Plasma RF Matching Control Using Intermodulation Filtering
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Solution Overview
Problem
Existing plasma processing apparatuses face challenges in efficiently managing intermodulation distortion and impedance matching during radio-frequency power supply, leading to suboptimal plasma generation and ion drawing processes.
Innovation Solution
The apparatus includes a radio-frequency power supply with a variable frequency that adjusts within phase periods of the electrical bias energy cycle, a matcher with a matching circuit, a sensor to detect impedance deviations, and a filter to remove intermodulation distortion components from electrical signals, ensuring optimal impedance matching and plasma generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If radio-frequency power is supplied to generate plasma and draw ions, then plasma generation and ion drawing are achieved, but intermodulation distortion components are generated in electrical signals causing impedance matching deviations
Solution Approach 1:
The patent extracts and removes the harmful intermodulation distortion components from the electrical signals using a filter unit. The filter specifically targets and eliminates frequency components that are sums and differences of the radio-frequency power frequency and bias energy frequency, thereby resolving the contradiction between maintaining plasma generation power and eliminating harmful distortion.
Solution Approach 2:
The patent converts the harmful intermodulation distortion into a detectable signal characteristic. By identifying the specific frequency components of the distortion (sum and difference frequencies), the system can selectively filter them out, transforming the problematic interaction between radio-frequency power and bias energy into a manageable signal processing task that improves overall system performance.
2Productivity
If bias energy is supplied to draw ions into the substrate, then ion drawing is achieved, but impedance matching deviation occurs due to intermodulation distortion
Solution Approach 1:
The patent implements a feedback mechanism where electrical signals are continuously monitored, filtered to remove intermodulation distortion, and the cleaned signals are used to maintain accurate impedance matching. The filter unit processes the electrical signals in real-time, and the resulting filtered signals feed back to the control system to adjust the radio-frequency power and bias energy, ensuring stable impedance matching while maintaining high ion drawing efficiency.
Solution Approach 2:
The filter unit acts as an intermediary between the power supply system and the impedance matching control. It processes the electrical signals by removing harmful frequency components before these signals affect the impedance matching accuracy, thereby mediating the conflict between ion drawing efficiency and impedance stability.
3Adaptability or versatility
If radio-frequency power with variable frequency is used, then plasma generation flexibility is improved, but intermodulation distortion with multiple frequency components is generated
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the radio-frequency power frequency based on processing requirements while maintaining a systematic filtering approach. The filter is designed to handle variable frequency inputs by targeting the characteristic intermodulation distortion frequencies (sum and difference frequencies) rather than requiring fixed frequency operation, thus maintaining adaptability without proportionally increasing filtering complexity.
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 solution effectively removes unnecessary components from electrical signals, allowing for precise impedance matching and improved plasma processing by suppressing reflected wave power, resulting in enhanced plasma generation and ion drawing efficiency.
Implementation Method 1
a radio-frequency power supply (31) configured to supply a radio-frequency power (RF) having a variable frequency into the chamber (10) through a matcher (31m) in order to generate plasma from gas in the chamber (10)
Implementation Method 2
a bias power supply (32) configured to supply an electrical bias energy (BE) to an electrode of the substrate support (11) in order to draw ions from plasma generated in the chamber (10) into a substrate (W) placed on the substrate support (11)
Implementation Method 3
a filter (35) configured to generate a filtered signal (SFI) by removing an intermodulation distortion component of the radio-frequency power (RF) and the electrical bias energy (BE) from the electrical signal (S)
Data Source
AI summary
A plasma processing apparatus includes: a chamber; a substrate support provided in the chamber; a bias power supply that supplies an electrical bias energy to an electrode of the substrate support; a matching box including a matching circuit; a radio-frequency power supply that supplies a radio-frequency power having a variable frequency into the chamber through the matching box, and adjusts the frequency of the radio-frequency power in each of a plurality of phase periods within the cycle of the electrical bias energy; a sensor that detects an electrical signal reflecting a deviation of a load impedance of the radio-frequency power supply from a matching state; and a filter that generates a filtered signal by removing and an intermodulation distortion component of the radio-frequency power and the electrical bias energy from the electrical signal in each of the plurality of phase periods.