Synchronized OES for Pulsed Plasma Stability Characterization
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Solution Overview
Problem
Existing optical emission spectroscopy (OES) methods for plasma processing lack sufficient time resolution and synchronization with power modulation in pulsed plasma processes, leading to missed information on power modulation pulse stability and sub-optimal signal-to-noise ratios.
Innovation Solution
Implement time-synchronized OES data acquisition with pulsed RF generators to collect data during selected time periods of interest in power modulation, enabling improved time resolution to milliseconds or sub-milliseconds and enhancing signal-to-noise ratio by separating data collection across different phases of the power modulation cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional OES methods are used for plasma processing, then continuous monitoring is possible, but time resolution is insufficient and synchronization with power modulation is lost
Solution Approach 1:
The patent applies periodic action by synchronizing OES data acquisition with the pulsed power modulation cycle. The system performs OES measurements at specific phases of the power modulation cycle (e.g., during ON periods or at specific duty cycles), enabling time-resolved characterization of plasma parameters while maintaining synchronization with the periodic power input. This allows capture of transient plasma behavior that conventional continuous OES would miss.
Solution Approach 2:
The patent implements preliminary action by pre-synchronizing the OES measurement timing with the power modulation cycle before data acquisition begins. The system is configured to trigger OES measurements at predetermined phases of the power cycle, ensuring that critical plasma information is captured at the optimal moments without requiring real-time adaptive timing adjustments.
2Reliability
If OES data is collected continuously during pulsed plasma, then complete plasma behavior is captured, but signal-to-noise ratio deteriorates
Solution Approach 1:
The patent applies the extraction principle by selectively collecting OES data only during specific phases of the power modulation cycle where the plasma emits the strongest signals. By extracting and analyzing only the high-signal portions of the plasma cycle (e.g., during RF ON periods or at peak power phases), the system improves signal-to-noise ratio while still capturing the essential plasma behavior characteristics needed for process monitoring.
3Measurement precision
If time-synchronized OES acquisition is implemented, then time resolution improves to milliseconds or sub-milliseconds, but system complexity increases
Solution Approach 1:
The patent implements feedback by using the power modulation signal itself as a trigger for OES data acquisition. The synchronization system monitors the power cycle status and automatically triggers measurements at the appropriate phases, creating a closed-loop system where the power signal directly controls the measurement timing. This feedback mechanism achieves precise time synchronization without requiring complex external timing circuits or manual calibration.
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
Enhances plasma stability monitoring in advanced pulsed technology processes by providing detailed characterization of plasma parameters, improving process control and reducing etch by-product formation.
Implementation Method 1
performing cyclic optical emission spectroscopy (OES) measurements for the pulsed plasma
Data Source
AI summary
A method of characterizing a plasma in a plasma processing system that includes: generating a pulsed plasma in a plasma processing chamber of the plasma processing system, the pulsed plasma being powered with a pulsed power signal, each pulse of the pulsed plasma including three periods: a overshoot period, a stable-ON period, and a decay period; performing cyclic optical emission spectroscopy (OES) measurements for the pulsed plasma, the cyclic OES measurements including: obtaining first OES data during one of the three periods from more than one pulses of the pulsed plasma; and obtaining a characteristic of the pulsed plasma for the one of the three periods based only on the first OES data.