Ytterbium Sputtering Target Surface Hardening
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Solution Overview
Problem
Ytterbium sputtering targets suffer from irregularities (gouges) during machining, leading to particle generation and contamination issues during sputtering, which are challenging to address due to the soft and chemically active nature of the metal.
Innovation Solution
Adjusting the Vickers hardness of the ytterbium target material surface to a range of 15 to 40 before final finish processing, combined with cold rolling and annealing in a vacuum or inert gas, and employing dry cutting to minimize gouges and surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If bite cutting is used to machine the ytterbium target surface, then the target can be formed to specification, but irregularities (gouges) are created on the soft surface
Solution Approach 1:
The invention changes the physical parameter of surface hardness from its natural soft state (Hv < 15) to a hardened state (Hv ≥ 15) through surface hardening treatment. This parameter change enables the surface to resist machining-induced gouges while maintaining the underlying softness for good adhesion and electrical conductivity.
Solution Approach 2:
The surface hardening is performed as a preliminary action before the final finish machining. By hardening the surface in advance, the subsequent bite cutting or polishing operations can be performed without creating the characteristic gouges that would occur on soft ytterbium surfaces.
2Manufacturing precision
If the target surface is made harder to reduce gouges, then machining irregularities decrease, but the material becomes more difficult to process
Solution Approach 1:
The invention applies local quality by hardening only the surface layer (affecting depth of 1-10 μm) while leaving the bulk material properties unchanged. This localized treatment provides the hardness needed for smooth machining without requiring the entire target to be difficult to process.
Solution Approach 2:
The invention replaces complex mechanical machining processes with controlled surface hardening followed by simpler finish operations. Instead of relying on complex machining parameters to avoid gouges on soft material, the solution substitutes a thermal/chemical hardening process that fundamentally changes surface properties.
3Reliability
If conventional machining is used on soft ytterbium, then the target can be manufactured, but particle generation occurs during sputtering due to surface flaws
Solution Approach 1:
The surface hardness parameter is changed from soft (Hv < 15) to hardened (Hv ≥ 15) to eliminate the formation of machining-induced flaws and gouges. This parameter change directly addresses the root cause of particle generation during sputtering by preventing flaw formation in the first place.
Solution Approach 2:
The invention converts the naturally soft and machinable property of ytterbium (which causes gouges) into a benefit by applying surface hardening. The soft bulk material remains easy to manufacture from, while the hardened surface provides the flaw-free quality needed for reliable sputtering, thus converting what was originally a harmful property into a beneficial dual-state material.
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
Significantly reduces irregularities and particle generation during sputtering, ensuring a smoother target surface and improved sputtering performance by maintaining surface hardness within the specified range.
Implementation Method 1
an ytterbium cast ingot is subject to cold rolling
Implementation Method 2
thereafter annealed in a vacuum or an inert gas at 350° C. or higher and 700° C. or lower
Implementation Method 3
the surface of the obtained ytterbium target material is subject to final finish processing by machining
Data Source
AI summary
Provided is a method of producing an ytterbium sputtering target, wherein an ytterbium target material having Vickers hardness (Hv) of the material surface of 15 or more and 40 or less is prepared in advance, and a surface of the ytterbium target material having the foregoing surface hardness is subject to final finish processing by way of machining. With the ytterbium sputtering target, present invention aims to remarkably reduce the irregularities (gouges) on the target surface after the final finish processing of the target material, and to inhibit the generation of particles during sputtering.