Sputtering Target Magnetic Field Control for Redeposition
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Solution Overview
Problem
Conventional sputtering methods experience high redeposition of films at the peripheral parts of the target due to weak magnetic field intensity, leading to delamination issues and potential operation failures.
Innovation Solution
A sputtering method and apparatus that control the magnetic field intensity at the target's peripheral parts to be lower during deposition and higher during standby modes, allowing for the removal of redeposited films during standby, thereby reducing redeposition amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the magnetic field intensity at the peripheral part of the target is kept weak to avoid sputtering of non-target parts, then the target holder is protected from sputtering, but the redeposition amount of the redeposited film becomes large
Solution Approach 1:
The magnetic field intensity is made dynamically adjustable rather than fixed. The control unit varies the magnetic field intensity at different angular positions during rotation, applying weak magnetic field when the peripheral part faces the target holder (to protect from sputtering) and strong magnetic field when it faces the vacuum chamber (to reduce redeposition).
Solution Approach 2:
The magnetic field intensity is applied periodically in sync with the rotation of the rotary cathode magnet. The control unit generates periodic variations in magnetic field strength corresponding to the rotational period, creating alternating zones of weak and strong magnetic field intensity that differentially affect sputtering and redeposition processes.
2Loss of substance
If the magnetic field intensity at the peripheral part of the target is increased to reduce redeposition, then the redeposition amount decreases, but the target holder becomes subject to sputtering
Solution Approach 1:
The magnetic field intensity is dynamically modulated according to the rotational position of the rotary cathode magnet. The control unit increases magnetic field intensity only when the peripheral part is oriented toward the vacuum chamber (reducing redeposition) and decreases it when oriented toward the target holder (preventing sputtering damage).
Solution Approach 2:
The magnetic field intensity varies periodically with the rotation of the magnet, creating time-dependent zones of high and low field strength. This periodic variation ensures that high field intensity (for reducing redeposition) and low field intensity (for protecting the target holder) are applied at appropriate times during each rotational cycle.
3Productivity
If the magnetic field intensity is uniformly strong across the target surface, then the sputtering rate is high, but the redeposition amount becomes large at the peripheral part
Solution Approach 1:
The magnetic field intensity is made non-uniform in space and time. The control unit creates local variations in field strength depending on the angular position, with the peripheral part experiencing strong magnetic field intensity only during specific portions of the rotation when it faces the vacuum chamber, while other parts maintain consistently strong fields for high sputtering rate.
Solution Approach 2:
The magnetic field distribution is dynamically adjusted rather than maintained uniformly. The control unit modulates the field intensity at different radial positions based on rotational phase, allowing the peripheral part to have strong field intensity temporarily (reducing redeposition) while maintaining overall high sputtering rates across the target surface.
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 approach effectively reduces redeposition amounts on the target, preventing delamination and operation failures by uniformly utilizing the target surface and ensuring consistent film deposition.
Implementation Method 1
a magnetic field parallel to a surface of a target
Implementation Method 2
During sputtering within the vacuum chamber of the sputtering apparatus, sputtering atoms 11 reach a substrate
Implementation Method 3
a portion of the sputtering atoms 11 become redepositing atoms 12 which are redeposited on the surface of the target 8 due to scattering of a process gas such as Ar gas
Data Source
AI summary
A sputtering method deposits a film on a substrate by controlling a magnetic field parallel to a surface of a target so that the magnetic field at a part of the target, other than parts of the target which are sputtered during a deposition mode in which a deposition process is performed with respect to the substrate, has an intensity lower than an arbitrary intensity at the other parts during the deposition mode and has an intensity higher than or equal to the arbitrary intensity during a standby mode in which the deposition process is not performed. A redeposited film which is deposited on the part of the target during the deposition mode is removed by performing a sputtering during the standby mode.