Chromic Oxide Sputtering Target Purity and Density Control

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Solution Overview

Problem

Chromic oxide sputtering targets often suffer from low purity and density, leading to cracking, impurity-induced particle generation, and abnormal discharge during sputtering, which affects the quality of thin films and layers in applications like LCD panels and magnetic recording media.

Innovation Solution

The development of chromic oxide powder with sulfur content of 100 wtppm or less and a purity of 99.95 wt% or higher, achieved through heat treatment in controlled atmospheres to reduce impurities and improve sintering conditions, resulting in a dense and crack-free sputtering target with refined crystal grains.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If chromic oxide is used as target material, then sputtering can be performed, but the target cracks easily and has low density

Engineering Contradiction:
Improvetarget integrityVSAvoidtarget density
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent applies parameter changes by controlling the sintering temperature (900-1100°C) and atmosphere (oxygen-containing) to optimize the density and prevent cracking of chromic oxide targets. This thermal treatment parameter optimization enables achieving relative density of 90% or higher while maintaining structural integrity during sputtering operations.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite structure by incorporating chromic oxide particles into a metal chromium matrix, forming a composite target material. This composite approach combines the beneficial properties of chromic oxide (for sputtering) with the mechanical strength and density of metal chromium, preventing cracking while maintaining sputtering functionality.

Inventive Principle:
Principle #40Composite materials

2Volume of stationary object

If chromic oxide powder is sintered to increase density, then pore reduction occurs, but crystal grains coarsen and surface becomes rough

Engineering Contradiction:
Improvetarget densityVSAvoidsurface uniformity
Core Design Contradiction:
Volume of stationary objectVSManufacturing precision

Solution Approach 1:

The patent optimizes sintering parameters (temperature range of 900-1100°C and oxygen-containing atmosphere) to achieve the optimal balance between density and surface quality. These parameter changes enable relative density of 90% or higher while maintaining average crystal grain size of 100 μm or less and surface roughness of 10 μm or less.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies preliminary heat treatment to the chromic oxide powder before sintering to pre-optimize particle morphology and distribution. This preliminary action prepares the powder structure to sinter into a dense target with fine crystal grains and smooth surface, preventing grain coarsening and surface roughening during the main sintering process.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If impurities are present in chromic oxide, then sputtering can proceed, but particles and nodules are generated causing abnormal discharge

Engineering Contradiction:
Improvesputtering rateVSAvoidparticle generation
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent controls impurity parameters by limiting sulfur content to 100 wtppm or less and carbon content to 200 wtppm or less through precise powder preparation and sintering conditions. These parameter controls prevent impurity-induced particle generation and abnormal discharge while maintaining continuous sputtering operation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent converts potentially harmful impurities into beneficial controlled features by precisely controlling their content levels. The controlled presence of minor elements at specific concentrations (S≤100 wtppm, C≤200 wtppm) actually improves target performance by preventing abnormal discharge and particle generation, transforming what would be harmful impurities into acceptable or beneficial compositional features.

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

This approach enhances the purity and density of sputtering targets, preventing cracks and pore formation, thereby improving the uniformity and stability of sputtered films, reducing particle generation, and inhibiting abnormal discharge, thus ensuring better film quality and target longevity.

Implementation Method 1

heat treatment in an oxygen-containing atmosphere

Methodology Applied
Scientific EffectOxidation: Oxidation

Implementation Method 2

heat treatment in an inert atmosphere to remove gas components

Methodology Applied
Scientific EffectThermal decomposition: Pyrolysis

Implementation Method 3

forming, via sputtering, thin films or layers

Methodology Applied
Scientific EffectSputtering: Sputtering

Data Source

PatentUS8877021B2Chromic oxide powder for sputtering target, and sputtering target manufactured from such chromic oxide powder
Publication Date: 2014.11.04 JX NIPPON MINING & METALS CORP

AI summary

Provided is chromic oxide powder for a sputtering target comprised of chromic oxide wherein sulfur is 100 wtppm or less. This sputtering target contains chromic oxide of 5 molar % or higher or chromic oxide, wherein the sulfur content in the sputtering target is 100 wtppm or less, and the purity excluding gas components of moisture, carbon, nitrogen and sulfur is 99.95 wt % or higher. The chromic oxide powder for a sputtering target is able to increase the purity of the chromic oxide itself as well as increase the sintered density upon manufacturing a sputtering target. As a result of manufacturing a sputtering target using this chromic oxide powder, the crystal grains are refined, and provided is a uniform and dense sputtering target that does not generate cracks.