Movable Plasma Containment Structure for Etch Uniformity
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Solution Overview
Problem
Parallel-plate plasma reactors suffer from center-to-edge non-uniformities in neutral species distribution, leading to inconsistent plasma processing results, particularly in small volume product chambers with large aspect ratios, which affects etch rates and film thickness uniformity.
Innovation Solution
A wedge-shaped plasma containment structure is introduced, rotating relative to the substrate, with a containment region that maintains a higher pressure for process gases within the plasma area and a lower pressure outside, using a containment ring and inner containment to constrain plasma and enhance gas conductance, ensuring uniform plasma exposure across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a typical parallel-plate plasma reactor is used with uniform plasma generation across the substrate, then the plasma processing chamber can handle large substrates, but center-to-edge non-uniformities in neutral species distribution occur leading to inconsistent etch rates and film thickness
Solution Approach 1:
The plasma containment structure is divided into multiple segments (containment ring and inner containment) that can be independently positioned and adjusted. This segmentation allows selective confinement of plasma to specific regions of the substrate, enabling uniform processing by addressing center-to-edge non-uniformities through localized plasma generation rather than uniform plasma across the entire substrate area
Solution Approach 2:
The movable plasma containment structure creates locally optimized plasma regions with different characteristics at different substrate locations. By adjusting the position and configuration of the containment structure, the plasma density, pressure, and gas flow can be tailored locally to compensate for center-to-edge variations, achieving uniform etch rates and film thickness across the entire substrate
2Manufacturing precision
If the plasma containment structure is made movable and rotating, then uniform plasma exposure across the substrate can be achieved, but the device complexity increases
Solution Approach 1:
The plasma containment structure is designed to be movable rather than fixed, allowing dynamic adjustment of plasma confinement regions. The structure can rotate and change position to expose different areas of the substrate to plasma at different times, achieving uniform plasma exposure across the entire substrate surface while maintaining a relatively simple containment structure design
Solution Approach 2:
The plasma containment structure undergoes periodic rotation and movement during the processing cycle, systematically exposing different regions of the substrate to plasma over time. This periodic action ensures that all areas of the substrate receive equivalent plasma exposure, achieving uniformity without requiring complex simultaneous multi-zone plasma generation
3Manufacturing precision
If the plasma containment structure confines plasma to a smaller region, then neutral species uniformity improves, but the pressure differential between inside and outside the containment structure requires additional pumping capacity
Solution Approach 1:
The containment structure is segmented with multiple gaps distributed around its perimeter, allowing controlled gas flow and pressure equalization. This segmentation enables the plasma containment region to maintain higher pressure for improved neutral species uniformity while the gaps facilitate efficient gas removal through distributed exhaust paths, reducing the burden on any single pumping location
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 more uniform neutral speciation across the substrate, improving etch uniformity and processing efficiency by balancing gas removal and plasma distribution, reducing radial and azimuthal variations, and avoiding plasma loading non-uniformities.
Implementation Method 1
a plasma containment structure defining a plasma containment region over a selected portion of a surface of the substrate
Implementation Method 2
the plasma containment region is moved relative to the substrate to selectively pass over the entire surface of the substrate
Data Source
AI summary
A method of processing a substrate is provided. The method includes loading a substrate in a processing chamber. The substrate is supported on a bottom electrode and the processing chamber includes a top electrode opposing the bottom electrode. The method includes placing a plasma containment structure over a selected portion of the surface of the substrate to define a plasma containment region of the selected portion of the surface of the substrate. Then, injecting at least one process gas into the plasma containment region and biasing the top electrode and the bottom electrode. The method further includes exhausting process byproducts from the plasma containment region and moving the plasma containment region relative to the substrate to selectively passes over the entire surface of the substrate.