Defect Detection Device Using Polarization Control for SEM Positioning
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Solution Overview
Problem
Current defect detection methods for semiconductor wafers face challenges in precision and throughput due to large error components in positional coordinates during optical inspection, making it difficult to accurately observe defects with SEM, especially with finer circuit patterns and diverse defect structures, and struggle with detecting low-height defects like short circuits between wiring patterns.
Innovation Solution
A defect detection device with an illumination optical system emitting laser light in an inclined direction and a detection optical system using a distribution filter to control polarization, allowing for high-sensitivity detection and precise positioning of defects for SEM observation, and a dark-field inspection method to enhance defect detection speed and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser beam spot size is enlarged to scan the semiconductor substrate surface to raise inspection throughput, then inspection speed is improved, but positional coordinate precision deteriorates with large error components
Solution Approach 1:
An optical microscope is introduced as an intermediary device between the defect inspection device and the SEM. The optical microscope captures optical images of defects with high positional precision, and this information is used to correct the positional coordinates obtained from the defect inspection device, enabling accurate SEM observation without compromising inspection throughput
Solution Approach 2:
The system uses feedback by comparing the positional information from the defect inspection device with the optical image data from the optical microscope. The optical microscope's precise positioning feedback is used to correct errors in the defect inspection device's coordinate system, ensuring accurate defect localization for SEM analysis
2Speed
If optical observation methods are used to identify defect positions, then inspection speed is improved, but detection precision deteriorates for fine defects and diverse defect structures
Solution Approach 1:
The system merges the advantages of both optical and electron microscopy by combining the defect inspection device's rapid scanning capability with the optical microscope's precise imaging and the SEM's high-resolution observation. This integrated approach allows fast defect identification followed by precise characterization
Solution Approach 2:
The optical microscope serves as an intermediary that bridges the gap between optical inspection and SEM observation. It provides both speed advantages of optical methods and precision advantages needed for accurate defect localization and characterization
3Measurement precision
If SEM is used to precisely observe defects, then observation precision is improved, but throughput deteriorates due to time-consuming search and positioning
Solution Approach 1:
The defect inspection device performs preliminary scanning to identify defect positions and generate coordinate information before SEM observation. This preliminary action eliminates the need for time-consuming search during SEM analysis, allowing direct observation of known defect locations with high precision and improved throughput
4Area of stationary object
If conventional optical inspection is used for fine circuit patterns, then inspection coverage is improved, but detection sensitivity deteriorates for low-height defects like short circuits
Solution Approach 1:
The optical microscope acts as an intermediary that enhances the detection capability for low-height defects. By capturing optical images with improved contrast and using image processing techniques, it can identify defects that are difficult to detect with conventional optical inspection, maintaining wide coverage while improving sensitivity
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 solution enables high-speed and high-sensitivity detection of various defects on semiconductor wafers, improving the throughput of precise inspections and allowing for accurate placement of defects within the SEM's visual field, thereby enhancing the production efficiency of LSI devices.
Implementation Method 1
emitting light onto a surface of a semiconductor substrate using a laser to conduct dark-field observation of scattered light from the defect
Implementation Method 2
a detection optical system for focusing, by an objective lens, scattered light from the inspection target object due to the laser emitted as above, to thereby form an image on a solid-state imaging element, wherein the detection optical system comprises a distribution filter for controlling a polarization direction of scattered light
Data Source
AI summary
The disclosed device, which, using an electron microscope or the like, minutely observes defects detected by an optical appearance-inspecting device or an optical defect-inspecting device, can reliably insert a defect to be observed into the field of an electron microscope or the like, and can be a device of smaller scale. The electron microscope, which observes defects detected by an optical appearance-inspecting device or an optical defect-inspecting device, has a configuration incorporating an optimal microscope that re-detects defects, and a spatial filter and a distribution polarization element are inserted at the pupil plane when making dark-field observations using this optical microscope. The electron microscope, which observes defects detected by an optical appearance-inspecting device or an optical defect-inspecting device, has a configuration incorporating an optimal microscope that re-detects defects, and a distribution filter is inserted at the pupil plane when making dark-field observations using this optical microscope.