Coupling Ring Electrode for Ion Flux Directionality Control
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Solution Overview
Problem
In plasma processing, controlling the directionality of ions at the edge of a wafer is challenging due to the tradeoff between etch rate and profile angle, and existing methods lead to uneven processing and premature wear of plasma chamber components, affecting uniformity and longevity.
Innovation Solution
The use of an electrode within a coupling ring in a plasma chamber, which provides independent control of plasma parameters through active or passive RF power, allows for precise adjustment of ion flux directionality by varying the capacitance between the electrode and the edge ring, maintaining a uniform plasma density and extending the edge ring's lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If RF power is applied to the edge ring to control ion flux directionality, then the profile angle is improved, but the edge ring wears faster and its lifetime is reduced
Solution Approach 1:
The system is divided into two independent RF-powered components: the upper electrode and the edge ring. This segmentation allows independent control of plasma parameters at different locations, enabling profile angle control at the edge ring without compromising its lifetime through excessive power application.
Solution Approach 2:
The patent applies parameter changes by independently adjusting RF power levels to the edge ring and upper electrode. By changing the power parameters dynamically and independently for each component, the system optimizes both profile angle (through edge ring power) and lifetime (by preventing excessive power-induced wear).
2Productivity
If ion flux directionality is controlled to increase etch rate, then productivity is improved, but uniformity of workpiece processing deteriorates
Solution Approach 1:
The patent implements local quality by applying different RF power levels to different regions: the edge ring receives power optimized for profile control and localized etching, while the upper electrode receives power optimized for overall plasma density and uniformity. This local differentiation enables high etch rates at the edges while maintaining central region uniformity.
Solution Approach 2:
Independent parameter control is achieved by separately adjusting RF power to the edge ring and upper electrode. This allows the system to change plasma parameters locally (at the edge ring) to increase etch rate while maintaining different parameters at the center region to preserve uniformity across the workpiece.
3Productivity
If RF power is applied to components to maintain plasma density, then processing efficiency is improved, but component wear increases and reliability deteriorates
Solution Approach 1:
The system maintains plasma density and processing efficiency by dynamically adjusting RF power parameters to both the edge ring and upper electrode. Simultaneously, it prevents component wear by avoiding excessive power application, thus maintaining component reliability while sustaining high processing efficiency.
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 achieves a consistent 90-degree profile angle, reduces etch rate variations, and extends the edge ring's operational life by maintaining uniform plasma sheath and ion flux directionality, ensuring efficient and uniform processing while prolonging component lifespan.
Implementation Method 1
The coupling ring includes the electrode that generates a capacitance between the electrode and the edge ring to control the directionality of the ion flux upon receiving the modified RF signal
Implementation Method 2
providing radio frequency (RF) power to the electrode or by coupling the electrode via a variable impedance RF filter to ground
Implementation Method 3
A plasma system includes multiple radio frequency (RF) sources, an impedance match, and a plasma reactor. A workpiece is placed inside the plasma chamber and plasma is generated within the plasma chamber to process the workpiece
Data Source
AI summary
Systems and methods for controlling directionality of ion flux at an edge region within a plasma chamber are described. One of the systems includes a radio frequency (RF) generator that is configured to generate an RF signal, an impedance matching circuit coupled to the RF generator for receiving the RF signal to generate a modified RF signal, and a plasma chamber. The plasma chamber includes an edge ring and a coupling ring located below the edge ring and coupled to the first impedance matching circuit to receive the modified RF signal. The coupling ring includes an electrode that generates a capacitance between the electrode and the edge ring to control the directionality of the ion flux upon receiving the modified RF signal.