High Purity Alumina Sputtering Target for Film Homogeneity

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Solution Overview

Problem

Current alumina sputtering targets, with a purity of 99.9% (3N), fail to provide excellent insulation resistance and homogeneity in sputtered films, especially as device miniaturization demands thinner films with stricter physical properties, and existing methods do not adequately address film thickness distribution and dielectric breakdown voltage.

Innovation Solution

The development of sputtering targets with alumina sintered bodies of higher purity (not less than 99.99% or 99.999%) and improved relative density and crystal grain size, achieved through hot-press sintering and annealing, to enhance the physical properties of sputtered films.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If alumina sintered body with purity of 99.9% (3N) is used, then manufacturing cost is reduced and ease of manufacture is improved, but insulation resistance and homogeneity of sputtered film are insufficient

Engineering Contradiction:
Improveinsulation resistance and homogeneity of sputtered filmVSAvoidpurity requirement of alumina sintered body
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent changes the purity parameter of alumina sintered body from 99.9% (3N) to 99.99% or higher (4N or higher), and simultaneously optimizes relative density (95-99.5%) and average grain size (3-20 μm) to achieve both high film quality and manufacturability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent specifies different optimal ranges for different parameters: purity ≥99.99%, relative density 95-99.5%, and average grain size 3-20 μm, creating a localized quality specification that balances film performance with manufacturing feasibility

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If higher purity alumina sintered body (99.99% or 99.999%) is used, then insulation resistance and homogeneity of sputtered film are improved, but manufacturing cost and difficulty increase

Engineering Contradiction:
Improveinsulation resistance and homogeneity of sputtered filmVSAvoidpurity requirement of alumina sintered body
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent optimizes the purity parameter to 99.99% or higher while simultaneously controlling relative density (95-99.5%) and average grain size (3-20 μm) to create a balanced specification that achieves high film quality without excessive manufacturing difficulty

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent defines specific optimal ranges for each parameter: purity ≥99.99%, relative density 95-99.5%, and average grain size 3-20 μm, creating a localized quality window that balances performance with manufacturability

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If alumina sintered body with larger grain size is used, then manufacturing is easier and cost is reduced, but film thickness distribution and homogeneity deteriorate

Engineering Contradiction:
Improvefilm thickness distribution and homogeneityVSAvoidcrystal grain size control
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent optimizes the average grain size parameter to 3-20 μm, which is sufficiently small to ensure homogeneous film deposition and good thickness distribution, while remaining practical for manufacturing

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent specifies a localized grain size range of 3-20 μm that balances film quality requirements with manufacturing feasibility, avoiding both excessive fineness and coarse grain structures

Inventive Principle:
Principle #3Local quality

4Manufacturing precision

If relative density of alumina sintered body is increased, then film quality and insulation resistance are improved, but manufacturing complexity and cost increase

Engineering Contradiction:
Improvefilm quality and insulation resistanceVSAvoidrelative density control
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent optimizes relative density to 95-99.5%, which provides sufficient density for high film quality and insulation resistance while avoiding the excessive complexity and cost associated with achieving near-theoretical density

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent defines a specific relative density range of 95-99.5% that balances film performance with manufacturing practicality, creating an optimal window for sputtering target production

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 resulting sputtered films exhibit excellent insulation resistance, small surface roughness, and homogeneity, ensuring stable electrical properties even in ultrathin films.

Implementation Method 1

an alumina sintered body which has a purity of not less than 99.99% by mass %, a relative density of not less than 98%, and an average grain size of less than 5 μm

Methodology Applied
Scientific EffectHot-press sintering: Sintering

Implementation Method 2

an alumina sintered body which has a purity of not less than 99.99% by mass %, a relative density of not less than 98%, and an average grain size of less than 5 μm

Methodology Applied
Scientific EffectAnnealing: Annealing

Implementation Method 3

Sputtering is a method of depositing a film on a substrate by accelerating ions typically by means of glow discharge so as to hit a sputtering target so that the target ejects a material for the film due to the kinetic energy of the ions

Methodology Applied
Scientific EffectSputtering: Sputtering

Data Source

PatentUS10504706B2Sputtering target and method for producing the same
Publication Date: 2019.12.10 FERROTEC CERAMICS CORP

AI summary

A sputtering target which is made of an alumina sintered body having a purity of not less than 99.99% by mass %, a relative density of not less than 98%, and an average grain size of less than 5 μm or is made of an alumina sintered body having a purity of not less than 99.999% by mass % and a relative density of not less than 98%. A sputtered film having an excellent insulation resistance and an excellent homogeneity can be obtained by using the sputtering target.