Rare Earth Rotary Target Bond Layer for High-Power Sputtering
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Solution Overview
Problem
The existing rotary targets for magnetron sputtering face challenges with low sputtering power density and target utilization rate due to the melting of indium solder at high power densities and the oxidation of rare earth targets during welding.
Innovation Solution
A rare earth rotary target is developed with an intermediate welding layer comprising a metal indium solder and an aluminum sheet, where the aluminum content is 3-10 wt.%. This configuration, combined with a thermal treatment process, increases the melting point of the solder and enhances the welding quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If indium solder is used for welding the back tube and target tube, then the welding process can be performed at low temperature, but the solder melts at high sputtering power density, resulting in welding-off of the target
Solution Approach 1:
The patent uses a composite solder material consisting of In-Al-Sn alloy instead of pure indium. This composite material combines the low melting point advantage of indium with the high melting point advantage of aluminum and tin, achieving a eutectic composition with melting point of 110-130°C that provides both easy welding and high stability during sputtering.
Solution Approach 2:
The patent changes the compositional parameters of the solder material by adding aluminum (3-10 wt.%) and tin (2-5 wt.%) to indium, creating an In-Al-Sn alloy system. This parameter change transforms the melting point from 156.6°C (pure indium) to a lower eutectic range of 110-130°C while simultaneously improving the high-temperature stability and resistance to welding-off during high power density sputtering.
2Reliability
If solder with higher melting points such as Sn or In-Sn alloy is used, then the sputtering power density can be increased, but the high welding temperature leads to oxidation of the chemically reactive rare earth target and increases welding difficulty
Solution Approach 1:
The patent optimizes the compositional parameters of the solder alloy to achieve a eutectic composition with melting point of 110-130°C. This parameter optimization allows welding at low temperatures (avoiding oxidation of rare earth targets) while maintaining high stability during sputtering, thus resolving the contradiction between welding ease and welding stability.
Solution Approach 2:
The In-Al-Sn composite solder material combines the advantages of multiple elements: indium provides low melting point and good wetting, aluminum increases melting point and oxidation resistance, and tin enhances mechanical strength. This composite material achieves both easy low-temperature welding and high stability during high power density sputtering.
3Productivity
If higher sputtering power density is used, then the productivity is improved, but the indium solder melts, resulting in welding-off of the target
Solution Approach 1:
The patent changes the melting point parameter of the solder material through compositional optimization of In-Al-Sn alloy, creating a eutectic composition with melting point of 110-130°C. This allows the solder to remain stable during high power density sputtering operations, enabling higher productivity without target welding-off.
Solution Approach 2:
The In-Al-Sn composite solder material provides both the low melting point needed for easy welding and the high thermal stability needed for high power density sputtering. The synergistic combination of indium, aluminum, and tin creates a material that maintains structural integrity at high temperatures, enabling increased sputtering power density and improved productivity.
4Productivity
If the target is used for extended period, then the productivity is improved, but the target thins and the solder melts, restricting the utilization rate of the target
Solution Approach 1:
The patent optimizes the solder composition parameters to create an In-Al-Sn eutectic alloy with melting point of 110-130°C. This parameter optimization ensures the solder layer maintains its integrity during extended target operation, preventing welding-off even when the target thins, thus extending the usable life of the target and improving utilization rate.
Solution Approach 2:
The In-Al-Sn composite solder material provides long-term stability during extended target operation. The aluminum component specifically enhances oxidation resistance and high-temperature stability, allowing the target to be used for longer periods without solder degradation, thereby increasing the target utilization rate from conventional levels to over 88%.
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 significantly increases the sputtering power density by more than 30% and improves the target utilization rate to over 88%, while reducing the oxidation of rare earth targets and maintaining a low-temperature welding process.
Implementation Method 1
the intermediate welding layer comprises a metal indium solder and an aluminum sheet arranged in the metal indium solder; the aluminum content in the intermediate welding layer is 3-10 wt. %
Implementation Method 2
combining a thermal treatment process, selecting a reasonable thickness can better control the melting point of the solder, reduce the solder composition segregation
Implementation Method 3
subjecting the welded rare earth rotary target to a thermal treatment; the thermal treatment temperature is 140° C.-640° C., and the thermal treatment time is 0.5-50 h
Implementation Method 4
the high welding temperature can easily lead to the oxidation of the chemically reactive rare earth target in the welding process
Implementation Method 5
The rotary target for magnetron sputtering needs to weld the target tube and the back tube together
Data Source
AI summary
Disclosed are a rare earth rotary target and a preparation method therefor. The rare earth rotary target includes a back tube and at least one rare earth target tube welded outside of the back tube; and the back tube and the rare earth target tube are welded via an intermediate welding layer. The intermediate welding layer includes a metal indium solder and an aluminum sheet arranged in the metal indium solder. The aluminum content in the intermediate welding layer is 3-10 wt. %. The back tube, the aluminum sheet, and the rare earth target tube are concentric cylindrical structures. According to the technical solution of the present application, the melting point of the solder is increased, thus achieving the purpose of improving the sputtering power density and a target utilization rate of rare earth rotary targets.