Angle-Resolved Spectral Interference for Multilayer Thin Film Measurement
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Solution Overview
Problem
Conventional methods for measuring the thickness and refractive index of multilayer thin films are limited in accuracy and speed, particularly in analyzing each layer using reflectometry and interferometry techniques.
Innovation Solution
An apparatus and method utilizing an angle-resolved spectral interference image acquiring unit to measure and analyze the thickness and refractive index of multilayer thin films by acquiring s-polarized and p-polarized interference images, with a polarization beam splitter and a rotating linear polarizer to control polarization axes, enabling precise measurement through reflectance ratios and phase differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional reflectometry is used to measure thin film thickness, then the measurement can be performed, but the measurement precision and analysis accuracy are limited
Solution Approach 1:
The invention segments the measurement process by separating s-polarized and p-polarized light paths using beam splitters and polarizers. This allows independent measurement of each polarization component, enabling more accurate extraction of thickness and refractive index for each layer in the multilayer thin film structure.
Solution Approach 2:
The invention transitions from conventional single-point or single-angle measurement to angle-resolved spectral measurement. By capturing interference patterns across multiple angles and wavelengths simultaneously using a spectral camera, the system adds dimensional information that significantly improves measurement precision and layer analysis accuracy.
2Productivity
If conventional interferometry is used for thin film measurement, then thickness information can be obtained, but the measurement speed is slow
Solution Approach 1:
The system performs preliminary action by capturing the complete angular and spectral information in a single shot using a spectral camera. This eliminates the need for sequential scanning at different angles or wavelengths, dramatically increasing measurement speed while preserving all necessary information for precise thickness and refractive index calculation.
Solution Approach 2:
The invention uses a spectral camera to capture a two-dimensional interference pattern that contains encoded information about multiple angles and wavelengths simultaneously. This optical copying approach replaces slow mechanical scanning methods, achieving high-speed measurement without sacrificing precision through advanced digital signal processing of the captured pattern.
3Measurement precision
If angle-resolved spectral imaging is implemented, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The invention uses a spectral camera that simultaneously performs spectral analysis and spatial imaging in a single device. This multi-functional component replaces what would otherwise require separate spectrometers and cameras, reducing overall system complexity while maintaining the ability to extract precise thickness and refractive index information from angle-resolved spectral interference patterns.
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 allows for more accurate and rapid measurement of each layer's thickness and refractive index in multilayer thin films by analyzing s-polarized and p-polarized interference images, enhancing precision and efficiency in thin film analysis.
Implementation Method 1
a beam splitter 2, and a condenser lens 3... the emitted light is split by the beam splitter 2 in a ratio of 50:50, and the reflected light of the split light is collected by the condenser lens 3
Implementation Method 2
an objective lens 30... input some of the light reflected from the first beam splitter 20 to a measurement object 1... and reflect the remaining light to a reference plane 31
Implementation Method 3
interference light of the first reflected light and the second reflected light is incident to the detector 4... interference light includes thickness information about the thin film
Implementation Method 4
a first angle-resolved spectral image acquiring unit 60 configured to receive interference light reflected from the second beam splitter 50 and first-polarize the interference light... and a second angle-resolved spectral image acquiring unit 70 configured to receive interference light transmitted from the second beam splitter 50 and second-polarize the interference light
Data Source
AI summary
The present invention relates to an apparatus and a method for measuring a thickness and a refractive index of a multilayer thin film using an angle-resolved spectral interference image according to polarization. More specifically, the present invention relates to an apparatus for measuring a thickness and a refractive index of a multilayer thin film using an angle-resolved spectral interference image according to polarization in an apparatus for measuring a thickness and a refractive index of a measurement object coated with the multilayer thin film, the apparatus including: an illumination optical module having a light source emitting light; a first beam splitter configured to reflect some of the light emitted from the illumination optical module; an objective lens configured to input some of the light reflected from the first beam splitter to the measurement object constituted by the multilayer thin film and reflect the remaining light to a reference plane to form interference light on a back focal plane; a second beam splitter in which interference light where the reflected light incident and reflected to the measurement object interferes with the reflected light reflected from the reference plane is incident, wherein some of the interference light is reflected and the remaining interference light is transmitted; a first angle-resolved spectral image acquiring unit configured to receive interference light reflected from the second beam splitter and first-polarize the interference light located in the back focal plane of the objective lens to acquire a first polarized interference image; and a second angle-resolved spectral image acquiring unit configured to receive interference light transmitted from the second beam splitter and second-polarize the interference light located in the back focal plane of the objective lens to acquire a second polarized interference image.