Optical Sensor Arc Detection in Plasma Chamber
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Solution Overview
Problem
Plasma processing systems face challenges in detecting arcing events, which can cause material degradation and damage to the system, as existing diagnostic tools like RF and acoustic techniques are inadequate for characterizing abnormal plasma conditions.
Innovation Solution
A method and apparatus for detecting optical events in a plasma processing system using a light collector and optical detector, with a controller to process light emission signals and identify signatures of arcing events, even in the presence of bright background light, allowing for real-time detection of arcs with high resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing diagnostic tools (RF and acoustic techniques) are used to detect arcing events, then the system can monitor plasma processing, but the detection precision and ability to characterize abnormal plasma conditions is inadequate
Solution Approach 1:
The patent replaces RF and acoustic diagnostic techniques with optical detection methods. Specifically, it uses a high-speed photodiode detector to capture light emission signals from arcing events, substituting the mechanical/electromagnetic RF measurement systems and acoustic measurement systems with an optical measurement system that provides superior detection precision for characterizing abnormal plasma conditions
Solution Approach 2:
The patent changes the detection parameter from RF signals and acoustic waves to optical parameters (light emission intensity, wavelength, duration). By measuring the optical characteristics of arcing events including peak intensity, full width at half maximum (FWHM), and temporal profile, the system achieves more precise characterization of arc severity and plasma abnormalities
2Measurement precision
If optical detection is used to detect arcing events in bright plasma environment, then detection sensitivity improves, but the ability to distinguish arc signals from background plasma light becomes challenging
Solution Approach 1:
The patent extracts the specific optical signature characteristics of arcing events from the overall plasma emission spectrum. By identifying and isolating the temporal and spectral features unique to arc discharges (such as rapid rise time, specific wavelength emissions, and characteristic pulse shapes), the system can detect arcs with high sensitivity while filtering out background plasma light that does not possess these specific extracted features
Solution Approach 2:
The patent employs high-speed temporal sampling and analysis of light emission signals to capture the periodic and transient nature of arcing events. The system uses fast photodiode detection with microsecond or nanosecond time resolution to capture the rapid onset and decay characteristics of arc pulses, distinguishing them from the more continuous background plasma emission through temporal pattern recognition
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 system effectively detects arcing events with high sensitivity and resolution, reducing material degradation and system damage by identifying arcs that other methods miss, and providing timely warnings for corrective action.
Implementation Method 1
detecting light emission signal from an optical event in the plasma processing chamber
Data Source
AI summary
An advanced optical sensor and method for detection of optical events in a plasma processing system. The method includes detecting at least one light emission signal in a plasma processing chamber. The at least one detected light emission signal including light emissions from an optical event. The method further includes processing the at least one light emission signal and detecting a signature of the optical event from the processed light emission signal.