Organotin Cluster Photoresists for EUV Lithography

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Solution Overview

Problem

Chemically amplified photoresists used in EUV lithography suffer from low etching resistance, insufficient etching selectivity, and pattern transfer errors due to diffusion of photo-generated acids, leading to decreased resolution and increased line edge roughness, making it difficult to achieve feature sizes below 32 nm with high integration densities.

Innovation Solution

Organometallic cluster compounds, specifically organotin cluster compounds with a Sn6 core and bridging oxo and carboxylate ligands, are used as photoresists, offering high EUV optical density, improved line edge roughness, and resolution, allowing direct etching of SOC under-layers without additional hard mask layers, thus reducing manufacturing costs and pattern-transfer errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If chemically amplified photoresists are used in EUV lithography, then sensitivity to EUV radiation is improved, but etching resistance deteriorates

Engineering Contradiction:

Improvesensitivity to EUV radiationVSAvoidetching resistance

Core Design Contradiction:

Use of energy by moving objectVSStrength

Solution Approach 1:

The patent uses organometallic cluster compounds containing metal atoms (such as bismuth, tin, or germanium) embedded in an organic matrix. These composite structures combine the radiation sensitivity of metal clusters with the processability of organic materials, achieving both high EUV sensitivity and superior etching resistance that neither component alone could provide.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent modifies the chemical composition and molecular structure of photoresist materials by incorporating organometallic clusters with specific metal atoms and ligand configurations. This changes the physical and chemical parameters of the photoresist, including etching resistance, radiation sensitivity, and pattern fidelity, to overcome the limitations of conventional chemically amplified photoresists.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If chemically amplified photoresists are used, then radiation sensitivity is improved, but resolution deteriorates due to acid diffusion

Engineering Contradiction:

Improveradiation sensitivityVSAvoidresolution

Core Design Contradiction:

Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

The patent eliminates the photoacid generator component from the photoresist formulation, extracting the source of acid diffusion that causes resolution degradation. The organometallic cluster compounds directly undergo photochemical reactions upon EUV exposure without generating mobile acids, thereby maintaining high radiation sensitivity while preventing the resolution loss caused by acid migration.

Inventive Principle:

Principle #2Taking out (Extraction)

3Strength

If additional hard mask layers are added to improve etching resistance, then etching selectivity is improved, but device complexity increases

Engineering Contradiction:

Improveetching resistanceVSAvoidprocess complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The organometallic cluster photoresist performs multiple functions simultaneously: it serves as the patterning layer, the etch mask, and the protective layer. This multi-functional material eliminates the need for separate hard mask layers and associated processing steps, reducing device complexity while maintaining high etching resistance and selectivity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Ease of manufacture

If conventional photoresists are used, then manufacturing cost is reduced, but pattern transfer accuracy deteriorates

Engineering Contradiction:

Improvemanufacturing costVSAvoidpattern transfer accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent employs organometallic cluster compounds that can be deposited as thin, single-use photoresist layers using spin-coating or other standard techniques. These materials provide high pattern transfer accuracy without requiring the thick, multi-layer structures of conventional photoresists, reducing material consumption and manufacturing cost while improving precision.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 organotin cluster compounds provide superior etching resistance and resolution, enabling direct etching of SOC layers and reducing manufacturing costs, while maintaining high aspect ratios and preventing pattern collapse, thus enhancing EUV lithography performance.

Implementation Method 1

The radiation exposure causes a chemical reaction in the exposed areas of the photoresist and creates a latent image corresponding to the mask pattern in the photoresist

Methodology Applied

Scientific EffectPhotochemical reaction: Photopolymerisation

Implementation Method 2

Organometallic cluster compounds, specifically organotin cluster compounds with a Sn6 core and bridging oxo and carboxylate ligands, are used as photoresists, offering high EUV optical density

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Data Source

PatentUS11767336B2Organometallic cluster photoresists for EUV lithography

Publication Date: 2023.09.26 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

The present disclosure is directed to organotin cluster compounds having formula (I) and their use as photoresists in extreme ultraviolet lithography processes.