Antireflective Hardmask Polymer for Lithography Etch Selectivity

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Solution Overview

Problem

In lithographic processes, the lack of antireflective hardmask materials leads to poor etch selectivity and reflectivity issues between imaging and target material layers, particularly when their compositions are similar, resulting in consumption of the imaging layer during etching.

Innovation Solution

A polymer with aromatic ring-containing groups, such as bis(phenyl)fluorene or naphthalene-backbone polymers, is used to create an antireflective hardmask composition that includes a crosslinker and organic solvent, optimizing refractive index and absorbance for improved lithography processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If an imaging layer and target material layer with similar compositions are used, then manufacturing precision is maintained, but etch selectivity deteriorates causing imaging layer consumption during etching

Engineering Contradiction:

Improvepattern transfer accuracyVSAvoidetch selectivity

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

A hardmask layer is introduced as an intermediate layer between the imaging layer and target material layer. This hardmask has different etch selectivity compared to both the imaging layer and target material layer, allowing the etch process to selectively remove the target material while protecting the imaging layer. The hardmask acts as a mediator that enables pattern transfer without causing imaging layer consumption.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If conventional hardmask materials are used, then etch selectivity is improved, but antireflective properties deteriorate leading to reflectivity issues during lithography

Engineering Contradiction:

Improveetch selectivityVSAvoidreflectivity

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The refractive index and absorbance parameters of the hardmask material are specifically optimized to provide antireflective properties. By adjusting these optical parameters, the hardmask reduces reflectivity at the interface between the imaging layer and underlying layers, preventing reflectivity-induced lithography defects while maintaining the necessary etch selectivity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The hardmask is formulated as a composite material that combines properties of both conventional hardmasks (etch selectivity) and antireflective coatings (optical properties). This composite structure allows simultaneous achievement of etch selectivity and antireflective functionality in a single layer.

Inventive Principle:

Principle #40Composite materials

3Adaptability or versatility

If imaging layer and target material layer have similar compositions, then material compatibility is improved, but reflectivity control deteriorates

Engineering Contradiction:

Improvematerial compatibilityVSAvoidreflectivity

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The hardmask layer serves as an intermediary that decouples the material composition requirements. It allows the imaging layer and target material layer to maintain similar compositions for compatibility while the hardmask provides the necessary optical property differences to control reflectivity during lithography.

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 antireflective hardmask composition enhances etch selectivity and reduces reflectivity, ensuring satisfactory lithography margins and maintaining pattern integrity during etching, with the polymer's self-crosslinking capabilities and suitable refractive indices at short wavelengths.

Implementation Method 1

The polymer may have a weight average molecular weight of about 1,000 to about 30,000... with the polymer's self-crosslinking capabilities and suitable refractive indices at short wavelengths

Methodology Applied

Scientific EffectAbsorbance: Absorption (EM radiation)

Implementation Method 2

The polymer having aromatic ring-containing groups in the backbone... with the polymer's self-crosslinking capabilities

Methodology Applied

Scientific EffectSelf-crosslinking: Chemical Bonding

Data Source

PatentUS7655386B2Polymer having antireflective properties, hardmask composition including the same, process for forming a patterned material layer, and associated device

Publication Date: 2010.02.02 CHEIL INDUSTRIES INC

AI summary

An antireflective hardmask composition includes an organic solvent, and at least one polymer represented by Formulae A, B or C:In Formulae A and B, the fluorene group is unsubstituted or substituted, in Formula C, the naphthalene group is unsubstituted or substituted, n is at least 1 and is less than about 750, m is at least 1, and m+n is less than about 750, G is an aromatic ring-containing group having an alkoxy group, and R1 is methylene or includes a non-fluorene-containing aryl linking group.