Plasma RF Bias Control Using Reflected Wave Frequency Peaks
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Solution Overview
Problem
Current plasma processing apparatuses lack effective control over radio-frequency power and bias power in relation to the substrate potential, leading to inefficient ion energy management during plasma processing.
Innovation Solution
A plasma processing apparatus with a controller that adjusts radio-frequency bias power levels and modulates radio-frequency power based on the peak values of negative frequency shifts in the reflected wave, correlating with the substrate potential, allowing precise control of ion energy striking the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If radio-frequency power and bias power are provided without control based on substrate potential, then plasma processing can be performed, but ion energy management is inefficient
Solution Approach 1:
The patent implements feedback control by measuring the frequency of the reflected wave and using this information to adjust the radio-frequency bias power levels. The controller continuously monitors the reflected wave frequency and modifies the bias power accordingly to maintain optimal ion energy management, creating a closed-loop control system that improves efficiency while adapting to changing plasma conditions.
Solution Approach 2:
The patent changes the operating parameters of the plasma processing apparatus by dynamically adjusting the radio-frequency bias power levels based on the measured reflected wave frequency. This parameter adjustment allows the system to optimize ion energy management in response to varying plasma conditions, transforming a static power delivery system into a dynamically adaptable one.
2Manufacturing precision
If radio-frequency bias power levels are adjusted based on reflected wave frequency, then ion energy control precision is improved, but control system complexity increases
Solution Approach 1:
The controller uses feedback from the measured reflected wave frequency to precisely control the radio-frequency bias power levels. By continuously monitoring the frequency and adjusting the power in response, the system achieves high precision ion energy control while keeping the controller design relatively simple, leveraging natural plasma responses rather than requiring complex control algorithms.
Solution Approach 2:
The patent replaces direct mechanical or electronic control of ion energy with an indirect control method using electromagnetic wave frequency measurement. Instead of directly measuring or controlling ion energy, the system uses the reflected wave frequency as a proxy indicator, substituting a simpler electromagnetic measurement and control approach for what would otherwise require complex ion energy sensing and control mechanisms.
3Productivity
If radio-frequency power is modulated in a cycle based on reflected wave frequency peaks, then plasma processing efficiency is improved, but measurement and control difficulty increases
Solution Approach 1:
The system performs preliminary measurement of the reflected wave frequency to identify peak occurrences before using this information to modulate the radio-frequency power. By measuring and storing the frequency characteristics in advance, the system can then use this pre-acquired data to drive the power modulation cycle, improving processing efficiency while simplifying the overall control strategy through sequential operations.
Solution Approach 2:
The patent implements periodic modulation of the radio-frequency power based on the cyclical nature of the reflected wave frequency peaks. By synchronizing the power modulation with the periodic occurrence of frequency peaks, the system achieves improved plasma processing efficiency through rhythmic, predictable control actions that are easier to implement and monitor than aperiodic control methods.
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 precise control of ion energy and etching rates by correlating the power levels with the substrate potential, improving the efficiency and accuracy of plasma processing.
Implementation Method 1
radio-frequency power is provided to generate plasma in the chamber
Implementation Method 2
Radio-frequency bias power is provided to the lower electrode to draw ions in the plasma toward the substrate
Implementation Method 3
The reflected wave is returned toward the radio-frequency power supply
Data Source
AI summary
A plasma processing apparatus includes a chamber, substrate support, radio-frequency (RF) power supply, bias power supply, measuring device, and controller. The RF power supply provides RF power to a lower electrode included in the substrate support in the chamber or to an upper electrode. The bias power supply provides RF bias power to the lower electrode. The measuring device measures a frequency of a reflected wave of the RF power returned toward the RF power supply. The controller controls the bias power supply to adjust a power level of the RF bias power to a peak value of absolute values of negative shifts in frequency of the reflected wave from a frequency of the RF power, or controls the RF power supply to modulate the RF power in a cycle obtained based on an occurrence time of the peak of absolute values.