Magnetron Sputtering Ground Shield Magnetic Field Redirection
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Solution Overview
Problem
In magnetron sputtering apparatuses, unintended discharge between the cathode and the ground shield can occur due to magnetic field lines attracting ions from the plasma, leading to potential damage and substrate pollution, especially in high-frequency sputtering with high ion density.
Innovation Solution
A sputtering apparatus design featuring a ground shield made of a magnetic material surrounding the target, with a magnetic member positioned between the shield and the backing plate to redirect magnetic field lines, reducing the likelihood of unintended discharge by concentrating the magnetic field vertically and improving plasma confinement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a ground shield made of magnetic material is used to confine plasma near the target, then sputtering efficiency is improved, but unintended discharge between the cathode and shield occurs due to magnetic field lines attracting ions
Solution Approach 1:
A non-magnetic spacer is introduced between the magnetic ground shield and the cathode/backing plate. This spacer acts as a mediator that physically separates the magnetic field lines from the cathode surface, preventing direct ion attraction and unintended discharge while allowing the magnetic shield to maintain plasma confinement. The spacer material (such as alumina or quartz) is positioned in the gap to block magnetic field lines from reaching the cathode, thereby eliminating the harmful effect of ion attraction to the shield structure.
2Stability of the object's composition
If the shield is grounded while voltage is applied to the backing plate and fixation part, then plasma confinement is enhanced, but voltage difference generates abnormal discharge in the space between shield and backing plate
Solution Approach 1:
The non-magnetic spacer serves as an intermediary barrier between the grounded magnetic shield and the high-voltage cathode assembly. By placing this spacer in the gap, the voltage difference is isolated and prevented from causing direct discharge. The spacer material has sufficient electrical insulation properties to withstand the voltage difference while maintaining the plasma confinement geometry established by the magnetic shield.
Solution Approach 2:
The harmful magnetic field interaction is extracted or removed from the critical discharge path by using a non-magnetic spacer. The spacer extracts the magnetic field lines from reaching the cathode surface, separating the beneficial plasma confinement function from the harmful ion attraction effect. This allows the magnetic shield to maintain its plasma confining role while eliminating the discharge problem.
3Manufacturing precision
If magnetic field lines flow along the shield into the yoke, then plasma is confined to the target area, but ions are attracted into the space between shield and backing plate causing damage
Solution Approach 1:
The non-magnetic spacer acts as a mediator that intercepts magnetic field lines before they can reach the cathode or fixation part. The spacer is positioned to block the path of magnetic field lines that would otherwise flow along the shield into the yoke and attract ions. By placing this intermediary barrier, the system maintains precise plasma confinement while preventing ion attraction to the shield structure and associated damage.
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 effectively reduces unintended discharge between the cathode and the ground shield, enhancing the efficiency of the magnetron sputtering process and improving film formation rates by minimizing plasma leakage and substrate contamination.
Implementation Method 1
a magnetron unit 8 that serves as a magnetic field generating means
Implementation Method 2
a magnetic member positioned between the shield and the backing plate to redirect magnetic field lines, reducing the likelihood of unintended discharge by concentrating the magnetic field vertically
Implementation Method 3
The magnetic field lines ML along the shield attract ions from the plasma formed near the target 5 into the space between the shield 14 and the backing plate 7
Implementation Method 4
sputter is a film formation technique in which ions collide with the surface of a target, and thereby particles are ejected from the surface and are deposited on a substrate to form a film
Data Source
AI summary
The present invention provides a highly efficient magnetron sputtering apparatus in which a ground shield made of a magnetic material is disposed on the outer circumference of a target, the sputtering apparatus being capable of reducing unintended discharge between a cathode and the ground shield. The sputtering apparatus according to an embodiment includes: a backing plate connected to a power supply and having a target mounting surface; a magnet disposed on the back surface of the backing plate; a grounded shield containing a magnetic material and surrounding the target mounting surface; and a fixation part located between the shield and the backing plate at an outer circumference of the target mounting surface and serving as a magnetic member. This structure reduces magnetic field lines which pass through a space between the shield and the fixation part.