Dry Etching Silicon Nitride with NF3 Gas

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Solution Overview

Problem

The use of sulfur hexafluoride (SF6) in dry etching processes for fabricating array substrates contributes significantly to global warming due to its high global warming potential, necessitating the replacement or reduction of this greenhouse gas without compromising etch rate or productivity.

Innovation Solution

Employing nitrogen trifluoride (NF3) as a reactive gas in dry etching processes for patterning silicon nitride-based protection layers, which has a lower global warming potential and high self-decomposition rate, allowing for the same etch rate as SF6 while reducing greenhouse gas emissions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If sulfur hexafluoride (SF6) is used as reactive gas for dry etching silicon nitride, then etch rate and productivity are maintained, but greenhouse gas emissions increase significantly

Engineering Contradiction:

Improveetch rateVSAvoidgreenhouse gas emissions

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the chemical composition parameter of the reactive gas from SF6 to NF3, which has lower global warming potential. The gas mixture parameters (flow rates, pressures, compositions) are optimized to maintain etch rate while reducing greenhouse gas emissions by approximately two-thirds compared to SF6-based processes

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs NF3 gas which has high self-decomposition rate during the etching process, eliminating the need for expensive decomposition apparatuses and emission trading systems required for SF6 management. This reduces both equipment complexity and operational costs

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Object-generated harmful factors

If NF3 is used as reactive gas instead of SF6, then greenhouse gas emissions are reduced, but etch rate may be compromised

Engineering Contradiction:

Improvegreenhouse gas emissionsVSAvoidetch rate

Core Design Contradiction:

Object-generated harmful factorsVSProductivity

Solution Approach 1:

The patent uses composite gas mixtures containing NF3 combined with other gases (such as oxygen, helium, or carbon monoxide) to achieve both reduced greenhouse gas emissions and maintained etch rate. The synergistic effect of the gas mixture components enables simultaneous achievement of environmental and productivity goals

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent optimizes multiple parameters including gas flow rates, chamber pressure, power density, and temperature to ensure that NF3-based etching processes achieve etch rates comparable to SF6 processes while maintaining significantly lower greenhouse gas emissions

Inventive Principle:

Principle #35Parameter changes

3Object-generated harmful factors

If SF6 decomposition apparatuses and emission trading systems are implemented, then environmental compliance is achieved, but fabrication costs increase

Engineering Contradiction:

Improvegreenhouse gas managementVSAvoiddecomposition apparatuses and emission trading systems

Core Design Contradiction:

Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The patent adopts NF3 gas which naturally decomposes during the etching process with high decomposition rates, eliminating the need for additional decomposition apparatuses and complex emission trading systems. This simplifies the fabrication system while achieving environmental compliance and reducing operational costs

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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

NF3 reduces greenhouse gas emissions by approximately two-thirds compared to SF6, lowers fabrication costs, and maintains productivity, eliminating the need for additional decomposition apparatuses and emission trading systems.

Implementation Method 1

nitrogen trifluoride (NF3) gas to form a contact hole exposing the line or the electrode. NF3 reduces greenhouse gas emissions by approximately two-thirds compared to SF6, lowers fabrication costs, and maintains productivity, eliminating the need for additional decomposition apparatuses and emission trading systems.

Methodology Applied

Scientific EffectSelf-decomposition: Decomposition (biological)

Implementation Method 2

performing a first dry etching process on the protection layer exposed between the photoresist patterns using a first gas mixture containing nitrogen trifluoride (NF3) gas to form a contact hole exposing the line or the electrode

Methodology Applied

Scientific EffectDry etching:

Data Source

PatentUS9236451B2Method of fabricating array substrate using dry etching process of silicon nitride

Publication Date: 2016.01.12 LG DISPLAY CO LTD

AI summary

A method of fabricating an array substrate includes: forming a line or an electrode on a substrate on which a pixel region is defined, forming a protection layer on the line or the electrode, the protection layer formed of silicon nitride (SiNX), forming photoresist patterns on the protection layer, and loading the substrate having the photoresist pattern into a chamber of a dry etching apparatus, and performing a first dry etching process on the protection layer exposed between the photoresist patterns using a first gas mixture containing nitrogen trifluoride (NF3) gas to form a contact hole exposing the line or the electrode.