Passive CCE Probe for Plasma Instability Detection
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Solution Overview
Problem
Current plasma processing technologies face challenges in detecting plasma instabilities, which can lead to process excursions, yield reduction, and damage to substrates and chamber components, as existing methods lack effective detection and characterization techniques for these events.
Innovation Solution
A passive capacitively-coupled electrostatic (CCE) probe arrangement that measures plasma processing parameters by monitoring induced currents through a measuring capacitor, eliminating the need for external RF excitation and using pattern recognition to detect plasma instability events, allowing for early detection and proactive adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional plasma monitoring methods are used, then direct measurement of process parameters is achieved, but plasma instabilities cannot be detected early enough to prevent process excursions
Solution Approach 1:
The patent applies preliminary action by detecting plasma instabilities through capacitively-coupled probes before they develop into full process excursions. The probe measures impedance changes that occur during the early stages of instability, enabling proactive detection and response rather than waiting for direct parameter deviations to manifest.
Solution Approach 2:
The patent uses an intermediary approach by introducing a capacitively-coupled probe that indirectly measures plasma conditions through impedance changes. This intermediary measurement method detects instabilities through electrical impedance variations caused by changes in plasma density, electron temperature, or ion flux, providing early warning before direct process parameters are affected.
2Measurement precision
If direct plasma parameter measurement is performed, then process control is achieved, but plasma instability detection sensitivity is insufficient
Solution Approach 1:
The patent uses an intermediary approach by introducing a capacitively-coupled probe that indirectly measures plasma conditions through impedance changes. This intermediary measurement method detects instabilities through electrical impedance variations caused by changes in plasma density, electron temperature, or ion flux, providing early warning before direct process parameters are affected.
Solution Approach 2:
The patent replaces complex direct measurement systems with a simpler electrical impedance-based detection method. Instead of using elaborate diagnostic equipment to directly measure plasma parameters, the system substitutes a relatively simple capacitively-coupled probe that measures electrical impedance changes, reducing device complexity while maintaining or improving detection sensitivity.
3Productivity
If plasma instabilities are detected early, then process excursions can be prevented, but additional detection infrastructure is required
Solution Approach 1:
The patent applies universality by designing a capacitively-coupled probe that can be integrated into existing plasma processing chambers with minimal modification. The probe serves multiple functions: it detects plasma instabilities, measures impedance changes, and provides early warning signals, all through a single integrated component that leverages existing chamber electrical infrastructure.
Solution Approach 2:
The patent applies self-service by utilizing the plasma's own electrical properties to generate the detection signal. The capacitively-coupled probe measures impedance changes that occur naturally during plasma instabilities, requiring no external excitation or additional infrastructure. The plasma process itself provides the measurement signal, eliminating the need for separate active sensing systems.
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 enables sensitive and minimally perturbing detection of plasma instabilities, reducing the risk of process excursions and chamber damage by identifying instability events before they lead to more severe issues like plasma unconfinement, thereby improving process control and yield.
Implementation Method 1
a plasma-facing sensor and a measuring capacitor, wherein the plasma-facing sensor is coupled to a first plate of the measuring capacitor
Implementation Method 2
Passive capacitively-coupled electrostatic (CCE) probe method for detecting plasma instabilities
Data Source
AI summary
A method for detecting plasma instability within a processing chamber of a plasma processing system during substrate processing is provided. The method includes collecting a set of process data, the process data including a set of induced current signals flowing through a measuring capacitor. The method further includes converting the set of induced current signals into a set of analog voltage signals and converting the set of analog voltage signals into a set of digital signals. The method also includes analyzing the set of digital signals to detect high frequency perturbations, the high frequency perturbations indicating the plasma instability.