Plasma RF Signal Superposition for Reflection-Aware Density Control
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Solution Overview
Problem
Current plasma processing methods face challenges in reducing the influence of RF reflection, which affects plasma density and electron temperature control.
Innovation Solution
A plasma processing method and apparatus that superimpose a second RF signal on a first RF signal based on the timing of a bias signal applied to the substrate support, using a combination of RF signals with different frequencies to optimize plasma generation and reduce reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single RF signal is used for plasma generation, then the device complexity is low, but the plasma density control and electron temperature control are insufficient
Solution Approach 1:
The patent combines multiple RF signals (first RF signal and second RF signal with different frequencies) into a single plasma generation system. The superposition of these signals allows independent control of plasma density and electron temperature, achieving precise manufacturing control while maintaining a unified device architecture.
Solution Approach 2:
The patent utilizes parameter changes by varying the frequencies of the first and second RF signals. By adjusting these frequency parameters and their superposition timing, the system can independently optimize plasma density and electron temperature for different processing requirements.
2Productivity
If RF signals are supplied continuously for plasma generation, then the plasma generation efficiency is maintained, but the RF reflection influence increases
Solution Approach 1:
The patent implements periodic action by controlling the timing of the second RF signal relative to the first RF signal. This periodic superposition strategy, synchronized with the bias signal timing, maintains continuous plasma generation while creating conditions that minimize RF reflection through constructive and destructive interference patterns.
3Quantity of substance
If multiple RF signals with different frequencies are superimposed, then the plasma density increases and electron temperature control improves, but the device complexity increases
Solution Approach 1:
The patent achieves multi-functionality by using the superimposed RF signals for multiple purposes simultaneously: the first RF signal generates plasma while the second RF signal modifies plasma characteristics. This universal approach allows one system to control both plasma density and electron temperature, as well as reduce RF reflection, without requiring separate dedicated systems for each function.
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 improves plasma generation efficiency, increases plasma density, and allows for better control of electron temperature, thereby reducing the impact of RF reflection.
Implementation Method 1
generating, in the chamber, a plasma from the processing gas by using a first RF signal and a second RF signal
Implementation Method 2
superimposing the second RF signal on the first RF signal based on a timing when the bias signal is supplied to the substrate support
Data Source
AI summary
A plasma processing method according to the present disclosure includes disposing a substrate on a substrate support, supplying, into a chamber, a processing gas for processing the substrate, generating, in the chamber, a plasma from the processing gas by using a first RF signal and a second RF signal, and applying a bias signal to the substrate support, and generating the plasma includes superimposing the second RF signal on the first RF signal based on a timing when the bias signal is applied to the substrate support.