Optical Emission Spectroscopy Calibration for Plasma Measurement Accuracy
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Solution Overview
Problem
Optical emission spectroscopy systems used in plasma processing face challenges in accurately measuring plasma characteristics due to differences in light intensities at various incidence angles, leading to unreliable comparisons between process chambers and potential failure to detect abnormal plasma production.
Innovation Solution
An optical emission spectroscopy system with a reference light source, calibrator, and analyzer that adjusts light receiving ratios based on incidence angles, allowing for calibration of light intensities and obtaining calibration factors to normalize measurements across multiple process chambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light intensity measurements are taken at various incidence angles without calibration, then the measurement process is simple and quick, but the measurement precision deteriorates due to unreliable comparisons between process chambers
Solution Approach 1:
The patent applies parameter changes by introducing calibration factors that account for incidence angle variations. The system measures light intensity at multiple angles and applies angle-specific calibration factors to normalize the measurements, transforming the raw intensity values into comparable standardized values across different process chambers.
Solution Approach 2:
The patent uses calibration factors as an intermediary element between the raw light intensity measurements and the final plasma characteristic analysis. These calibration factors serve as mediators that compensate for angular dependencies, enabling accurate comparisons without requiring complex hardware modifications to multiple process chambers.
2Reliability
If calibration factors are obtained for each incidence angle, then the measurement reliability improves, but the loss of time increases due to additional calibration steps
Solution Approach 1:
The patent implements preliminary action by pre-obtaining calibration factors for each incidence angle before actual plasma measurements are performed. This allows the calibration data to be stored and reused for multiple measurements, so while the initial calibration requires time, subsequent measurements benefit from the pre-established calibration without repeating the full calibration process each time.
Solution Approach 2:
The patent applies local quality by obtaining specific calibration factors for each incidence angle rather than using a single general calibration factor. This localized calibration approach ensures that each angle-specific measurement is optimized for its particular geometric conditions, improving overall reliability while maintaining a systematic organization of calibration data by angle.
3Manufacturing precision
If light receiving ratios are adjusted according to incidence angles, then the manufacturing precision of plasma process control improves, but the device complexity increases due to additional calibration components
Solution Approach 1:
The patent uses parameter changes by adjusting the light receiving ratio based on incidence angle parameters. The system varies the effective light collection efficiency according to the angle at which light enters the detector, applying calibration factors that modify the raw signal to account for angular dependencies in the optical path.
Solution Approach 2:
The patent applies segmentation by dividing the calibration process into angle-specific segments. Instead of attempting a single comprehensive calibration, the system separately characterizes and calibrates for each incidence angle, allowing independent optimization and simplifying the overall calibration methodology into manageable angular segments.
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 reliability and accuracy of plasma measurements by compensating for differences in light intensities at various angles, enabling more precise monitoring and detection of plasma states in process chambers.
Implementation Method 1
a reference light source, an analyzer to receive and analyze light transmitted from the reference light source
Implementation Method 2
a calibrator to calibrate light emitted from the reference light source. The calibrator may change a light receiving ratio in accordance with an incidence angle of the light incident on the light
Data Source
AI summary
An optical emission spectroscopy system may include a reference light source, an analyzer to receive and analyze light transmitted from the reference light source, and a calibrator to calibrate light emitted from the reference light source. The calibrator may change a calibration ratio in accordance with an incidence angle of the light.