Edge Ring RF Circuit for Plasma Sheath Control
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Solution Overview
Problem
Existing plasma processing methods face challenges in maintaining consistent plasma sheath characteristics at the edge of a substrate due to edge ring erosion, leading to undesirable processing effects and reduced yield, and current solutions either increase particle formation or require expensive dual-frequency RF generators.
Innovation Solution
A substrate support assembly with an electrostatic chuck, edge ring, and RF power sources, coupled through a matching network and RF circuit that allows independent tuning of RF amplitude and phase for multiple frequencies, enabling precise control of the plasma sheath without moving parts or separate generators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an independent RF generator with a separate RF match network is used to directly drive the edge ring, then the plasma sheath can be controlled, but the system becomes very expensive when multiple RF frequencies are used
Solution Approach 1:
The patent combines multiple RF power sources and their match networks into a single integrated RF circuit that can simultaneously drive both the substrate and the edge ring. This consolidation reduces the number of separate components while maintaining the ability to independently control plasma sheath characteristics at different frequencies.
Solution Approach 2:
The RF circuit is designed to perform multiple functions: it can drive the substrate at one frequency while simultaneously driving the edge ring at another frequency, and it includes built-in match networks that can be independently adjusted for each load. This multi-functional design eliminates the need for separate dedicated RF generators and match networks for each component.
2Manufacturing precision
If movable edge rings are used to control the plasma sheath, then the sheath position can be adjusted, but particle formation in the process chamber increases
Solution Approach 1:
The patent replaces the mechanical approach of moving the edge ring physically with an electrical approach using RF power control. By adjusting the RF amplitude and phase delivered to the edge ring, the plasma sheath position and characteristics can be controlled without any mechanical movement, thereby eliminating particle generation from moving parts.
Solution Approach 2:
The system controls plasma sheath characteristics by changing RF parameters (amplitude and phase) rather than physical parameters (position). The RF circuit can independently adjust these electrical parameters to achieve precise control over the plasma sheath at the edge ring without mechanical intervention.
3Reliability
If the edge ring is severely eroded and replaced, then processing characteristics can be restored, but downtime and costs increase
Solution Approach 1:
The system provides self-adjustment capability through the RF circuit that can compensate for edge ring erosion by modifying RF power delivery. Instead of requiring physical replacement of the eroded edge ring, the system automatically adjusts RF parameters to maintain consistent plasma sheath characteristics and processing quality.
Solution Approach 2:
The RF circuit is designed to proactively compensate for edge ring degradation before it becomes severe enough to affect processing. By continuously monitoring and adjusting RF parameters, the system maintains optimal plasma sheath characteristics throughout the edge ring's service life, preventing the need for frequent replacements.
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 solution allows for adjustment of the plasma sheath at the substrate edge without affecting the center, improving yield, reducing downtime and costs, and providing precise control over extreme edge process profiles and feature tilting, while minimizing particle formation and eliminating the need for frequent edge ring replacements.
Implementation Method 1
two or more radio frequency (RF) power sources coupled to the edge ring and at least one of a baseplate disposed beneath the electrostatic chuck or an electrode disposed in the electrostatic chuck
Implementation Method 2
Due to exposure of the edge ring to plasma within the process chamber
Data Source
AI summary
Methods and apparatus for processing a substrate positioned on a substrate support assembly are provided. For example, a substrate support assembly includes an electrostatic chuck having one or more chucking electrodes embedded therein for chucking a substrate to a substrate support surface of the electrostatic chuck; an edge ring disposed on the electrostatic chuck and surrounding the substrate support strike; two or more radio frequency (RF) power sources coupled to the edge ring and at least one of a baseplate disposed beneath the electrostatic chuck or an electrode disposed in the electrostatic chuck; a matching network coupling the edge ring to the two or more RF power sources; and an RF circuit coupling the edge ring to the two or more RF power sources, the RF circuit configured to simultaneously tune at least one of an RF amplitude or an RF phase of respective signals of the two or more RF power sources.