Embedded Electrode Current Sensing for Plasma Coating Stability
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Solution Overview
Problem
Plasma stability issues in remote plasma sources lead to coating degradation and potential 'punch through' situations, causing particle and performance problems, and are not effectively monitored for timely detection of changes affecting downstream processes.
Innovation Solution
An in-situ current sensing apparatus is integrated into plasma processing systems, featuring an electrically conductive housing coupled with a dielectric coating layer and a current probe for sensing capacitively-coupled currents, allowing for real-time monitoring of plasma stability and coating thickness, with optional features like embedded electrodes and dielectric breaks for isolation and grounding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a remote plasma source is used to generate plasma remotely from the material being processed, then charged species contact with the material is minimized, but reactive neutral species delivery is maintained
Solution Approach 1:
The patent applies preliminary action by implementing current sensing capability that monitors plasma conditions in advance before instability leads to coating degradation or punch-through. The system detects changes in plasma current to predict and prevent future failures, allowing preventive maintenance actions to be taken before the plasma source fails.
2Reliability
If dielectric coating is applied to the plasma-facing surface to maintain plasma stability, then plasma stability is improved, but coating wear and degradation occur over time
Solution Approach 1:
The patent implements feedback by continuously monitoring the current through the dielectric coating and using this information to detect coating degradation. The system measures changes in capacitive current that occur as the coating wears, providing real-time feedback on coating condition. This allows the system to track coating health and predict when replacement will be needed, optimizing the coating lifecycle.
3Difficulty of detecting and measuring
If current sensing is implemented to monitor plasma stability, then detection capability is improved, but device complexity increases
Solution Approach 1:
The patent applies self-service by having the plasma source structure serve its own monitoring function. The existing dielectric coating and housing structure are utilized as integral parts of the sensing apparatus. The capacitive coupling between the plasma-facing surface and the housing creates the sensing mechanism without requiring separate dedicated sensing components, thereby reducing overall system complexity while maintaining detection capability.
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 continuous monitoring of plasma stability and dielectric coating thickness, preventing coating degradation and ensuring consistent plasma performance by detecting changes in real-time, thus preventing downstream defects and maintaining process integrity.
Implementation Method 1
a current probe, inductively or electrically connected to the assembly, for sensing a capacitively-coupled current within the assembly caused by the formation of plasma in the plasma channel
Implementation Method 2
an electrically conductive housing coupled to a dielectric coating layer, wherein a surface of the dielectric coating layer is configured to physically contact at least one of the process gas or the plasma in the plasma channel
Data Source
AI summary
An in-situ current sensing apparatus for a plasma processing system has one or more sections defining a plasma channel, the plasma processing system configured to form a plasma in the plasma channel using a process gas. The in-situ current sensing apparatus includes an assembly including an electrically conductive housing coupled to a dielectric coating layer, wherein a surface of the dielectric coating layer is configured to physically contact at least one of the process gas or the plasma in the plasma channel. The in-situ current sensing apparatus also includes a current probe, inductively or electrically connected to the assembly, for sensing a capacitively-coupled current within the assembly caused by the formation of plasma in the plasma channel. The in-situ current-sensing apparatus further includes at least one dielectric break for electrically isolating the assembly from the one or more sections. The assembly may include an electrode embedded within the housing.