Positive Resist Composition Acid Diffusion Control

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Solution Overview

Problem

Current positive resist compositions face challenges in achieving high resolution and minimizing edge roughness and dimensional variation, particularly at sub-45 nm feature sizes, due to acid diffusion issues during the manufacturing of microelectronic devices, where conventional methods fail to control acid diffusion effectively.

Innovation Solution

A positive resist composition is developed with a base polymer end-capped with an ammonium salt of an iodized acid linked to a sulfide group, combined with repeat units having carboxy or phenolic hydroxy groups with acid labile substitutions, which minimizes acid diffusion and enhances absorption during EUV exposure, leading to improved edge roughness and dimensional uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

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

Engineering Contradiction:

Improveacid diffusionVSAvoidsensitivity and contrast

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies local quality by incorporating acid diffusion suppressors at specific locations within the resist composition - both as terminal groups on polymer chains and as side chain substituents. This localized placement allows acid diffusion control without requiring global temperature reduction, thereby maintaining sensitivity and contrast while suppressing acid diffusion in the critical pattern regions.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent creates a composite resist composition by combining multiple functional components: base polymer, acid generator, acid diffusion suppressor with terminal group, and acid diffusion suppressor with side chain substituent. This composite structure allows simultaneous achievement of acid diffusion suppression and maintained sensitivity/contrast through the synergistic effects of different components.

Inventive Principle:

Principle #40Composite materials

2Area of moving object

If feature size is reduced to achieve higher integration density, then integration density improves, but image blurs due to acid diffusion worsen

Engineering Contradiction:

Improvefeature sizeVSAvoidimage blur

Core Design Contradiction:

Area of moving objectVSManufacturing precision

Solution Approach 1:

The acid diffusion suppressors are strategically positioned at terminal groups and side chains of polymer molecules, creating localized zones of suppressed acid diffusion exactly where needed for fine pattern definition. This localized suppression prevents image blur in sub-45 nm features while maintaining the small feature size required for high integration density.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The acid diffusion suppressor acts as an intermediary substance between the acid generator and the polymer matrix. It intercepts and neutralizes diffusing acid protons, preventing them from causing image blur in adjacent unexposed regions, thereby enabling precise imaging at reduced feature sizes.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If polymer end is made mobile to allow acid generator attachment, then acid generator functionality improves, but acid diffusion is promoted

Engineering Contradiction:

Improveacid generator functionalityVSAvoidacid diffusion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent resolves this contradiction by creating local quality differentiation: the terminal group contains the acid diffusion suppressor functionality that restricts acid diffusion, while the side chain contains the acid generator that provides acid generation capability. This spatial separation allows each functional element to perform its role without compromising the other - the acid generator remains functional while the terminal suppressor prevents excessive acid diffusion.

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 exhibits a significant acid diffusion-suppressing effect, increased alkaline dissolution contrast, and high resolution, resulting in a pattern with reduced edge roughness and improved dimensional uniformity, making it suitable for advanced microelectronic device manufacturing.

Implementation Method 1

The addition of an acid generator capable of generating a bulky acid is an effective means for suppressing acid diffusion

Methodology Applied

Scientific EffectAcid diffusion suppression: Diffusion Barrier

Implementation Method 2

the addition of an acid generator capable of generating a bulky acid is an effective means for suppressing acid diffusion

Methodology Applied

Scientific EffectPhotoacid generation: Photodissociation

Implementation Method 3

repeat units having carboxy or phenolic hydroxy groups with acid labile substitutions, which minimizes acid diffusion and enhances absorption during EUV exposure, leading to improved edge roughness and dimensional uniformity

Methodology Applied

Scientific EffectAlkaline dissolution: Hydrolysis

Data Source

PatentUS20230161255A1Positive resist composition and pattern forming process

Publication Date: 2023.05.25 SHIN ETSU CHEMICAL CO LTD

AI summary

A positive resist composition is provided comprising a base polymer end-capped with an ammonium salt of an iodized acid, linked to a sulfide group. 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.