Ceramic Sputtering Target Microcrack Reduction

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Solution Overview

Problem

Current sputtering targets with ceramic materials face issues of microcracks and particle generation during machining, leading to substrate particles and nodules, which affect the quality of thin films formed in semiconductor devices, with existing methods insufficiently addressing microcrack suppression and particle reduction.

Innovation Solution

A ceramic sputtering target with a controlled amount of microcracks and peeling particles, achieved through surface grinding using a sponge polishing material and subsequent finishing with a vibration tool, to reduce microcrack frequency and depth, and peeling particle area ratio, resulting in a smoother sputtering surface with reduced nodules and improved target strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If surface grinding is performed on ceramic sintered body, then flat sputtering surface is obtained, but microcracks are generated on the surface

Engineering Contradiction:

Improveflatness of sputtering surfaceVSAvoidmicrocracks on surface

Core Design Contradiction:

ShapeVSObject-affected harmful factors

Solution Approach 1:

A slurry comprising ceramic particles and a liquid is introduced as an intermediary substance during the grinding process. The slurry serves as a mediator between the grinding tool and the ceramic sintered body, enabling effective material removal while significantly reducing microcrack generation on the sputtering surface

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the physical-chemical parameters of the grinding environment by introducing a specific slurry composition. The slurry's viscosity, particle size distribution, and chemical composition are optimized to reduce mechanical stress and thermal effects during grinding, thereby minimizing microcrack formation while maintaining surface flatness

Inventive Principle:

Principle #35Parameter changes

2Strength

If microcracks are present on target surface, then target strength is reduced and particles are easily peeled off, but complete elimination of microcracks increases manufacturing complexity

Engineering Contradiction:

Improvetarget strengthVSAvoidmanufacturing process complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The slurry is introduced during the grinding process as a preliminary protective measure. This preliminary action prevents microcrack formation before they can compromise target strength, eliminating the need for subsequent complex repair or reinforcement processes

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention replaces purely mechanical grinding with a combined chemical-mechanical process using the slurry. The chemical components of the slurry soften or react with the ceramic surface, reducing the mechanical impact and microcrack generation during grinding, thereby maintaining target strength without increasing overall process complexity

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Object-generated harmful factors

If grinding powder adheres to target surface, then nodules are generated during sputtering, but removing grinding powder increases processing time

Engineering Contradiction:

Improvenodule generationVSAvoidprocessing time

Core Design Contradiction:

Object-generated harmful factorsVSLoss of time

Solution Approach 1:

The slurry acts as an intermediary that prevents grinding powder adhesion in the first place. By maintaining the surface in a slurry-coated state during grinding, the grinding powder remains suspended and does not adhere to the target surface, eliminating the need for subsequent cleaning operations and reducing total processing time

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts the potentially harmful effect of grinding powder adhesion into a beneficial outcome. The slurry transforms the grinding process into a self-cleaning operation where the liquid medium continuously flushes away particles, preventing nodule formation while actually reducing the need for separate cleaning steps

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

The approach significantly reduces the generation of fine nodules and substrate particles during sputtering, ensuring stable sputtering performance and improved film quality by minimizing microcracks and peeling particles, while maintaining a suitable surface roughness for mechanical strength.

Implementation Method 1

there is a sputtering surface peeling particle area ratio of 1.0% or less in a case where a peel test is performed on the sputtering surface

Methodology Applied

Scientific EffectVibration: Vibration

Implementation Method 2

surface grinding using a sponge polishing material and subsequent finishing with a vibration tool

Methodology Applied

Scientific EffectAbrasion: Abrasion

Data Source

PatentUS20220319823A1Sputtering Target And Method For Manufacturing The Same

Publication Date: 2022.10.06 JX NIPPON MINING & METALS CORP

AI summary

A ceramic sputtering target, wherein when a cross-sectional structure of a sputtering surface is observed with an electron microscope, an amount of microcracks defined below is 50 μm/mm or less, and after performing a peel test on the sputtering surface, an area ratio of peeled particles confirmed by observing the cross-sectional structure with an electron microscope is 1.0% or less.Amount of microcracks=frequency of microcracks×average depth of microcracks