Plasma Source Electrode Phase Control for CVD Film Deposition
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Solution Overview
Problem
The existing plasma sources for plasma CVD apparatuses have insufficient plasma density near the electrodes, leading to low reactivity of the source gas and inadequate film deposition rates.
Innovation Solution
A plasma source with an electrode group of four hollow electrodes connected to an AC power supply, where two pairs of electrodes are in the same phase, and source gas is supplied between adjacent electrodes, enhancing plasma density through controlled voltage phases and gas distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a conventional plasma source with electrodes connected to high-frequency AC power supply is used, then plasma can be generated, but the plasma density near the electrodes is insufficient
Solution Approach 1:
The electrode system is segmented into multiple electrodes (first electrode, second electrode, third electrode, fourth electrode) arranged in a row. Each electrode can be independently controlled with different voltage phases, allowing localized optimization of plasma generation. This segmentation enables creating multiple plasma regions with different density characteristics along the electrode array.
Solution Approach 2:
Different voltage phases are applied to different electrodes to create localized plasma density variations. Specifically, adjacent electrodes (first and second, third and fourth) are supplied with voltages in the same phase, while non-adjacent electrodes have voltages shifted by 180 degrees. This creates regions of high plasma density between adjacent electrodes, locally optimizing conditions for source gas activation and film deposition.
2Length of moving object
If low-frequency AC power supply is used to provide sufficient plasma length, then plasma length is improved, but plasma density near electrodes remains insufficient
Solution Approach 1:
The system uses periodic alternating voltage applied to the electrode group to generate plasma. By periodically reversing the voltage phase between adjacent electrode pairs, the plasma generation is maintained continuously along the electrode length while creating periodic regions of high density. This periodic action allows both sufficient plasma length and adequate plasma density to be achieved.
3Quantity of substance
If source gas is supplied between adjacent electrodes, then gas distribution is improved, but reactivity remains low due to insufficient plasma density
Solution Approach 1:
The system preliminarily activates the source gas by exposing it to plasma generated between adjacent electrodes before the gas reaches the substrate. By creating high-density plasma regions in advance (between the first-second and third-fourth electrodes), the source gas molecules are pre-ionized and chemically activated, improving their reactivity for subsequent film deposition processes.
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
Significantly increases plasma density and reactivity, resulting in improved film deposition rates and efficiency in plasma CVD processes.
Implementation Method 1
when a discharge is started between the electrodes by the high-frequency AC power supply, plasma is formed between the electrodes
Implementation Method 2
when a discharge is started between the electrodes by the high-frequency AC power supply, plasma is formed between the electrodes
Implementation Method 3
atoms and/or molecules of the source gas are exited and made to be chemically active, and, thereby, a chemical reaction occurs
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3~4
AI summary
A plasma source for a plasma CVD apparatus that includes an electrode group including four electrodes, which are a first electrode, a second electrode, a third electrode and a fourth electrode arranged in a row in that order, characterized in that said electrode group is connected to at least one AC power supply, a voltage supplied to two of said four electrodes is shifted in phase from a voltage supplied to the remaining two electrodes, a space to which a source gas is supplied is provided between the adjacent electrodes, and voltages applied to at least one set among the adjacent two electrodes are in the same phase.