Multi-Stage Polishing for Sputtering Target Surface Flatness
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Solution Overview
Problem
Conventional sputtering targets with low Vickers hardness (HV) often develop thick oxidized layers during bonding, leading to surface irregularities that cause abnormal discharge during sputtering, which cannot be effectively removed by single-stage polishing without increasing surface roughness or damaging the material.
Innovation Solution
A multi-stage polishing method using abrasives with different grit numbers in ascending order from small to large is employed to reduce surface irregularities and oxidized layers on sputtering targets with low Vickers hardness, specifically using grit numbers where the latter stage is 1.0 to 2.5 times larger than the former stage, and the final stage grit number is #800 or more and #1500 or less, to achieve a smooth and stable sputtering surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polishing is performed to remove the oxidized layer, then the oxidized layer is removed, but surface irregularities increase causing abnormal discharge
Solution Approach 1:
The polishing process is divided into multiple stages with progressively finer abrasives. The first stage uses coarse abrasive to remove the oxidized layer, while subsequent stages use finer abrasives to reduce surface irregularities. This segmentation allows the process to achieve both oxidized layer removal and surface smoothing without causing abnormal discharge.
Solution Approach 2:
The abrasive grain size parameter is changed progressively through multiple stages. By transitioning from coarse to fine abrasives in sequence, the process adapts the removal rate and surface finish characteristics to achieve the desired balance between oxidized layer removal and surface irregularity reduction.
2Productivity
If single-stage polishing is used to remove oxidized layer, then processing time is short, but surface irregularities increase
Solution Approach 1:
The polishing operation is segmented into multiple stages, each with a specific function. The first stage focuses on material removal, while subsequent stages focus on surface smoothing. This segmentation efficiently allocates processing time to achieve both productivity and precision goals.
Solution Approach 2:
The coarse abrasive polishing is performed as a preliminary action to remove the oxidized layer quickly, preparing the surface for subsequent fine polishing stages. This preliminary removal action reduces the burden on later stages, allowing them to focus on surface smoothing.
3Productivity
If coarse abrasive is used to remove oxidized layer, then material removal rate is high, but surface irregularities increase
Solution Approach 1:
The abrasive selection is segmented into a sequence from coarse to fine. Coarse abrasives are used only in the first stage for high-rate material removal, while finer abrasives are used in subsequent stages to reduce surface roughness. This segmentation allows each stage to optimize for its specific function without compromising the other.
Solution Approach 2:
The polishing process applies periodic action with alternating abrasive grain sizes. Each stage uses a specific abrasive size appropriate for its function, creating a periodic pattern of removal and refinement that achieves both high material removal rate and low surface roughness.
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 effectively reduces surface irregularities and variations, minimizing the occurrence of abnormal discharge and ensuring a stable sputtering process by maintaining a low average arithmetic average roughness (Ra) of 0.5 μm or less and standard deviation of 0.1 μm or less on the sputtering surface.
Implementation Method 1
performing multi-stage polishing on a sputtering surface of a target material by using a plurality of abrasives having different grit numbers
Data Source
AI summary
A sputtering target that is less likely to cause abnormal discharge is manufactured. A method for manufacturing a sputtering target includes performing multi-stage polishing on a sputtering surface of a target material having a Vickers hardness of 100 or less being made of metal by using a plurality of abrasives having different grit numbers in ascending order of grit number from a small grit number to a large grit number.