Sputtering Target Recycling via Melting and Casting
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Solution Overview
Problem
The manufacturing of large sputtering targets for semiconductor and liquid-crystal components is hindered by high costs and impurity contamination, as conventional methods struggle to maintain purity and prevent particle generation, especially as target sizes increase.
Innovation Solution
A method involving surface treatment and melting of used sputtering targets and scrap materials to form ingots, followed by forging, rolling, and machining, which reduces impurities and eliminates the need for multiple refining processes, thereby lowering costs and enhancing target purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If conventional manufacturing methods (sintering or melting) are used to produce large sputtering targets, then target size increases, but manufacturing cost increases and impurity contamination increases
Solution Approach 1:
The invention recycles used sputtering targets by melting them down to create new targets. The used targets are collected, melted in a vacuum or inert atmosphere to prevent contamination, and cast into new target forms. This recycling process eliminates the need for raw material refinement and reduces manufacturing costs while maintaining high purity levels.
Solution Approach 2:
The invention changes the physical state of the used target material from solid to liquid through melting, then to solid again through controlled cooling and casting. This phase transformation allows the material to be reformed into new targets with random crystal orientation while removing surface contaminants and impurities that accumulated during previous use.
2Volume of stationary object
If conventional manufacturing methods are used to produce large sputtering targets, then target size increases, but impurity levels increase
Solution Approach 1:
The melting and casting process is performed in a vacuum or inert gas atmosphere (such as argon) to prevent oxidation and contamination of the molten metal. This controlled environment ensures that no new impurities are introduced during the recycling process, maintaining the high purity required for semiconductor applications.
Solution Approach 2:
By melting used targets and recasting them, the invention removes surface contaminants and impurities that accumulated during previous sputtering operations. The melting process homogenizes the material and eliminates localized contamination, producing a cleaner final product.
3Manufacturing precision
If conventional manufacturing methods are used, then multiple refining processes are required, but this increases manufacturing complexity and cost
Solution Approach 1:
The recycling method consolidates multiple refining steps into a single melting and casting operation. Since the material is already highly purified from the original manufacturing process, the melting step serves both to remove surface contaminants and to homogenize the material, eliminating the need for multiple sequential refining processes.
Solution Approach 2:
The invention extracts the used target material from its spent state and transforms it directly into a reusable form through melting and casting. This extraction and transformation process replaces the need for complex multi-step refining sequences required when starting from raw materials.
4Ease of manufacture
If used sputtering targets are recycled without surface treatment, then manufacturing cost decreases, but particle generation increases
Solution Approach 1:
The melting process transforms the solid used target material into a liquid state, which eliminates the crystal structure and incorporates any surface contaminants or particles into the molten matrix. Upon controlled cooling and casting, the material solidifies with a homogeneous structure and random crystal orientation, preventing particle generation in the final product.
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 results in sputtering targets with purity equal to or higher than the original targets, reduced impurity levels (e.g., oxygen, iron, aluminum, and copper), and random crystal orientation, while minimizing manufacturing costs and preventing particle generation.
Implementation Method 1
melting at least one of the used sputtering target and the scrap material after the surface treatment to form an ingot
Data Source
AI summary
The manufacturing cost of a sputtering target is reduced and the impurity concentration of the manufactured sputtering target is also reduced. A method of manufacturing a sputtering target includes: surface-treating at least one of a used sputtering target and a scrap material; melting at least one of the used sputtering target and the scrap material after the surface treatment to form an ingot; and manufacturing a sputtering target by subjecting the ingot to forging, rolling, heat treating, and machining.