Magnetron Assembly Segmented Magnet Arrays for Sputtering
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Solution Overview
Problem
Standard magnetron assemblies face challenges in providing adequate magnetic flux for thicker targets, leading to inadequate magnetic flux at the target surface and increased erosion rates, which shortens the target life and reduces material utilization.
Innovation Solution
A magnetron assembly with four or more rows of magnets arranged in independent linear arrays, forming a pattern with an outer and inner portion, where the magnets in the turnaround sections are arranged to break up the curve into multiple offset curves, optimizing magnetic flux distribution and minimizing erosion at the target ends.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the target thickness is increased to improve material utilization and reduce fabrication cost, then the amount of usable material increases, but the magnetic flux at the target surface becomes inadequate
Solution Approach 1:
The magnetron assembly is divided into multiple independent linear arrays of magnets (at least four rows), allowing each row to independently contribute to the magnetic flux. This segmentation enables the system to provide sufficient magnetic flux at the target surface even when the target thickness is increased, as each magnet row can be optimized to penetrate through the thicker target material effectively.
2Reliability
If the magnetic flux is increased to maintain adequate flux at the target surface, then the sputtering efficiency improves, but the turn-around width broadens causing increased erosion at target ends
Solution Approach 1:
The magnet rows are positioned and configured to create localized magnetic field distributions that are optimized for different regions of the target. The independent linear arrays allow for tailored magnetic flux density at the target surface without unnecessarily broadening the turn-around regions, thus maintaining high sputtering efficiency while minimizing erosion at the target ends.
3Duration of action of moving object
If the target thickness is increased to extend production campaign duration, then the target life increases, but the relative erosion rate at target ends increases due to broadened turn-around
Solution Approach 1:
By segmenting the magnetron into multiple independent magnet rows, the system can maintain a compact turn-around geometry even with thicker targets. Each magnet row independently contributes to the magnetic flux distribution, preventing the turn-around from broadening and thus reducing the relative erosion rate at target ends while extending production campaign duration.
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 enhances magnetic flux at the target surface, reduces target erosion, and increases material utilization, allowing for thicker targets with longer production campaigns without premature burn-through.
Implementation Method 1
A magnetron assembly is disposed within the tube and supplies magnetic flux which permeates the target such that there is adequate magnetic flux at the outer surface of the target. The magnetic field is designed in a way such that it retains electrons emitted from the target so as to increase the probability that they will have ionizing collisions with the working gas
Implementation Method 2
This field retains the electrons and causes them to drift in a direction perpendicular to the magnetic field lines, which is parallel to the rows 102 of magnets. This is known as the ExB drift
Implementation Method 3
increase the probability that they will have ionizing collisions with the working gas, hence enhancing the efficiency of the sputtering process
Implementation Method 4
Magnetron sputtering of rotating targets is well known in the art and is used extensively for producing a wide variety of thin films on a wide variety of substrates
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
One embodiment is directed to a magnetron assembly comprising a plurality of magnets, and a yoke configured to hold the plurality of magnets in at least four straight, parallel, independent linear arrays. The plurality of magnets is arranged in the yoke so as to form a pattern comprising an outer portion and an inner portion, wherein the outer portion substantially surrounds the perimeter of the inner portion. The end portions of the linear array comprise a pair of turnaround sections, wherein each turnaround section substantially spans respective ends of the pair of elongated sections of the outer portion. The magnets in each turnaround section are arranged to form at least two or more different curves in the magnetic field that are offset from each along the target rotation axis.