Sulfonium Salt Resist Composition for LWR and CDU Control

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Solution Overview

Problem

In the development of microelectronic devices, particularly at the 5-nm node and beyond, acid diffusion leads to image blurring, necessitating improved dissolution contrast and acid diffusion control in resist compositions, while conventional methods to reduce acid diffusion result in decreased sensitivity and contrast.

Innovation Solution

A resist composition incorporating a sulfonium salt with an acid labile group of aromatic cyclic secondary or tertiary ester type in the cation moiety, which enhances acid-catalyzed elimination reactions and alkaline developer affinity, thereby improving line width roughness (LWR) and critical dimension uniformity (CDU) and resolution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If acid diffusion is suppressed by reducing temperature and/or time of post-exposure bake, then resolution is improved, but sensitivity and contrast are drastically reduced

Engineering Contradiction:

ImproveresolutionVSAvoidsensitivity

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent changes the chemical parameters of the acid generator by introducing a bulky acid structure with specific molecular weight and volume characteristics. This modifies the acid diffusion behavior without requiring extreme temperature or time reductions, thereby maintaining sensitivity while improving resolution.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite acid generator structure combining a bulky acid moiety with a polymer backbone, creating a molecule that simultaneously provides high sensitivity through efficient acid generation and controlled diffusion through steric bulk, resolving the contradiction between sensitivity and resolution.

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If acid diffusion is suppressed by using smaller acid generators, then resolution is improved, but sensitivity and contrast are drastically reduced

Engineering Contradiction:

ImproveresolutionVSAvoidsensitivity

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent changes the physical parameters of the acid generator by introducing a bulky acid structure with controlled molecular weight (50-500 Da) and volume, which modifies diffusion characteristics while maintaining or enhancing acid generation efficiency, thereby improving resolution without sacrificing sensitivity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the potential harm of excessive acid diffusion into a benefit by using the bulky acid structure to define precise pattern boundaries, where the controlled diffusion length becomes a useful parameter for achieving sharp edges and high resolution patterns.

Inventive Principle:

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

3Manufacturing precision

If dissolution contrast is enhanced by using base polymer of carboxy generation type, then resolution is improved, but acid diffusion control becomes more critical

Engineering Contradiction:

ImproveresolutionVSAvoidacid diffusion

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the parameters of the acid generator to match the high dissolution contrast requirements of carboxy-generation base polymers by using bulky acids with specific pKa values and diffusion characteristics, enabling precise pattern formation while controlling acid diffusion effects.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality control by using bulky acid generators that provide concentrated acid generation at the exposure site with limited diffusion range, creating a localized effect that enhances dissolution contrast in the exposed regions while minimizing unwanted diffusion to unexposed areas.

Inventive Principle:

Principle #3Local quality

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 resist composition achieves high sensitivity, improved LWR, and CDU, along with a wide process margin, by effectively managing acid diffusion and enhancing dissolution contrast through acid-catalyzed reactions.

Implementation Method 1

enhances acid-catalyzed elimination reactions and alkaline developer affinity, thereby improving line width roughness (LWR) and critical dimension uniformity (CDU) and resolution

Methodology Applied

Scientific EffectAcid-catalyzed elimination reaction: Catalysis

Implementation Method 2

acid diffusion leads to image blurring, necessitating improved dissolution contrast and acid diffusion control in resist compositions

Methodology Applied

Scientific EffectAcid diffusion: Diffusion

Implementation Method 3

a base polymer of polarity switch type capable of generating a phenol or carboxy group through acid-catalyzed deprotection reaction

Methodology Applied

Scientific EffectDeprotection reaction: Hydrolysis

Data Source

PatentUS20230259027A1Resist composition and pattern forming process

Publication Date: 2023.08.17 SHIN ETSU CHEMICAL CO LTD

AI summary

A resist composition comprising a sulfonim salt having an acid labile group of aromatic group-containing cyclic secondary or tertiary ester type in the cation as the acid generator exhibits a high sensitivity and reduced LWR or improved CDU.