EUV Material Supply Filter with Through Holes

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Solution Overview

Problem

In the production of extreme ultraviolet (EUV) light for photolithography, existing methods face challenges in effectively removing non-target particles from the target material mixture, which can lead to debris and impurities in the plasma, affecting the quality of the EUV light produced.

Innovation Solution

A dual-filter system is employed, where the first filter, which can be sintered or mesh, and the second filter, with uniformly-sized through holes, are used in series to remove non-target particles from the target material mixture before it reaches the target location, with the second filter having a significantly reduced exposed surface area compared to a sintered filter of equivalent transverse extent, and made of materials like glass or tungsten to enhance compatibility and filtration efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a sintered filter is used to remove non-target particles, then filtration effectiveness is improved, but the exposed surface area increases causing higher pressure drop

Engineering Contradiction:

Improvefiltration effectivenessVSAvoidpressure drop

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The patent changes the geometric parameters of the filter by transitioning from a sintered structure to a manufactured structure with through holes. Specifically, the exposed surface area is reduced by a factor of at least 100 while maintaining filtration effectiveness through the through hole configuration, thereby reducing pressure drop.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the traditional sintered mechanical filtration structure with a manufactured filter featuring through holes. This substitution allows for controlled pore sizes and significantly reduced surface area, achieving both effective particle removal and minimized pressure drop.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If a filter with large exposed surface area is used, then particle removal efficiency is improved, but the filter becomes more prone to clogging and pressure build-up

Engineering Contradiction:

Improveparticle removal efficiencyVSAvoidclogging resistance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent fundamentally changes the surface area parameter by reducing it by at least a factor of 100 compared to conventional sintered filters. This parameter change maintains particle removal efficiency while dramatically reducing the filter's susceptibility to clogging and pressure build-up.

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If uniformly-sized through holes are used in the second filter, then flow uniformity is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improveflow uniformityVSAvoidhole size uniformity

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent employs manufactured through holes instead of sintered pores, enabling precise control over hole dimensions. This manufacturing approach allows for uniformly-sized holes with tight tolerances, ensuring consistent flow distribution while achieving the required manufacturing precision through modern fabrication techniques.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 dual-filter system effectively reduces non-target particles, minimizing debris and improving the purity of the EUV light produced, ensuring better plasma characteristics and EUV light quality by blocking impurities and maintaining a negligible pressure drop across the filters.

Implementation Method 1

a first filter through which the target mixture is passed; a second filter through which the target mixture is passed

Methodology Applied

Scientific EffectPhysical filtration: Filter (physical)

Data Source

PatentUS9669334B2Material supply apparatus for extreme ultraviolet light source having a filter constructed with a plurality of openings fluidly coupled to a plurality of through holes to remove non-target particles from the supply material

Publication Date: 2017.06.06 ASML NETHERLANDS BV

AI summary

A filter is used in a target material supply apparatus and includes a sheet having a first flat surface and a second opposing flat surface, and a plurality of through holes. The first flat surface is in fluid communication with a reservoir that holds a target mixture that includes a target material and non-target particles. The through holes extend from the second flat surface and are fluidly coupled at the second flat surface to an orifice of a nozzle. The sheet has a surface area that is exposed to the target mixture, the exposed surface area being at least a factor of one hundred less than an exposed surface area of a sintered filter having an equivalent transverse extent to that of the sheet.