Parallel-Plate Plasma Electrode Gap Layout for Uniform VHF Processing
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Solution Overview
Problem
Existing plasma processing apparatuses face challenges in achieving uniform plasma distribution, particularly in parallel plate-type systems operating at VHF or UHF frequencies, due to the generation of standing waves that affect plasma uniformity.
Innovation Solution
The apparatus incorporates a non-uniform gap between the upper electrode and dielectric plate, adjusted to suppress standing wave formation by varying the electric field gradient, and includes a drive mechanism to fine-tune the gap width, extending the wavelength of surface waves and enhancing plasma uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a parallel plate-type plasma processing apparatus uses VHF or UHF frequency for plasma excitation, then plasma processing efficiency is improved, but standing waves are generated that reduce plasma uniformity
Solution Approach 1:
The gap width between the upper electrode and dielectric plate is made non-uniform in the direction in which the dielectric plate extends. This local variation in gap width creates corresponding variations in electric field strength, which compensates for the non-uniform plasma distribution caused by standing waves, thereby improving overall plasma uniformity while maintaining high processing efficiency
Solution Approach 2:
The invention introduces asymmetric gap configuration between the upper electrode and dielectric plate. By making the gap width non-uniform rather than symmetric and uniform, the design disrupts the standing wave patterns that cause plasma non-uniformity, allowing efficient plasma generation without the harmful effects of standing waves
2Device complexity
If a uniform gap is maintained between the upper electrode and dielectric plate, then device simplicity is preserved, but standing wave formation occurs that affects plasma uniformity
Solution Approach 1:
Rather than maintaining a completely uniform gap structure, the invention introduces localized variations in gap width. This approach preserves much of the structural simplicity while creating the necessary non-uniformity to suppress standing waves and improve plasma uniformity
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 improves plasma uniformity by reducing the generation of standing waves, ensuring consistent plasma distribution across the processing area, and prevents thermal cracking of components.
Implementation Method 1
The waveguide guides a high frequency of a VHF band or an UHF band. The end portion of the waveguide is located toward the space and radiates a high frequency into the space
Implementation Method 2
An gap is provided between the upper electrode and the dielectric plate. The width of the gap is non-uniform in a direction in which the dielectric plate extends
Implementation Method 3
The width of the gap is non-uniform in a direction in which the dielectric plate extends, which helps suppress standing wave formation by reducing the electric field gradient and optimizing the wavelength of surface waves
Data Source
AI summary
There is provided a technique capable of improving plasma uniformity in a parallel plate-type plasma processing apparatus having a plasma excitation frequency of a VHF band or an UHF band. A plasma processing apparatus according to an exemplary embodiment includes a process container, a stage provided in the process container, a dielectric plate provided above the upper surface of the stage via a space in the process container, and an upper electrode provided above the dielectric plate. An gap is provided between the upper electrode and the dielectric plate, and the width of the gap is non-uniform in a direction in which the dielectric plate extends.