RF Source Frequency Control for Low-Reflection Plasma Processing
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Solution Overview
Problem
Existing plasma processing apparatuses face challenges in reducing the degree of reflection of source radio-frequency power, which affects the efficiency and stability of plasma generation.
Innovation Solution
A plasma processing apparatus with a radio-frequency power supply and bias power supply that adjusts the source frequency and phase difference to minimize reflection by setting specific frequencies and phase relationships in a frequency adjustment cycle, including a maximum and minimum frequency in distinct phases, and interpolating frequencies in other phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If source radio-frequency power is provided to generate plasma, then plasma generation is achieved, but reflection of source radio-frequency power occurs reducing efficiency
Solution Approach 1:
The patent applies dynamics by making the source frequency adjustable and time-variable. The radio-frequency power supply dynamically changes the source frequency according to a predetermined time series that includes a maximum frequency, minimum frequency, and interpolated frequencies. This dynamic frequency adjustment allows the system to adapt to changing plasma conditions and minimize reflection, thereby improving plasma generation efficiency while reducing energy loss.
Solution Approach 2:
The patent implements parameter changes by modifying the source frequency parameter over time. The system changes the frequency from a fixed value to a time-varying parameter following a specific pattern (maximum frequency at first specific phase, minimum frequency at second specific phase, and interpolated frequencies in between). This parameter transformation enables optimization of power transfer and reduction of reflected power.
2Productivity
If frequency adjustment is implemented to reduce reflection, then plasma generation efficiency improves, but system complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-defining the frequency adjustment pattern before plasma generation begins. The time series including maximum frequency, minimum frequency, and interpolated frequencies is predetermined and stored in advance. During operation, the system simply follows this pre-planned frequency schedule rather than requiring complex real-time calculations, thus reducing computational complexity while maintaining efficiency benefits.
Solution Approach 2:
The patent implements feedback mechanisms to monitor and adjust the frequency settings. By observing plasma conditions and power reflection levels, the system can identify optimal frequency points and adjust the time series parameters accordingly. This feedback loop allows the system to learn and optimize performance over time without requiring overly complex control architecture.
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 effectively reduces the degree of reflection of source radio-frequency power, enhancing plasma generation efficiency and stability by optimizing frequency and phase settings.
Implementation Method 1
The radio-frequency power supply generates source radio-frequency power having a source frequency to generate plasma from a gas in the chamber
Implementation Method 2
generate plasma from a gas in the chamber
Implementation Method 3
The bias power supply provides an electrical bias to the substrate support to draw ions from plasma in the chamber
Data Source
AI summary
In a plasma processing apparatus, a bias power supply provides an electrical bias having a waveform cycle to a substrate support. A radio-frequency power supply sets a time series of source frequencies of source radio-frequency power in a frequency adjustment cycle to include a maximum frequency in a first specific phase, a minimum frequency in a second specific phase, and an interpolated frequency in a phase other than at least two specific phases including the first and second specific phases. A phase difference between the frequency adjustment cycle and the waveform cycle is set to reduce a reflection degree of the source radio-frequency power. The radio-frequency power supply changes the maximum frequency in the first specific phase and the minimum frequency in the second specific phase in the time series of the source frequencies in the frequency adjustment cycle in a direction opposite to each other.