Sputtering Target with Conductive Edge for Spark Suppression
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Solution Overview
Problem
Reactive sputtering processes, particularly HiPIMS, face instability and spark discharges when depositing electrically insulating layers like aluminum oxide, leading to process destabilization and defects due to the formation of insulating films on the target surface.
Innovation Solution
A target design with distinct areas of different materials, where the core area is made of the primary material for layer deposition and the edge area is made of a second material with higher electrical conductivity to prevent spark discharges, such as aluminum-chromium combinations, reducing the insulating character of deposited films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If reactive gas is introduced to deposit electrically insulating layers like aluminum oxide, then the desired insulating layer is formed, but spark discharges occur from the target surface to the anode causing process instability
Solution Approach 1:
The target is designed with different materials in different regions: the central area uses aluminum for depositing high-quality aluminum oxide layers, while the edge area uses a conductive material such as chromium or copper to prevent spark discharges. This local differentiation allows each region to perform its specific function optimally without interfering with the other.
Solution Approach 2:
The target employs a composite structure combining aluminum (for oxide layer deposition) with a conductive material (such as chromium, copper, or aluminum-chromium alloy) at the edges. This composite design leverages the complementary properties of both materials: aluminum's ability to form high-quality insulating oxide layers and the conductive material's ability to prevent spark discharges.
2Manufacturing precision
If the target surface is fully covered with electrically insulating composite material, then complete layer deposition is achieved, but charge build-up occurs leading to electrical breakdown and spark discharges
Solution Approach 1:
The target is designed with different materials in different regions: the central area uses aluminum for depositing high-quality aluminum oxide layers, while the edge area uses a conductive material such as chromium or copper to prevent spark discharges. This local differentiation allows each region to perform its specific function optimally without interfering with the other.
Solution Approach 2:
The harmful effect of charge build-up is extracted and localized to specific regions by removing the insulating material property from the target edges. The conductive material at the edges prevents charge accumulation by providing a charge dissipation path, effectively separating the layer deposition function (central area) from the charge management function (edge area).
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 design significantly reduces the occurrence of spark discharges and ensures a stable deposition process for electrically insulating layers, maintaining the properties of the deposited aluminum oxide layers without process instabilities.
Implementation Method 1
Coating processes using sputtering techniques are carried out in vacuum coating chambers using at least one so-called target, which is switched as a cathode by applying a negative voltage using a voltage or power supply. During the sputtering process, at least one additional electrode, which is also located in the coating chamber, is connected as an anode. A so-called working gas, which is usually an inert gas, is admitted into the coating chamber and positively charged ions are generated from it. The positively charged working gas ions are accelerated towards the target surface in such a way that collisions with the accelerated ions release particles from the surface of the target.
Implementation Method 2
If you want to deposit non-metallic layers from metallic targets by means of sputtering processes, you can let a so-called reactive gas into the coating chamber, which can react with the metallic ions generated from the metallic target. In this way, the material resulting from the reaction between the reactive gas and the ions generated from the target is applied as a thin layer to the substrate surfaces to be coated. By using metallic targets and by adding reactive gases such as O2, N2, C2H2, CH4 to name a few, a reaction and formation of corresponding composite materials such as oxides, nitrides, carbides or a mixture thereof then occurs on the substrate surface.
Implementation Method 3
The particles and ionized atoms already sputtered out of the target can be directed back to the target by scattering processes in the ambient gas within the coating chamber, as well as by electrical or electromagnetic forces of attraction. In the context of the present invention, this phenomenon is called 'redeposition'.
Data Source
Figure 1~3
Figure 2a
Figure 2b
AI summary
The invention relates to a target, the target surface thereof being designed in such a way that due to the use of the implied target for reactive sputter-deposition of electrically insulating layers in a coating chamber, a spark discharge from the target surface to an anode which is also prevented in the coating chamber, is formed.