Counter Electrode Phase Switching for Fast Plasma Impedance Control
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Solution Overview
Problem
Existing plasma processing apparatuses struggle to control the impedance of counter electrodes to follow the frequency of high-frequency signals, particularly in atomic layer processes where mechanical phase controllers are inadequate for rapid impedance adjustments.
Innovation Solution
A plasma processing apparatus equipped with a phase control circuit that includes a semiconductor switch, such as a field effect transistor (FET), connected to the counter electrode. The phase control circuit generates an ON signal shorter than one cycle of the high-frequency signal, synchronized with the frequency of the high-frequency signal, to control the impedance of the counter electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a mechanical phase controller is used to adjust impedance, then the device structure is simple, but the response speed is slow and cannot follow rapid frequency changes in atomic layer processes
Solution Approach 1:
The patent replaces the mechanical phase controller with an electronic phase control circuit based on semiconductor switches (FETs). This substitution enables rapid impedance adjustment by controlling the switching timing of the semiconductor devices, achieving response speeds that can follow the high-frequency signal variations in atomic layer processes, thereby resolving the contradiction between response speed and device complexity.
Solution Approach 2:
The patent implements a dynamic phase control system where the phase control circuit continuously adjusts the impedance of the lower electrode in real-time by varying the switching timing of semiconductor switches. This dynamic adjustment capability allows the system to track and respond to rapid frequency changes during atomic layer processes, overcoming the static nature of mechanical controllers.
2Manufacturing precision
If the impedance control responds rapidly to frequency changes, then the plasma distribution and density improve, but the control system complexity increases
Solution Approach 1:
The patent employs a feedback mechanism where the phase control circuit receives detection signals representing the actual impedance or plasma state, compares them with target values, and adjusts the switching timing of semiconductor switches accordingly. This closed-loop control enables precise plasma distribution control while managing system complexity through intelligent algorithms rather than purely hardware complexity.
Solution Approach 2:
The patent achieves precise plasma control by dynamically changing the electrical parameters (impedance, phase angle) of the lower electrode through semiconductor switch timing adjustments. By controlling parameters such as the duty cycle and switching phase of the FETs, the system can precisely regulate plasma distribution and density without requiring complex mechanical adjustments.
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 allows for precise control of the impedance of the counter electrode, enabling it to follow the frequency of the high-frequency signal, thereby improving the distribution and density of plasma during processing, particularly in atomic layer processes.
Implementation Method 1
The high-frequency power supply may be electrically connected to the upper electrode and configured to generate plasma of the processing gas by applying a high-frequency voltage to the upper electrode
Implementation Method 2
A phase control circuit is configured to include a semiconductor switch and connected to the counter electrode. An ON signal shorter than one cycle of a high-frequency signal outputted from the high-frequency power supply, which is a control signal, is inputted to the semiconductor switch in synchronization with the frequency of the high-frequency signal
Data Source
AI summary
A plasma processing apparatus comprises a processing chamber configured to form a processing space, an application electrode disposed on one side of the processing space and connected to a high-frequency power supply, a counter electrode disposed on the other side of the processing space, and a phase control circuit configured to include a semiconductor switch and connected to the counter electrode. An ON signal shorter than one cycle of a high-frequency signal outputted from the high-frequency power supply, which is a control signal, is inputted to the semiconductor switch in synchronization with the frequency of the high-frequency signal.