Semiconductor Measurement With Multi-Angle Mueller Imaging
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Solution Overview
Problem
Existing semiconductor measurement apparatuses struggle to accurately determine critical dimensions due to the influence of interactions between different dimensions on spectral distribution, particularly as structures become increasingly miniaturized, leading to measurement inaccuracies.
Innovation Solution
A semiconductor measurement apparatus that obtains data across a wide range of incidence angles and azimuths by imaging once, using a Mueller matrix to determine critical dimensions based on polarization components, including an illumination unit, optical unit, and image sensor to process multi-interference images, reducing the impact of other dimensions on measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If ellipsometry is used to measure critical dimension at a fixed azimuth and incidence angle, then the measurement process is simple, but the measurement accuracy deteriorates due to interaction between different critical dimensions
Solution Approach 1:
The patent transitions from single-angle measurement to multi-angle measurement by capturing images at multiple incidence angles simultaneously using a curved image sensor. This dimensional expansion in the angular domain provides additional independent data to decouple the interactions between different critical dimensions, thereby improving measurement accuracy while maintaining operational simplicity through automated multi-angle imaging.
Solution Approach 2:
The patent changes the measurement parameter from single fixed-angle spectral distribution to multi-angle spectral distribution. By varying the incidence angle parameter and capturing images across a range of angles, the system obtains multiple spectral distributions that can be used to independently determine different critical dimensions, reducing the harmful interaction effects.
2Measurement precision
If multiple measurements at different angles and azimuths are performed to improve accuracy, then measurement precision improves, but measurement time and productivity deteriorate
Solution Approach 1:
The patent merges multiple measurement operations into a single imaging action. By using a curved image sensor that simultaneously captures light reflected at multiple incidence angles in one shot, the system combines what would traditionally require multiple sequential measurements into a single parallel operation, thereby maintaining high measurement precision while dramatically improving productivity.
Solution Approach 2:
The patent introduces the angular dimension as a spatial dimension on the image sensor rather than requiring temporal sequencing of measurements. The curved sensor surface maps different incidence angles to different spatial positions, allowing simultaneous multi-angle measurement in a single exposure, thus eliminating the time penalty associated with sequential measurements.
3Device complexity
If only intensity difference and phase difference of polarization components are used, then the analysis is simple, but the ability to resolve interacting critical dimensions deteriorates
Solution Approach 1:
The patent segments the spectral distribution data obtained from multi-angle measurements into multiple independent datasets, each corresponding to a specific incidence angle. By dividing the overall measurement into angle-specific spectral distributions, the system can analyze each critical dimension's contribution separately, reducing the interaction effects while maintaining manageable analysis complexity through systematic data segmentation.
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 precise determination of critical dimensions by minimizing the influence of interacting dimensions, improving measurement efficiency and process yield by utilizing parameters like degree of polarization and spectral distribution.
Implementation Method 1
an illumination unit including a light source and at least one illumination polarization element disposed on a path of light emitted by the light source
Implementation Method 2
a light receiving unit including at least one light-receiving polarization element disposed on a path of light passing through the at least one illumination polarization element and reflected by a sample
Implementation Method 3
at least one illumination polarization element disposed on a path of light emitted by the light source
Implementation Method 4
an image sensor positioned to receive light passing through the at least one light-receiving polarization element and configured to output an original image
Data Source
AI summary
A semiconductor measurement apparatus includes an illumination unit including a light source and at least one illumination polarization element, a light receiving unit including at least one light-receiving polarization element disposed on a path of light reflected by a sample, and an image sensor positioned to receive light passing through the at least one light-receiving polarization element and configured to output an original image, and a control unit configured to determine, by processing the original image, a selected critical dimension among critical dimensions of a structure included in a region of the sample. The control unit is configured to obtain a plurality of sample images by selecting regions of the original image in which a peak due to interference appears, to determine a plurality of elements included in a Mueller matrix using the plurality of sample images, and to determine the selected critical dimension based on the plurality of elements.