Microwave Plasma Frequency Control Using Reflected Sweep Waves
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Solution Overview
Problem
Existing plasma processing apparatuses face challenges in timely adjusting the frequency of microwaves for plasma generation due to mechanical delays in matching devices, which fail to follow plasma state variations.
Innovation Solution
A plasma processing apparatus with a controller that adjusts the frequency of microwaves based on reflected wave groups, using a modulator and demodulator to modulate and demodulate microwaves, enabling timely frequency adjustments in response to plasma state changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a mechanical matching device is used to adjust microwave frequency, then frequency adjustment capability is provided, but response speed is slow due to mechanical delays
Solution Approach 1:
The patent replaces the mechanical matching device with an electronic control system comprising a modulator, demodulator, and controller. The controller receives reflected wave signals, determines plasma state, and electronically adjusts the microwave frequency output without mechanical moving parts, thereby eliminating mechanical delays and significantly improving response speed.
Solution Approach 2:
The patent implements a feedback mechanism where the demodulator receives reflected wave groups from the plasma chamber, the controller analyzes these signals to determine plasma state, and automatically adjusts the microwave frequency accordingly. This closed-loop feedback system enables real-time frequency adjustment that follows plasma state variations without mechanical delay.
2Loss of time
If mechanical matching devices are used for frequency adjustment, then frequency control is achieved, but timing follows plasma state variations is delayed
Solution Approach 1:
The patent eliminates mechanical components by using an electronic control system where the controller directly adjusts the modulator's frequency output based on real-time plasma state detection. This electronic approach removes mechanical inertia and adjustment delays, enabling instantaneous frequency changes that accurately track plasma state variations.
Solution Approach 2:
The system continuously monitors plasma state through reflected wave detection and maintains readiness to adjust frequency. The controller is pre-configured to immediately respond to plasma state changes by adjusting the modulator, eliminating the delay between detection and adjustment that occurs with mechanical systems.
3Measurement precision
If broadband sweep wave group is added for plasma state detection, then plasma state detection capability is improved, but microwave signal complexity increases
Solution Approach 1:
The patent introduces a demodulator as an intermediary device that receives the reflected broadband sweep wave groups from the plasma chamber and extracts plasma state information. The demodulator converts the complex reflected signals into usable data for the controller, enabling precise plasma state detection without requiring the control system to directly process complex microwave signals.
Solution Approach 2:
The patent separates the microwave signal into distinct functional components: the output wave for plasma generation and the broadband sweep wave group for detection. The modulator independently generates these components, and the demodulator separately processes the reflected detection signals, allowing precise plasma state measurement without interfering with the plasma generation process.
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
Enables easy and timely adjustment of microwave frequency for effective plasma excitation, ensuring optimal plasma generation in response to plasma state variations.
Implementation Method 1
The modulator is configured to modulate the microwaves and transmit the modulated microwaves to the waveguide
Implementation Method 2
The demodulator is configured to receive, via the waveguide, and demodulate a reflected wave group obtained by the sweep wave group being reflected by plasma in the chamber
Implementation Method 3
a reflected wave group obtained by the sweep wave group being reflected by plasma in the chamber
Implementation Method 4
The microwave output device is configured to output microwaves provided into the chamber via a waveguide and an antenna
Data Source
AI summary
A plasma processing apparatus is provided in one exemplary embodiment. A microwave output device of the plasma processing apparatus is configured to output microwaves that are provided into a chamber, and a controller is configured to control the operation of the microwave output device. The microwaves outputted by the microwave output device include an output wave for transmitting a power used for plasma generation, and a broadband sweep wave group used for detection of a plasma state. In the microwave output device, a modulator modulates the microwaves and transmits the modulated microwaves to a waveguide, and a demodulator receives and demodulates a reflected wave group obtained by the sweep wave group being reflected by plasma in the chamber. The controller is configured to determine a frequency of the output wave based on the reflected wave group, and control the microwave output device to output the output wave of the frequency.