Unignited Plasma Detection via Reflected Wave Continuity
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Solution Overview
Problem
Conventional methods for detecting the unignited state of plasma using peak values of reflected waves often lead to false detection in ignited states, causing unstable plasma conditions and potential damage to RF power amplifier elements due to heat storage, resulting in product quality deterioration and equipment damage.
Innovation Solution
A method and device that detect the unignited state of plasma by analyzing the continuous state of reflected waves, distinguishing between normal and abnormal plasma conditions, and performing protective output drooping or suspension only when the plasma is unignited, using conversion steps to calculate equivalent heat values and compare them with thresholds to prevent thermal failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional methods detect unignited plasma state using peak values of reflected waves, then detection simplicity is maintained, but false detection occurs in ignited states causing unstable plasma conditions
Solution Approach 1:
The patent changes the detection parameter from peak value (conventional method) to continuous state analysis. By monitoring whether the reflected wave state persists throughout the entire pulse width period, the system accurately distinguishes between unignited and ignited states without false detection, while maintaining detection system simplicity
Solution Approach 2:
The patent replaces the conventional threshold-based peak detection mechanism with a continuous state monitoring approach. Instead of comparing peak values against thresholds, the system analyzes the temporal continuity of reflected wave states throughout the pulse duration, eliminating false detection in ignited states
2Reliability
If protective operation is performed based on false detection in ignited state, then element damage is prevented, but radio frequency power supply is restricted causing plasma extinction
Solution Approach 1:
The patent implements feedback-based protective operation that activates only when unignited plasma state is accurately detected. By using continuous state monitoring throughout the pulse width, the system provides accurate feedback about actual plasma conditions, enabling protective actions only when truly necessary, thus preventing both element damage and false plasma extinction
Solution Approach 2:
The patent performs preliminary detection of the unignited state by monitoring the continuous reflected wave state before damage occurs. By detecting the persistent high-impedance condition throughout the pulse width, the system can initiate protective operations in advance, preventing element damage while avoiding unnecessary interruption of legitimate plasma operation
3Speed
If reflected wave peak value detection is used, then detection speed is maintained, but transient fluctuations cause inaccurate unignited state determination
Solution Approach 1:
The patent applies continuous monitoring of the reflected wave state throughout the entire pulse width period. By continuously analyzing whether the high-impedance condition persists for the full duration, the system eliminates the impact of transient fluctuations that occur with peak-value-only detection, achieving both speed and precision
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
Prevents false detection of plasma ignition and protects RF power amplifier elements from thermal damage by accurately distinguishing between ignited and unignited states, ensuring stable plasma operation and preventing equipment damage.
Implementation Method 1
plasma generated by radio frequency (RF) is used in a plasma processor such as semiconductor producing equipment and electronic device producing equipment
Implementation Method 2
When the RF output is switched between the on-state and the off-state, a reflected wave is generated
Implementation Method 3
detecting voltage of a reflected wave that returns from a plasma load to an RF power source
Data Source
Figure 1
Figure 2
Figure 3A~3H
AI summary
In detecting the unignited state of plasma based on a reflected wave, false detection during a normal plasma ignition time is prevented so as to detect the unignited state during plasma abnormality. When a pulse output is supplied to a plasma load by pulse driving from an RF power source, the unignited state of plasma abnormality is detected on the basis of the continuous state of the reflected wave, whereby a total reflected wave generated in the unignited state during plasma abnormality is detected in distinction from the reflected wave generated in the normal ignited state. With this configuration, in detecting the unignited state by comparing a peak value of the reflected wave with a threshold, it is possible to prevent that a reflected wave generated in the normal ignited state is erroneously detected as the total reflected wave that is generated in the abnormal unignited state.