Multi-Electrode RF Tuning Circuit 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 in high aspect ratio feature fabrication.
Innovation Solution
A plasma processing chamber with an RF electrode assembly and a tuning circuit that adjusts impedance between electrodes to control RF waveforms, using a variable impedance producing element and an LC circuit to create resonant frequency matching, thereby controlling plasma uniformity and eliminating the need for multiple RF generators and impedance matching networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional multi-electrode approach with separate RF generators and impedance matching networks is used for each electrode, then plasma radial uniformity can be controlled, but device complexity and cost increase significantly
Solution Approach 1:
The patent combines multiple RF generators and impedance matching networks into a single shared RF source and matching network system. The tuned circuit acts as an impedance transformation network that can independently control the impedance seen by each electrode while sharing the same RF power source, thereby reducing system complexity while maintaining plasma uniformity control capability
Solution Approach 2:
The single RF generator and impedance matching network serve multiple functions: they provide RF power to multiple electrodes simultaneously and independently control the impedance for each electrode through the tuned circuit. This multi-functional design eliminates the need for separate dedicated RF systems for each electrode
2Adaptability or versatility
If separate RF generators and impedance matching networks are used for each electrode, then each electrode can be independently controlled, but system cost increases
Solution Approach 1:
Multiple electrodes share a common RF generator and impedance matching network infrastructure. The tuned circuit enables independent impedance control for each electrode without requiring separate RF generators or matching networks, significantly reducing system cost while preserving independent control capability
Solution Approach 2:
The tuned circuit acts as an intermediary impedance transformation network between the shared RF power source and individual electrodes. It enables independent control of each electrode's impedance and power distribution while utilizing a single shared RF system, reducing overall system cost
3Manufacturing precision
If conventional RF power delivery is used without resonant tuning circuits, then system simplicity is maintained, but plasma uniformity control is insufficient
Solution Approach 1:
The patent introduces resonant tuning circuits that can dynamically adjust impedance parameters to optimize plasma uniformity. By changing the electrical parameters (impedance, resonant frequency) of the tuned circuits, the system achieves precise control over RF power distribution to different electrodes, improving plasma uniformity despite increased circuit complexity
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 improves plasma uniformity control, reduces system complexity and cost, and allows for simultaneous multiple frequency power delivery to electrodes, enhancing the precision and consistency of plasma processing for semiconductor manufacturing.
Implementation Method 1
A tuning circuit has an input coupled to the output of the impedance matching network and an output coupled to the second electrode, wherein the tuning circuit has a plurality of impedance producing elements that comprise a first variable impedance producing element
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.