Plasma Sensor Phase-Synchronized Sampling for Noise Reduction
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Solution Overview
Problem
Current plasma processing technologies face challenges in achieving high sensitivity and accuracy for monitoring the state of plasma and processes during substrate processing, particularly in end point detection and noise reduction in sensor output values.
Innovation Solution
A detecting method that synchronizes sensor output value sampling with the phase of the bias waveform, specifying a first phase and a second phase of the waveforms, and sampling after predetermined times to stabilize and smooth sensor output values, thereby improving the signal-to-noise ratio and accuracy of monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous monitoring of plasma state is performed, then process control accuracy is improved, but noise in sensor output values increases
Solution Approach 1:
The patent applies periodic action by sampling sensor output values at specific phases of the bias waveform cycle rather than continuously monitoring. The sampling is performed at a predetermined phase where plasma conditions are most stable, converting continuous monitoring into periodic sampling that avoids noise while maintaining measurement precision.
Solution Approach 2:
The patent uses preliminary action by pre-determining the optimal sampling phase based on the bias waveform characteristics before actual measurement. The system calculates the phase at which plasma conditions are most stable and sets the sampling timing in advance, ensuring accurate measurements without requiring real-time noise filtering.
2Ease of operation
If sampling is performed at arbitrary timing, then measurement simplicity is improved, but sensor output stability deteriorates
Solution Approach 1:
The patent implements feedback by using the bias waveform signal as a reference to control the sampling timing. The sampling is synchronized with the bias waveform phase, creating a feedback loop where the measurement system responds to the plasma generation rhythm, ensuring stable sensor output while maintaining operational simplicity through automated phase-locked sampling.
3Speed
If high-frequency sampling is performed, then response speed is improved, but noise in detected values increases
Solution Approach 1:
The patent resolves this contradiction by performing sampling at a specific phase of the bias waveform rather than at high frequency continuously. This periodic sampling at optimal moments captures essential plasma state information while avoiding the noise that would result from high-frequency sampling during unstable phases of the plasma cycle.
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 stability and accuracy of sensor output values, improving the monitoring of plasma and process states by reducing noise and fluctuation effects, leading to more precise control and detection in plasma processing.
Implementation Method 1
detecting light of a predetermined wavelength emitted from plasma
Data Source
AI summary
A detecting method includes: supplying a bias power to a lower electrode, and supplying a source power to an upper electrode or the lower electrode; and detecting an output value of a sensor attached to a chamber. The detecting the output value of the sensor includes (a) specifying a first phase of a bias waveform for each cycle of the bias waveform, (b) specifying a second phase of a source waveform after a predetermined first time elapses from a timing when the first phase is specified, and (c) sampling the output value of the sensor after a predetermined second time elapses from a timing when the second phase is specified. The steps (a) to (c) are repeated for each cycle of the bias waveform.