Planar Sputtering Target Porous Microstructure
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Solution Overview
Problem
Planar sputtering targets face limitations in target utilization and manufacturing due to residual stress, localized erosion, and differences in microstructure compared to rotary targets, leading to reduced efficiency and limited application in sputtering processes.
Innovation Solution
A planar sputtering target with a target material layer built by varying splat layering, incorporating anisotropic microstructure and porosity, which allows for stress relaxation and counteracts the local avalanching effect, achieved through a method involving a spray source that varies its angle with respect to the carrier surface during thermal spraying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thermal spray process is used to manufacture planar sputtering targets, then target material layer can be formed, but internal stresses increase leading to target failure by cracking or spallation
Solution Approach 1:
The patent introduces a porous layer within the target material that absorbs internal stresses generated during thermal spraying, preventing crack propagation and spallation. The porous structure acts as a stress buffer while maintaining coating integrity, directly resolving the contradiction between ease of manufacture and reliability.
Solution Approach 2:
The patent creates a localized porous layer at specific depths within the target material, rather than uniformly throughout. This localized modification allows stress management where most critical while maintaining dense structure where adhesion and barrier properties are most important, balancing manufacturing ease with reliability.
2Ease of manufacture
If conventional thermal spraying is used for planar targets, then target can be manufactured, but target utilization is limited due to localized erosion groove formation
Solution Approach 1:
The patent creates a porous layer at specific depths within the target material, rather than uniformly throughout. This localized modification allows stress management where most critical while maintaining dense structure where adhesion and barrier properties are most important, balancing manufacturing ease with reliability.
Solution Approach 2:
The patent employs dynamic control of spray parameters during the thermal spraying process, adjusting conditions to create the porous layer at optimal depths. This dynamic approach allows precise control over porous layer formation, enabling consistent stress management and improved target utilization across different manufacturing batches.
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 solution results in more robust and reliable planar sputtering targets with higher target utilization, enabling better matching of characteristics with rotary targets, thus allowing for more efficient and comparable sputter coating production.
Implementation Method 1
In a thermal spray process, superheated molten or semi-molten particles are projected at high velocities onto the proportionally much colder carrier material and solidify rapidly in a typical splat-like microstructure to form a coating
Implementation Method 2
US20120055783A1 describes the manufacture of either a planar or rotary sputtering target by thermal spraying assisted by cryogenic cooling jets, to reduce internal stresses without increasing porosity
Implementation Method 3
which can be used as a source for forming thin coatings in a sputtering process (e.g. a magnetron sputtering process)
Data Source
Figure 1~8b
Figure 2
Figure 3a~3b
AI summary
In a first aspect, the present invention relates to a planar sputtering target (400) comprising a target material layer (410) built up by a layering of splats, wherein the target material layer (410) has a layer width (w) and has a microstructure which varies across the layer width (w). In a second aspect, the present invention relates to a method for manufacturing such a planar sputtering target (400).