Optical Microscope Defect Detection via Phase-Modulated Interference
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Solution Overview
Problem
Existing defect observation methods for semiconductor wafers face challenges in achieving high-resolution, two-dimensional defect detection without increasing device size or cost, and require time-consuming adjustments in illumination direction, which hampers throughput.
Innovation Solution
A defect observation method using an optical microscope that phase-modulates illumination lights in one direction and slightly shifts them in a different direction to create a two-dimensional intensity pattern, allowing for high-resolution defect detection without changing the relative incident azimuth, thereby improving throughput and resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical microscope uses conventional illumination to detect micronized defects, then the device structure remains simple, but the detection resolution is insufficient for highly integrated semiconductor patterns
Solution Approach 1:
The patent changes the illumination parameters by introducing periodic intensity variation in two-dimensional directions through interference patterns, rather than using conventional uniform illumination. This parameter change enables super-resolution detection of micronized defects without requiring complex mechanical or structural modifications to the optical microscope system.
2Measurement precision
If the microscope system changes illumination direction to achieve high-resolution defect detection, then the detection accuracy improves, but the time required for illumination adjustment increases, reducing throughput
Solution Approach 1:
The patent employs periodic action by using interference patterns that create standing wave illumination with periodic intensity variation. This periodic illumination structure allows the system to capture multiple directional information simultaneously without physically changing illumination directions, thereby maintaining high detection accuracy while improving throughput by eliminating mechanical adjustment time.
3Measurement precision
If the optical microscope system is enlarged to accommodate multiple illumination directions, then the defect detection capability improves, but the device size and cost increase
Solution Approach 1:
The patent merges multiple illumination direction capabilities into a single optical path by using interference between light beams. Instead of requiring separate illumination systems for different directions, the interference pattern combines directional information in a unified illumination structure, achieving two-dimensional super-resolution without enlarging the device.
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 defect detection resolution and throughput by generating high-resolution images without enlarging the device or increasing costs, while maintaining efficient defect observation processes.
Implementation Method 1
phase modulating a plurality of illumination lights in one direction on a sample surface having a defect
Implementation Method 2
illumination lights phase modulated in one direction and slightly shifted sequentially in a direction different from the one direction to create a two-dimensional intensity pattern
Data Source
AI summary
A defect observation method for observing a defect on a sample detected by another inspection device with a scanning electron microscope including the steps of: optically detecting the defect using the position information for the defect: illuminating the sample including the defect with an illumination intensity pattern having periodic intensity variation in two dimensions by irradiating a plurality of illumination light beams onto the surface of the sample while phase modulating the light beams in a single direction and successively moving the light beams in small movements in a direction different from the single direction, imaging the surface of the sample that is illuminated by the illumination intensity pattern having periodic intensity variation in two dimensions and includes the defect detected by the other inspection device, and detecting the defect detected by the other inspection device from the image obtained through the imaging of the surface of the sample.