Reactive Material Casting for Uniform Grain Lithium Targets

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Solution Overview

Problem

The challenge lies in producing lithium targets with uniform grain size distribution and rotary targets for sputtering, as existing methods like evaporation are not well-suited for lithium battery applications and planar targets have limitations in reactive sputtering environments.

Innovation Solution

A method and system for casting reactive material targets, including lithium, using a mold with a stainless steel mandrel in a vacuum or inert atmosphere, allowing molten reactive material to flow into a cylindrical mold, and controlling heating and cooling to form tubular or planar targets with uniform grain size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If evaporation is used to deposit lithium films, then film uniformity is improved, but substrate configuration complexity and equipment limitations increase

Engineering Contradiction:

Improvefilm uniformityVSAvoidsubstrate configuration complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces the thermal field-based evaporation process with a mechanical field-based sputtering process. Instead of using thermal energy to evaporate lithium material, the invention uses ion bombardment and plasma physics to deposit lithium films, thereby eliminating the need for complex parabolic substrate configurations and enabling versatile coating applications.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If planar targets are pressed or forged, then target formation is simplified, but grain size uniformity and reactive environment resistance deteriorate

Engineering Contradiction:

Improvetarget formation simplicityVSAvoidgrain size uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent changes the manufacturing parameters from cold pressing or forging to a process involving material deposition under controlled conditions. By controlling deposition parameters such as ion energy, flux rate, and substrate temperature, the invention achieves uniform grain size distribution while maintaining manufacturing simplicity.

Inventive Principle:

Principle #35Parameter changes

3Quantity of substance

If planar targets are used in reactive sputtering, then initial material availability is high, but target life and utilization decrease due to re-deposition

Engineering Contradiction:

Improveinitial material availabilityVSAvoidtarget life

Core Design Contradiction:

Quantity of substanceVSDuration of action of moving object

Solution Approach 1:

The patent transitions from static planar targets to dynamic rotary targets that rotate during sputtering. This dynamic configuration allows fresh material to continuously enter the erosion zone, preventing re-deposition buildup and extending target life while maintaining high material utilization efficiency.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention pre-conditions the target surface through controlled erosion patterns that prevent insulating oxide buildup. By maintaining optimal erosion conditions from the start, the system prevents re-deposition issues before they occur, maximizing target utilization throughout its operational life.

Inventive Principle:

Principle #10Preliminary action

4Duration of action of moving object

If rotary targets are used, then target life and utilization are improved, but manufacturing complexity increases

Engineering Contradiction:

Improvetarget lifeVSAvoidtarget structure complexity

Core Design Contradiction:

Duration of action of moving objectVSDevice complexity

Solution Approach 1:

The patent divides the rotary target into modular segments or uses a simple cylindrical geometry that can be manufactured using standard techniques. This segmentation approach simplifies the manufacturing process while maintaining the rotational dynamics needed for extended target life and improved material utilization.

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

This approach enables the production of reactive material targets with uniform grain size, extending target life and improving utilization, particularly for lithium and cerium, by using rotary cathodes, which are more suitable for sputtering and can withstand reactive environments.

Implementation Method 1

forming a vacuum or inert atmosphere

Methodology Applied

Scientific EffectVacuum: Vacuum

Implementation Method 2

melting the reactive material in the reservoir

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 3

heating the mold to above a casting temperature

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 4

cooling the mold to form the PVD target

Methodology Applied

Scientific EffectFreezing: Freezing

Data Source

PatentUS10138544B2Sputtering target

Publication Date: 2018.11.27 SOLERAS ADVANCED COATINGS LTD

AI summary

A method for casting a reactive material PVD target, as well as targets thus obtained and a mold for casting. The method includes providing a mold defining an opening, placing a reactive material ingot in to a reservoir (140) proximate the mold, forming a vacuum and melting the reactive material in the reservoir, heating the mold to above a casting temperature and forming a vacuum therein, introducing molten reactive material from the reservoir into the opening and cooling the mold to form the PVD target.