Positive Resist Composition with Acid Labile Groups for Fine Patterning

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Solution Overview

Problem

Current positive resist compositions face challenges in achieving high sensitivity, resolution, and low edge roughness while minimizing acid diffusion, which affects the formation of fine patterns in microelectronic devices, particularly at the 5-nm node and beyond.

Innovation Solution

A positive resist composition incorporating a base polymer with repeat units having a carboxy group or phenolic hydroxy group substituted with an acid labile group, which minimizes acid diffusion while maintaining high sensitivity and resolution, is developed. This composition includes specific acid labile groups and an acid generator to enhance dissolution contrast and suppress acid diffusion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

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

Engineering Contradiction:

ImproveresolutionVSAvoidsensitivity

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent changes the chemical parameters of the resist composition by incorporating specific base polymers with amino groups and carboxy groups, and using acid generators that produce bulky acids. This chemical parameter change allows acid diffusion to be suppressed at standard PEB temperatures, resolving the contradiction between resolution and sensitivity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite resist system combining base polymers with amino groups, carboxy groups, and acid generators. This composite material approach enables the system to achieve both high resolution (through suppressed acid diffusion) and high sensitivity (through maintained dissolution contrast) simultaneously.

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If acid diffusion distance is reduced to improve resolution, then edge roughness is reduced, but dissolution contrast and sensitivity decline

Engineering Contradiction:

Improveedge roughnessVSAvoiddissolution contrast

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent modifies the chemical composition parameters by introducing base polymers with specific functional groups (amino and carboxy) and acid generators that produce bulky acids. This changes the acid diffusion characteristics while maintaining dissolution contrast, resolving the contradiction between edge roughness and dissolution contrast.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If conventional acid generators are used, then sensitivity is maintained, but acid diffusion causes image blur and resolution loss

Engineering Contradiction:

ImprovesensitivityVSAvoidresolution

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the physical-chemical parameters of the acid generator by selecting compounds that produce bulky acids with larger molecular sizes. This parameter change reduces acid diffusion distance while maintaining generation efficiency, resolving the contradiction between sensitivity and resolution.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful effect of acid diffusion into a beneficial control mechanism by using bulky acids that diffuse less. The reduced diffusion, which would normally be harmful to sensitivity, is actually beneficial for resolution, thus converting the harm into a benefit.

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 resist composition achieves high sensitivity, improved dissolution contrast, and reduced edge roughness, enabling the formation of fine patterns with good profile quality, suitable for advanced microelectronic devices such as VLSIs and photomasks.

Implementation Method 1

the control of acid diffusion is also important as reported in Non-Patent Document 1 Since chemically amplified resist compositions are designed such that sensitivity and contrast are enhanced by acid diffusion

Methodology Applied

Scientific EffectPhotoacid generation: Photodissociation

Implementation Method 2

image blurs due to acid diffusion become a problem. To insure resolution for fine patterns with a size of 45 mu et seq., not only an improvement in dissolution contrast is important as previously reported, but the control of acid diffusion is also important

Methodology Applied

Scientific EffectAcid diffusion: Diffusion

Implementation Method 3

a base polymer comprising repeat units having a carboxy group whose hydrogen is substituted by an acid labile group

Methodology Applied

Scientific EffectAcid-catalyzed deprotection: Hydrolysis

Data Source

PatentUS11914294B2Positive resist composition and pattern forming process

Publication Date: 2024.02.27 SHIN ETSU CHEMICAL CO LTD

AI summary

A positive resist composition comprising a base polymer comprising repeat units having a carboxy group whose hydrogen is substituted by an acid labile group in the form of a tertiary hydrocarbon group containing a nitrogen atom and aromatic group exhibits a high sensitivity, high resolution, low edge roughness and small size variation, and forms a pattern of good profile after exposure and development.