Defect Inspection Device Parallel Signal Processing
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Solution Overview
Problem
Existing defect inspection methods face challenges in detecting various shapes of defects at high sensitivity, particularly in mirror wafers before circuit pattern formation, as they require multiple detectors and increased computational costs for signal processing to differentiate between defects and noise.
Innovation Solution
A defect inspection device with an illumination optical portion, multiple detectors for scattering light detection at different angles, and a signal processing portion that performs parallel gain adjustments and threshold decisions to extract defects effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple detectors are used to detect various shapes of defects at high sensitivity, then detection capability is improved, but computational cost increases
Solution Approach 1:
The patent segments the defect detection process by dividing the scattering light detection into multiple independent detector channels, each detecting specific angular ranges. By processing signals from each detector separately and then combining results, the system achieves high-sensitivity multi-shape defect detection while managing computational complexity through modular signal processing.
Solution Approach 2:
The patent changes detection parameters by varying the angular ranges and detection conditions for different detectors. By optimizing detection parameters for each detector type and combining results, the system achieves high sensitivity for various defect shapes without requiring excessive computational resources for unified processing.
2Ease of operation
If signals from multiple detectors are combined under arbitrary conditions, then defect detection is simplified, but detection accuracy for various defect shapes deteriorates
Solution Approach 1:
The patent applies local quality by assigning different detection characteristics and signal processing methods to different detector channels based on their specific angular ranges and detection capabilities. Each detector's signals are processed according to its local detection characteristics, preserving defect shape information while maintaining operational simplicity through standardized processing protocols.
3Reliability
If computational processing is increased to differentiate defects from noise, then detection reliability is improved, but processing time increases
Solution Approach 1:
The patent performs preliminary action by pre-processing detector signals through calibration and baseline establishment before actual defect detection. By preparing detection thresholds and reference profiles in advance, the system achieves reliable defect-noise discrimination during operation without requiring excessive real-time computational processing.
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 device enables high-sensitivity detection of microscopic defects on or in the surface of samples by optimizing signal processing and reducing computational costs, allowing for robust detection of multiple defect species simultaneously.
Implementation Method 1
detect components of scattering light scattering from the inspected object each in a different direction of azimuthal angle or in a different direction of angle of elevation
Data Source
AI summary
Disclosed is a defect inspection device comprising: an illumination optical portion which illuminates an object to be inspected with illuminating light; a detection optical portion system illuminated by the illumination optical portion and provided with a plurality of detectors which respectively detects components of scattering light which scatter from the inspected object each in a different direction of azimuthal angle or in a different direction of angle of elevation with respect to a surface of the inspected object; and a signal processing portion which makes gain adjustments and defect decisions in parallel on plural signals based on the components of the scattering light from the inspected object detected by the detectors, respectively, the defect decisions being based on a threshold value decision, and which extracts defects based on results of the gain adjustments and of the defect decisions.