Magnet Unit with Folded Magnetic Poles for Sputtering Uniformity
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Solution Overview
Problem
Existing magnetron sputtering apparatuses face challenges in achieving uniform film thickness distribution on substrates due to limitations in adjusting magnetic field strength and track length, especially when using ferromagnetic targets, which result in increased target consumption and running costs.
Innovation Solution
A magnet unit design featuring a yoke with an annular peripheral magnet and an inner magnet with extending and projecting magnetic pole portions forming 2n-1 folded shape portions, which enhances magnetic field lines at the ends of the target without increasing the target's length or width, ensuring uniform film thickness distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the length of the target is increased to improve film thickness distribution, then the film thickness distribution is improved, but the target consumption and running cost are increased
Solution Approach 1:
The invention applies different magnetic pole configurations to different regions of the target. Specifically, the first and second magnetic poles are positioned at the end portions of the target while the third magnetic pole is positioned at the central portion, creating localized magnetic field variations that optimize sputtering uniformity without requiring a longer target.
Solution Approach 2:
Instead of extending the target in the longitudinal direction (one dimension), the invention introduces a new dimensional arrangement by positioning magnetic poles at different locations (end portions vs. central portion) and using a yoke structure that extends in the width direction, thereby achieving improved film thickness distribution through spatial redistribution rather than simple extension.
2Manufacturing precision
If the height of magnets is changed to regulate magnetic field strength, then the film thickness distribution is improved, but the magnetic field strength on ferromagnetic targets is insufficient for discharge ignition
Solution Approach 1:
The invention uses a composite magnetic circuit structure combining permanent magnets (first, second, and third magnetic poles) with a ferromagnetic yoke. This composite arrangement allows the permanent magnets to provide the necessary magnetic field strength for discharge ignition while the yoke distributes and regulates the magnetic field to achieve uniform film thickness distribution.
Solution Approach 2:
The yoke acts as an intermediary between the magnetic poles and the target. It receives magnetic flux from the first, second, and third magnetic poles and distributes it uniformly across the target surface, particularly enhancing the magnetic field at the end portions where it is most needed for discharge ignition while maintaining overall field uniformity.
3Manufacturing precision
If the target length is increased to improve film thickness distribution, then the film thickness uniformity is improved, but the device complexity and manufacturing cost are increased
Solution Approach 1:
The magnetic pole system is segmented into three distinct parts: first magnetic poles at one end portion, second magnetic poles at the other end portion, and a third magnetic pole at the central portion. This segmentation allows independent optimization of magnetic field distribution in different regions, achieving uniform film thickness without increasing target length or overall complexity.
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 reinforces magnetic field lines at the ends of the target, achieving uniform film thickness distribution on substrates without extending the target, thereby reducing target consumption and running costs while improving film formation efficiency.
Implementation Method 1
a magnet unit disposed on the back side of a cathode electrode supporting a target causes generation of magnetron on a discharge surface of the target to entrap a plasma
Implementation Method 2
a magnetron sputtering apparatus, a magnet unit disposed on the back side of a cathode electrode supporting a target causes generation of magnetron
Implementation Method 3
a yoke formed of a ferromagnetic plate material
Implementation Method 4
ions of the plasma generated in this apparatus collide with the target to thereby flick a target material. The target material is then adhered onto a substrate, whereby a thin film is formed
Data Source
AI summary
A magnet unit, which can realize uniform film thickness distribution of a thin film formed on a substrate without increasing the length and width of a target. The magnet unit includes a peripheral magnet, which is disposed on the yoke on the back side of a cathode electrode so as to follow the outline of a target, and an inner magnet disposed in the peripheral magnet and having a polarity different from the polarity of the peripheral magnet. The magnet unit provides a magnetic track MT that is a set of regions which tangents of magnetic field lines M generated on the target parallels to the target surface. The magnet unit further includes n (n is a positive integer of two or more) extending magnetic pole portions and n−1 projecting magnetic pole portions, which form 2n−1 folded shape portions U at the both ends in the longitudinal direction of the magnetic track.