Refractory Metal Sputtering Targets with Random Crystallographic Orientation

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Solution Overview

Problem

The production of high-quality sputtering targets for Physical Vapor Deposition (PVD) is hindered by the difficulty in achieving a uniformly fine and crystallographically random microstructure, particularly in tantalum (Ta) and niobium (Nb) targets, due to limitations in thermomechanical processing which result in non-uniform grain size and texture banding, and the high costs associated with complex processing and target replacement.

Innovation Solution

A method utilizing cold spray or kinetic spraying of fine metal powders directly onto a backing plate to create sputtering targets with a uniformly fine, randomly oriented grain structure without melting, allowing for cost-effective production and rejuvenation of targets with improved microstructural uniformity and mechanical strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If thermomechanical processing is used to reduce grain size and reduce crystallographic alignment, then grain size is reduced and texture is reduced, but the process is extensive and expensive and still results in non-uniform microstructure with banding

Engineering Contradiction:

Improvemicrostructure uniformityVSAvoidprocessing complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent changes the fundamental processing parameters by transitioning from thermomechanical processing to a powder metallurgy approach followed by rapid solidification. This involves changing the starting material state (from ingot to fine powder), the processing temperature regime (from high temperature thermomechanical to low temperature consolidation), and the solidification rate (from slow cooling to rapid solidification), thereby achieving uniform random microstructure without complex multi-step thermomechanical processing

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical thermomechanical processing system with a chemical/metallurgical system. Instead of using mechanical deformation and heat treatment to achieve grain refinement and texture reduction, the invention uses powder metallurgy consolidation and rapid solidification processes that inherently produce the desired microstructure through controlled material deposition and solidification, substituting mechanical action with metallurgical transformation

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If complex thermomechanical processing is used to achieve fine grain structure and random orientation, then grain size and texture are improved, but manufacturing cost increases significantly

Engineering Contradiction:

Improvegrain structure uniformityVSAvoidmanufacturing cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent performs preliminary action by starting with fine powder material that already has the desired grain size characteristics before consolidation. The powder is pre-prepared with appropriate particle size distribution and compositional uniformity, so that the subsequent consolidation and solidification processes directly yield the target microstructure without requiring extensive post-processing to achieve grain refinement and uniformity

Inventive Principle:

Principle #10Preliminary action

3Reliability

If targets are replaced frequently due to non-uniform microstructure, then quality issues are avoided, but productivity decreases and waste increases

Engineering Contradiction:

Improvefilm quality consistencyVSAvoidtarget utilization efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes the microstructural parameters of the target material through controlled rapid solidification and powder metallurgy processing, creating a uniformly random fine-grained structure that eliminates the banding and non-uniformity that cause sputtering rate variations. This parameter change in the target's internal structure ensures consistent film quality throughout the target's service life, allowing complete utilization without premature replacement

Inventive Principle:

Principle #35Parameter changes

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 direct fabrication of sputtering targets with a reproducible, fine-grained, and randomly oriented microstructure, reducing grain size and texture banding, and allowing for efficient repair and reuse of targets, thereby enhancing the quality and uniformity of thin films produced.

Implementation Method 1

Methodology Applied

Scientific EffectCold spray:

Implementation Method 2

Methodology Applied

Scientific EffectKinetic spraying:

Implementation Method 3

Physical properties of sputtering targets employed for Physical Vapor Deposition (PVD) in the electronics industry

Methodology Applied

Scientific EffectSputtering: Sputtering

Data Source

PatentUS9783882B2Fine grained, non banded, refractory metal sputtering targets with a uniformly random crystallographic orientation, method for making such film, and thin film based devices and products made therefrom

Publication Date: 2017.10.10 MATERION NEWTON INC

AI summary

In various embodiments, a sputtering target initially formed by ingot metallurgy or powder metallurgy and rejuvenated by, e.g., cold spray, is utilized in sputtering processes to produce metallic thin films.