Nanotube Pellicle Membrane Structure for Low-Deflection EUV Lithography

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Solution Overview

Problem

In extreme ultraviolet (EUV) lithography, particle contaminants on the photomask cause defects in the transferred pattern due to the use of pellicle membranes that sag or deflect, leading to contamination and potential breakage, which are not adequately addressed by current pellicle designs.

Innovation Solution

The development of pellicle membranes with nanotube bundles and a multi-layered structure that includes graphene and/or carbon nanotube bundles that are designed to minimize deflection and maintain high transmittance of EUV light and particle protection, using thick and thin nanotube layers with a conformal coating to enhance mechanical properties and reduce sagging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a pellicle membrane is used to protect the photomask, then particle protection is improved, but the membrane sags or deflects causing contamination and potential breakage

Engineering Contradiction:

Improveparticle protectionVSAvoidmembrane stability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The pellicle membrane employs a composite structure combining multiple materials including silicon nitride, silicon oxide, and metal layers (such as chromium or molybdenum). This composite construction provides both particle protection and mechanical stability, preventing sagging and deflection while maintaining reliability during EUV lithography operations.

Inventive Principle:

Principle #40Composite materials

2Illumination intensity

If the pellicle membrane is made thinner to maintain high transmittance, then light transmission is improved, but mechanical strength decreases leading to sagging

Engineering Contradiction:

ImproveEUV light transmittanceVSAvoidmembrane mechanical strength

Core Design Contradiction:

Illumination intensityVSStrength

Solution Approach 1:

The multi-layer composite structure allows the membrane to achieve high EUV transmittance while maintaining mechanical strength. The specific combination of materials (silicon nitride, silicon oxide, metal layers) provides optimized optical properties for EUV wavelengths while the layered construction delivers the necessary mechanical support to prevent sagging.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The membrane design optimizes the thickness and composition parameters of each layer to achieve the desired balance between transmittance and strength. By carefully controlling the thickness of each material layer, the membrane maintains high EUV light transmission while possessing sufficient mechanical strength to resist deflection.

Inventive Principle:

Principle #35Parameter changes

3Strength

If the pellicle membrane is made thicker to improve mechanical strength, then sagging is reduced, but EUV light transmittance decreases

Engineering Contradiction:

Improvemembrane mechanical strengthVSAvoidEUV light transmittance

Core Design Contradiction:

StrengthVSIllumination intensity

Solution Approach 1:

Rather than simply increasing overall thickness, the invention uses a composite material approach where different layers contribute different properties. The metal layers provide mechanical strength, while the silicon nitride and oxide layers maintain optical transparency. This allows achieving high strength without proportionally increasing thickness, thus preserving EUV transmittance.

Inventive Principle:

Principle #40Composite materials

4Strength

If a multi-layered structure with conformal coating is used, then mechanical properties are enhanced, but device complexity increases

Engineering Contradiction:

Improvemembrane mechanical propertiesVSAvoidmembrane structure complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The multi-layer composite structure enhances mechanical properties through the synergistic combination of materials with different strengths and properties. The conformal coating provides additional protection and stability. While the structure is more complex than a single-layer membrane, the complexity is justified by the significant improvement in mechanical performance and reliability.

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 efficacy of the efficacy is achieved by the efficacy of the efficacy of the efficacy of the pellicle membranes with nanotube bundles and a multi-layered structure that includes graphene and/or carbon nanotube bundles that are designed to minimize deflection and maintain high transmittance of EUV light and particle protection, using thick and thin nanotube layers with a conformal coating to enhance mechanical properties and reduce sagging.

Implementation Method 1

maintain high transmittance of EUV light

Methodology Applied

Scientific EffectLight transmission: Light

Implementation Method 2

conformal coating to enhance mechanical properties and reduce sagging

Methodology Applied

Scientific EffectPhysical barrier protection: Physical Containment

Data Source

PatentUS20250362587A1Pellicle membrane with improved properties

Publication Date: 2025.11.27 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A pellicle assembly includes a pellicle membrane with a nanotube layer formed from thick nanotube bundles. The pellicle membrane can be formed with multiple layers and has a combination of long lifetime, high transmittance, low deflection, and small pore size. A conformal coating may applied to an outer surface of the pellicle membrane. The conformal coating protects the pellicle membrane from damage that can occur due to heat and hydrogen plasma created during EUV exposure.