Polarized Multi-Angle CD Metrology for Semiconductor Structures
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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
The apparatus employs an illumination unit and optical system that irradiate light at various azimuths and incidence angles, using a Mueller matrix to analyze polarization components, allowing for the determination of critical dimensions through multi-interference imaging and spectral data analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If ellipsometry is used to measure critical dimension at fixed azimuth and incidence angle, then measurement process is simple, but measurement accuracy deteriorates due to interaction between different critical dimensions affecting spectral distribution
Solution Approach 1:
The patent transitions from measuring at a fixed azimuth and incidence angle to measuring across multiple azimuths (0-360 degrees) and wide incidence angles. This dimensional expansion in measurement space allows separation of the target critical dimension from interfering dimensions, resolving the spectral distribution interactions that plague single-angle measurements.
Solution Approach 2:
The patent changes the measurement parameters from fixed angle to variable angles across multiple azimuths and incidence angles. By varying these optical parameters and analyzing the resulting spectral distributions at each angle, the system can isolate the target critical dimension's contribution from other dimensional interactions.
2Measurement precision
If multiple azimuths and incidence angles are measured to improve accuracy, then measurement precision improves, but measurement time and complexity increase
Solution Approach 1:
The patent combines multiple measurements at different azimuths and incidence angles into a single integrated analysis framework. Rather than performing separate measurements and analyses for each angle, the system collects spectral distribution data across all angles simultaneously and processes them together to extract the target critical dimension, significantly reducing total measurement time.
Solution Approach 2:
The measurement system is designed to perform multiple functions: it measures spectral distributions at all azimuths and incidence angles, separates polarization components, and extracts multiple critical dimensions from a single measurement session. This multi-functionality eliminates the need for separate measurement procedures for each angle.
3Ease of operation
If spectral distribution analysis is used to determine critical dimension, then measurement process is straightforward, but accuracy deteriorates due to interaction effects between different critical dimensions
Solution Approach 1:
The patent extracts the target critical dimension's contribution from the mixed spectral distribution by analyzing measurements at multiple azimuths and incidence angles. Through polarization component separation and angular-dependent spectral analysis, the system isolates the specific critical dimension signal from the interfering signals of other dimensions, enabling accurate determination despite their interactions.
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 enables precise measurement of critical dimensions by reducing the influence of other dimensions, improving measurement accuracy and process yield in semiconductor manufacturing.
Implementation Method 1
at least one illumination polarization element disposed on a path of light emitted by the light source
Implementation Method 2
a semiconductor measurement apparatus may measure a critical dimension using ellipsometry
Implementation Method 3
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 4
obtain, by processing the multi-interference image, a degree of polarization determined from the polarization components
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.