Inductive Plasma Generator Parameter Measurement
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Solution Overview
Problem
Existing methods for measuring and controlling power delivery in inductively-coupled plasma generators lack precision due to distance-related measurement inaccuracies and failure to accurately estimate plasma resistance, affecting repeatability and process diagnosis.
Innovation Solution
Measuring electrical parameters on both the primary and secondary sides of the inductive element to determine plasma resistance and power, using a method that involves measuring current and voltage across the transformer windings and employing models like Kalman filters for iterative estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If measurement equipment is positioned at a distance from the inductive element, then the system complexity is reduced, but the measurement precision deteriorates
Solution Approach 1:
The patent uses mathematical models and algorithms as intermediaries to bridge the gap between distant measurements and plasma parameters. By measuring easily accessible quantities (voltage, current, frequency) and using plasma physics models to infer plasma resistance and power, the system achieves precise plasma characterization without requiring measurement equipment to be positioned close to the plasma or complex direct measurement systems.
2Measurement precision
If plasma power and plasma resistance are accurately measured, then the control precision is improved, but the device complexity increases
Solution Approach 1:
The patent replaces complex physical measurement systems with mathematical and computational approaches. Instead of using complex instrumentation to directly measure plasma power and resistance, the system uses mathematical models that process standard electrical measurements (voltage, current, frequency) to calculate plasma parameters, thereby achieving high precision without proportional increases in device complexity.
3Ease of operation
If only primary-side measurements are used, then the ease of operation is improved, but the measurement precision deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where primary-side measurements serve as input to a mathematical model, and the model output (plasma resistance, power) feeds back to control the plasma generation process. This allows the system to achieve precise plasma characterization using only primary-side measurements, maintaining operational simplicity while improving measurement precision through iterative model refinement and feedback control.
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 provides precise and accurate characterization of plasma behavior, enhancing control over power delivery and ensuring process repeatability by directly measuring plasma resistance and power, thus improving plasma generation efficiency and diagnosing issues effectively.
Implementation Method 1
RF discharges can be achieved by electrostatically or inductively coupling energy from a power supply to a plasma. Inductively-coupled plasma generators typically employ complex power delivery systems.
Implementation Method 2
RF discharges produce high energy ions and, therefore, are often used to generate plasmas for applications where the material being processed comes into contact with the plasma.
Data Source
AI summary
Methods, systems, and computer program products are described for measuring and controlling parameters of a plasma generator. A current in a primary winding of a transformer or inductive element that generates a plasma is measured. A voltage across a secondary winding of the transformer or inductive element is measured. Based on the current of the primary winding and the voltage across the secondary winding, a parameter of the plasma is determined. The parameter includes a resistance value associated with the plasma, a power value associated with the plasma, or both.