Cylindrical Ceramic Sputtering Target Bonding Defect Resolution

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Cylindrical ceramic sputtering targets face issues with cracking, chipping, extraordinary discharge, and nodules due to bonding layer defects caused by volume changes in the solder material during cooling, leading to poor thermal and electrical conduction, and high power input per unit area.

Innovation Solution

Filling a molten bonding material in a cavity defined by a cylindrical ceramic target and base material, starting cooling from one end towards the other, and controlling the bonding layer's area without material using X-ray radiography to minimize defects, ensuring a high volume proportion of filled bonding material.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a solder material is used to bond the cylindrical target material and base material, then the production cost is reduced and high density ceramic sintered body can be used, but the volume decrease during solidification and cooling causes bonding layer defects

Engineering Contradiction:

Improveproduction costVSAvoidbonding layer quality

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The cavity is pre-formed with sufficient volume to accommodate the solder material in its solidified state. The space between the cylindrical target material and base material is designed in advance to compensate for the 3.9% volume decrease, ensuring complete filling without defects after cooling and solidification.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If a large power per unit area is input to achieve high film deposition rate, then the productivity is improved, but the bonding layer defects cause cracks, chips, and extraordinary discharge

Engineering Contradiction:

Improvefilm deposition rateVSAvoidtarget operational stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

X-ray radiography is used to create a visual copy/image of the bonding layer interior, allowing non-destructive inspection of the bonding quality. This enables detection of bonding layer defects without damaging the target, ensuring operational reliability while maintaining high productivity.

Inventive Principle:

Principle #26Copying

3Stability of the object's composition

If the solder material volume decreases during cooling, then the phase change is complete, but the cavity volume increases due to thermal expansion difference causing bonding defects

Engineering Contradiction:

Improvesolder material solidificationVSAvoidbonding layer uniformity

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The cavity design accounts for local variations in thermal expansion between the ceramic target material and metal base material. The space is engineered to accommodate differential expansion at the bonding interface while ensuring uniform solder distribution, preventing bonding defects despite thermal expansion differences.

Inventive Principle:

Principle #3Local quality

4Strength

If arc spray method or HIP method is used to form the target, then the target structure is integral, but the cylindrical base material cannot be reused and the equipment cost is high

Engineering Contradiction:

Improvetarget structure integrityVSAvoidequipment cost and base material reusability

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The target assembly is divided into separate components: the cylindrical base material, cylindrical target material, and solder material. This segmentation allows the base material to be reused after target erosion, while the solder provides reliable bonding. The separate components are assembled using simple equipment, avoiding the need for expensive arc spray or HIP equipment.

Inventive Principle:

Principle #1Segmentation

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

Significantly reduces the occurrence of cracks, chips, and extraordinary discharges, achieving a high target utilization ratio and film deposition rate with improved thermal and electrical conduction.

Implementation Method 1

a decrease in volume attributable to a phase change of the solder material from a liquid state to a solid state

Methodology Applied

Scientific EffectPhase change: Phase Change

Implementation Method 2

a decrease in volume attributable to cooling from the melting point of the solder material to normal temperature

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Implementation Method 3

the difference in the thermal expansion coefficient between both materials

Methodology Applied

Scientific EffectThermal expansion coefficient difference: Thermal Expansion

Data Source

PatentUS10366870B2Cylindrical sputtering target and process for producing the same

Publication Date: 2019.07.30 TOSOH CORP

AI summary

Provided is a cylindrical ceramic sputtering target, which significantly reduces the occurrence of a crack, a chip, extraordinary discharge and a nodule.By filling a molten bonding material in a cavity defined by a cylindrical ceramic target material and a cylindrical base material, starting cooling the molten bonding material from its one end toward its other end in a cylindrical axial direction in sequence, and further filling the molten bonding material in the cavity during cooling, a cylindrical ceramic sputtering target is manufactured so as to be characterized in that as observed by an X-ray radiograph of the bonding material, the total area of portions where no bonding material exists is 10 cm2 or less per 50 cm2 of X-ray radiograph area, and the maximum area of the portions where no bonding material exists is 9 cm2 or less.