Defect Inspection Apparatus Using Multi-Axis Light Capture
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Solution Overview
Problem
Existing defect inspection systems for semiconductor substrates face challenges in accurately detecting infinitesimal defects due to insufficient scattered light capture, especially when the optical axis is not orthogonal to the longitudinal direction of linear illumination, leading to inconsistent optical distance across the visual field.
Innovation Solution
A defect inspection apparatus comprising an illumination unit, a detection unit with multiple directional detection capabilities, and a photoelectric conversion unit that synthesizes electrical signals from divided images to enhance defect detection accuracy by optimizing illumination angles and polarization states for improved scattered light capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical axis of the detection system is arranged orthogonal to the longitudinal direction of linear illumination, then the optical distance at the center and edge of the visual field becomes consistent, but the scattered light from the sample surface cannot be completely captured
Solution Approach 1:
The detection system is divided into multiple detection systems with different optical axis orientations. Each detection system captures scattered light from a different angular direction, and the images are synthesized to achieve both complete scattered light capture and consistent optical distance measurement
Solution Approach 2:
The problem is solved by adding a spatial dimension - arranging detection systems at different angular positions around the sample. This multi-dimensional arrangement allows simultaneous capture of scattered light from various directions while maintaining optical distance consistency through proper geometric configuration
2Quantity of substance
If the optical axis of the detection system is not arranged orthogonal to the longitudinal direction of linear illumination, then more scattered light can be captured, but the optical distance at the center and edge of the visual field becomes inconsistent
Solution Approach 1:
Instead of using a single detection system with compromised performance, the system is segmented into multiple detection systems, each optimized for specific angular detection. This allows the synthesis of images that collectively achieve both goals
Solution Approach 2:
Multiple images captured by different detection systems are merged/synthesized to produce a final image that combines the advantages of all individual detection systems - complete scattered light capture with consistent optical distance
3Measurement precision
If a smaller aperture detection system is used, then the visual field coverage is reduced, but the optical distance consistency is improved
Solution Approach 1:
The visual field is segmented into multiple regions, each covered by a detection system with appropriate aperture size. The smaller aperture systems provide consistent optical distance for their respective fields, while the collective coverage of all systems achieves comprehensive visual field coverage
Solution Approach 2:
The system transitions from a single large-aperture detection system to multiple smaller-aperture systems arranged in space. This spatial arrangement allows each system to maintain optimal optical distance consistency while the ensemble provides extended visual field coverage
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
The apparatus enables high-accuracy detection of defects on semiconductor substrates by effectively capturing and processing scattered light, overcoming the limitations of previous systems in terms of light capture and defect resolution.
Implementation Method 1
detect scattered light in a plurality of directions, which is generated from the inspection object region
Implementation Method 2
a photoelectric conversion unit configured to convert the scattered light detected by the detection unit into an electrical signal
Data Source
AI summary
A defect inspection apparatus includes: an illumination unit configured to illuminate an inspection object region of a sample with light emitted from a light source; a detection unit configured to detect scattered light in a plurality of directions, which is generated from the inspection object region; a photoelectric conversion unit configured to convert the scattered light detected by the detection unit into an electrical signal; and a signal processing unit configured to process the electrical signal converted by the photoelectric conversion unit to detect a defect in the sample. The detection unit includes a lens array configured to divide an image to form a plurality of images on the photoelectric conversion unit. The signal processing unit is configured to synthesize electrical signals corresponding to the plurality of formed images to detect a defect in the sample.