Plasma Treatment Device Balun Electrode Configuration
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Solution Overview
Problem
In plasma processing apparatuses, the self-bias voltage and plasma potential tend to fluctuate over time due to film deposition on the vacuum container, making it difficult to maintain consistent film or etching characteristics during long-term use.
Innovation Solution
A plasma processing apparatus with a balun configuration, where the second electrode surrounds the first electrode, reducing impedance and minimizing in-phase current to prevent the vacuum container from functioning as an anode, thereby stabilizing the plasma potential. This is achieved by insulating the electrodes from the vacuum container and using a blocking capacitor to block DC current, ensuring the plasma potential is less affected by the inner wall state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the vacuum container functions as an anode in addition to the grounded electrode, then the plasma processing can be performed, but the self-bias voltage changes depending on the state of the vacuum container, causing plasma potential fluctuations
Solution Approach 1:
The patent divides the electrical connection path into separate components: the balun provides galvanic isolation between the grounded electrode and the vacuum container, while the blocking capacitor blocks DC current. This segmentation prevents the vacuum container from functioning as an anode while maintaining plasma processing capability.
Solution Approach 2:
The patent introduces a balun and blocking capacitor as intermediary components between the grounded electrode and the vacuum container. These intermediaries block DC current and in-phase current while allowing RF power transmission, preventing the vacuum container from becoming an anode and stabilizing the self-bias voltage.
2Productivity
If the sputtering apparatus is used continuously, then productivity increases, but film deposition on the vacuum container changes its state, causing self-bias voltage and plasma potential to change
Solution Approach 1:
The balun and blocking capacitor create an electrical isolation that segments the system into two independent parts: the plasma generation zone (electrodes) and the vacuum container. This allows continuous operation without the vacuum container state affecting plasma parameters, maintaining consistent film characteristics over time.
Solution Approach 2:
The blocking capacitor acts as an intermediary that blocks DC current and prevents charge accumulation on the vacuum container during continuous operation. This intermediary component ensures that even with prolonged use and film deposition, the vacuum container state does not influence the self-bias voltage or plasma potential.
3Device complexity
If the grounded electrode and vacuum container are electrically connected, then the structure is simple, but the in-phase current flows through the vacuum container, affecting plasma potential
Solution Approach 1:
The balun and blocking capacitor are introduced as intermediary components that block in-phase current and DC current while maintaining electrical connection for RF power transmission. This increases device complexity slightly but dramatically improves plasma potential stability by preventing current flow through the vacuum container.
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 effectively stabilizes the plasma potential over long-term use, maintaining consistent film or etching characteristics by preventing the vacuum container from influencing the plasma potential, even with film deposition on its inner surface.
Implementation Method 1
the second electrode is arranged to surround an entire circumference of the first electrode... insulating the electrodes from the vacuum container and using a blocking capacitor to block DC current
Implementation Method 2
A high frequency is applied between the first and second electrodes, and plasma is generated between the first and second electrodes (between the target and the substrate). When plasma is generated, a self-bias voltage is generated on the surface of the target. This causes ions to collide against the target, and the particles of a material constituting the target are discharged from the target.
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A plasma processing apparatus includes a balun having a first input terminal, a second input terminal, a first output terminal, and a second output terminal, a vacuum container, a first electrode insulated from the vacuum container and electrically connected to the first output terminal, and a second electrode insulated from the vacuum container and electrically connected to the second output terminal. The second electrode is arranged to surround an entire circumference of the first electrode.