Plasma Current Control via Magnitude Sensor Feedback
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Solution Overview
Problem
Conventional plasma processing systems lack effective current control, leading to significant variations in plasma characteristics due to impedance changes, requiring frequent re-calibration and re-qualification, which reduces productivity and increases costs.
Innovation Solution
A plasma processing system with a current magnitude sensor that measures the magnitude of the supplied current without phase angle measurements, enabling closed-loop control of the current to maintain consistent plasma characteristics, and a splitter to distribute current to multiple coils for precise control of plasma characteristics across a wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional open-loop power control mode is used, then the system is simple to operate, but plasma characteristics vary significantly due to impedance changes
Solution Approach 1:
The patent implements closed-loop control by measuring the actual power delivered to the plasma using a directional coupler and sensor, then using this feedback signal to adjust the RF generator output. This feedback mechanism compensates for impedance changes automatically, maintaining consistent plasma characteristics without requiring complex manual recalibration, thus resolving the contradiction between operational simplicity and plasma consistency.
2Reliability
If closed-loop power control with phase angle measurement is implemented, then plasma characteristics can be controlled, but measurement costs and system complexity increase significantly
Solution Approach 1:
The patent extracts only the necessary measurement component (power magnitude) from the complete power measurement system, eliminating the need for phase angle measurement. By using a directional coupler to measure only the forward and reflected power magnitudes, the system achieves plasma control without the complexity of phase detection circuitry, resolving the contradiction between control capability and system complexity.
3Reliability
If frequent re-calibration and re-qualification are performed, then plasma characteristics can be maintained, but productivity decreases and costs increase
Solution Approach 1:
The patent implements a self-adjusting system where the RF generator automatically compensates for impedance changes using real-time power measurement feedback. This self-service capability eliminates the need for manual re-calibration and re-qualification operations, maintaining plasma consistency continuously while keeping the manufacturing process running without interruption, thus resolving the contradiction between reliability and productivity.
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 solution provides run-to-run and chamber-to-chamber repeatability, eliminating the need for re-calibration and re-qualification, improving productivity and reducing costs by using low-cost current magnitude sensors and allowing for precise control of plasma characteristics across a wafer.
Implementation Method 1
a coil for conducting a supplied current for generating and sustaining at least a portion of the plasma
Implementation Method 2
a current magnitude sensor coupled with the coil for measuring a magnitude of the supplied current without measuring any phase angle of the supplied current
Implementation Method 3
a controller coupled with the current magnitude sensor for adjusting the supplied current in response to the measured magnitude of the supplied current
Data Source
AI summary
A plasma processing system for generating plasma to process at least a wafer. The plasma processing system includes a coil for conducting a current for sustaining at least a portion of the plasma. The plasma processing system also includes a sensor coupled with the coil for measuring a magnitude of a supplied current to provide a magnitude measurement without measuring any phase angle of the supplied current. The supplied current is the current or a total current that is used for providing a plurality of currents (e.g., including the current). The plasma processing system also includes a controller coupled with the sensor for generating a command using the magnitude measurement and/or information derived using the magnitude measurement, without using information related to phase angle measurement, and for providing the command for controlling the magnitude of the supplied current and/or a magnitude of the total current.