Segmented Electrode Plasma Control for Uniform Density
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Solution Overview
Problem
Conventional plasma processing apparatuses face challenges in generating highly uniform plasma at high excitation frequencies, particularly for large substrates, due to standing wave issues and difficulty in controlling plasma density distribution, which affects film quality and processing uniformity.
Innovation Solution
A plasma processing apparatus with multiple electrodes and an impedance variable circuit connected between them, allowing for control of high-frequency current flow and impedance, enabling uniform plasma generation and density distribution even at high excitation frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the plasma excitation frequency is increased to improve plasma density and reduce electron temperature, then film quality and formation speed are improved, but plasma uniformity deteriorates due to standing wave generation
Solution Approach 1:
The electrode is divided into multiple segments (first electrode, second electrode, third electrode) arranged in the vertical direction. Each segment can be independently controlled to generate high frequency waves, allowing the plasma excitation process to be segmented and managed separately, thereby reducing standing wave effects while maintaining high frequency operation for improved film formation speed and uniformity
Solution Approach 2:
The patent introduces a vertical dimension to electrode arrangement by placing multiple electrodes at different heights above the substrate. This spatial distribution in the vertical direction allows for better control of electromagnetic field distribution, reducing standing wave patterns that cause non-uniform plasma while maintaining the benefits of high frequency excitation
2Quantity of substance
If the plasma excitation frequency is increased to generate high density plasma, then throughput is improved, but plasma density uniformity deteriorates
Solution Approach 1:
The plasma generation process is segmented across multiple electrodes positioned at different vertical levels. Each electrode segment contributes to plasma density in a controlled manner, allowing high overall plasma density to be achieved while maintaining uniformity through independent control of each segment's power and frequency
Solution Approach 2:
Each electrode segment can be independently controlled to provide locally optimized plasma conditions. The first, second, and third electrodes can be adjusted to create appropriate plasma density distribution at different vertical positions, ensuring uniform plasma density across the substrate while maintaining high overall density for improved throughput
3Device complexity
If a single high frequency application electrode is used in a parallel plate configuration, then device complexity is reduced, but control over plasma density distribution is lost
Solution Approach 1:
The single electrode is segmented into multiple independent electrodes arranged vertically. This segmentation enables independent control of each electrode's high frequency power, providing adaptability to control plasma density distribution while adding only moderate complexity to the electrode configuration
Solution Approach 2:
The system transitions from a static single-electrode configuration to a dynamic multi-electrode system where each electrode's power and frequency can be independently adjusted. This dynamic control capability allows flexible adaptation to different plasma density distribution requirements while maintaining a relatively simple overall device structure
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
The solution effectively controls plasma density distribution and enhances plasma uniformity, improving film quality and processing efficiency for large substrates by adjusting impedance and current flow between electrodes.
Implementation Method 1
a high frequency power supply configured to supply a high frequency power for generating plasma
Implementation Method 2
applying a high frequency wave of several MHz to several hundred MHz to an electrode provided in the processing container
Implementation Method 3
an impedance variable circuit configured to control an impedance, and electrically connected between two different electrodes out of the plurality of electrodes or between one of the plurality of electrodes and the processing container
Implementation Method 4
a standing wave is generated due to the influence of a surface wave propagating on the surface of an electrode to which the high frequency wave is applied
Data Source
AI summary
A plasma processing apparatus according to one embodiment includes a grounded processing container, a mounting table configured to support a workpiece inside the processing container, a plurality of electrodes arranged to face the mounting table and insulated from one another, a high frequency power supply configured to supply a high frequency power for generating plasma and electrically connected between two different electrodes out of the plurality of electrodes or between one of the plurality of electrodes and the processing container, and an impedance variable circuit configured to control an impedance and electrically connected between two different electrodes out of the plurality of electrodes or between one of the plurality of electrodes and the processing container.