Ag Alloy Sputtering Target Composition for Corrosion Resistance

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Solution Overview

Problem

Conventional Ag alloy films face issues with high material costs due to the use of noble metals, insufficient optical properties, and inability to meet the requirement for improved luminous transmittance, especially in humid environments, where they suffer from deterioration in electrical and optical properties.

Innovation Solution

An Ag alloy sputtering target with a composition of 0.1 at% to 2.0 at% Sn, 2.0 at% to 10.0 at% Cu, optionally 0.1 at% to 3.0 at% Ti, and a total amount of 100 mass ppm or lower of Na, Si, V, Cr, Fe, and Co, which prevents Ag aggregation, segregation, and abnormal discharge, enhancing environment resistance and maintaining optical and electrical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If noble metals (platinum, palladium, gold, rhodium, ruthenium, or iridium) are added to Ag to improve environment resistance, then corrosion resistance is improved, but material costs increase significantly

Engineering Contradiction:
Improveenvironment resistanceVSAvoidmaterial cost
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent replaces expensive noble metals with cheaper base metals (Cu, Sn, Zn, Al, Ga, In, Si, Ge, or Ti) that provide similar corrosion protection functionality. This substitution dramatically reduces material costs while maintaining the essential function of improving environment resistance against humidity and sulfur corrosion.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent optimizes the composition parameters by specifying precise ranges for Ag (97.0-99.9 at%), Cu (0.1-2.0 at%), and other alloying elements. By carefully controlling these compositional parameters, the patent achieves effective corrosion resistance without requiring expensive noble metals, thus resolving the cost-reliability contradiction.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If Ag or Ag alloy is used to achieve high electrical conductivity and transmittance, then electrical and optical properties are improved, but the film is prone to corrosion and deterioration in humid environments

Engineering Contradiction:
Improveelectrical conductivity and transmittanceVSAvoidcorrosion by humidity and sulfur
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent creates a composite alloy system combining Ag with multiple protective elements (Cu as base alloying element and at least one additional element from Sn, Zn, Al, Ga, In, Si, Ge, or Ti). This composite structure provides both the high electrical conductivity and transmittance of Ag while the alloying elements form protective phases that resist corrosion from humidity and sulfur, thus protecting the Ag matrix.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The alloying elements (Cu, Sn, Zn, Al, Ga, In, Si, Ge, or Ti) act as intermediary protective layers or phases within the Ag matrix. These elements preferentially react with corrosive substances (humidity, sulfur) to form stable compounds, thereby protecting the Ag from direct corrosion while maintaining the film's electrical and optical properties.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Illumination intensity

If the film thickness is reduced to 15 nm or less to achieve semi-transparent properties, then transmittance is improved, but speckles and aggregation occur more significantly

Engineering Contradiction:
ImprovetransmittanceVSAvoiduniformity and speckle formation
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

The patent controls the compositional parameters of the alloy, specifically maintaining Ag content at 97.0-99.9 at% with controlled amounts of alloying elements. This precise parameter control ensures uniform deposition at thin film thicknesses (15 nm or less), preventing aggregation and speckle formation while maintaining high transmittance and semi-transparent properties.

Inventive Principle:
Principle #35Parameter changes

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 Ag alloy film formed using this target exhibits excellent electrical properties, environment resistance, and optical properties, with improved luminous transmittance and reduced absorptance, making it suitable for transparent conducting and optical functional films.

Implementation Method 1

Ag alloy sputtering target and manufacturing method for ag alloy film

Methodology Applied
Scientific EffectSputtering: Sputtering

Data Source

PatentEP3196333B1Ag alloy sputtering target and manufacturing method for ag alloy film
Publication Date: 2020.01.15 MITSUBISHI MATERIALS CORP
  • EP3196333B1 patent drawingFigure 1(a)~1(b)
  • EP3196333B1 patent drawingFigure 2(a)~2(b)
  • EP3196333B1 patent drawing

AI summary

An Ag alloy sputtering target of the present invention includes, as a composition, 0.1 at% to 3.0 at% of Sn, 1.0 at% to 10.0 at% of Cu, and a balance ofAg and inevitable impurities. In addition, an Ag alloy film of the present invention includes, as a composition, 0.1 at% to 3.0 at% of Sn, 1.0 at% to 10.0 at% of Cu, and a balance of Ag and inevitable impurities.