providing high debris suppression effectiveness only where necessary without causing system-wide radiation loss.
Solution Approach 2:
The debris filter structure acts as an intermediary component that contains the high-pressure buffer gas in a localized volume. This mediator allows the buffer gas to perform its debris-suppressing function in a confined space while preventing the high-pressure gas from spreading throughout the vacuum chamber, thus avoiding excessive EUV radiation attenuation.
2Object-generated harmful factors
If buffer gas is injected into the entire vacuum chamber to decelerate fast particles, then particle flow suppression is improved, but gas load and vacuum maintenance complexity increase
Solution Approach 1:
Instead of filling the entire vacuum chamber with buffer gas, the patent confines the buffer gas injection and high-pressure region to the localized debris filter volume. This reduces the overall gas load in the vacuum chamber, simplifying vacuum maintenance while still achieving effective particle flow suppression where it is most needed.
Solution Approach 2:
The patent extracts the buffer gas function from the entire vacuum chamber environment and concentrates it in a specific debris filter component. This separation allows the buffer gas to perform its particle suppression function in isolation, reducing the complexity of vacuum system management while maintaining effective particle flow control.
3Reliability
If mechanical filter structures with high flow resistance are used to decelerate debris, then debris suppression is improved, but EUV radiation transmission is reduced
Solution Approach 1:
The high flow resistance mechanical filter structure is implemented only within the localized debris filter volume where buffer gas is present. The filter structure works in conjunction with the localized high-pressure buffer gas to suppress debris, while the rest of the vacuum chamber remains open for optimal EUV radiation transmission. This spatial localization resolves the contradiction between debris suppression and radiation transmission.
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
Effectively suppresses debris particles by decelerating them to prevent sputtering on optical surfaces while maintaining the reflectivity of collector optics and reducing maintenance costs, without significant attenuation of EUV radiation.
Implementation Method 1
decel erating them to kinetic energies significantly below 10 eV which no longer allow sputtering
Implementation Method 2
the filter structure generates a flow resistance in direction of the plasma and in direction of propagation of the radiation
Implementation Method 3
the buffer gas exiting from the filter structure of the debris filter is sucked out of the vacuum chamber by vacuum pumps
Data Source
AI summary
The invention is directed to a method and arrangements for the suppression of debris in short-wavelength radiation sources based on a plasma, particularly for EUV sources for semiconductor lithography. The object of the invention is to find a novel possibility for suppressing the particle flow (debris) from a plasma which keeps the debris away from primarily optical components located downstream without excessive attenuation of the desired radiation emitted from the plasma. According to the invention, this object is met in that a buffer gas is injected inside the filter structure of the debris filter lateral to openings that are provided for passing the radiation. The filter structure generates a flow resistance in direction of the plasma and in direction of propagation of the radiation so that an increased gas pressure of buffer gas remains limited to a defined volume layer in the debris filter relative to the pressure in the vacuum chamber, and the buffer gas exiting from the filter structure of the debris filter is sucked out of the vacuum chamber by vacuum pumps.