Magnetron Sputtering Apparatus Plasma Density
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Solution Overview
Problem
Existing magnetron sputtering apparatuses face challenges in achieving a high density of plasma with target material ejected towards a substrate, often resulting in insufficient plasma production area and reduced components perpendicular to the electric field, making it difficult to form uniform thin films.
Innovation Solution
A magnetron sputtering apparatus design featuring a magnetic circuit with elongated permanent magnets spaced around a rotating cathode target, supported by a yoke, which creates an opening for plasma ejection with an adjustable angle between 60 to 120 degrees, and includes a ground shield to prevent target material deposition on the magnets, along with a cooling water system within the backing plate for temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a conventional magnetron sputtering apparatus is used, then the structure is simple, but the plasma density is insufficient and the plasma production area is small
Solution Approach 1:
The magnetic circuit is divided into multiple permanent magnets arranged in alternating polarity patterns (N-S-N-S sequence) around the cathode target. This segmentation creates multiple discrete plasma production zones, increasing the overall plasma density and production area compared to a single continuous magnetic structure
Solution Approach 2:
The magnetic circuit transitions from a planar arrangement to a three-dimensional configuration with magnets positioned at different radial distances and angular positions around the cathode target. This spatial distribution creates overlapping magnetic fields that enhance plasma confinement and increase the effective plasma production volume
2Adaptability or versatility
If the magnetic circuit is fixed, then the installation is simple, but the plasma ejection angle cannot be adjusted for optimal deposition
Solution Approach 1:
The magnetic circuit is designed with rotational capability around the cathode target, transforming it from a static structure to a dynamic one. This allows the entire magnetic circuit to be rotated to different angular positions, thereby adjusting the plasma ejection angle and the position where target material deposits on the substrate
Solution Approach 2:
The magnetic circuit structure serves multiple functions: it generates the magnetic field for plasma confinement, defines the plasma ejection direction through its angular position, and controls the deposition pattern on the substrate. This multi-functionality reduces the need for separate adjustment mechanisms
3Quantity of substance
If permanent magnets are used without shielding, then the magnetic field is strong, but target material deposits on the magnets reducing performance
Solution Approach 1:
The harmful effect of target material deposition on magnets is isolated by extracting the magnets from direct exposure to the plasma flux. Ground shields are positioned between the plasma source and the magnets, selectively blocking material transport to the magnets while allowing plasma to maintain magnetic field intensity
Solution Approach 2:
Ground shields act as intermediary components that mediate between the plasma environment and the permanent magnets. These shields are positioned strategically to intercept target material before it reaches the magnets, protecting them from contamination while maintaining the integrity of the magnetic field
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 enhances plasma density and uniformity by optimizing the magnetic field and electric field interaction, allowing for efficient target material ejection and deposition on the substrate with minimal moving parts, while simplifying magnetic circuit installation and intensity adjustment.
Implementation Method 1
a magnetic circuit that is spaced from the outer side of the cathode target and defines an opening through which a plasma including a target material removed from the cathode target is ejected
Implementation Method 2
ions (for example, argon ions) are sputtered to a target material in vacuum and a material removed off the target material due to the sputtered ions sticks to a substrate opposite the target material, thereby forming a layer
Implementation Method 3
Cooling water may be supplied inside the backing plate
Data Source
AI summary
A magnetron sputtering apparatus includes a vacuum chamber, a cathode target that rotates on the outer side of a backing plate in the vacuum chamber, a magnetic circuit that is spaced from the outer side of the cathode target and defines an opening through which a plasma including a target material removed from the cathode target is ejected, and a yoke around the outer side of the cathode target, the yoke supporting the magnetic circuit.