Resist Top Coat Composition for EUV Lithography

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Solution Overview

Problem

Current resist top coat compositions for EUV lithography face challenges such as contamination from atmospheric amine, film loss, bridging between patterns, and sensitivity to out-of-band (OOB) light, which affect pattern resolution and edge roughness.

Innovation Solution

A resist top coat composition incorporating a polymer with a styrene repeating unit containing a 1,1,1,3,3,3-hexafluoro-2-propanol group, combined with a C6-C10 ether solvent and a C7-C12 hydrocarbon solvent, which is soluble in alkaline developers, reducing film loss and absorption of OOB light while maintaining sensitivity to EUV light.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the sensitivity of the resist is enhanced for EUV lithography, then the throughput is improved, but the resolution and edge roughness deteriorate

Engineering Contradiction:

ImprovethroughputVSAvoidresolution and edge roughness

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

A top coat layer is introduced as an intermediary between the EUV resist and the environment. This top coat acts as a protective mediator that prevents amine contamination from reaching the resist, thereby maintaining both high sensitivity and good resolution/edge roughness characteristics during the lithography process

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a top coat is formed on the resist to prevent amine contamination, then environmental resistance is improved, but the resist shape may be altered during development

Engineering Contradiction:

Improveenvironmental resistanceVSAvoidresist shape

Core Design Contradiction:

ReliabilityVSShape

Solution Approach 1:

The top coat composition is specifically designed with controlled solubility parameters. By adjusting the chemical composition and molecular weight of the top coat polymer, its dissolution rate in alkaline developers is optimized to ensure it does not alter the resist shape during development while still providing environmental protection

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If conventional solvents are used for the top coat, then the composition is easy to prepare, but film loss and bridging between patterns occur

Engineering Contradiction:

Improvepreparation easeVSAvoidfilm loss and bridging

Core Design Contradiction:

Ease of manufactureVSLoss of substance

Solution Approach 1:

The solvent system parameters are optimized by selecting specific ether solvents (C6-C10) and hydrocarbon solvents (C7-C12) with controlled polarity and evaporation rates. This parameter optimization prevents excessive dissolution of the resist film and avoids bridging between patterns while maintaining ease of preparation

Inventive Principle:

Principle #35Parameter changes

4Use of energy by moving object

If the resist is made highly sensitive to EUV light, then the light intensity requirement is reduced, but the resist becomes more susceptible to OOB light absorption

Engineering Contradiction:

Improvelight intensity requirementVSAvoidOOB light absorption

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The top coat is designed with specific optical properties that differ from the underlying resist. It has low absorption coefficient for EUV light (13.5 nm) to maintain sensitivity, while simultaneously providing protection against OOB light through its specific molecular structure and composition

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 composition effectively shields against OOB light, minimizes film loss and bridging, and enhances resist sensitivity, leading to improved pattern resolution and reduced edge roughness without altering the resist shape during development.

Implementation Method 1

Methodology Applied

Scientific EffectSolvation: Solvation

Implementation Method 2

reducing film loss and absorption of OOB light while maintaining sensitivity to EUV light

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Data Source

PatentUS9507262B2Resist top-coat composition and patterning process

Publication Date: 2016.11.29 SAMSUNG ELECTRONICS CO LTD

AI summary

There are provided a top coat composition and a patterning process using that composition, which reduce the effect of contaminants in the surrounding atmosphere on the resist film in absorbing OOB light and in reducing film loss of the resist pattern and bridging between patterns, and also enhances the sensitivity of the resist film and suppresses the emission of outgas from the resist film. The resist top coat composition of the present invention is formed on a photoresist film formed on a wafer, and is used in a patterning process performed by lithography in which, after exposure, developing is performed. The resist top coat composition contains a polymer as a base resin having a repeating unit p of styrene having a 1,1,1,3,3,3-hexafluoro-2-propanol group shown by the following general formula (1), a C6-C10 ether compound, and a C7-C12 hydrocarbon compound, and wherein m is 1 or 2, and p is in the range of 0<p≦1.0.