RF Generator Control Using FFT Filtering for Impedance Matching
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Solution Overview
Problem
In substrate processing apparatuses, interference between RF antennas hinders effective impedance matching due to close-frequency RF power applications, leading to incomplete impedance matching and reduced reflected wave reduction.
Innovation Solution
The RF generator device employs multiple RF generators and controllers with fast Fourier transformers and digital filters to decompose reflected waves into frequency components, allowing for the removal of interfering waves by controlling frequency differences between RF outputs to within a range where interference can be attenuated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RF powers of close frequencies are applied from multiple antennas, then plasma generation is achieved, but interference occurs between antennas leading to incomplete impedance matching
Solution Approach 1:
The reflected wave signal is segmented into multiple frequency components using Fast Fourier Transform (FFT), allowing individual analysis and processing of each frequency component to identify and eliminate interference waves
Solution Approach 2:
Interference waves are extracted and removed from the reflected wave signal by identifying frequency components that do not correspond to the output frequencies of the RF generators, using band-pass filters to eliminate harmful frequency components
2Manufacturing precision
If impedance matching is performed on one antenna, then matching for that antenna is achieved, but interference waves from other antennas prevent complete reflected wave reduction
Solution Approach 1:
The system uses feedback by continuously monitoring the reflected wave signal, performing FFT analysis to identify interference components, and adjusting the matching network based on this information to achieve complete impedance matching
Solution Approach 2:
A signal processing intermediary system consisting of FFT analyzer and band-pass filters is introduced between the reflected wave detection and impedance matching control, allowing interference waves to be removed before they affect the matching accuracy
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 approach enables accurate impedance matching and stable, high-quality plasma generation by eliminating interference effects, ensuring effective substrate processing.
Implementation Method 1
a fast Fourier transformer, and a filter. The fast Fourier transformer performs fast Fourier transform on a signal introduced as a reflected wave to decompose the signal into frequency components
Implementation Method 2
the filter removes waves having frequency components that are not outputted from the corresponding RF generator
Data Source
AI summary
A radio frequency (RF) generator device for supplying RF powers of different frequencies to multiple antennas disposed in a chamber is provided. The RF generator device includes a plurality of RF generators configured to supply the RF powers of the different frequencies to the multiple antennas, and a plurality of RF controllers configured to control the RF generators, respectively. Each of the RF controllers includes a fast Fourier transformer, and a filter. The fast Fourier transformer performs fast Fourier transform on a signal introduced as a reflected wave to decompose the signal into frequency components, and the filter removes waves having frequency components that are not outputted from the corresponding RF generator.