Negative Tone Resist Patterning via Ester Solvent Development

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Solution Overview

Problem

Current pattern formation techniques face challenges in achieving fine hole patterns with high accuracy and resolution, particularly in negative tone development, due to issues with dissolution contrast, safety concerns, and the limitations of existing organic solvents in photolithography for advanced node devices.

Innovation Solution

A pattern forming process using a resist composition comprising (meth)acrylate copolymers with acid labile groups and lactone rings, combined with an organic solvent developer containing solvents like methyl benzoate and ethyl benzoate, which provides high dissolution contrast and safety, enabling the formation of fine hole patterns through ArF immersion lithography or EUV lithography.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional organic solvents are used for negative tone development, then the development process can be performed, but the dissolution contrast is insufficient and safety concerns arise due to low flash points

Engineering Contradiction:

Improvedissolution contrastVSAvoidsafety hazards

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical parameters of the developer by using ester solvents with specific molecular structures (containing oxygen atoms in ester groups) and controlled carbon chain lengths. This parameter change achieves both high dissolution contrast and improved safety through higher flash points, resolving the contradiction between development performance and safety hazards.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite solvent systems combining multiple ester components (e.g., ethyl acetate, butyl acetate, amyl acetate) to achieve optimal balance between dissolution contrast and safety. The composite approach allows tuning of both performance and safety characteristics simultaneously.

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If existing resist compositions are used for fine hole pattern formation, then patterning can be achieved, but the resolution and accuracy are limited due to insufficient dissolution contrast

Engineering Contradiction:

Improvepattern resolutionVSAvoidpattern accuracy

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent modifies the resist composition parameters by incorporating specific (meth)acrylate copolymers with acid labile groups and lactone rings, combined with the specialized ester developer. This parameter optimization enhances dissolution contrast, enabling formation of finer hole patterns with improved resolution and accuracy.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces conventional development mechanisms with a chemically amplified approach using acid generators and specific polymer-resist systems. This substitution enables better control over dissolution behavior, achieving superior pattern accuracy and resolution.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If ArF immersion lithography or EUV lithography is used for advanced node devices, then finer patterning is achieved, but the complexity of the process increases

Engineering Contradiction:

Improvepatterning resolutionVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent extracts and optimizes the critical development step from the overall lithography process, creating a specialized resist composition and developer system that simplifies the development phase. This extraction allows the complex lithography process to achieve finer patterning while managing overall process complexity through targeted optimization.

Inventive Principle:

Principle #2Taking out (Extraction)

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 process ensures safe and effective formation of negative tone patterns with high dissolution contrast, allowing for the creation of fine hole patterns with improved accuracy and resolution, addressing the limitations of existing methods.

Implementation Method 1

deprotection reaction with the aid of acid and heat

Methodology Applied

Scientific EffectDeprotection reaction:

Implementation Method 2

heat treating the composition to form a resist film

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Implementation Method 3

developing the exposed film with a developer... the unexposed region is dissolved

Methodology Applied

Scientific EffectDissolution: Solvation

Implementation Method 4

exposing the resist film to high-energy radiation

Methodology Applied

Scientific EffectPhotopolymerisation: Photopolymerisation

Data Source

PatentUS9316909B2Patterning process

Publication Date: 2016.04.19 SHIN ETSU CHEMICAL CO LTD

AI summary

A pattern is formed by applying a resist composition comprising a (meth)acrylate copolymer comprising both recurring units having an acid labile group-substituted carboxyl group and recurring units having a lactone ring, an acid generator, and an organic solvent onto a substrate, prebaking the composition to form a resist film, exposing the resist film to high-energy radiation, baking, and developing the exposed film with a developer. The developer comprises at least 40 wt % of an organic solvent selected from methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate, and 2-phenylethyl acetate.