Dielectric Upper Electrode Structure for Uniform Plasma Density
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Solution Overview
Problem
Existing plasma processing apparatuses face challenges in achieving uniformity of plasma density across the processing area, particularly due to non-uniform electric field distribution caused by the use of conductive materials in electrode configurations.
Innovation Solution
The plasma processing apparatus incorporates a dielectric plate with a central portion, an outer peripheral portion, and an intermediate portion, where the intermediate portion has a thickness greater than the central and outer peripheral portions, allowing for uniform radio-frequency electric field distribution and plasma generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a dielectric plate with uniform thickness is used in the upper electrode, then the structure is simple and easy to manufacture, but the plasma density distribution becomes non-uniform across the processing area
Solution Approach 1:
The dielectric plate is designed with non-uniform thickness, where the central portion has a first thickness and the peripheral portion has a second thickness different from the first. This local variation in thickness compensates for the non-uniform plasma density distribution, creating more uniform plasma across the processing area by adjusting the electric field distribution locally in different regions.
2Manufacturing precision
If conductive materials are used in the electrode configuration, then the electrode can effectively generate plasma, but non-uniform electric field distribution occurs leading to poor plasma uniformity
Solution Approach 1:
A dielectric plate is introduced as an intermediary component between the conductive upper electrode and the processing atmosphere. This dielectric plate serves as a mediator that transforms the non-uniform electric field from the conductive electrode into a more uniform electric field distribution, thereby producing uniform plasma without directly contacting the conductive electrode with the plasma-generating environment.
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 enhances in-plane uniformity of plasma density, facilitating more effective and uniform plasma processing on substrates, especially in diffusion mode operations that minimize substrate damage.
Implementation Method 1
the intermediate portion has a thickness larger than the thicknesses of the central portion and the outer peripheral portion... allowing for uniform radio-frequency electric field distribution and plasma generation
Implementation Method 2
facilitating more effective and uniform plasma processing on substrates, especially in diffusion mode operations that minimize substrate damage
Data Source
AI summary
A plasma processing apparatus includes a stage provided in a processing container, and an upper electrode. The upper electrode includes a dielectric plate facing the stage, and a conductor formed on a surface of the dielectric plate opposite to a surface of the dielectric plate facing the stage. The dielectric plate includes a central portion, an outer peripheral portion, and an intermediate portion between the central portion and the outer peripheral portion. The intermediate portion has a thickness larger than the thicknesses of the central portion and the outer peripheral portion.