RF Magnetic Field Sensing for Plasma Sheath Uniformity Control
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Solution Overview
Problem
Existing plasma processing systems struggle to control the plasma sheath profile over a wafer surface effectively, leading to suboptimal processing results due to inadequate adjustment of operational parameters.
Innovation Solution
A magnetic field sensor is deployed proximal to the power rod in the impedance matching network to detect both forward and reflective RF currents, allowing precise identification and fine-tuning of specific time intervals in the RF signal to influence the plasma sheath profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If general adjusting of operational parameters is performed, then the plasma sheath profile is influenced, but the control precision is insufficient
Solution Approach 1:
The patent segments the RF signal detection by using multiple magnetic field sensors positioned at different locations along the power rod to detect magnetic fields at different time intervals during the RF cycle. This segmentation allows precise identification of specific time intervals in the RF signal that influence plasma sheath formation, enabling targeted adjustment rather than general parameter tuning.
Solution Approach 2:
The patent replaces direct electrical measurement of RF current with magnetic field sensing. Magnetic field sensors detect the magnetic field generated by RF current in the power rod, providing non-contact, high-precision measurement of RF signal attributes including time interval detection. This substitution enables more precise measurement capability compared to traditional electrical measurement methods.
2Productivity
If RF power is increased to improve processing results, then plasma generation is enhanced, but reflective power is generated causing system instability
Solution Approach 1:
The patent implements feedback control by detecting magnetic field signals that represent both forward and reflected RF power components. The system analyzes the detected RF signal attributes and provides feedback to adjust RF power delivery, enabling dynamic optimization of plasma generation while minimizing reflected power and maintaining system stability.
Solution Approach 2:
The patent enables dynamic adjustment of RF power delivery by detecting time interval characteristics of the RF signal and adjusting power parameters in real-time during the RF cycle. This dynamic control allows the system to optimize plasma generation efficiency while preventing excessive reflected power, maintaining both productivity and reliability.
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 enables better control over the plasma sheath profile by adjusting the RF signal at specific time intervals, improving the uniformity and efficiency of processes like etching or deposition on the wafer surface.
Implementation Method 1
The magnetic field sensor is disposed proximate to the first end of the power rod to detect magnetic field generated by the power supplied to the power rod
Data Source
AI summary
A magnetic field sensor for measuring magnetic field of a current applied to a lower electrode defined within a plasma chamber includes a conductor element disposed along a length of a tubular housing. A plurality of slots is defined on one side of the tubular housing to expose the conductor element.