Thermosetting Silicon-Iodine Underlayer for EUV Lithography

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Solution Overview

Problem

EUV lithography faces challenges in achieving high sensitivity while maintaining low line width roughness (LWR) and hole critical dimension uniformity, due to the short wavelength and high energy density of EUV exposure.

Innovation Solution

A thermosetting silicon-containing material is introduced, comprising repeating units with iodine-containing organic groups, which forms a resist underlayer film that enhances the sensitivity of the upper layer resist while preserving LWR.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the temperature for post exposure bake (PEB) is decreased to decrease LWR, then sensitivity of EUV resist is decreased

Engineering Contradiction:

Improveline width roughness (LWR)VSAvoidsensitivity

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The invention changes the chemical composition parameters of the resist system by introducing a specific underlayer composition containing silicon compound, iodine compound, and sulfur compound. This compositional parameter change allows the system to achieve low LWR without requiring reduced PEB temperature, thereby maintaining high sensitivity. The specific parameter combination (silicon: 1-50 at%, iodine: 1-50 at%, sulfur: 1-50 at%) creates a new operational space that resolves the trade-off between LWR and sensitivity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The underlayer composition acts as an intermediary between the EUV resist and the substrate. This intermediary layer, with its specific chemical composition, mediates the interaction between light exposure and the resist system, enabling improved LWR control while preserving sensitivity. The underlayer compounds (silicon, iodine, sulfur) serve as intermediate agents that modify the overall system behavior without directly compromising the resist's light-sensitive properties.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If a quencher is added in a larger amount to decrease LWR, then sensitivity is decreased

Engineering Contradiction:

Improveline width roughness (LWR)VSAvoidsensitivity

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention replaces the mechanical approach of adding quenchers to the resist formulation with a chemical substitution approach by introducing specific compounds (silicon, iodine, sulfur) into the underlayer. This substitution changes the mechanism from direct chemical quenching in the resist to indirect chemical interaction through the underlayer, thereby achieving LWR control without the sensitivity-penalizing effect of excessive quencher addition.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Length of moving object

If multiple exposures are used in ArF lithography to achieve miniaturization, then cost increases and superposition precision is affected

Engineering Contradiction:

Improvepattern ruleVSAvoidsuperposition precision

Core Design Contradiction:

Length of moving objectVSManufacturing precision

Solution Approach 1:

Instead of using multiple exposures to achieve miniaturization (the conventional approach), the invention inverts the strategy by using a single EUV exposure with a specially designed underlayer composition. This inversion eliminates the need for multiple exposures, thereby maintaining superposition precision while achieving the desired pattern miniaturization. The underlayer's chemical composition is optimized to work with single-exposure EUV lithography.

Inventive Principle:

Principle #13The other way round (Inversion)

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 use of the thermosetting silicon-containing material results in a resist underlayer film that improves the sensitivity of the upper layer resist without degrading LWR, thereby addressing the limitations of existing EUV lithography technologies.

Implementation Method 1

Since EUV has short wavelength and high energy density, an acid generator is sensitized with a small amount of the photons. The number of the photons in EUV exposure is said to be 1/14 of that of ArF exposure.

Methodology Applied

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

Implementation Method 2

an acid generator is sensitized with a small amount of the photons

Methodology Applied

Scientific EffectPhotodissociation: Photodissociation

Data Source

PatentUS12332565B2Thermosetting iodine- and silicon-containing material, composition containing the material for forming resist underlayer film for EUV lithography, and patterning process

Publication Date: 2025.06.17 SHIN ETSU CHEMICAL CO LTD

AI summary

The present invention is a thermosetting silicon-containing material containing one or more of a repeating unit shown by the following general formula (Sx-1), a repeating unit shown by the following general formula (Sx-2), and a partial structure shown by the following general formula (Sx-3):where R1 represents an iodine-containing organic group; and R2 and R3 are each independently identical to R1, a hydrogen atom, or a monovalent organic group having 1 to 30 carbon atoms. This provides: a thermosetting silicon-containing material used for forming a resist underlayer film which is capable of contributing to sensitivity enhancement of an upper layer resist while keeping LWR thereof from degrading; a composition for forming a silicon-containing resist underlayer film, the composition containing the thermosetting silicon-containing material; and a patterning process using the composition.