Defect Observation Using Structured Illumination for Semiconductor Substrates
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Solution Overview
Problem
Conventional defect observation methods struggle to detect minute defects on semiconductor substrates due to these signals being buried in background noise, making it difficult to achieve high resolution and throughput in semiconductor device manufacturing.
Innovation Solution
A defect observation method using structured illumination with a space distribution optical element on the pupil plane of the detection optical system, which blocks background noise and enables highly-sensitive super-resolution microscopy by modulating stationary waves and combining signals in frequency space to enhance defect detection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical microscopy is used to detect defects on semiconductor substrates, then the detection process is simple, but minute defects cannot be detected due to signals being buried in background noise
Solution Approach 1:
The patent introduces a spatial light modulator as an intermediary component between the light source and the specimen. This modulator creates structured illumination patterns (such as stripes or dots) that act as a mediator to enhance the contrast between defects and background noise, enabling detection of minute defects that would otherwise be invisible in conventional optical microscopy
Solution Approach 2:
The patent changes the illumination parameters by using structured illumination patterns instead of uniform light. By modulating the spatial distribution of illumination light and using multiple illumination angles/phases, the system transforms the optical contrast mechanism to enable super-resolution defect detection beyond the conventional diffraction limit
2Measurement precision
If the resolution is increased to detect smaller defects, then defect detection sensitivity improves, but the throughput decreases due to technical difficulties and slow processing
Solution Approach 1:
The patent employs periodic modulation of the structured illumination patterns by varying the phase and orientation of illumination in multiple steps. This periodic action allows the system to extract high-frequency spatial information through computational processing, achieving super-resolution while maintaining reasonable throughput by systematically sampling the specimen from multiple illumination angles
Solution Approach 2:
The patent replaces conventional mechanical scanning or physical proximity methods with optical field-based structured illumination and computational image processing. This substitution eliminates the need for physically moving components or achieving near-field proximity, thereby maintaining high throughput while achieving enhanced resolution through optical interference and algorithmic reconstruction
3Measurement precision
If super-resolution techniques such as near-field microscopy are used, then high resolution is achieved, but the throughput becomes slow and the technique is technically difficult to implement
Solution Approach 1:
The patent uses a spatial light modulator as an intermediary to create structured illumination patterns that encode high-frequency spatial information into the optical field. This approach achieves super-resolution without requiring near-field proximity or complex nanoscale positioning, thereby simplifying the technical implementation while maintaining high spatial resolution
Solution Approach 2:
The patent replaces mechanically complex near-field scanning systems with an optical field-based structured illumination approach combined with computational processing. This substitution eliminates the need for sub-wavelength mechanical positioning or complex near-field probe manipulation, making the system easier to implement while achieving comparable or superior resolution
4Measurement precision
If the wavelength of illumination is shortened to increase resolution, then the resolution limit is reduced, but the throughput and sensitivity are compromised due to limitations in practical implementation
Solution Approach 1:
The patent changes the illumination parameters by using structured patterns (stripes, dots, or other spatial modulations) rather than simply shortening the wavelength. By modulating the spatial distribution of light and using multiple illumination phases, the system achieves resolution enhancement without the need for extreme wavelength reduction, thereby maintaining broader applicability and higher throughput
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 reliable detection and observation of smaller defects, improving the throughput of detailed defect observation and enabling the detection of minute defects that were previously obscured by noise.
Implementation Method 1
forming stationary waves on the specimen by allowing two illumination lights having the same wavelength to enter the same incidence plane of the specimen at the same incidence angle from directions that are opposite to each other interfering with each other
Implementation Method 2
removing scattered light components generated from minute irregularities on the surface of the specimen among scattered light from the specimen
Implementation Method 3
removing scattered light components generated from minute irregularities on the surface of the specimen among scattered light from the specimen on which the stationary waves are formed by a spatial filter
Implementation Method 4
detecting an image of scattered light from the specimen that are not removed by the spatial filter
Data Source
AI summary
The present invention is detection of a defect signal which is small enough to be buried in a background noise, by a method that includes detecting a defect on a specimen which is detected by another inspection device by using a detection device equipped with an optical microscope, amending positional information of the defect, observing the defect by using an SEM, wherein the detecting the defect is carried out such that forming stationary waves on the specimen by irradiating the specimen with two illumination lights having the same wavelength from the opposite directions on the same incidence plane at the same incidence angle and cause the two illuminating light to interfere; removing scattered components generated by minute irregularities on the specimen surface by a spatial filter, detecting an image formed by the scattered light not removed by the spatial filter; and processing the detected image to detect the defect.