Confocal Inspection Optics for Accurate Reflection and Fluorescence Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semiconductor defect detection systems struggle with obtaining highly accurate reflection images due to low light intensity and sensitivity, especially when using ultraviolet illumination, which affects the signal-to-noise ratio and limits defect detection precision.
Innovation Solution
The inspection device employs a confocal optical system with separate illumination and excitation laser light sources, allowing for simultaneous measurement of directly reflected light and fluorescence, and uses a common optical path with a shared objective lens for improved accuracy and speed, enabling defect detection on the substrate surface and at different depths through multiple wavelength excitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-wavelength illumination beam is used to obtain both reflection image and photoluminescence image, then the device structure is simplified, but the sensor or imaging optical system for obtaining reflection image cannot be freely selected and it is not easy to obtain a highly accurate reflection image
Solution Approach 1:
The patent divides the detection system into separate reflection detection and photoluminescence detection subsystems. The reflection detection system uses a reflection sensor and imaging optical system optimized for reflection imaging, while the photoluminescence detection system uses a fluorescence sensor and excitation light source. This segmentation allows each subsystem to be independently optimized for its specific function, enabling high-accuracy reflection imaging while maintaining overall system efficiency.
2Illumination intensity
If ultraviolet light is used for reflection measurement, then the illumination intensity is sufficient, but the quantum efficiency of the image sensor in ultraviolet region is low and light receiving sensitivity is low, making it not easy to obtain a reflection image with excellent S/N ratio
Solution Approach 1:
The patent changes the wavelength parameter of the illumination light used for reflection measurement from ultraviolet to visible light range. By using visible light illumination, the image sensor operates in its high quantum efficiency region, significantly improving light receiving sensitivity and S/N ratio. The system uses a visible light source (such as LED or laser) for reflection imaging while maintaining UV light source for photoluminescence excitation, optimizing the wavelength parameter for each detection purpose.
3Manufacturing precision
If a narrow slit is used to transmit ultraviolet illumination light, then the spatial resolution is improved, but the intensity of light transmitted through the slit is weak, making it difficult to generate sufficient fluorescence for detection and not easy to obtain a highly accurate reflection image
Solution Approach 1:
The patent separates the illumination paths for reflection imaging and photoluminescence excitation. The reflection imaging system uses visible light illumination without requiring passage through a narrow slit, maintaining high light intensity. The photoluminescence system uses UV light that can be focused through appropriate optical elements. This segmentation allows each system to have optimal illumination conditions without compromising the other.
Solution Approach 2:
The patent introduces a dichroic mirror as an intermediary optical element that separates visible light for reflection imaging from UV light for photoluminescence excitation. This intermediary allows both illumination types to coexist in the same optical path setup without interfering with each other, enabling both high-intensity reflection imaging and sufficient fluorescence generation.
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 accuracy and speed by securing sufficient light intensity and enabling selective detection of surface defects and defects at varying depths, improving the precision of defect classification and characterization.
Implementation Method 1
an illumination beam is projected toward a SiC substrate, reflected light and photoluminescence light emitted from the SiC substrate are separately detected
Implementation Method 2
photoluminescence light emitted from the SiC substrate are separately detected
Implementation Method 3
a fluorescence observation device including a fluorescence sensor, in which measurement light is acquired by the reflection observation device and fluorescence is acquired by the fluorescence observation device
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
An object is to obtain a highly accurate reflection image or the like. An inspection device includes: a surface defect detection system including an illumination device including an illumination laser light source device and a reflection observation device including a reflection sensor; and a photoluminescence detection system including a UV irradiation device including an excitation laser light source device and a fluorescence observation device including a fluorescence sensor, in which measurement light is acquired by the reflection observation device and fluorescence is acquired by the fluorescence observation device while irradiating an object with illumination light by the illumination laser light source device and irradiating the object with excitation light by the excitation laser light source device through a common optical path.