Distributed Multi-Zone Plasma Source for Uniform Etching
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Solution Overview
Problem
Plasma reaction chambers suffer from center-to-edge non-uniformities in neutral species distribution, leading to inconsistent plasma processing across substrates, particularly in small volume product chambers with large aspect ratios, which affects processes like dielectric etch and other neutral-dependent applications.
Innovation Solution
A distributed multi-zone plasma source system with multiple ring plasma sources, each equipped with a primary winding and ferrites, arranged in arrays around the process chamber, which generates a concentrated magnetic field to induce a secondary current and plasma, allowing for more uniform gas distribution and processing across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single plasma source is used in a small volume product chamber with large aspect ratio, then the chamber volume is reduced for productivity, but center-to-edge non-uniformities in neutral species distribution occur
Solution Approach 1:
The single plasma source is divided into multiple distributed plasma sources (first, second, third, and fourth plasma sources) positioned at different locations within the chamber. Each plasma source independently generates plasma that contributes to the overall neutral species distribution, enabling uniform coverage across the substrate even in a compact chamber volume with large aspect ratio.
Solution Approach 2:
The plasma sources are arranged in a spatial distribution pattern (e.g., surrounding the substrate or positioned at different heights and radial positions) to create three-dimensional plasma distribution. This spatial arrangement ensures that neutral species are generated throughout the chamber volume, achieving uniform delivery to the substrate surface without requiring a larger chamber.
2Ease of operation
If process gases are introduced across the width of the processing chamber through a single plasma source, then the gas flow is simple to control, but non-uniformities arise from differences in flow velocity and effective gas residence time between center and edge
Solution Approach 1:
The gas delivery system is segmented into multiple independent gas delivery channels, each associated with a specific plasma source. This allows individual control of gas flow to each plasma source, enabling optimization of flow velocity and residence time for neutral species generation at different chamber locations, thereby achieving uniform process conditions across the substrate.
Solution Approach 2:
Each plasma source is equipped with its own gas delivery system that can be independently controlled to provide locally optimized gas flow conditions. This enables different regions of the chamber to receive gas flows tailored to their specific requirements, ensuring uniform neutral species generation despite variations in position within the chamber.
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 system achieves improved center-to-edge uniformity in plasma processing by evenly distributing radicals and neutral species across the substrate, enhancing the consistency of processes like etch and reducing plasma-related non-uniformities.
Implementation Method 1
applying a primary current to a respective primary winding around the exterior of the selected plasma source, generating magnetic field in the primary winding
Implementation Method 2
concentrating the magnetic field with multiple ferrites in the selected plasma source, inducing a secondary current in the process gas in a plasma chamber in selected the plasma source
Implementation Method 3
concentrating the magnetic field with multiple ferrites in the selected plasma source
Implementation Method 4
inducing a secondary current in the process gas in a plasma chamber in selected the plasma source and generating a plasma in the process gas in the plasma chamber in the selected plasma source with the secondary current
Data Source
AI summary
A processing chamber including multiple plasma sources in a process chamber top. Each one of the plasma sources is a ring plasma source including a primary winding and multiple ferrites. A plasma processing system is also described. A method of plasma processing is also described.