Multi-feed RF Distribution for Plasma Chamber Uniformity
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Solution Overview
Problem
Plasma processing systems face challenges in maintaining uniform film thickness and characteristics across large substrates due to standing waves caused by the wavelength of the excitation frequency approaching the physical dimensions of the electrode, leading to difficulties in achieving uniform electromagnetic field distribution.
Innovation Solution
A method involving M power generators coupled to N feed points on an electrode system, where power is absorbed at K feed points and delivered at N-K feed points, with controlled impedance and phase/amplitude adjustments, using an M+N port network that includes hybrid combiners and directional couplers to achieve uniform electromagnetic field distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the wavelength of the excitation frequency approaches the physical dimensions of the electrode, then plasma processing can be achieved, but standing waves form causing non-uniform electromagnetic field distribution
Solution Approach 1:
The electrode system is divided into multiple feed points (N feed points) across its surface. Each feed point receives RF power through separate impedance matching networks, allowing the electromagnetic field to be segmented and controlled at multiple locations simultaneously. This segmentation prevents standing wave formation by distributing power injection points throughout the electrode area.
Solution Approach 2:
The system dynamically adjusts the phase and amplitude of RF power delivered to each feed point independently. By varying these parameters in real-time, the system adapts to prevent standing wave patterns and maintains uniform electromagnetic field distribution across the electrode surface during plasma processing.
Solution Approach 3:
The impedance matching networks at each feed point independently control local electromagnetic parameters (impedance, phase, amplitude). By changing these parameters at different feed points, the system optimizes power distribution to eliminate standing waves and achieve uniform field distribution across the entire electrode surface.
2Manufacturing precision
If multiple feed points are used on the electrode system, then electromagnetic field uniformity can be improved, but the system complexity increases
Solution Approach 1:
The M power generators are designed with multi-functionality, capable of both delivering and absorbing RF power depending on system requirements. This universal capability reduces the need for separate dedicated components for each function, simplifying the overall system architecture despite having multiple feed points.
Solution Approach 2:
The system recovers RF power at K feed points where power is absorbed rather than discarded. This recovered power can be redistributed to other feed points or reused, improving overall system efficiency and reducing the total power input required, thereby offsetting the increased complexity of having multiple feed points.
3Manufacturing precision
If power is absorbed at some feed points and delivered at others, then electric field variation is reduced, but the system requires advanced impedance control
Solution Approach 1:
The impedance matching networks at each feed point independently adjust impedance parameters to optimize power transfer. By dynamically changing impedance values at different feed points, the system achieves both power delivery and absorption functions while maintaining precise control over the electromagnetic field distribution for uniform deposition.
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 approach significantly reduces electric field variation across the substrate, improving deposition uniformity from 12% to 1.25%, enhancing the precision and efficiency of thin film layer deposition in plasma processing systems.
Implementation Method 1
coupling M power generators to N feed points on an electrode system, absorbing power at K of the N feed points and delivering power at the other N-K feed points
Implementation Method 2
Each impedance matching network presents a controlled impedance to its respective generator when it is delivering power and a controlled impedance to the drive point on the electrode when the generator is absorbing power
Data Source
AI summary
Improved power distribution architectures for the uniform delivery of single frequency RF power to plasma chambers are disclosed. The architectures include feeding into multiple points across a single large-area electrode, multiple electrodes driving a common plasma discharge as well as multiple coils driving a common plasma discharge. The time-averaged electromagnetic field distribution may be controlled using an array of generator and match (delivery) systems, one of which may be capable of absorbing net power and presenting controlled impedance to the plasma load. In variations, an M+N port network (with M the number of generators and N the number of feed points on the electrode) may be implemented to level the power required from each generator while maintaining a desired field strength distribution.