Spectroscopic Reflectometer Internal Calibration Mechanism
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Solution Overview
Problem
Conventional spectroscopic reflectometers require frequent measurement of calibration samples, which is time-consuming and complicated, involving the need to adjust and replace samples, leading to increased expense and complexity in measurement configurations.
Innovation Solution
A spectroscopic reflectometer design that includes a head, photo-detector, internal reflection mechanism, and reflectance calculation unit, allowing for the omission of supplementary calibration sample measurements by separating light source-related and non-light source-related offset factors, enabling simplified configuration and reduced measurement time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration sample measurement is performed every time inspection work is measured, then measurement precision is maintained, but measurement time increases and operation becomes complicated
Solution Approach 1:
The patent performs calibration sample measurement in advance (before actual inspection work measurement) to obtain reference data. The measured optical reflectance values from calibration samples are stored and reused for subsequent inspection measurements, eliminating the need to repeatedly measure calibration samples while maintaining measurement precision through the use of pre-acquired reference data.
2Adaptability or versatility
If head is made movable to measure calibration sample and dark sample at different locations, then measurement flexibility is improved, but device complexity increases
Solution Approach 1:
The patent makes the head capable of performing multiple functions: it can measure both calibration samples and inspection works using the same optical path and detection system. The head is designed to accommodate different sample types without requiring separate measurement systems or complex reconfiguration, achieving versatility through a unified measurement platform.
3Measurement precision
If calibration sample measurement is performed frequently, then measurement accuracy is maintained, but ease of operation deteriorates
Solution Approach 1:
The system performs calibration sample measurement once in advance to establish reference optical reflectance values. These pre-measured calibration data are then reused for multiple inspection measurements, eliminating the need for operators to repeatedly perform calibration measurements and significantly simplifying the operational process while maintaining measurement accuracy.
4Reliability
If separate measurement of calibration sample and inspection work is required, then measurement reliability is improved, but productivity decreases
Solution Approach 1:
The patent measures calibration samples in advance to obtain reference optical reflectance values, which are then stored and applied to multiple subsequent inspection measurements. This preliminary calibration approach ensures measurement reliability through proper calibration while significantly improving productivity by eliminating the need to repeat calibration measurements for each inspection work.
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 design reduces measurement time and simplifies the device configuration by allowing the calibration sample to be measured only during initial adjustments, eliminating the need for frequent calibration sample measurements and minimizing device complexity and cost.
Implementation Method 1
an internal reflection mechanism 8 having a constant light reflectance and placed in a position at which a part of the measurement light arrives and reflection light reflected by the internal reflection mechanism reaches the light receiving part of the photo-detector 2 within the head 4
Implementation Method 2
a beam splitter 3 arranged inside a main body of the head 4 so that a part of the measurement light is reflected by the beam splitter 3 to irradiate the object and a part of the measurement light is passed through the beam splitter 3 to irradiate the internal reflection mechanism 8
Implementation Method 3
the photo-detector 2 receives the reflection light introduced to the head 4 and detects an intensity of the reflection light
Data Source
AI summary
In a spectroscopic reflectometer, in order to make it possible to omit a supplementary measurement (specifically, measurement of a calibration sample) which has been needed every time a light reflectance of an inspection work is measured to promote the reduction in measurement time and simplification in measurement configuration, an internal reflection mechanism having a constant light reflectance is arranged inside a head so that light reflected by the internal reflection mechanism is received by a photo-detector, whereby the light reflectance of the inspection work is calculated based on an output value of the photo-detector in a state of having substantially no light introduced, an output value of the photo-detector when a dark sample that substantially reflects no light is used, an output value that is an output value of the photo-detector when a calibration sample of a known light reflectance is used as the object, and an output value of the photo-detector when an inspection work to be measured is used.