Pellicle Membrane Recovery Layer SP2 Bond Control

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Solution Overview

Problem

Current pellicles for photomasks suffer from damage due to pinholes and dangling bonds, leading to aperture loss and contamination, which affects the reliability and durability of the photolithography process.

Innovation Solution

A pellicle membrane structure is developed with a base layer and a recovery layer, where the recovery layer fills pinholes and covers the base layer, using catecholamine to form hexagonal aromatic rings, reducing SP2 covalent bonds and enhancing mechanical strength and optical characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a pellicle membrane is used to protect the photomask, then contamination protection is improved, but damage from pinholes and dangling bonds occurs leading to aperture loss

Engineering Contradiction:

Improvecontamination protectionVSAvoidaperture loss

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies preliminary action by forming a recovery layer that proactively fills pinholes and covers dangling bonds on the base layer before they can cause damage during photolithography. This preventive approach addresses the technical contradiction by eliminating the harmful effects (pinholes and dangling bonds) before they lead to aperture loss, while maintaining the protective function against contamination.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements discarding and recovering by removing defective base layers with pinholes and dangling bonds, then recovering the pellicle membrane by forming a new recovery layer on the remaining intact base layer. This process restores the protective function while eliminating the harmful defects that cause aperture loss.

Inventive Principle:

Principle #34Discarding and recovering

2Strength

If the pellicle membrane structure is enhanced with a recovery layer, then mechanical strength and durability are improved, but the complexity of fabrication increases

Engineering Contradiction:

Improvemechanical strengthVSAvoidfabrication complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by controlling the thickness of the recovery layer (5-50 nm) and adjusting the SP2 covalent bond content (30-70%) to optimize mechanical strength. By carefully controlling these parameters, the patent enhances durability while managing fabrication complexity through defined process windows.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by combining a base layer (graphene or graphite) with a recovery layer containing carbon atoms with specific SP2 covalent bond content. This composite structure provides enhanced mechanical strength and durability while the defined composition ranges help manage fabrication complexity.

Inventive Principle:

Principle #40Composite materials

3Illumination intensity

If SP2 covalent bonds are reduced in the recovery layer, then optical characteristics are improved, but mechanical strength may be compromised

Engineering Contradiction:

Improveoptical characteristicsVSAvoidmechanical strength

Core Design Contradiction:

Illumination intensityVSStrength

Solution Approach 1:

The patent applies parameter changes by optimizing the SP2 covalent bond content in the recovery layer to fall within 30-70%, balancing optical characteristics and mechanical strength. This controlled parameter adjustment resolves the technical contradiction by finding the optimal range where both optical performance and mechanical integrity are satisfied.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements local quality by having the recovery layer with different SP2 covalent bond content (30-70%) compared to the base layer, creating localized regions with optimized properties. The recovery layer's specific SP2 content optimizes optical characteristics while maintaining sufficient mechanical strength through its protective function.

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 pellicle membrane exhibits improved durability, mechanical strength, and optical characteristics, reducing damage from hydrogen in photolithography and maintaining surface uniformity, thus enhancing the reliability and lifespan of the photomask during the lithography process.

Implementation Method 1

performing a first heat treatment process at a first process temperature to form a first recovery layer that is bonded to the base layer

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Implementation Method 2

using catecholamine to form hexagonal aromatic rings

Methodology Applied

Scientific EffectAromatic ring formation:

Implementation Method 3

a first recovery layer that covers the first surface of the base layer

Methodology Applied

Scientific EffectProtective coverage:

Data Source

PatentUS11262648B2Pellicle for photomask and method of fabricating the same

Publication Date: 2022.03.01 SAMSUNG ELECTRONICS CO LTD

AI summary

A pellicle for a photomask comprises a pellicle membrane. The pellicle membrane incudes a base layer having a first surface and a second surface facing the first surface, and a first recovery layer covering the first surface of the base layer. A content of SP2 covalent bonds between carbon atoms contained in the first recovery layer is less than or equal to a content of SP2 covalent bonds between carbon atoms contained in the base layer.