Plasma Processing Device Discharge Detection Sensor

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Solution Overview

Problem

Conventional plasma processing devices face challenges in accurately monitoring plasma discharge states and predicting abnormal discharge, leading to potential thermal damage and poor processing quality.

Innovation Solution

A plasma processing device equipped with a discharge detection sensor featuring a plate-shaped dielectric member and a probe electrode, which detects potential changes induced by arc discharges and analyzes signals to differentiate between normal and abnormal discharge patterns, allowing for real-time monitoring and prediction of abnormal discharge.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional detection methods (camera imaging, voltage variation detection, parameter-based prediction) are used to monitor plasma discharge, then some aspect of abnormal discharge detection is achieved, but measurement precision and reliability are insufficient

Engineering Contradiction:

Improveabnormal discharge detection accuracyVSAvoidfalse prediction rate

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

A dielectric member is introduced as an intermediary between the plasma discharge and the probe electrode. The dielectric member couples the electric field from the plasma discharge to the probe electrode, enabling indirect detection of discharge characteristics. This intermediary approach allows for more precise and reliable detection by translating plasma electrical characteristics into measurable signals on the probe electrode without direct contact with the plasma.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention replaces mechanical/optical detection systems (camera imaging) and indirect electrical measurements (voltage variations at impedance matching device) with direct electrical field detection using the probe electrode-dielectric member system. This substitution enables more precise measurement of discharge characteristics by directly sensing the electric field changes associated with abnormal discharge.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If detection sensitivity is increased to detect early signs of abnormal discharge, then detection capability is improved, but false detection rate increases

Engineering Contradiction:

Improveearly abnormal discharge detection capabilityVSAvoidfalse detection rate

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The system continuously monitors the potential change signals on the probe electrode and compares them against established patterns of normal and abnormal discharge. This feedback mechanism allows the system to learn and adapt to normal discharge variations while maintaining sensitivity to detect actual abnormal discharge events, thereby reducing false detections while preserving early detection capability.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The dielectric member is positioned to detect potential changes before abnormal discharge fully develops. By detecting early electrical field disturbances through the dielectric member, the system can identify incipient abnormal discharge conditions before they manifest as full-scale discharge events, enabling preventive action while maintaining accurate detection through pattern recognition.

Inventive Principle:

Principle #10Preliminary action

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

Enables effective monitoring of plasma discharge states and early detection of abnormal discharge, preventing thermal damage and ensuring stable processing by accurately distinguishing between normal and abnormal arc discharge patterns.

Implementation Method 1

a probe electrode arranged on the other surface of the dielectric member; and a signal analyzing portion configured to detect a signal of a potential change induced in the probe electrode in response to a change in the plasma discharge

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a plate-shaped dielectric member arranged such that one surface thereof opposes plasma discharge generated in the processing chamber

Methodology Applied

Scientific EffectDielectric properties: Dielectric

Data Source

PatentUS8855949B2Plasma processing device and method of monitoring discharge state in plasma processing device

Publication Date: 2014.10.07 PANASONIC HOLDINGS CORP

AI summary

An object is to provide a plasma processing device capable of properly monitoring a state of plasma discharge and detecting a precursor to abnormal discharge, and a method of monitoring the state of discharge in the plasma processing device. In analysis processing for monitoring executed by detecting, by a signal analyzing portion 30, a signal of a potential change induced in a discharge detection sensor 23 in response to a change in plasma discharge of the inside of a processing chamber and recorded in a signal recorder 20, based on a counter value N3 obtained by detecting a signal of abnormal discharge (first arc discharge) generated between an electrode portion and an object to be processed by a first detector 33 and a counter value N4 obtained by detecting a signal of micro-arc discharge (second arc discharge) generated by deposition of a foreign substance in the processing chamber by a second detector 35, an abnormal discharge determining portion 39 calculates a difference (N3−N4) and compares the difference (N3−N4) with a threshold value a2 for determination and determines whether there is a possibility of generation of abnormal discharge in the processing chamber.