Optical Measurement Structure for Semiconductor Wafer Analysis
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Solution Overview
Problem
Conventional optical measurement techniques in semiconductor manufacturing face inaccuracies due to light spot deviation from the measurement structure, leading to noise in the light scattering spectrum and unreliable structural parameter determination.
Innovation Solution
A method and system for optical measurements that involve a first matching process to identify standard optical scattering spectra, followed by a second matching process that accounts for potential light spot deviations by combining standard spectra with a plain-wafer spectrum, ensuring accurate structural parameter determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the size of the cutting area containing the structure for optical measurement is increased, then the reliability of measurement is improved, but the manufacturing cost increases due to limited scribe-line space
Solution Approach 1:
The patent extracts and separates the measurement structure from the main semiconductor device structure, placing it in a dedicated cutting area. This allows the measurement structure to be independently optimized without affecting the main device design, resolving the contradiction by enabling reliable measurement while maintaining manufacturing efficiency through separate structure optimization.
Solution Approach 2:
The patent utilizes the cutting area dimension (scribe-line space) as a separate design space for placing measurement structures. By transitioning from two-dimensional device layout to incorporating the third dimension of the cutting area, the measurement structures can be positioned without interfering with the main device footprint, thus improving measurement reliability without increasing manufacturing cost.
2Measurement precision
If the size of the illuminating light spot is decreased to lower the probability of deviation from the structure for optical measurement, then the measurement precision is improved, but the signal-to-noise ratio decreases
Solution Approach 1:
The patent creates different local qualities within the measurement structure by designing specific geometric features (such as gratings, trenches, or patterned regions) that have optimized light scattering properties. These locally optimized structures ensure that even when the light spot is small and precisely positioned, the scattering signal remains strong and informative, thus maintaining both measurement precision and signal-to-noise ratio.
Solution Approach 2:
The measurement structure is pre-designed and fabricated with specific geometric patterns before optical measurement occurs. This preliminary structuring ensures that when the light spot illuminates the structure, the scattering characteristics are already optimized for detection, allowing small light spots to achieve high precision without sacrificing signal strength.
3Productivity
If conventional single-matching process is used for spectrum analysis, then the processing speed is maintained, but the accuracy of structural parameter determination deteriorates due to noise from light spot deviations
Solution Approach 1:
The patent segments the spectrum matching process into multiple independent stages, each analyzing different aspects of the scattering spectrum. This segmentation allows noise from light spot deviations to be filtered out in earlier stages while preserving the useful measurement information for final parameter determination, thus improving accuracy without significantly compromising processing speed through efficient staged analysis.
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 enhances the accuracy of structural parameter measurement by filtering out noise from light spot deviations, improving the reliability of semiconductor device quality assessment.
Implementation Method 1
light spot 2 may be used to illuminate the structure for optical measurement 1 such that light scatters in the structure for optical measurement 1
Implementation Method 2
Optical detectors receive the incident light and scattered light for analysis and modulation
Implementation Method 3
the obtained measured light scattering spectrum may be matched with each standard optical scattering spectrum in a library or database
Data Source
AI summary
The present disclosure includes a method for optical measurements. The method includes providing a substrate with a structure for optical measurement on the substrate; and illuminating a light spot on the structure for optical measurement to obtain a measured light scattering spectrum. The method also includes performing a first matching process to obtain a plurality of matching standard optical scattering spectra and a plurality of first matching degrees, each standard optical scattering spectrum corresponding to one first matching degree; obtaining a plurality of combined optical scattering spectra based on the plurality of matching standard optical scattering spectra; and performing a second matching process to obtain a plurality second matching degree, each corresponding to one combined optical scattering spectrum.