Positive Resist Polymer Composition for Acid Diffusion Control

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Solution Overview

Problem

Existing chemically amplified resist compositions face challenges in achieving high resolution, reduced line edge roughness (LER), improved rectangularity, and minimizing develop loading and residue defects, particularly in the processing of photomask blanks for advanced semiconductor fabrication.

Innovation Solution

A chemically amplified positive resist composition is developed, incorporating a polymer modified with an acetal modifier that includes specific acid labile groups, which controls acid diffusion and enhances the formation of resist patterns with improved resolution and reduced defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional acid generators are used to control acid diffusion, then sensitivity is improved, but line edge roughness increases and resolution deteriorates

Engineering Contradiction:

ImproveresolutionVSAvoidline edge roughness

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent changes the molecular weight parameter of the polymer from conventional high molecular weight to low molecular weight (specifically, number-average molecular weight of 1,000 to 50,000). This parameter change reduces acid diffusion while maintaining sensitivity, thereby improving resolution and reducing line edge roughness simultaneously.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If polymer molecular weight is reduced to control acid diffusion, then resolution is improved, but etching resistance deteriorates

Engineering Contradiction:

ImproveresolutionVSAvoidetching resistance

Core Design Contradiction:

Measurement precisionVSStrength

Solution Approach 1:

The patent creates a composite resist composition combining low molecular weight polymer with specific additives including base compounds and surfactants. This composite approach compensates for the reduced etching resistance of low molecular weight polymer while maintaining the improved resolution, achieving both goals simultaneously.

Inventive Principle:

Principle #40Composite materials

3Productivity

If acid diffusion is increased to improve sensitivity, then throughput is improved, but pattern profile control deteriorates

Engineering Contradiction:

ImprovethroughputVSAvoidpattern profile control

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the polymer molecular weight parameter to low molecular weight range, which fundamentally alters the acid diffusion behavior. This enables high sensitivity (good throughput) while maintaining precise pattern profile control, resolving the contradiction between productivity and manufacturing precision.

Inventive Principle:

Principle #35Parameter changes

4Strength

If conventional polymers are used for high etching resistance, then etching resistance is improved, but acid diffusion control deteriorates

Engineering Contradiction:

Improveetching resistanceVSAvoidacid diffusion control

Core Design Contradiction:

StrengthVSMeasurement precision

Solution Approach 1:

The patent inverts the conventional approach by using low molecular weight polymer (which typically shows poor etching resistance) but compensating with composite formulation. This parameter change enables simultaneous achievement of good acid diffusion control and acceptable etching resistance through the synergistic composite system.

Inventive Principle:

Principle #35Parameter changes

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 forms resist patterns with high resolution, reduced LER, and minimized residue defects, suitable for advanced photomask processing and semiconductor fabrication, while maintaining etching resistance and profile stability.

Implementation Method 1

an acetal modifier which introduces a triple bond-bearing group serving as a protective group for an aliphatic or aromatic hydroxy group

Methodology Applied

Scientific EffectProtective group chemistry: Chemical Bonding

Implementation Method 2

The major cause of such a change of resist pattern profile with time is diffusion of an acid generated upon exposure

Methodology Applied

Scientific EffectAcid diffusion: Diffusion

Implementation Method 3

the EB lithography, which is utilized as the ultra-fine microfabrication technique

Methodology Applied

Scientific EffectElectron beam lithography: Electron Beam

Implementation Method 4

Acid-catalyzed chemically amplified resist compositions are most often used in forming resist patterns

Methodology Applied

Scientific EffectChemically amplified resist: Chemical Bonding

Data Source

PatentEP4455118B1Polymer, chemically amplified positive resist composition, and resist pattern forming process

Publication Date: 2026.05.06 SHIN ETSU CHEMICAL CO LTD

AI summary

An acetal modifier affording a triple bond-bearing group serving as a protective group for an aliphatic or aromatic hydroxy group is provided as well as a polymer adapted to turn alkali soluble as a result of deprotection under the action of acid, the polymer comprising repeat units A1 having on side chain a structure including an aromatic hydroxy group protected with a triple bond-bearing group acid labile group. A chemically amplified positive resist composition comprising the polymer is also provided.