Sulfonium-Capped Polymer Resist for High-Resolution Patterning

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Solution Overview

Problem

Existing positive resist compositions face challenges in achieving high resolution and minimizing acid diffusion, leading to image blurs and poor pattern profiles in microelectronic devices, particularly at sub-45 nm sizes, due to the mobility of acid generators and acid diffusion.

Innovation Solution

A positive resist composition is developed with a base polymer end-capped by a sulfonium salt containing a carboxylate anion and incorporating repeat units with carboxy or phenolic hydroxy groups substituted by acid labile groups to minimize acid diffusion and enhance dissolution contrast.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If acid diffusion is increased to enhance sensitivity and contrast in chemically amplified resist compositions, then sensitivity and contrast are improved, but image blurs occur and resolution deteriorates

Engineering Contradiction:

ImproveresolutionVSAvoidimage blurs due to acid diffusion

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

A polymer-bound acid generator is introduced as an intermediary component that generates acid in situ within the polymer structure, minimizing acid diffusion while maintaining effective deprotection. The acid generator is covalently bonded to the polymer backbone, serving as a localized source that prevents acid migration to adjacent regions, thus resolving the contradiction between achieving sufficient acid generation and preventing image blurs.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The acid generation function is localized to specific positions within the polymer chain through the polymer-bound acid generator structure. This localizes the acid source to the immediate vicinity of the acid-labile groups, ensuring that acid diffusion is confined to minimal distances. The local quality principle enables high sensitivity and contrast while preventing image blurs by restricting acid movement to localized regions only.

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If temperature and/or time of post-exposure bake (PEB) are reduced to minimize acid diffusion, then acid diffusion is suppressed, but sensitivity and contrast are drastically reduced

Engineering Contradiction:

ImproveresolutionVSAvoidsensitivity and contrast

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The polymer-bound acid generator acts as an intermediary that decouples the relationship between PEB conditions and acid diffusion. By anchoring the acid generator to the polymer backbone, the system achieves effective acid generation at reduced PEB temperatures and times without sacrificing sensitivity or contrast, as the localized acid source maintains deprotection efficiency even under milder thermal conditions.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If conventional polymer structures are used in positive resist compositions, then ease of manufacture is maintained, but acid diffusion cannot be effectively controlled and resolution is insufficient

Engineering Contradiction:

ImproveresolutionVSAvoidpolymer structure complexity

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention employs a composite polymer structure combining a conventional polymer backbone with integrated polymer-bound acid generator units. This composite approach maintains ease of manufacture by using standard polymerization techniques while incorporating the acid generator functionality directly into the polymer chain. The composite structure achieves superior resolution control without requiring entirely new manufacturing processes.

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 composition achieves high resolution, reduced edge roughness, and improved dimensional uniformity, making it suitable for micropatterning in photomasks and semiconductor circuits.

Implementation Method 1

the acid diffusion distance should be minimized... When a polymer is end-capped with a sulfonium salt containing a carboxylate anion to become a quencher, acid diffusion is minimized

Methodology Applied

Scientific EffectPhotolysis: Photodissociation

Implementation Method 2

repeat units with carboxy or phenolic hydroxy groups substituted by acid labile groups to minimize acid diffusion and enhance dissolution contrast

Methodology Applied

Scientific EffectAcid-catalyzed deprotection: Hydrolysis

Data Source

PatentUS12436462B2Positive resist composition and pattern forming process

Publication Date: 2025.10.07 SHIN ETSU CHEMICAL CO LTD

AI summary

A positive resist composition is provided comprising a base polymer end-capped with a sulfonium salt containing a carboxylate anion having a sulfide group linked thereto. 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.