A device and a method for detecting crystalline defects in a substrate by dark field
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Solution Overview
Problem
Existing dark-field detection methods are not specific or selective enough to distinguish crystalline defects from other defects on monocrystalline substrates, such as silicon carbide, leading to difficulties in accurate detection and classification.
Innovation Solution
A device and method utilizing a dark-field configuration with illumination light sources positioned in specific angular orientations relative to the crystallographic growth axis, allowing for improved discrimination of crystalline defects by exploiting their unique scattering patterns, while minimizing specular reflection and maximizing scattered light collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dark-field detection is used to detect crystalline defects, then detection simplicity and efficiency are improved, but specificity and selectivity deteriorate making it difficult to distinguish crystalline defects from other defects
Solution Approach 1:
The patent segments the detection process into two distinct illumination configurations: dark-field configuration for detecting crystalline defects and bright-field configuration for detecting non-crystalline defects. This segmentation allows each configuration to be optimized for its specific defect type, resolving the contradiction between detection efficiency and classification accuracy.
Solution Approach 2:
The patent changes the illumination parameters by switching between dark-field and bright-field configurations. By adjusting the illumination angle and collection angle parameters, the system can selectively detect different defect types, thereby improving both detection efficiency and classification accuracy simultaneously.
2Measurement precision
If multiple detection techniques are combined to improve defect classification, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent employs dynamic switching between dark-field and bright-field illumination configurations using a single detection system. The system can dynamically adjust the illumination angle and collection angle to adapt to different defect types, achieving high classification accuracy without requiring multiple permanent detection systems.
Solution Approach 2:
The patent makes a single detection system universal by enabling it to perform both dark-field and bright-field detection modes. This multi-functionality allows one system to detect both crystalline and non-crystalline defects, reducing device complexity while maintaining high measurement precision.
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 enhances the detection of crystalline defects on off-axis monocrystalline substrates by providing high throughput and minimizing measurement time, with improved discrimination from non-crystalline defects like particles or scratches.
Implementation Method 1
Dark-field detection allows revealing the defects present at the surface of a substrate. This technique is based on an illumination of the surface and the collection of the scattered light.
Implementation Method 2
The illumination is arranged with an angle of incidence such that the specular reflection is not collected.
Data Source
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AI summary
The invention relates to a device (100) for detecting crystalline defects in an off-axis monocrystalline substrate (10), wherein the normal to the surface of the substrate (10) is tilted with respect to the crystallographic growth axis by a tilt angle, the tilt angle being contained in a plane, called angle plane, perpendicular to the surface of the substrate, the device (100) comprising: - a detector (14), - at least one illumination light source (12) configured to illuminate the substrate (10) with an illuminating light beam (13), said at least one illumination light source (12) being arranged in at least one of a first position and a second position, - imaging means (16) configured to image the substrate (10) according to a field of view on the detector (14), said detector (14) producing at least one image of the substrate (10), and - processing means (18) configured to detect crystalline defects using said at least one image of the substrate, wherein the at least one illumination light source (12) and the imaging means (16) are arranged in a dark-field configuration, and wherein in the first position, the at least one illumination light source (12) is arranged such that the illuminating light beam is parallel or quasi-parallel to the angle plane, and in the second position, the at least one illumination light source (12) is arranged such that the illuminating light beam is parallel or quasi-parallel to a plane, called perpendicular plane, containing the normal to the surface of the substrate and being perpendicular to the angle plane. The invention also relates to a method for detecting crystalline defects in an off-axis monocrystalline substrate.