Magnetron Sputtering Layout for Uniform Erosion of Ferromagnetic Targets
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Solution Overview
Problem
Existing magnetron sputtering devices face issues with non-uniform target erosion and inefficient cooling due to misalignment of the magnetic field vector, leading to suboptimal plasma distribution and frequent target replacement, especially when sputtering ferromagnetic materials.
Innovation Solution
A magnetron sputtering device with a cylindrical shield casing containing concentrically placed inner and outer magnets, mu-metal magnetic circuits, and a disc-shaped target with a thick ferromagnetic material, allowing for a parallel magnetic field and efficient cooling through hollow tubes, which reduces magnetic field shielding and enables precise target positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a supporting target is elevated above the main target to form a parallel magnetic field, then uniform target erosion is achieved, but the cooling system becomes inefficient and magnets are exposed to high temperatures
Solution Approach 1:
The base is divided into functionally distinct components: an inner base portion directly contacting the target for heat dissipation, and an outer base portion positioned away from the target to house cooled magnets. This segmentation allows each component to perform its optimal function without compromise.
Solution Approach 2:
A magnetic circuit is introduced as an intermediary element between the magnets and the target. This magnetic circuit guides the magnetic field lines to achieve parallel configuration for uniform erosion, while physically separating the magnets from the high-temperature zone near the target.
2Force
If the supporting target is placed close to the magnetic field source for sufficient field strength, then a strong magnetic field is obtained, but cooling efficiency decreases
Solution Approach 1:
The base structure is segmented into inner and outer portions at different radial positions. The inner base portion extends close to the target to provide strong magnetic field, while the outer base portion is positioned away to enable efficient cooling of the magnets without compromising field strength where needed.
3Manufacturing precision
If the magnetic field vector is inclined with respect to the target, then the central supporting magnet provides some improvement, but non-uniform erosion occurs
Solution Approach 1:
The magnetic circuit acts as an intermediary that transforms the inclined magnetic field from the central magnet into a parallel field configuration at the target surface. This allows the simple central magnet structure to produce the complex parallel field pattern needed for uniform erosion.
Solution Approach 2:
The magnetic circuit changes the orientation parameter of the magnetic field vectors, transforming them from an inclined configuration to a parallel configuration relative to the target surface, thereby achieving uniform erosion patterns.
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 configuration ensures uniform target erosion and plasma distribution, allowing for longer target operation without replacement and effective cooling, maintaining high magnetic field strength and preventing contamination, even with thicker targets.
Implementation Method 1
concentrically placed: an inner central magnet and an annular outer magnet... between the outer pole-piece and the outer magnet, an outer magnetic circuit is provided, made of mu-metal... between the inner pole-piece and the inner magnet there is an inner magnetic circuit made of mu-metal
Implementation Method 2
The disc shaped target is made of a ferromagnetic material... In case of sputtering ferromagnetic materials, an additional problem is that the target shields the magnetic field
Implementation Method 3
through which two sealed, hollow tubes protrude, for supplying and discharging a cooling fluid... channels for the cooling fluid are provided in it, connected to the hollow tubes
Implementation Method 4
channels for the cooling fluid are provided in it, connected to the hollow tubes... for supplying and discharging a cooling fluid
Implementation Method 5
a ring of plasma above the disc shaped target can be created... During the use of the device according to the invention, it is placed in the vacuum chamber, to which a small amount of sputtering gas is added during the sputtering time, which enables plasma formation
Implementation Method 6
JPS6338576A discloses a method for efficiently generation of a leakage magnetic field near the surface of a target to improve the utilizing efficiency of the target and the uniformity of a film thickness
Implementation Method 7
The invention concerns a device for magnetron sputtering from a target... a magnetron sputtering device with a cylindrical shield casing containing concentrically placed inner and outer magnets... allowing for a parallel magnetic field and efficient cooling through hollow tubes
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
A device for magnetron sputtering from a target comprising a substantially cylindrical casing (18), inside of which there is an outer tube (1), and in which are concentrically placed: an inner central magnet (7) and an annular outer magnet (6), and an inner tube (3) placed between them. Below the magnets a bottom pole-piece is placed (8), through which two sealed, hollow tubes (9a, 9b) protrude, for supplying and discharging a cooling fluid. Above the magnets, there is placed a base of the target on which the angular outer pole-piece (10) is placed and the inner pole-piece (12), and placed between them disc shaped target (14) made of the ferromagnetic material. The base of the target is created by concentrically placed and tightly fitted and connected: the outer tube (1), the outer magnetic circuit (2), the upper part of the inner tube (3), the inner magnetic circuit (4).