Magnetic Loop Antenna Plasma Sensing Without Invasive Probes
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Solution Overview
Problem
Existing plasma diagnostic techniques are invasive and disruptive to plasma characteristics, making them unsuitable for industrial semiconductor processing where real-time, non-invasive, and installation-free monitoring is essential.
Innovation Solution
A system utilizing a magnetic field antenna, specifically a magnetic loop antenna, positioned in the near electromagnetic field of a coupled plasma source to remotely monitor plasma currents without physical alteration of the discharge vessel, employing radio emission spectroscopy to analyze near-field radio emissions and extract plasma parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If invasive plasma diagnostic techniques are used, then plasma parameters can be measured, but the plasma characteristics are altered and the system becomes disruptive to existing fabrication infrastructures
Solution Approach 1:
The patent introduces an intermediary electromagnetic field as a mediator between the measurement system and the plasma. Instead of directly inserting probes into the plasma, the system uses electromagnetic radiation that naturally interacts with the plasma without requiring physical intrusion. This intermediary field allows measurement of plasma parameters while avoiding direct contact that would alter plasma characteristics.
Solution Approach 2:
The patent replaces mechanical/invasive probe-based measurement systems with electromagnetic field-based remote sensing. Instead of physically inserting diagnostic equipment into the plasma chamber, the system uses electromagnetic waves to probe the plasma from a distance, substituting mechanical intrusion with field-based interaction that does not perturb the plasma.
2Measurement precision
If invasive probes are installed in existing fabrication infrastructures, then plasma monitoring is achieved, but additional complexities are introduced that adversely impact process replication
Solution Approach 1:
The electromagnetic field serves as an intermediary that enables plasma monitoring without requiring physical modification of existing fabrication equipment. By using the natural electromagnetic environment already present in the plasma processing chamber, the system avoids adding complex invasive probe installations while maintaining monitoring capabilities.
Solution Approach 2:
The system utilizes the plasma's own electromagnetic emissions and the existing electromagnetic field in the chamber for diagnostic purposes. Rather than requiring separate invasive measurement systems, the plasma processing equipment's inherent electromagnetic characteristics are exploited for self-diagnosis, reducing overall system complexity.
3Object-affected harmful factors
If remote sensing is implemented using electromagnetic fields, then non-invasive plasma monitoring is achieved, but signal strength decreases with distance from the plasma source
Solution Approach 1:
The system employs parameter changes in the electromagnetic field frequency and wavelength to optimize signal strength at different distances from the plasma source. By tuning the electromagnetic parameters to match the plasma characteristics and detection distance, the system maintains measurement precision while preserving the non-invasive nature of remote sensing.
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
Enables remote, non-invasive, and installation-free monitoring of plasma parameters, reducing perturbation of the plasma and facilitating deployment on existing fabrication lines, with diagnostic advantages for endpoint detection and identification of nuisance events.
Implementation Method 1
A magnetic field antenna is positioned in the near field of a plasma source. Magnetic flux from plasma currents, present in the vicinity of the viewport, is intercepted via a calibrated loop antenna.
Implementation Method 2
a magnetic field antenna positioned in the near field electromagnetic field of a coupled plasma source wherein the magnetic field antenna is a magnetic loop antenna placed in the near electromagnetic field
Data Source
AI summary
The invention provides a method and system to remotely monitor a plasma (3) comprising a magnetic field antenna (2) positioned in the near electromagnetic field of a coupled plasma source wherein the magnetic field antenna is a magnetic loop antenna placed in the near electromagnetic field and measure near field signals emitted from the plasma source. A radio system (1) is utilised to analyse the low power signal levels across a wide frequency band. Plasma parameters such as series, or geometric, resonance plasma and electron-neutral collision frequencies are evaluated via a fitting of resonant features present on higher harmonics of the driving frequency to identify arcing, pump or matching failure events, common in fabrication plasma systems.