Graphene Spectral Purity Filter for EUV Lithography

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Solution Overview

Problem

Lithographic apparatuses face contamination issues due to fast and slow-moving particles produced during EUV radiation generation, which can degrade imaging performance and require frequent replacement of patterning devices, leading to operational inefficiencies.

Innovation Solution

A lithographic apparatus with a membrane and particle trapping structure that allows EUV radiation to pass through while preventing contamination particles, using materials like graphene to ensure the radiation beam's integrity and extend the lifespan of patterning devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a membrane is used to block contamination particles, then particle filtration is improved, but EUV radiation transmission may be reduced

Engineering Contradiction:

Improvecontamination particle blockingVSAvoidEUV radiation transmission

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The patent employs an ultrathin membrane (such as graphene or silicon oxide) that acts as a selective barrier. The membrane is thin enough to transmit EUV radiation effectively while being dense enough to block contamination particles. This resolves the contradiction by using a thin film structure that simultaneously achieves particle filtration and radiation transmission.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent uses composite structures combining different materials with complementary properties. For example, a graphene-coated grid or multi-layer membrane structure where each layer contributes specific functions: one layer blocks particles while another transmits radiation. This composite approach optimizes both particle blocking and radiation transmission.

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If a particle trapping structure is added to the chamber, then contamination removal is improved, but device complexity increases

Engineering Contradiction:

Improvecontamination particle removalVSAvoidchamber structure complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent introduces a particle trapping structure as an intermediary component within the chamber that captures contamination particles before they reach critical areas. This mediator structure simplifies the overall system by providing a dedicated particle capture mechanism rather than requiring complex filtration systems throughout the entire apparatus.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs porous or grid-like structures that allow gas flow while trapping particles. These porous materials provide effective particle removal through their physical structure without requiring complex active filtration systems, thus reducing device complexity while maintaining contamination removal effectiveness.

Inventive Principle:

Principle #31Porous materials

3Reliability

If graphene is used to prevent oxygen passage, then oxidation protection is improved, but manufacturing complexity increases

Engineering Contradiction:

Improveoxidation resistanceVSAvoidgraphene application complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent uses ultrathin graphene films as protective barriers against oxidation. The graphene layer is deposited directly onto critical components, forming a conformal protective shell. This thin film approach provides excellent oxidation protection while minimizing the added complexity, as the deposition process can be integrated into existing manufacturing workflows.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent creates composite structures where graphene is combined with existing materials (such as metal grids or substrate materials). This composite approach leverages the oxidation resistance of graphene while utilizing the structural properties of the base material, simplifying manufacturing by combining materials with complementary strengths rather than requiring pure graphene components.

Inventive Principle:

Principle #40Composite materials

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 effectively reduces contamination, maintains imaging performance, and decreases the frequency of patterning device replacements, enhancing operational efficiency and reducing downtime.

Implementation Method 1

the grid is covered with graphene which prevents the passage of oxygen to the grid

Methodology Applied

Scientific EffectOxidation prevention: Oxidation

Implementation Method 2

A spectral purity filter may comprise a tungsten/graphene multi-layered structure which blocks infrared radiation

Methodology Applied

Scientific EffectInfrared radiation blocking: Absorption (EM radiation)

Implementation Method 3

The membrane is configured to permit the passage of the radiation beam through the membrane, and to prevent the passage of contamination particles through the membrane

Methodology Applied

Scientific EffectParticle filtration: Filter (physical)

Data Source

PatentUS10481510B2Graphene spectral purity filter

Publication Date: 2019.11.19 ASML NETHERLANDS BV

AI summary

A pellicle that includes graphene is constructed and arranged for an EUV reticle. A multilayer mirror includes graphene as an outermost layer.