Plasma RF Measurement Module for Forward and Reflected Power
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Solution Overview
Problem
Conventional VI probes in plasma apparatuses struggle to accurately measure RF power transmission due to limitations in phase difference measurements, leading to unreliable power control and monitoring of plasma states.
Innovation Solution
A module with capacitor and inductance properties is introduced to detect phase differences for RF power measurement, allowing for precise measurement of forward and reflected power as scalar values, using directional couplers and measurement units to monitor RF voltage, current, and power in a plasma apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional VI probe with phase difference measurement is used, then RF voltage and current measurement accuracy is secured, but transmission power measurement reliability deteriorates
Solution Approach 1:
The measurement system is segmented into separate functional modules: a voltage measurement unit with capacitor properties for voltage detection, a current measurement unit with inductance properties for current detection, and directional couplers for power detection. Each module independently measures specific parameters, avoiding the integrated phase difference measurement approach that compromises power measurement reliability.
Solution Approach 2:
Directional couplers are introduced as intermediary devices between the RF power source and the plasma processing chamber. These couplers separately detect forward power and reflected power through coupled lines, providing reliable power measurement without relying on phase difference calculations from voltage and current measurements.
2Measurement precision
If phase difference method is used for power calculation, then voltage and current measurement is accurate, but power control and monitoring capability deteriorates
Solution Approach 1:
The measurement system is segmented into separate functional modules: a voltage measurement unit with capacitor properties for voltage detection, a current measurement unit with inductance properties for current detection, and directional couplers for power detection. Each module independently measures specific parameters, avoiding the integrated phase difference measurement approach that compromises power measurement reliability.
Solution Approach 2:
The system implements feedback control by directly measuring forward and reflected power through directional couplers and providing real-time feedback signals. This enables automatic power control and monitoring without the complexity of calculating power from phase difference measurements, improving ease of operation and control capability.
3Loss of information
If vector value measurement is used, then phase information is captured, but scalar power measurement capability deteriorates
Solution Approach 1:
The measurement system is segmented into separate functional modules: a voltage measurement unit with capacitor properties for voltage detection, a current measurement unit with inductance properties for current detection, and directional couplers for power detection. Each module independently measures specific parameters, avoiding the integrated phase difference measurement approach that compromises power measurement reliability.
Solution Approach 2:
The system extracts only the necessary scalar power information using directional couplers that directly measure forward and reflected power magnitudes. Phase information is not required for the primary power measurement function, allowing the system to take out and measure only the relevant scalar power parameters with high accuracy.
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 accurate measurement and control of RF power input into a processing space, enhancing the reliability and uniformity of substrate processing by providing precise measurements of incident and reflected waves.
Implementation Method 1
a voltage measurement unit 500 disposed adjacent to the application line 100 to measure the RF voltage by using capacitance
Implementation Method 2
a current measurement unit 600 disposed adjacent to the application line 100 to measure the RF current by using inductance
Implementation Method 3
a first directional coupler 300 disposed adjacent to the application line 100 to measure the power output by the input wave; a second directional coupler 400 disposed adjacent to the application line 100 to measure the power output by the reflected wave
Data Source
AI summary
Provided is a module for measuring current/voltage/power of a plasma apparatus, which includes a process chamber having a sealed processing space in which plasma is formed to process a substrate; a substrate support unit disposed in the processing space and on which a substrate is seated; and a gas injection unit configured to inject gas for performing a process in the processing space, wherein, in a substrate processing apparatus configured to process the substrate by applying RF power to the process chamber, the gas support unit, and the gas injection unit, the module for measuring current/voltage/power of the plasma apparatus is disposed adjacent to at least one application line among a first power application line for applying the RF power and a ground line for grounding to measure a RF voltage, current, and power of an input wave and a reflected wave generated by plasma generated in the processing space.