Resist Composition Surfactant for Immersion Lithography

Solution Overview

Problem

In ArF immersion lithography, the challenge lies in achieving improved pattern rectangularity and mask fidelity due to acid diffusion issues, while also preventing blob defects and charge accumulation during electron beam exposure, without the need for additional antistatic coatings.

Innovation Solution

A resist composition comprising a polymer that changes alkali solubility under acid action, combined with a copolymer containing carboxylic acid ammonium salt and fluorine atoms, which enhances dissolution contrast and prevents intermixing with protective layers, and includes a surfactant to control acid distribution and surface hydrophilicity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a protective coating is applied to prevent resist leaching in water, then leaching is prevented, but intermixing between resist and protective layers occurs causing pattern profile degradation

Engineering Contradiction:

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

A surfactant comprising recurring units with carboxylic acid ammonium salt and fluorine atoms is introduced as an intermediary substance between the resist polymer and the protective coating. This surfactant prevents direct intermixing between the resist and protective layer while maintaining the protective coating's water barrier function, thus resolving the contradiction between preventing leaching and maintaining pattern profile.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The resist composition is formulated as a composite material containing the resist polymer, surfactant, and other components in specific ratios. This composite structure allows the surfactant to modulate the interface between resist and protective coating, preventing harmful intermixing while preserving the beneficial water resistance, thereby simultaneously achieving both reliability and manufacturing precision.

Inventive Principle:

Principle #40Composite materials

2Productivity

If the circuit line width is reduced to achieve higher integration, then device integration is improved, but acid diffusion influence increases lowering mask fidelity and pattern rectangularity

Engineering Contradiction:

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The surfactant modifies the chemical and physical parameters of the resist composition, particularly affecting acid diffusion characteristics. By incorporating the surfactant with specific fluorine-containing recurring units, the resist's response to acid diffusion is altered, maintaining sharp pattern edges and high rectangularity even at reduced line widths, thus enabling higher integration without sacrificing manufacturing precision.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If electron beam exposure is used for patterning, then patterning capability is achieved, but charge accumulation occurs on the resist film surface

Engineering Contradiction:

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The surfactant acts as an intermediary that mitigates charge accumulation during electron beam exposure. Its molecular structure with carboxylic acid ammonium salt groups provides charge dissipation pathways, reducing the harmful electrostatic effects while preserving the resist's patterning performance under electron beam irradiation.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 resolution and improved pattern rectangularity, prevents blob defects, and effectively manages charge accumulation, eliminating the need for separate antistatic coatings.

Implementation Method 1

a copolymer comprising recurring units containing a carboxylic acid ammonium salt and recurring units containing at least one fluorine atom

Methodology Applied

Scientific EffectHydrophobic interaction: Hydrophobe

Implementation Method 2

includes a surfactant to control acid distribution and surface hydrophilicity

Methodology Applied

Scientific EffectSurfactant action: Surfactant

Implementation Method 3

a polymer which changes its alkali solubility under the action of an acid as a base resin

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Data Source

PatentUS7598016B2Resist composition and patterning process

Publication Date: 2009.10.06

AI summary

To a resist composition comprising a polymer which changes its alkali solubility under the action of an acid as a base resin, is added a copolymer comprising recurring units containing a carboxylic acid ammonium salt and recurring units containing at least one fluorine atom as an additive. The composition is suited for immersion lithography.