Plasma Probe Cleaning Voltage for Accurate State Measurement
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Solution Overview
Problem
Existing plasma measurement systems face challenges in accurately estimating plasma state due to the formation of conductive fluoride films on probe devices, which interfere with the measurement accuracy by introducing resistance components that complicate the estimation of plasma electron temperature and density.
Innovation Solution
A method is employed where the absolute value of the voltage applied to the probe device during cleaning is increased beyond the measurement voltage, utilizing AC, DC, or pulse voltages to attract and remove conductive fluoride, thereby maintaining the integrity of plasma measurement by preventing the formation of conductive films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a probe device is used for plasma measurement, then plasma state can be measured, but conductive fluoride films form on the probe device reducing measurement accuracy
Solution Approach 1:
A cleaning process is performed before plasma measurement to remove conductive fluoride films from the probe device surface. This preliminary cleaning action prevents the films from interfering with subsequent measurements, thereby maintaining measurement accuracy without requiring complex real-time cleaning mechanisms during measurement.
Solution Approach 2:
The conductive fluoride films that would normally degrade measurement accuracy are removed through a controlled cleaning process using RF power. By converting the harmful accumulation of films into a beneficial periodic cleaning cycle, the system maintains probe performance and extends operational life between cleanings.
2Measurement precision
If cleaning process is performed to remove conductive fluoride, then measurement accuracy is maintained, but additional time and energy are required
Solution Approach 1:
Instead of continuous cleaning, the system employs periodic cleaning cycles at predetermined intervals. The controller automatically initiates cleaning processes based on usage time or measurement quality indicators, optimizing the balance between maintaining measurement accuracy and minimizing time loss to cleaning operations.
Solution Approach 2:
The cleaning process uses adjustable RF power parameters and duration settings that can be optimized based on the accumulated contamination level. By dynamically adjusting cleaning parameters rather than using fixed high-power cleaning, the system reduces cleaning time while still effectively removing conductive fluoride films.
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 enhances the accuracy of plasma state estimation by effectively removing conductive fluoride, ensuring precise measurement of plasma electron temperature and density even during cleaning processes.
Implementation Method 1
an absolute value of a voltage applied to the probe device during cleaning of the plasma processing apparatus is greater than an absolute value of the AC voltage for the plasma measurement
Data Source
AI summary
Provided is a method for controlling a plasma measurement system including a probe device of a plasma processing apparatus, and a measurement circuit that outputs an AC voltage for plasma measurement to the probe device and measures a state of plasma generated by the plasma processing apparatus, wherein an absolute value of a voltage applied to the probe device during cleaning of the plasma processing apparatus is greater than an absolute value of the AC voltage for the plasma measurement.