Multi-Electrode RF Source Assembly for Plasma Uniformity Control
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Solution Overview
Problem
Current plasma processing systems for semiconductor manufacturing face challenges in achieving radial plasma uniformity due to variations in electrical characteristics and spatial arrangements of processing components, leading to non-uniform etched features and reduced device yield, particularly with the complexity and cost of conventional multi-electrode approaches.
Innovation Solution
A plasma processing chamber with an RF electrode assembly and a tuning circuit that adjusts impedance between electrodes to control RF waveforms, eliminating the need for separate RF generators and impedance matching networks, thereby improving plasma uniformity and reducing system complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional multi-electrode approach is used to control plasma radial uniformity, then plasma uniformity can be improved, but device complexity and cost increase due to requiring separate RF generators and impedance matching networks for each electrode
Solution Approach 1:
The patent combines multiple RF electrodes (first electrode and second electrode) into a single integrated RF electrode assembly that is driven by a single RF generator. The tuning circuit adjusts the electrical characteristics between the electrodes to achieve independent plasma density control without requiring separate RF generators and impedance matching networks for each electrode, thus reducing system complexity while maintaining plasma uniformity control capability
Solution Approach 2:
The single RF generator and impedance matching network serve multiple functions by powering both the first electrode and second electrode through the tuning circuit. The tuning circuit itself provides multiple functions by simultaneously adjusting impedance and controlling RF waveform characteristics to achieve plasma uniformity control, eliminating the need for dedicated control systems for each electrode
2Manufacturing precision
If a conventional multi-electrode approach is used to control plasma radial uniformity, then plasma uniformity can be improved, but cost increases due to multiple RF generators and impedance matching networks
Solution Approach 1:
The patent merges the functionality of multiple RF generators and impedance matching networks into a single RF generator and impedance matching network combination. The tuning circuit provides the additional control functionality needed for multi-electrode operation, significantly reducing the overall system cost while maintaining the ability to control plasma radial uniformity
Solution Approach 2:
The single RF generator and impedance matching network are designed to serve multiple electrodes through the tuning circuit, providing cost-effective multi-functionality. The tuning circuit enables this single system to perform what would traditionally require multiple separate systems, reducing both equipment cost and manufacturing complexity
3Manufacturing precision
If separate RF generators are used for each electrode to control plasma uniformity, then plasma uniformity control can be improved, but the number of components and system complexity increase
Solution Approach 1:
The patent combines multiple RF generation functions into a single RF generator that powers both electrodes through the tuning circuit. This merging of components reduces the total number of parts while maintaining the ability to independently control plasma density at different radial positions through impedance adjustment in the tuning circuit
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 enhances plasma uniformity control, reduces system complexity and cost, and allows for simultaneous operation with multiple frequencies, improving the consistency and efficiency of semiconductor manufacturing processes.
Implementation Method 1
an impedance matching network having an input coupled to the output of the first RF generator and an output coupled to the first electrode
Implementation Method 2
the tuning circuit has a plurality of impedance producing elements that comprise a first variable impedance producing element
Implementation Method 3
a plasma is formed over the substrate by use of a radio frequency (RF) generator that is coupled to an electrode disposed on or within the plasma processing chamber
Data Source
AI summary
Apparatus and methods for controlling the uniformity of a plasma formed using a radio frequency (RF) source power assembly that includes one or more resonant tuning circuits coupled to two or more electrodes disposed within a multi-electrode source assembly. Improved plasma uniformity control and reduced system cost are achieved by eliminating multiple RF generators and matches that power the multiple electrodes separately. Multiple frequencies may also be provided to multiple electrodes at the same time, which can include another cost savings when using a multi-frequency RF source assembly. Local plasma density and sheath voltage over a surface of a substrate are controlled with segmented electrodes disposed within the processing region of a plasma processing chamber. The ion flux and direction, as well as energetic electron flux towards the substrate, are controlled to address the plasma non-uniformity and global tilt during processing of a semiconductor substrate.