Lensless Diffraction Inspection Using Multi-Wavelength Light Switching
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Solution Overview
Problem
Lens-less microscopes for defect inspection in semiconductors face limitations in image resolution and suffer from twin image artifacts due to the symmetry of light propagation, and the movement of samples or light sources causes vibration, reducing inspection accuracy.
Innovation Solution
An inspection apparatus and method that uses multiple light sources with different wavelength ranges to obtain and align diffraction images without moving the sample or detector, achieving high-resolution images by compositing aligned diffraction images based on shift amount information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple images are obtained by moving the light source or sample horizontally, then image resolution is improved, but vibration occurs reducing inspection accuracy
Solution Approach 1:
The patent applies dynamics by sequentially turning on and off multiple light sources at different positions rather than physically moving components. This dynamic switching of light sources creates the effect of multiple imaging perspectives without mechanical movement, thereby achieving high resolution while avoiding vibration-induced accuracy degradation
Solution Approach 2:
The patent replaces the mechanical movement system (moving light source or sample) with an optical control system (sequentially activating multiple fixed light sources). This substitution eliminates mechanical vibration while maintaining the capability to obtain multiple diffraction images for high-resolution reconstruction
2Measurement precision
If the sample or sensor moves vertically to remove twin image artifacts, then image quality is improved, but vibration occurs reducing inspection accuracy
Solution Approach 1:
The patent uses dynamic switching of multiple light sources positioned at different vertical locations instead of physically moving the sample or sensor. This allows obtaining diffraction images from different vertical positions to eliminate twin image artifacts while avoiding vibration that would compromise inspection accuracy
Solution Approach 2:
The patent replaces vertical mechanical movement of sample or sensor with sequential activation of multiple fixed light sources at different vertical positions. This substitution achieves twin image artifact removal through optical geometry changes without mechanical vibration
3Device complexity
If lens-less microscope is used to avoid mechanical components, then device complexity is reduced, but image resolution is limited by sensor size
Solution Approach 1:
The patent segments the illumination system into multiple independent light sources positioned at different locations. By capturing diffraction images from multiple light source positions and computationally combining them, the system achieves super-resolution beyond the single sensor pixel limit while maintaining the lens-less simple structure
Solution Approach 2:
The patent transitions from single-point illumination to multi-point illumination in spatial distribution. By utilizing the spatial dimension of multiple light source positions and combining diffraction patterns from different angles, the system achieves resolution enhancement without adding mechanical complexity
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 high-resolution and high-quality images of inspection targets with fixed light sources and detectors, minimizing vibration and reducing maintenance costs while maintaining image quality.
Implementation Method 1
a light source irradiates light onto the sample to obtain a diffraction pattern
Data Source
AI summary
An inspection method includes: obtaining a plurality of diffraction images of an inspection target object by performing a plurality of lighting cycles in which a plurality of light sources are configured to sequentially irradiate light onto the inspection target object; and obtaining an output image of the inspection target object based on the plurality of diffraction images, wherein for each of the plurality of lighting cycles, the light irradiated to the inspection target object has a different wavelength range.