Time-Resolved OES Pulsing for Low-Signal Plasma Diagnostics
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Solution Overview
Problem
In semiconductor manufacturing, advanced process characterization in plasma processing is challenging due to limited sensitivity of existing optical emission spectroscopy (OES) methods, especially in pulsed plasma, low-powered plasma, or plasma-less processes, where subtle changes in optical emission spectra are difficult to detect and OES signal detection is hindered by rapid decay during the power OFF phase.
Innovation Solution
The method involves applying short duty power spikes during the power OFF phase of a pulsed plasma process to enhance OES signal detection by increasing electron temperature, synchronizing source power pulsing with excitation pulsing, and using power modulation during OES acquisition to retrieve additional information on plasma reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional OES methods are used in pulsed plasma or low-powered plasma processes, then the measurement system remains simple and continuous operation is maintained, but the OES signal intensity is insufficient and subtle changes in optical emission spectra are difficult to detect
Solution Approach 1:
The patent applies periodic action by implementing pulsed power delivery to the plasma process and synchronizing OES detection with specific phases of the power cycle. The power source delivers power in periodic pulses rather than continuously, creating distinct plasma phases (on-phase and off-phase) that enhance the detectability of subtle spectral changes. The OES detector is synchronized to measure during specific phases of this periodic cycle, maximizing signal intensity while maintaining a relatively simple system architecture.
Solution Approach 2:
The patent implements dynamics by modulating the power delivery to the plasma process in real-time and dynamically adjusting detection parameters. The power source transitions between on and off states, creating dynamic plasma conditions that enhance signal contrast. The OES detection system dynamically synchronizes its measurement timing with the power cycle phase, adapting to changing plasma conditions to optimize detection sensitivity without requiring complex additional hardware.
2Loss of information
If continuous power is applied during plasma processing, then stable plasma conditions are maintained, but time-resolved diagnostics of plasma reactions cannot be achieved
Solution Approach 1:
The patent uses periodic action by implementing pulsed power delivery with synchronized OES detection. The power source operates in periodic cycles with distinct on-phases and off-phases, allowing the plasma to undergo predictable temporal evolution. By detecting OES signals at specific phases of this periodic cycle, the system captures time-resolved information about plasma reactions while the repetitive nature of the cycling maintains overall plasma stability and process reliability.
Solution Approach 2:
The patent applies preliminary action by predicting optimal detection timing based on the known power cycle phase. The system预先 determines when to perform OES measurements during the power cycle to capture critical plasma reaction information. This preliminary planning of detection timing ensures that temporal information is captured at the most informative moments while maintaining stable plasma conditions through controlled power delivery.
3Measurement precision
If power spikes are applied during the power OFF phase to enhance OES signal, then detection sensitivity is improved, but the energy input to the plasma process increases
Solution Approach 1:
The patent applies partial action by delivering power spikes only during specific portions of the power cycle (the off-phase periods) rather than continuously. These targeted power spikes provide sufficient energy enhancement to improve OES signal intensity during detection phases, while avoiding continuous high energy input that would unnecessarily increase total energy consumption. The power spikes are applied partially in time, exactly when needed for enhanced detection sensitivity.
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 significantly enhances OES signal intensity, enabling effective time-resolved diagnostics with minimal impact on the plasma process, improving sensitivity for advanced process characterization in complex semiconductor manufacturing environments.
Implementation Method 1
exposing the substrate in a plasma processing chamber to a plasma powered by applying a first power to a first electrode
Implementation Method 2
applying a pulsed RF power to a first electrode of a plasma processing chamber
Implementation Method 3
detecting an optical emission spectrum (OES) from species in the plasma processing chamber
Implementation Method 4
applying a second power to a second electrode of the plasma processing chamber for a second time duration... an energy of the second power over the second time duration is less than an energy of the first power over the first time duration
Data Source
AI summary
A method of processing a substrate that includes: exposing the substrate in a plasma processing chamber to a plasma powered by applying a first power to a first electrode of a plasma processing chamber; turning OFF the first power to the first electrode after the first time duration; while the first power is OFF, applying a second power to a second electrode of the plasma processing chamber for a second time duration, the second time duration being shorter than the first time duration, an energy of the second power over the second time duration is less than an energy of the first power over the first time duration by a factor of at least 2; and detecting an optical emission spectrum (OES) from species in the plasma processing chamber.