Tubular Sputtering Target Density Gradient
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Solution Overview
Problem
Existing tubular sputtering targets experience uneven material removal and reduced utilization due to increased sputtering rates at the ends, leading to non-uniform layer thickness and potential arcing, especially when made from refractory metals, which are crucial for microelectronics but challenging to produce with homogeneous material composition.
Innovation Solution
A tubular target with sections of varying relative densities, where one section has a larger outside diameter than the other, achieving a density ratio of (RDy−RDx)/RDy≧0.001, produced through powder metallurgy and pressureless or pressure-assisted sintering, ensuring uniform sputter removal and reduced arcing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the tube ends have a larger outer diameter than the central region, then the material utilization of the target can be significantly increased, but uneven removal cannot be avoided and the magnetic field strength is weakened
Solution Approach 1:
The patent applies local quality by creating tube end regions with a different material composition (containing a chemical compound of an element present in the central region) compared to the central region. This compositional variation locally modifies the sputtering rate at the tube ends, compensating for the uneven removal caused by the larger outer diameter and achieving more uniform overall material removal across the target.
2Productivity
If additional processing steps are used to achieve the geometry with larger end diameter, then the material utilization increases, but the manufacturing complexity and material usage increase
Solution Approach 1:
The patent changes the material composition parameter of the tube end regions by incorporating a chemical compound of an element found in the central region. This parameter change allows the desired geometry (larger end diameter) to be achieved with improved material utilization while avoiding complex additional processing steps, as the compositional modification can be integrated into the existing manufacturing process.
3Duration of action of stationary object
If the material thickness at the target ends is increased, then the service life of the tube targets is extended, but the magnetic field strength is weakened which affects sputtering performance
Solution Approach 1:
The patent applies local quality by modifying the material composition specifically in the tube end regions where the outer diameter is larger. By incorporating a chemical compound of an element present in the central region, the sputtering rate at the ends is adjusted to compensate for the increased thickness, thereby extending service life without significantly weakening the overall magnetic field strength and maintaining sputtering performance.
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 a high degree of material utilization, uniform layer thickness over large areas, and minimized arcing and particle generation, enhancing the performance and efficiency of refractory metal targets in sputtering processes.
Implementation Method 1
Cathode sputtering is also commonly called sputtering, sputtering sources sputtering targets
Implementation Method 2
The superimposition of the electric and magnetic fields lengthens the path of the charge carriers and increases the number of collisions per electron
Implementation Method 3
produced through powder metallurgy and pressureless or pressure-assisted sintering
Data Source
Figure 1~3
Figure 4
AI summary
The invention relates to a tubular target of refractory metal or a refractory metal alloy, which has at least one tubular portion X having a relative density RDx and at least one tubular portion Y having a relative density RDy, wherein at least one tubular portion X comprises at least in some regions a larger outer diameter than at least in some regions a tubular portion Y and the density ratio satisfies the relation (RDy-RDx)/RDy >= 0.001. The invention further relates to a method for producing a tubular target from refractory metal or a refractory metal alloy by sintering and local deformation of different degree. The tubular target has a more uniform sputter removal over the entire surface area compared with tubular targets according to the prior art. The tubular targets do not exhibit any tendency to arcing or to particle regeneration.