Positive resist composition and pattern forming process

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Solution Overview

Problem

Existing positive resist compositions face challenges in achieving high resolution and uniform acid diffusion, leading to issues with edge roughness and dimensional variation in microelectronic device manufacturing, particularly at the 5-nm node and beyond.

Innovation Solution

A positive resist composition is developed with a base polymer end-capped with an ammonium cation linked to a sulfide group and a fluorinated anion, incorporating repeat units with carboxy or phenolic hydroxy groups substituted by acid labile groups to minimize acid diffusion and suppress swelling in alkaline developers, thereby improving resolution and reducing edge roughness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If acid diffusion is enhanced to improve sensitivity and contrast in chemically amplified resist compositions, then sensitivity and contrast are enhanced, but acid diffusion control becomes difficult leading to image blurs and resolution degradation

Engineering Contradiction:

ImproveresolutionVSAvoidacid diffusion

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by placing acid diffusion suppressing groups at specific locations (side chains or terminal ends) of the polymer structure. These groups are positioned locally to suppress acid diffusion in critical areas without affecting the overall chemically amplified resistance mechanism, thereby achieving both high sensitivity/contrast and controlled acid diffusion.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining polymer chains with embedded acid diffusion suppressing groups (such as fluorinated groups or bulky groups) into a unified resist material. This composite structure integrates the beneficial properties of both the chemically amplified polymer and the acid diffusion suppressing moieties, achieving enhanced resolution while controlling acid diffusion.

Inventive Principle:

Principle #40Composite materials

2Object-generated harmful factors

If polymer end-capped with acid generator is used to suppress acid diffusion, then acid diffusion is reduced, but the mobile end promotes acid diffusion

Engineering Contradiction:

Improveacid diffusionVSAvoidend mobility

Core Design Contradiction:

Object-generated harmful factorsVSStability of the object's composition

Solution Approach 1:

The patent addresses end mobility by introducing acid diffusion suppressing groups specifically at the polymer chain ends or near terminal regions. This local placement stabilizes the mobile end regions without affecting the bulk polymer properties, preventing the mobile end from promoting acid diffusion while maintaining the overall composition stability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses acid diffusion suppressing groups as intermediary elements between the polymer chain and the external environment. These groups act as mediators that reduce acid diffusion from the polymer matrix while the bulky or fluorinated nature of these groups also stabilizes the terminal regions, preventing excessive mobility.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-generated harmful factors

If amino group is used at polymer end to function as quencher, then swelling in developer is suppressed, but hydrogen bond causes polymer agglomeration leading to non-uniform acid diffusion and edge roughness degradation

Engineering Contradiction:

Improveswelling in developerVSAvoidedge roughness

Core Design Contradiction:

Object-generated harmful factorsVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by modifying the chemical properties of the terminal groups from amino groups to fluorinated groups or other non-hydrogen-bonding groups. This parameter change eliminates hydrogen bonding while maintaining the quencher function and swelling suppression, thereby achieving uniform acid diffusion and reduced edge roughness.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful effect of hydrogen bonding (which causes agglomeration) into a beneficial design feature by selecting terminal groups that do not form hydrogen bonds. The fluorinated groups or bulky groups provide swelling suppression and quencher functionality without the harmful hydrogen bonding effect, turning the problem of terminal group selection into an opportunity to achieve uniform acid diffusion.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 composition achieves remarkable acid diffusion suppression, increased dissolution contrast, and forms patterns with reduced edge roughness and improved dimensional uniformity, suitable for advanced lithography processes in VLSIs and photomasks.

Implementation Method 1

image blurs due to acid diffusion become a problem

Methodology Applied

Scientific EffectAcid diffusion: Diffusion

Implementation Method 2

improvement in dissolution contrast

Methodology Applied

Scientific EffectDissolution:

Data Source

PatentUS12554197B2Positive resist composition and pattern forming process

Publication Date: 2026.02.17 SHIN ETSU CHEMICAL CO LTD

AI summary

A positive resist composition is provided comprising a base polymer end-capped with a salt consisting of an ammonium cation linked to a sulfide group and a fluorinated anion. Because of controlled acid diffusion, a resist film of the composition forms a pattern of good profile with a high resolution and reduced edge roughness or dimensional variation.