L-Shaped Exhaust Duct Layout for Plasma Discharge Suppression
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Solution Overview
Problem
Existing plasma processing apparatuses face issues with abnormal discharge due to strong electric fields generated by high RF power, particularly around exhaust mechanisms, which can lead to process failures and inefficiencies.
Innovation Solution
The plasma processing apparatus incorporates an exhaust duct with an L-shaped radial cross-section and strategically positioned exhaust holes, recessed to minimize the electric field intensity near the exhaust opening, ensuring the duct is grounded to prevent plasma introduction and reduce discharge risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high RF power is supplied to the upper electrode, then plasma processing efficiency is improved, but abnormal discharge occurs around the exhaust duct
Solution Approach 1:
The patent grounds the exhaust duct to convert the harmful effect of the exhaust duct acting as an antenna that attracts plasma and causes abnormal discharge. By grounding it, the harmful electrical charge is dissipated, transforming the exhaust duct from a harmful element into a safe component that can handle high RF power without causing abnormal discharge.
Solution Approach 2:
The patent introduces a groove structure as an intermediary feature on the exhaust duct surface. This groove acts as a mediator that redistributes the electric field and prevents plasma accumulation at specific high-field regions, thereby preventing abnormal discharge while allowing high RF power operation.
2Volume of stationary object
If the exhaust duct is positioned close to the processing space, then the processing container size is reduced, but electric field intensity increases causing abnormal discharge
Solution Approach 1:
The patent applies local quality by creating a groove at a specific location on the exhaust duct surface where the electric field is most intense. This localized modification changes the electrical properties only at the critical high-field region, allowing the exhaust duct to be positioned close to the processing space without causing abnormal discharge elsewhere.
Solution Approach 2:
The patent addresses the spatial constraint by modifying the surface topology of the exhaust duct through groove formation. This adds a dimensional feature to the otherwise flat surface, creating a three-dimensional structure that redistributes the electric field in a way that prevents plasma accumulation while maintaining compact container dimensions.
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 effectively prevents abnormal discharge, enhances process performance, and reduces the size of the processing container by managing electric fields, thus improving operational reliability and efficiency.
Implementation Method 1
the exhaust duct includes an exhaust hole communicating with an internal exhaust path, and the exhaust hole is configured such that, with respect to a first length and a second length of two sides of the L-shape, a distance from a corner portion of the L-shape to the exhaust hole is equal to and less than the first length and is equal to and less than the second length
Data Source
AI summary
A plasma processing apparatus includes: a processing container; a stage in the processing container; an upper electrode provided to face a placement surface of the stage; and an exhaust duct provide to define a processing space inside the processing container together with the placement surface and the upper electrode, wherein a radial cross-section of an outer wall of the exhaust duct facing the processing space is an L-shape, the exhaust duct includes an exhaust hole communicating with an internal exhaust path, and the exhaust hole is configured such that, with respect to first and second lengths of two sides of the L-shape, a distance from a corner portion of the L-shape to the exhaust hole is equal to or less than each of the first and second lengths, the first length is 7 mm or more, and the second length is equal to or greater than the first length.