Racetrack Magnet Design for Uniform Sputtering Erosion
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Solution Overview
Problem
Magnetron sputtering apparatuses face uneven target erosion due to non-uniform magnetic flux distribution, leading to inefficient film formation and target material usage.
Innovation Solution
A racetrack-shaped magnetic-field-generating apparatus with inclined permanent magnets and adjusted distances between magnetic pole members and the target, allowing for more uniform magnetic flux distribution and expanded erosion regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If permanent magnets are arranged with magnetization direction parallel to the target surface in corner portions, then magnetic flux concentration in corner portions is improved, but erosion uniformity deteriorates due to excessive plasma concentration in corners
Solution Approach 1:
The patent applies different magnetization directions to different regions: corner portions use parallel magnetization to concentrate magnetic flux where needed, while linear portions use perpendicular magnetization to distribute plasma evenly. This local differentiation resolves the contradiction by optimizing each region's magnetic field characteristics for its specific functional requirements.
Solution Approach 2:
The patent introduces asymmetric magnetization arrangements where the magnetization direction varies by position (parallel in corners, perpendicular in linear portions). This asymmetric configuration allows tailored magnetic field distribution that prevents excessive plasma concentration in corners while maintaining sufficient magnetic flux where required.
2Area of stationary object
If the distance between center magnetic pole member and target is increased, then erosion region expansion is improved, but magnetic field intensity at target surface decreases
Solution Approach 1:
The patent optimizes the distance parameter between the center magnetic pole member and target surface to achieve a balance: increasing the distance sufficiently to expand the erosion region while maintaining it within limits to preserve adequate magnetic field intensity for effective sputtering.
3Productivity
If magnetic flux density vertical component is zero in certain portions, then erosion speed increases in those portions, but erosion uniformity deteriorates due to non-uniform erosion distribution
Solution Approach 1:
The patent creates localized regions with zero vertical magnetic flux density component in specific positions (corner portions with parallel magnetization) to accelerate erosion where additional material removal is beneficial, while maintaining non-zero vertical components in other regions to control erosion rates and achieve overall uniformity.
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
The solution achieves more uniform target erosion and improved film formation efficiency by shifting the deepest erosion portion towards the center, enhancing the use efficiency of the target material.
Implementation Method 1
permanent magnets arranged between the center magnetic pole member and the peripheral magnetic pole member with one magnetic pole opposing the center magnetic pole member and the other magnetic pole opposing the peripheral magnetic pole member
Implementation Method 2
secondary electrons discharged from the target are captured by a magnetic field generated by the magnetic-field-generating apparatus, causing a cyclotron motion on a target surface
Implementation Method 3
each permanent magnet arranged at least in the linear portion having a magnetic pole surface opposing the center magnetic pole member, which has a magnetization direction inclined away from the target
Implementation Method 4
A phenomenon that atoms or molecules are ejected from a target by a high-speed bombardment of an inert substance such as Ar, etc. is called 'sputtering.'
Data Source
AI summary
A racetrack-shaped magnetic-field-generating apparatus for magnetron sputtering having a linear portion and corner portions, which comprises a center magnetic pole member; a peripheral magnetic pole member surrounding the center magnetic pole member; pluralities of permanent magnets arranged between the center magnetic pole member and the peripheral magnetic pole member to have magnetic poles aligned in one direction; and a non-magnetic base member supporting them; permanent magnets arranged in at least the linear portion being inclined with their surfaces on the side of the center magnetic pole member lower, and with their outside magnetic pole surfaces not in contact with the peripheral magnetic pole member in lower portions; the distance between the center magnetic pole member and the target being the same as the distance between the peripheral magnetic pole member and the target, thereby generating a uniform magnetic field on a target surface.