Imaging Ellipsometer With Polarization Camera for Areal Thickness Mapping
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Solution Overview
Problem
Conventional imaging ellipsometers are complex, expensive, and time-consuming, producing inaccurate results due to sensitivity fluctuations and requiring laborious point-wise measurements, which are not suitable for efficient areal layer thickness measurements.
Innovation Solution
An imaging ellipsometer equipped with a polarization camera having filters at 0°, 45°, 90°, and 135° alignments, combined with a quarter-wave plate and angle-selective lenses, allows for real-time, contactless, and cost-effective areal layer thickness measurements by calculating intensity ratios of polarized light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional point-wise measurement systems are used, then measurement accuracy is maintained, but measuring speed and productivity are reduced
Solution Approach 1:
The patent divides the measurement task into multiple parallel measurements by using an array of polarization filters arranged in different orientations (0°, 45°, 90°, 135°). Instead of measuring one point at a time, the system segments the measurement across multiple pixels that simultaneously capture polarization information from different orientations, enabling areal measurement while maintaining precision through the segmented filter array.
Solution Approach 2:
The patent transitions from one-dimensional point-wise measurement to two-dimensional areal measurement by implementing a camera-based system with an array of polarization filters. This dimensional change allows simultaneous measurement across the entire sample surface, dramatically improving productivity while maintaining measurement accuracy through the spatial distribution of filter orientations.
2Measurement precision
If complex laboratory measurement technology is used, then measurement precision is improved, but device complexity and costs increase
Solution Approach 1:
The patent combines multiple measurement functions into a single integrated system. The camera body integrates an array of polarization filters directly in front of the sensor, merging the functions of light detection, polarization filtering, and image capture into one device. This eliminates the need for separate laboratory instruments and complex optical setups while maintaining measurement precision.
Solution Approach 2:
The imaging ellipsometer is designed as a universal measurement system that can measure layer thickness across large sample areas in real-time. The system combines the capabilities of traditional ellipsometry with digital imaging, creating a multi-functional device that performs areal measurement, generates visual images, and provides quantitative thickness data, replacing multiple specialized instruments.
3Measurement precision
If multiple cameras with different polarizers are used, then polarization measurement accuracy is improved, but device complexity and costs increase
Solution Approach 1:
The patent merges the functionality of multiple cameras with different polarizers into a single camera by integrating an array of polarization filters with different orientations directly in front of the sensor array. This allows one camera to perform the measurements that previously required multiple cameras, reducing system complexity while maintaining polarization measurement accuracy.
Solution Approach 2:
Instead of using multiple separate cameras, the patent segments the polarization filtering function across multiple filter elements within a single camera system. Each pixel or group of pixels has access to filters at different orientations (0°, 45°, 90°, 135°), allowing the single camera to capture polarization information from all orientations simultaneously through the segmented filter array.
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
The system provides accurate, rapid, and robust layer thickness measurements with reduced complexity and cost, enabling simultaneous measurement of inner and outer wall coatings on cylindrical samples and real-time monitoring in roll-to-roll processes.
Implementation Method 1
a polarizer that is configured to linearly polarize the light emitted by the light source
Implementation Method 2
a quarter-wave plate that is arranged between the sample and the polarization camera for changing the polarization of the light, with a principal optical axis of the quarter-wave plate that is rotated by +/−45° with respect to a light plane, which is configured such that it converts specific linear polarization orientations of the light into circular polarization orientations
Implementation Method 3
The polarization camera has polarization filters/polarization layers in 0°, 45°, 90° and 135° alignments/positions and is configured to polarize the light emitted by the light source into linear polarization orientations/polarization directions and to detect and measure their light intensities
Implementation Method 4
an angle-selective lens, the light reflected by the sample passes through the angle-selective lens
Data Source
AI summary
An imaging ellipsometer is provided for the areal measurement of the layer thickness of a preferably cylindrical sample, including a monochromatic light source configured to shine light onto the sample, a polarizer configured to polarize the light emitted by the light source, an angle-selective lens, and a polarization camera. The polarization camera has polarization filters in 0°, 45°, 90° and 135° orientations and is adapted to polarize the light emitted by the light source into linear polarization orientations and to detect and measure their respective light intensities. A quarter-wave plate is disposed between the sample and the polarization camera in order to change polarization of the light. The quarter-wave plate is adapted to convert certain linear polarization orientations of the light into circular polarization orientations and the ellipsometer is adapted to calculate a layer-thickness-dependent ratio of the detected light intensities. Furthermore, a method is provided for using an imaging ellipsometer.