Optical Emission Spectrometer Calibration via In-Situ Light Source
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Solution Overview
Problem
Conventional calibration methods for optical emission spectrometers used in semiconductor processing are time-consuming and often inaccurate, leading to inconsistent measurements due to drift over time, which affects the quality of plasma process control in semiconductor manufacturing.
Innovation Solution
A method and system for calibrating an optical emission spectrometer by measuring and comparing the optical intensity of a light source at two separate times, allowing for modifications to the OES to correct for any intensity differences, while the OES remains attached to the process chamber, using a light fixture with a light source positioned to provide an optical path through the process chamber window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional calibration methods are used for OES, then calibration accuracy can be maintained, but calibration time becomes very long and productivity decreases
Solution Approach 1:
A reference spectrum is obtained and stored in memory before the OES is installed in the process chamber. This preliminary calibration reference is saved and later used for comparison during operational calibration, eliminating the need for time-consuming conventional calibration procedures while maintaining accuracy.
Solution Approach 2:
The reference spectrum obtained during preliminary calibration is copied and stored in memory. During operational calibration, the OES measurements are compared against this stored reference copy, allowing quick calibration without requiring the time-consuming conventional methods while maintaining measurement accuracy.
2Reliability
If the OES is calibrated frequently to maintain accuracy, then measurement reliability improves, but device complexity and operational time increase
Solution Approach 1:
The system continuously compares OES measurements against the stored reference spectrum and calculates drift corrections. This automated feedback mechanism maintains measurement reliability by detecting and correcting drift over time, while simplifying the calibration procedure through automatic comparison and correction factor application.
Solution Approach 2:
The OES system performs self-calibration by automatically comparing its measurements against the stored reference spectrum and applying correction factors. This self-service calibration reduces the need for complex external calibration procedures while maintaining measurement consistency over time.
3Productivity
If the OES remains installed in the process chamber during calibration, then downtime is reduced, but the calibration process becomes more difficult to perform accurately
Solution Approach 1:
The reference spectrum is obtained and stored in memory while the OES is installed in the process chamber, before any processing occurs. This preliminary action captures the baseline calibration data in situ, enabling subsequent quick calibrations without removing the OES from the chamber.
Solution Approach 2:
The reference spectrum obtained during initial installation is copied and stored in memory. This allows the OES to be calibrated by comparing against the stored reference while remaining installed in the chamber, eliminating the need to remove and reinstall the device for calibration while maintaining calibration accuracy.
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 enables quicker and more accurate calibration of the OES, reducing downtime and improving the consistency of plasma process measurements, ensuring better control over semiconductor substrate processing.
Implementation Method 1
measuring an optical intensity of radiation from a light source mounted within a process chamber with an OES located outside the process chamber
Data Source
AI summary
One or more embodiments described herein generally relate to systems and methods for calibrating an optical emission spectrometer (OES) used for processing semiconductor substrates. In embodiments herein, a light fixture is mounted to a plate within a process chamber. A light source is positioned within the light fixture such that it provides an optical path that projects directly at a window through which the OES looks into the process chamber for its reading. When the light source is on, the OES measures the optical intensity of radiation from the light source. To calibrate the OES, the optical intensity of the light source is compared at two separate times when the light source is on. If the optical intensity of radiation at the first time is different than the optical intensity of radiation at the second time, the OES is modified.