Refurbishing Non-Circular Sputtering Targets via Hot Pressing
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Solution Overview
Problem
Sputtering targets are not uniformly consumed, leading to premature wear and high costs due to non-uniform erosion, resulting in significant material wastage and increased costs for replacing precious metal targets.
Innovation Solution
A process for refurbishing non-circular spent sputtering targets by re-processing leftover metal, combining it with fresh metal powder of the same or different composition, and reforming a new target through effective cleaning and hot pressing with spacers to accommodate thermal expansion, ensuring a solid state diffusion bond without damaging the toolset.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the sputtering target is used until complete metal consumption, then material utilization is maximized, but the target reaches end of useful life after only 30% consumption due to non-uniform erosion and depletion grooves form
Solution Approach 1:
The patent recovers and reuses the remaining 70% of metal in spent sputtering targets by collecting depleted regions, processing them through cleaning and mixing with fresh powder, and reforming new targets. This transforms waste material into usable product, significantly reducing metal loss while maintaining target performance through the refurbishment cycle.
2Reliability
If a new sputtering target is manufactured to replace the spent target, then target performance is restored, but material costs and inventory carrying costs increase significantly
Solution Approach 1:
Instead of discarding spent targets and manufacturing entirely new ones, the patent recovers remaining metal, processes it through cleaning and mixing with fresh powder, and reforms refurbished targets. This reduces the need for new precious metal inventory while restoring target performance, lowering both material costs and inventory carrying costs.
Solution Approach 2:
The patent changes the physical and chemical parameters of spent target material through cleaning processes to remove contaminants, and through mixing with fresh powder to restore compositional uniformity. These parameter changes enable the recovered metal to meet performance requirements for refurbished targets, reducing dependence on new material production.
3Loss of substance
If the spent sputtering target is refined to recover metal, then material recovery is achieved, but the refining process is complex and increases costs
Solution Approach 1:
The patent applies simplified parameter change processes - cleaning to remove surface contaminants and mixing with fresh powder to restore compositional uniformity - rather than complex refining operations. This achieves effective metal recovery and target refurbishment with substantially reduced process complexity and cost compared to traditional refining methods.
4Manufacturing precision
If the eroded region is refilled with metal powder and consolidated through hot pressing, then the target is refurbished successfully, but the toolset may be damaged due to anisotropic thermal expansion of the non-circular spent target
Solution Approach 1:
The patent accounts for anisotropic thermal expansion of non-circular spent targets during hot pressing by designing tooling and processes that accommodate differential expansion rates in different directions. This prevents toolset damage while achieving successful consolidation of refilled metal powder with the spent target, maintaining refurbished target quality.
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 refurbished sputtering targets achieve high relative densities and uniform microstructure, extending the life of the target and reducing material costs by utilizing existing metal, while maintaining structural integrity and performance.
Implementation Method 1
applying sufficient heat and force to a top surface of the powder-filled spent sputtering target while maintaining the temperature below that of the melting point of the metal to consolidate the metal powder together with the spent sputtering target through a solid state diffusion process
Implementation Method 2
preparing a hot press die having a bottom punch and a die wall surrounding a cavity capable of accommodating the spent sputtering target; applying sufficient heat and force to a top surface of the powder-filled spent sputtering target while maintaining the temperature below that of the melting point of the metal
Implementation Method 3
centering the spent sputtering target within the cavity of the hot press die to accommodate anisotropic thermal expansion
Implementation Method 4
unique toolset designs as well as sintering procedures with combinations of pressure and temperature are used to accommodate the an isotropic thermal expansion caused by the non-circular sputtering target
Data Source
AI summary
Processes for refurbishing a spent sputtering target with a non-circular shape are disclosed. In one form, the processes include the steps of receiving one or more spent sputtering targets, inspecting and weighing the spent sputtering targets, removing any contaminants or other surface impurities from the spent sputtering target surfaces, preparing a hot press die with spacers, disposing the spent sputtering targets in the hot press die, the spacers used to center the spent sputtering targets therein, loading fresh metal refilling powder into the die to account for depleted regions of the spent sputtering targets to produce a powder-filled sputtering target, and applying sufficient heat and force to the filled sputtering target to produce a refurbished sputtering target with homogeneous composition and sufficient adhesion strength.