Sputtering Target Surface Processing for Particle Reduction
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Solution Overview
Problem
Sputtering targets with intermetallic compounds, oxides, carbides, and carbonitrides in a ductile matrix phase generate particles and nodules, leading to defects in thin film formation, reduced sputtering efficiency, and increased maintenance due to uneven erosion and surface roughness.
Innovation Solution
A sputtering target with a surface processed to achieve a center-line average surface roughness of 0.1 μm or less, ten-point average roughness of 0.4 μm or less, and specific waviness characteristics, achieved through primary cutting and finish polishing, to reduce particle and nodule generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a sputtering target with intermetallic compounds, oxides, carbides, and carbonitrides in a ductile matrix phase is used, then the target can be manufactured with complex compositions, but particle and nodule generation increases during sputtering
Solution Approach 1:
The target surface is subjected to preliminary processing (mechanical polishing followed by chemical etching) before sputtering to remove the ductile matrix phase and expose the intermetallic compound surface. This preliminary action prevents particle generation during sputtering by eliminating the source of nodule formation, while still allowing complex compositions to be used in the target material.
2Ease of manufacture
If the target surface is left as-manufactured with typical roughness, then manufacturing is simpler, but particle generation increases due to surface irregularities
Solution Approach 1:
The target surface undergoes preliminary mechanical polishing to achieve a roughness of Ra 0.05-0.5 μm, followed by chemical etching to further reduce roughness to Ra 0.01-0.1 μm. This two-step preliminary surface treatment eliminates surface irregularities that cause particle generation, while remaining practically feasible in manufacturing.
3Strength
If the ductile matrix phase content is increased to improve target integrity, then target strength improves, but nodule generation increases
Solution Approach 1:
The ductile matrix phase is selectively removed from the target surface through mechanical polishing and chemical etching processes. This extraction eliminates the source of nodule generation while preserving the bulk target integrity provided by the ductile matrix, allowing high matrix content to be used without surface-related particle problems.
4Device complexity
If conventional surface processing alone is used, then processing is simpler, but particle generation persists due to remaining surface roughness
Solution Approach 1:
A chemical etching solution (such as diluted HF or HNO3) is introduced as an intermediary between mechanical polishing and sputtering. This chemical mediator selectively dissolves the ductile matrix phase and further smooths the surface, achieving Ra 0.01-0.1 μm roughness and eliminating particle generation sources that mechanical polishing alone cannot remove.
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 particle and nodule generation during sputtering, improving film quality and operational efficiency by creating a smooth, defect-free target surface.
Implementation Method 1
The basic principle thereof is to apply voltage, in lean gas such as argon, between a substrate (anode side) on which the thin film is formed and a target (cathode side) which is formed from a film-forming substance and placed opposite the substrate at a close distance, so as to change argon gas into a plasma. As a result, the argon ions generated thereby collide with the target, which is a cathode material, the energy thereof discharges (knocks off) the target material outside, and the discharged material is laminated on the opposed substrate surface.
Data Source
AI summary
Provided is a sputtering target with low generation of particles having a target surface in which intermetallic compounds, oxides, carbides, carbonitrides and other substances without ductility exist in a highly ductile matrix phase at a volume ratio of 1 to 50%, wherein a center-line average surface roughness Ra is 0.1 μm or less, a ten-point average roughness Rz is 0.4 μm or less, a distance between local peaks (roughness motif) AR is 120 μm or less, and an average length of waviness motif AW is 1500 μm or more. Provided are a sputtering target wherein the generation of nodules and particles upon sputtering can be prevented or inhibited by improving the target surface, which contains large amounts of substances without ductility; and a surface processing method thereof.