Polarization Interferometer for High-Speed Spectral Ellipsometry
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Solution Overview
Problem
Polarization measurement techniques often require complex hardware configurations and lengthy measurement times due to mechanical or electronic modulation, limiting their efficiency in high-speed imaging applications.
Innovation Solution
An inspection apparatus utilizing a polarization interferometer with a polarizing splitter, mirrors, and a line converter to generate and modulate linearly polarized light, allowing for high-speed imaging without mechanical rotation or electronic modulation, by creating a phase difference between two polarized lights and converting the output light into a linear line-shape for interference analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanical rotational polarizer mechanism or electronic polarization modulation device is used, then polarization measurement can be achieved, but hardware configuration becomes complex and measurement time increases
Solution Approach 1:
The patent replaces mechanical rotational polarizer mechanisms and electronic polarization modulation devices with a polarization interferometer that uses optical path difference to achieve polarization measurement. This substitution eliminates complex mechanical and electronic components while maintaining measurement capability through interference patterns generated by the interferometer.
Solution Approach 2:
The patent introduces a polarization beam splitter as an intermediary component that separates incident light into orthogonal polarization components. This mediator enables the measurement system to obtain polarization information through spatial separation and interference without requiring complex modulation mechanisms.
2Measurement precision
If mechanical rotational polarizer mechanism or electronic polarization modulation device is used, then polarization measurement can be achieved, but measurement time becomes long
Solution Approach 1:
The patent replaces sequential mechanical or electronic modulation processes with a parallel optical interference-based measurement approach. The polarization interferometer captures polarization information simultaneously through interference patterns, eliminating the time-consuming sequential scanning inherent in mechanical and electronic modulation methods.
Solution Approach 2:
The patent enables continuous polarization measurement by using the polarization interferometer to continuously capture interference patterns that encode polarization information. This continuous action eliminates the intermittent measurement process required by mechanical rotation or electronic modulation, significantly reducing measurement time.
3Volume of moving object
If polarization beam splitter with perpendicular mirrors is used, then compact design is achieved, but optical path difference for interference is insufficient
Solution Approach 1:
The patent introduces asymmetry by tilting one of the mirrors relative to the perpendicular configuration. This asymmetric adjustment creates the necessary optical path difference between the two polarization beams while maintaining the compact overall structure. The tilt angle is optimized to provide sufficient path difference for clear interference patterns without significantly increasing device volume.
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 rapid and efficient measurement of spectral ellipsometric information, achieving high-speed imaging and detection of defects or nano-pattern uniformity, several hundred times faster than prior art, without the need for complex mechanical or electronic modulation.
Implementation Method 1
a polarizing splitter that splits the linearly polarized light into a first light and a second light
Implementation Method 2
a first mirror on the first reflective surface to reflect the first light transmitted through the first reflective surface; and a second mirror on the second reflective surface to reflect the second light transmitted through the second reflective surface
Implementation Method 3
a polarization interferometer that splits the linearly polarized light into a first light and a second light and that modulates the first light and the second light to have phase difference information
Implementation Method 4
a second linear polarizer that receives a measurement light and linearly polarizes the first light and the second light of the measurement light to generate an interference light
Implementation Method 5
an imaging spectrograph that receives the interference light to obtain an image of the measured object
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
The present inventive concepts comprises linearly polarizing light, splitting the linearly polarized light into a first light and a second light, modulating the first light and the second light to have a phase difference to produce an output wave light, converting the output wave light to have a linear line-shape in a first direction to radiate the converted output wave light to a measured object, receiving a measurement light coming out of the measured object and linearly polarizing the first light and the second light of the measurement light to generate an interference light, and obtaining from the interference light an image of the measured object. The measured object may be scanned in a second direction intersecting the first direction or may be scanned rotationally about an axis in a third direction perpendicular to the first and second directions to obtain spatio-spectral ellipsometric information (e.g., spectral ellipsometric cubic information) along two-dimensional spatial axes in real time speed.