RF Sensing Apparatus Return Path Design for Plasma Chamber Impedance Stability
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Solution Overview
Problem
The introduction of RF sensing apparatuses into plasma processing chambers alters the electrical characteristics of the chamber, affecting the accuracy of RF measurements and process outcomes in semiconductor fabrication.
Innovation Solution
An RF sensing apparatus is designed with a penetration unit, a main return path unit, and a secondary return path unit, which form a return current path to minimize changes in the chamber's electrical characteristics by allowing a majority of the return current to flow through the main path and a smaller portion through the secondary path, reducing interference and maintaining process stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an RF sensing apparatus is introduced into a plasma processing chamber to obtain RF measurement data, then RF measurement capability is improved, but the electrical characteristics (impedance) of the plasma processing chamber change
Solution Approach 1:
A dielectric member is introduced as an intermediary between the RF sensing apparatus and the plasma processing chamber. This dielectric member electrically isolates the sensing apparatus from directly interacting with the plasma chamber's electrical environment, thereby preventing the sensing apparatus from significantly altering the chamber's impedance and electrical characteristics while still enabling RF measurement functionality
Solution Approach 2:
The return current path is segmented into multiple paths (first return path and second return path) with different impedances. By providing multiple return paths with controlled impedance values, the system can manage current distribution to minimize interference with the plasma chamber's electrical characteristics while maintaining effective RF sensing
2Measurement precision
If a conducting rod is inserted into the plasma processing chamber for RF sensing, then RF measurement is enabled, but the physical presence of the rod alters the RF environment
Solution Approach 1:
The dielectric member serves as a mediator that allows the conducting rod to be present for RF sensing while preventing it from directly disturbing the plasma chamber's RF environment. The dielectric material blocks direct electromagnetic interaction between the rod and the plasma, reducing unwanted alterations to the RF environment
Solution Approach 2:
A dielectric coating or thin film is applied to the conducting rod. This dielectric layer acts as a protective shell that electrically isolates the conducting rod from the plasma environment, allowing the rod to function for RF sensing while minimizing its physical disruption to the RF environment and plasma processes
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 configuration significantly reduces the change in electrical characteristics, enhancing the accuracy of RF measurements and maintaining process stability, thereby ensuring that processes run closer to specifications.
Implementation Method 1
a coil-type wiring disposed between the main return path unit and the secondary return path unit
Data Source
AI summary
An RF sensing apparatus configured for use with a plasma processing chamber includes a penetration unit opened in an up/down direction, a main return path unit surrounding all or a portion of the penetration unit, and a secondary return path unit located between the penetration unit and the main return path unit, spaced apart from the main return path unit, and surrounding all or a portion of the penetration unit. The main return path unit and the secondary return path unit include a path through which a current flows in one of the up/down directions.