Top Coat Layer Composition for EUV Lithography

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Solution Overview

Problem

Conventional top coat layers used in photolithography with extreme ultraviolet rays suffer from poor absorption of deep ultraviolet light, leading to resist pattern deterioration and gas volatilization, which contaminates exposure apparatus and affects sensitivity.

Innovation Solution

A top coat layer composition comprising an aromatic compound with a molecular weight of 180 to 800 and an aromatic hydroxyl group, combined with an aqueous solvent, is applied to absorb deep ultraviolet light and inhibit gas volatilization, enhancing sensitivity and pattern formation accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional top coat layers are used in photolithography with extreme ultraviolet rays, then the process can proceed, but the absorption rate of deep ultraviolet light is poor, leading to resist pattern deterioration and gas volatilization

Engineering Contradiction:

Improveabsorption of deep ultraviolet lightVSAvoidresist pattern quality

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the top coat layer by incorporating aromatic compounds with specific molecular weights (180-800) and aromatic hydroxyl groups. This parameter change enables the top coat layer to absorb deep ultraviolet light with wavelengths of 193 nm and 248 nm, preventing resist pattern deterioration while maintaining extreme ultraviolet ray transparency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite top coat layer composition by combining aromatic compounds (such as phenolic resins, polyhydroxystyrene, or polyhydroxy naphthalene) with aqueous solvents. This composite structure provides both deep ultraviolet absorption capability and extreme ultraviolet transparency, resolving the contradiction between protecting the resist and allowing exposure

Inventive Principle:

Principle #40Composite materials

2Productivity

If conventional resist compositions are used for extreme ultraviolet ray exposure, then exposure can be performed, but gas volatilization occurs during exposure, contaminating the optics system

Engineering Contradiction:

Improveexposure process efficiencyVSAvoidgas volatilization

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces a top coat layer as an intermediary substance between the resist layer and the exposure environment. This top coat layer acts as a barrier that suppresses gas volatilization from the resist during extreme ultraviolet exposure, preventing contamination of mirrors and photo masks while allowing the exposure process to proceed efficiently

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The top coat layer is applied in advance before exposure to preemptively prevent gas volatilization. By forming this protective layer beforehand, the patent prevents the harmful effect of gas contamination before it can occur during the exposure process

Inventive Principle:

Principle #9Preliminary anti-action

3Device complexity

If the content of deep ultraviolet rays is not controlled in the exposure light, then the exposure process is simpler, but the shape of resist patterns deteriorates

Engineering Contradiction:

Improveexposure system configurationVSAvoidresist pattern shape accuracy

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

Instead of attempting to remove deep ultraviolet rays from the exposure light source (which would increase system complexity), the patent converts the harmful deep ultraviolet rays into a beneficial effect by using them to form a protective top coat layer. This top coat layer then protects the resist from the harmful effects of deep ultraviolet exposure, transforming the problem into a solution

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 top coat layer achieves a high absorption rate of deep ultraviolet light (>90%) and prevents gas contamination, resulting in improved resist pattern quality and reduced roughness, while maintaining sensitivity and preventing gas volatilization during exposure.

Implementation Method 1

The top coat layer achieves a high absorption rate of deep ultraviolet light (>90%)

Methodology Applied

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

Data Source

PatentUS10268117B2Top-layer membrane formation composition and method for forming resist pattern using same

Publication Date: 2019.04.23 MERCK PATENT GMBH

AI summary

[Object] To provide compositions for forming a top coat layer capable of forming patterns with an excellent roughness and pattern shape in a pattern formation method by exposure to extreme ultraviolet rays, and a pattern formation method using the composition.[Means for solving problem] Provided are compositions for forming a top coat layer comprises an aromatic compound having an aromatic hydroxyl group and an aqueous solvent; and a method of forming patterns by applying the composition onto the resist surface and subjecting the resultant to exposure and development. This composition can further comprise binders.