Phase-Based RF Frequency Control for Stable Plasma Processing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing plasma processing devices experience variations in source radio-frequency power frequency and significant reflection of source radio-frequency power, which affect processing consistency and efficiency.
Innovation Solution
A plasma processing device with a power supply controller that adjusts the source radio-frequency power frequency based on reflection feedback, using predetermined shift values and conditions to stabilize the frequency and reduce reflection, by implementing a feedback mechanism that adjusts the source frequency in response to reflection trends and changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the source radio-frequency power frequency is adjusted to reduce reflection, then the reflection is reduced, but the frequency stability deteriorates due to continuous adjustments
Solution Approach 1:
The patent applies periodic action by dividing the waveform cycle into multiple phase periods and adjusting the source frequency at specific intervals (e.g., every 16 waveform cycles or when reflection exceeds thresholds). This periodic adjustment strategy reduces continuous frequency changes while maintaining reflection control, thereby resolving the contradiction between reducing reflection and maintaining frequency stability.
Solution Approach 2:
The patent implements feedback control by monitoring the reflection of source radio-frequency power and adjusting the source frequency based on reflection trends (upward or downward). The controller compares current reflection with previous values and adjusts frequency accordingly, creating a closed-loop system that reduces reflection while adapting to maintain stability.
2Loss of energy
If the source frequency is frequently adjusted to minimize reflection, then the reflection is reduced, but the processing consistency deteriorates due to frequency variations
Solution Approach 1:
The patent limits frequency adjustments to periodic intervals (e.g., every 16 waveform cycles) or specific conditions (when reflection exceeds thresholds), rather than continuous adjustments. This periodic approach minimizes the number of frequency changes while still effectively controlling reflection, thereby maintaining processing consistency.
Solution Approach 2:
The patent changes the source frequency parameter in controlled increments (adding or subtracting a predetermined shift value Δf[n]) based on reflection trends. By limiting the magnitude and frequency of parameter changes, the system reduces reflection while maintaining processing consistency through controlled parameter adjustment.
3Device complexity
If a simple frequency adjustment mechanism is used, then the device complexity is reduced, but the ability to handle reflection trends deteriorates
Solution Approach 1:
The patent implements a feedback mechanism that monitors reflection trends (comparing current reflection with previous values) and adjusts the source frequency accordingly. The controller determines whether reflection is on an upward or downward trend and adjusts frequency in the appropriate direction, providing adaptive response to reflection trends without requiring complex control mechanisms.
Solution Approach 2:
The patent adjusts the source frequency parameter based on reflection trends by adding or subtracting a predetermined shift value. This simple parameter change approach, guided by reflection trend detection, provides effective adaptability to handling reflection trends while maintaining relatively simple device 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
The solution reduces variations in source radio-frequency power frequency and minimizes reflection, enhancing processing stability and reproducibility in plasma processing devices.
Implementation Method 1
a radio-frequency power supply configured to provide source radio-frequency power to generate plasma in the chamber
Implementation Method 2
a bias power supply electrically coupled to the substrate support to provide an electrical bias to the substrate support
Data Source
AI summary
In a plasma processing device, power supply circuitry uses, when the degree of reflection of source radio-frequency power in an n-th phase period in an i-th waveform cycle of an electrical bias is greater than a predetermined value, a frequency obtained by adding a shift value Δf[n] to a source frequency f[i,n] as a source frequency for the n-th phase period in the subsequent waveform cycle and changes the sign of the shift value Δf[n] when the degree of reflection in the n-th phase period is on an upward trend in waveform cycles up to the i-th waveform cycle. A radio-frequency power supply changes the sign of the shift value Δf[n] when the source frequencies in the phase periods preceding and subsequent to the n-th phase period in the i-th waveform cycle are both higher than or lower than the source frequency in the n-th phase period.