Magnet Unit for Uniform Target Erosion in Magnetron Sputtering
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Solution Overview
Problem
Existing magnetron sputtering apparatuses face challenges in achieving uniform target erosion across the entire surface, particularly when the target is made of magnetic material, leading to uneven erosion speeds and reduced target life due to non-uniform magnetic flux density and geometric design limitations.
Innovation Solution
A magnet unit design featuring an internal magnet unit with radially extending magnet elements and an external magnet unit surrounding it, forming a magnetic track with regions parallel and perpendicular to the rotation direction, ensuring uniform erosion by controlling magnetic flux distribution and reducing concentration of plasma in specific regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional magnet arrangement is used, then the magnetic field can confine plasma, but the magnetic flux density becomes non-uniform causing uneven erosion and reduced target life
Solution Approach 1:
The magnet unit is divided into multiple independent magnets arranged in an alternating polarity pattern around the cathode electrode. This segmentation allows each magnet to contribute to the magnetic flux distribution, creating a more uniform overall field that prevents localized plasma concentration and achieves uniform target erosion.
Solution Approach 2:
The magnet arrangement uses alternating polarities (N-S-N-S pattern) positioned at specific angles around the cathode electrode, creating an asymmetric magnetic field configuration. This asymmetric arrangement generates a uniform magnetic flux density distribution that prevents erosion concentration in specific regions, thereby extending target life.
2Productivity
If the erosion speed is increased to improve productivity, then more material is deposited, but the target wears out faster requiring frequent replacements
Solution Approach 1:
The magnet unit is designed to be rotatable around the cathode electrode, creating a dynamic magnetic field configuration. This rotation distributes the plasma confinement and erosion effects uniformly across the entire target surface over time, allowing high deposition rates to be maintained without localized over-erosion, thus extending target service life while preserving productivity.
Solution Approach 2:
The rotating magnet unit creates periodic movement of the magnetic field relative to the target surface. This periodic action ensures that all regions of the target experience equivalent plasma exposure and erosion over complete rotation cycles, enabling sustained high-speed deposition without premature target failure.
3Productivity
If the magnetic field is concentrated in specific regions to enhance plasma confinement, then sputtering efficiency increases, but erosion becomes non-uniform and target life decreases
Solution Approach 1:
The alternating polarity magnet arrangement creates a magnetic field configuration where multiple regions simultaneously contribute to plasma confinement across the entire cathode surface. Each magnet pair works together to confine plasma in its local region while the overall arrangement ensures uniform distribution, achieving both high sputtering efficiency and uniform erosion through multi-functional magnetic zones.
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 effectively extends target life by promoting uniform erosion across the target surface, regardless of target size or material, and improves the operational efficiency of the sputtering process by reducing the need for frequent target replacements.
Implementation Method 1
A magnetron sputtering apparatus generates magnetron on a target discharge surface using a magnet unit which is disposed on the back side of a cathode electrode supporting the target and confines the plasma to obtain a high density state thereof
Implementation Method 2
a magnetic tunnel is formed on the target surface having an endless track shape by a magnetic force line generated from a cathode magnet
Implementation Method 3
When electric power is applied to the target in this state, an electric field is generated in the normal line direction of the target surface. An electron is confined in a region where the magnetic field and the electric field cross perpendicularly to each other
Implementation Method 4
The ion is accelerated by an electric field generated on the target front and causes the sputtering
Implementation Method 5
the ion flicks a sputter particle from the target surface as material of a film
Implementation Method 6
the magnetic track which extends in a direction perpendicular to the rotation direction of the magnet unit when the magnet unit rotates about a rotation center
Data Source
AI summary
The present invention provides a magnet unit and a magnetron sputtering apparatus which can suppress the consumption amount of a target by efficiently consuming the target and can easily cause erosion on the target to progress uniformly regardless whether the target size is small or large and whether the target is made of magnetic material or not. A magnet unit according to an embodiment of the present invention includes a member configured to be provided with a predetermined magnet, an internal magnet unit which is provided for the member and includes n magnet elements extending radially in the surface of the member from a predetermined position of the member in at least n (n: positive integer equal to or larger than 3) directions, the n magnet elements having one polarity on a side opposite to the member, and an external magnet unit which is provided for the member so as to surround the internal magnet unit along the shape of the internal magnet unit, the external magnet unit having the other polarity on a side opposite to the member.