Azimuthal RF Current Sensor Array for Plasma Chamber Uniformity
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Solution Overview
Problem
Modern plasma processing chambers face challenges in achieving azimuthal uniformity due to non-symmetric components such as cantilever arms and uneven gas flow, which affect RF current return paths and plasma density, leading to non-uniform processing around the substrate.
Innovation Solution
The implementation of RF current sensors positioned azimuthally around the chamber to monitor and measure RF return currents, using RF ground straps and trench machined components to improve RF ground return uniformity and characterize azimuthal non-uniformity, allowing for strategic adjustments to achieve uniform processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If non-symmetric components such as cantilever arms are used in the plasma processing chamber, then device integration density is improved, but azimuthal uniformity deteriorates
Solution Approach 1:
The patent modifies the physical state and distribution parameters of the plasma by introducing controlled azimuthal non-uniformity through non-symmetric components. By changing parameters such as gas flow distribution, RF power distribution, and plasma density profiles, the system achieves both high device integration density and acceptable azimuthal uniformity through parameter optimization rather than geometric symmetry.
2Measurement precision
If RF current sensors are positioned azimuthally around the chamber, then measurement precision of azimuthal non-uniformity is improved, but device complexity increases
Solution Approach 1:
The RF current sensors are designed to serve multiple functions: they measure RF return current magnitude, detect azimuthal non-uniformity patterns, and provide diagnostic information for process optimization. This multi-functionality reduces the need for separate measurement systems and justifies the added complexity by delivering comprehensive chamber characterization through a single sensor type.
3Productivity
If exhaust gas flows around the cantilever arm, then pumping efficiency is maintained, but pressure uniformity in the azimuthal direction deteriorates
Solution Approach 1:
The patent applies different gas flow characteristics to different azimuthal regions of the chamber. By allowing exhaust gas to flow around the cantilever arm in specific regions while maintaining different flow patterns in other regions, the system creates locally optimized flow fields that preserve pumping efficiency while managing pressure uniformity through regional differentiation rather than global uniformity.
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 enables precise monitoring and adjustment of RF return currents, ensuring improved azimuthal uniformity and process consistency, meeting stringent modern processing requirements by allowing for real-time monitoring and adaptive strategies to address non-uniformity.
Implementation Method 1
RF current sensors positioned azimuthally around the chamber to monitor and measure RF return currents
Data Source
AI summary
Apparatus and methods for assessing RF return current azimuthal uniformity are disclosed. A plurality of non-linear substantially-enclosed RF current sensors are disposed azimuthally around a central axis of a plasma processing chamber. When a plasma is ignited in the plasma processing chamber, the RF return currents are sensed in the plurality of non-linear substantially-enclosed RF current sensors and analyzed to ascertain whether RF return current azimuthal uniformity is acceptable.