Plasma Processing Electrode with Buried Metal Plates
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Solution Overview
Problem
In plasma processing apparatuses, the non-uniformity of plasma density due to high-frequency RF power supply leads to uneven electric field intensity distribution, causing stress concentration and potential contamination from adhesive peeling off, especially with taper-shaped dielectric bodies.
Innovation Solution
The apparatus incorporates a dielectric body with buried metal plate electrodes, which are adjusted to ground potential, creating a uniform electric field intensity distribution without significantly lowering the maximum electric field intensity, similar to a taper-shaped dielectric body, while preventing stress concentration and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a taper-shaped dielectric body is used to improve plasma uniformity, then electric field intensity distribution is improved, but stress concentration occurs due to thermal expansion difference and machining precision deterioration
Solution Approach 1:
The dielectric body is segmented into multiple sections along its length, with each section having a different cross-sectional area. This segmentation allows the structure to accommodate thermal expansion differences between the dielectric material and metal base member, preventing stress concentration and adhesive peeling while maintaining plasma uniformity.
Solution Approach 2:
Different sections of the dielectric body have different cross-sectional areas tailored to local requirements. The varying cross-section provides both the plasma uniformity improvement needed at certain locations and the stress relief capability needed at other locations, resolving the contradiction between manufacturing precision and reliability.
2Manufacturing precision
If a flat dielectric body is installed at the lower center of the upper electrode, then electric field intensity at the central portion is lowered, but plasma uniformity is not sufficiently improved
Solution Approach 1:
The dielectric body employs an asymmetric taper shape with varying cross-sectional areas along its length rather than a symmetric flat shape. This asymmetric configuration enables differential control of electric field intensity at different radial positions, achieving both electric field distribution improvement and sufficient plasma uniformity.
Solution Approach 2:
The cross-sectional area parameter of the dielectric body is varied continuously or in steps along its length. By changing this geometric parameter, the electric field intensity distribution is optimized to achieve both proper field intensity control and improved plasma uniformity simultaneously.
3Quantity of substance
If high-frequency RF power is supplied to generate high-density plasma, then plasma density is increased, but electric field intensity becomes non-uniform causing stress concentration
Solution Approach 1:
The dielectric body acts as an intermediary element between the RF power supply and the plasma generation region. It mediates the electric field distribution by its varying cross-sectional geometry, enabling high-density plasma generation while maintaining electric field uniformity and preventing stress concentration.
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 achieves uniform plasma density and prevents contamination by maintaining the electric field intensity distribution, improving the precision and reliability of the plasma processing.
Implementation Method 1
since a capacitance component becomes larger at an end portion of the dielectric body 920 than that at a central portion thereof, the electric field intensity distribution E/Emax may not be excessively lowered at the end portion of the dielectric body 920 as compared with the case of the flat dielectric body 920a
Implementation Method 2
a radio frequency (RF) power is supplied to at least one of an upper electrode and a lower electrode facing to each other, and a gas is excited by an energy of an electric field of the RF power to thereby generate a plasma
Data Source
AI summary
A plasma processing apparatus includes a processing chamber in which a target substrate is processed; an application electrode and a facing electrode provided to face each other in the processing chamber, a plasma generation space being formed between the application electrode and the facing electrode; and an RF power supply connected to the application electrode, an RF power being supplied from the RF power supply to the application electrode. At least one of the application electrode and the facing electrode includes a base formed of a metal, and a dielectric body inserted into the base, one or more metal plate electrodes being buried in the dielectric body.