Polishing Apparatus Light Source Service Life Determination
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Solution Overview
Problem
Existing polishing apparatuses face challenges in accurately determining the service life of a light source and measuring film thickness without calibrating the optical film-thickness measuring device, due to decreasing light intensity over time and difficulties in distinguishing between light source degradation and other factors.
Innovation Solution
A polishing apparatus and method that utilize an internal optical fiber to transmit light directly to a spectrometer, allowing for accurate determination of the light source's service life and correction of reflected light intensity using a correction formula, eliminating the need for calibration and ensuring accurate film thickness measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical film-thickness measuring device is calibrated using a tool, then measurement precision is improved, but loss of time increases and device complexity increases
Solution Approach 1:
The system performs self-calibration by automatically comparing the measured spectral waveform against a predetermined reference spectral waveform stored in memory. The processor calculates the film thickness using this comparison without requiring external calibration tools or manual intervention, thereby eliminating calibration time while maintaining measurement precision.
Solution Approach 2:
The reference spectral waveform is predetermined and stored in advance in the memory unit. This preliminary preparation of reference data enables the system to perform rapid comparisons and calculations during actual measurements, eliminating the need for time-consuming calibration procedures while preserving measurement accuracy.
2Measurement precision
If the light source is replaced before service life is reached, then measurement precision is maintained, but loss of time increases and productivity decreases
Solution Approach 1:
The system continuously monitors the light source performance by comparing measured spectral waveforms against the reference spectral waveform. The processor detects changes in light intensity and characteristics, providing feedback on light source degradation. This enables predictive maintenance scheduling based on actual performance data rather than arbitrary time intervals, maintaining measurement precision while minimizing interruptions to productivity.
3Measurement precision
If the quantity of light from the light source decreases, then measurement precision deteriorates, but replacing the light source increases loss of time
Solution Approach 1:
The system continuously monitors light source performance through spectral waveform analysis and compares it against the reference spectral waveform. When degradation is detected, the system provides feedback signals to alert operators, enabling proactive scheduling of light source replacement at optimal moments rather than causing unexpected interruptions. This feedback mechanism maintains measurement precision while minimizing productivity loss.
Solution Approach 2:
The system automatically detects and quantifies light source degradation through continuous spectral analysis, eliminating the need for manual monitoring or conservative replacement schedules. This self-monitoring capability enables precise timing of light source replacements based on actual performance thresholds, maintaining measurement precision while optimizing replacement timing to minimize productivity impact.
4Measurement precision
If calibration is performed frequently, then measurement precision is maintained, but productivity decreases
Solution Approach 1:
The system performs automatic self-calibration by continuously comparing measured spectral waveforms against the predetermined reference spectral waveform stored in memory. The processor automatically calculates film thickness values without requiring external calibration tools or manual intervention. This eliminates the need for frequent scheduled calibration interruptions, maintaining measurement precision while maximizing polishing process productivity.
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
Enables precise determination of the light source's service life and accurate film thickness measurement without calibration, improving operational efficiency and reducing errors caused by light intensity degradation.
Implementation Method 1
an internal optical fiber coupled to the light source
Implementation Method 2
a spectrometer configured to decompose reflected light from the wafer in accordance with wavelength and measure an intensity of the reflected light at each of wavelengths
Implementation Method 3
an optical-path selecting mechanism configured to selectively couple either the light-receiving fiber or the internal optical fiber to the spectrometer
Data Source
AI summary
A polishing apparatus capable of accurately determining a service life of a light source, and further capable of accurately measuring a film thickness of a substrate, such as a wafer, without calibrating an optical film-thickness measuring device, is disclosed. The polishing apparatus includes a spectrometer configured to decompose reflected light from a substrate in accordance with wavelength and measure an intensity of the reflected light at each of wavelengths a film thickness of the substrate is determined based on a spectral waveform indicating a relationship between the intensity of the reflected light and wavelength. An optical-path selecting mechanism is configured to selectively couple either a light-receiving fiber or an internal optical fiber to the spectrometer.