Amorphous Carbon Pellicle for EUV Lithography

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Solution Overview

Problem

Current pellicles for extreme ultraviolet lithography face challenges in achieving high extreme ultraviolet transmittance and low reflectance while maintaining mechanical and thermal stability, especially when using graphene as a core layer due to its sp2 bonding structure.

Innovation Solution

The use of an amorphous carbon pellicle layer with a core layer formed of graphene or amorphous carbon, and a capping layer also made of amorphous carbon, along with buffer layers, to achieve high transmittance and low reflectance. This configuration stabilizes the capping layer formation on the graphene core and controls the refractive index to optimize performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a graphene core layer is used to achieve high extreme ultraviolet transmittance, then transmittance is improved, but capping layer formation stability deteriorates due to sp2 bonding structure

Engineering Contradiction:

Improveextreme ultraviolet transmittanceVSAvoidcapping layer formation stability

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

An amorphous carbon buffer layer is introduced as an intermediary between the graphene core layer and the capping layer. This buffer layer facilitates stable capping layer formation on the graphene surface while preserving the high transmittance properties of the graphene core, resolving the contradiction between transmittance and formation stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The pellicle structure combines multiple materials including graphene (for high transmittance), amorphous carbon buffer layer (for stability), and capping layer (for protection). This composite structure allows each material to contribute its advantageous properties, achieving both high transmittance and stable capping layer formation.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If conventional pellicle materials are used to achieve mechanical and thermal stability, then stability is improved, but extreme ultraviolet transmittance deteriorates

Engineering Contradiction:

Improvemechanical and thermal stabilityVSAvoidextreme ultraviolet transmittance

Core Design Contradiction:

Stability of the object's compositionVSIllumination intensity

Solution Approach 1:

The pellicle employs a composite structure where the graphene core layer provides high transmittance, while the amorphous carbon buffer layer and capping layer provide mechanical and thermal stability. Each layer is optimized for its specific function, achieving both transmittance and stability simultaneously.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

Different regions of the pellicle have different material properties optimized for their specific functions: the core layer is optimized for transmittance, while the buffer and capping layers are optimized for stability. This local optimization allows the overall structure to achieve both contradictory requirements.

Inventive Principle:

Principle #3Local quality

3Illumination intensity

If amorphous carbon layer thickness is reduced to maintain high transmittance, then transmittance is improved, but reflectance control becomes more difficult

Engineering Contradiction:

Improveextreme ultraviolet transmittanceVSAvoidreflectance control

Core Design Contradiction:

Illumination intensityVSManufacturing precision

Solution Approach 1:

The refractive index of the amorphous carbon buffer layer is precisely controlled as a key parameter. By adjusting the density and composition of the amorphous carbon, the refractive index is optimized to simultaneously achieve high transmittance and low reflectance, resolving the contradiction between thickness reduction and reflectance control.

Inventive Principle:

Principle #35Parameter changes

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 amorphous carbon-based pellicle achieves extreme ultraviolet transmittance of 90% or more and reflectance of 0.04% or less in high-power extreme ultraviolet environments, while providing mechanical and thermal stability, thus addressing the limitations of existing materials.

Implementation Method 1

a pellicle for extreme ultraviolet lithography containing amorphous carbon having an extreme ultraviolet transmittance of 90% or more

Methodology Applied

Scientific EffectExtreme ultraviolet transmission: Absorption (EM radiation)

Implementation Method 2

a reflectance of 0.04% or less in an extreme ultraviolet output environment of 350 W or more

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS12321092B2Pellicle for extreme ultraviolet lithography containing amorphous carbon and method for manufacturing the same

Publication Date: 2025.06.03 KOREA ELECTRONICS TECH INST

AI summary

This application relates to a pellicle for extreme ultraviolet lithography containing amorphous carbon and a manufacturing method thereof. In one aspect, the pellicle includes a substrate having an opening formed in a central portion, a support layer formed on the substrate to cover the opening, and a pellicle layer formed on the support layer and containing amorphous carbon. The pellicle layer may include a core layer formed on the support layer, and a capping layer formed on the core layer and may further include a buffer layer. At least one of the core layer, the capping layer, or the buffer layer may be an amorphous carbon layer.