Specular Reflection Substrate Inspection for Edge Bead Removal
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Solution Overview
Problem
Conventional substrate inspection methods are inefficient in evaluating the edge bead removal line (EBR line) and detecting edge defects on semiconductor wafers, particularly due to misalignment issues and the need for complex image processing, which hinders streamlined inspection and accurate evaluation of coating film quality.
Innovation Solution
A substrate inspection apparatus and method that uses a rotator to rotate the substrate, a light irradiator to capture specularly reflected light, and an image processor to generate a two-dimensional image by arranging scanning lines in a sub-scanning direction, with a judgment band to assess the edge line quality, allowing for efficient detection of edge defects and misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dark-field image method is used to inspect the EBR line, then the inspection method can identify fluorescent EBR lines, but the resolution is not improved and the method requires fluorescent dyes and solutions which limits applicability to arbitrary inspection targets
Solution Approach 1:
The patent changes the illumination parameter from dark-field to specular reflection illumination, and changes the detection parameter from fluorescent light to specularly reflected light. This allows inspection of arbitrary coating films without requiring fluorescent dyes, while maintaining EBR line identification capability through the characteristic specular reflection pattern at the edge bead removal line.
2Measurement precision
If conventional image processing methods are used to evaluate the entire edge part, then comprehensive evaluation can be achieved, but the process takes time and is inefficient
Solution Approach 1:
The patent extracts only the critical evaluation information from the captured image by detecting the EBR line position and comparing it with the judgment band, rather than processing the entire image comprehensively. This extraction approach maintains evaluation accuracy for the edge bead removal line while dramatically reducing processing time and improving inspection efficiency.
Solution Approach 2:
The patent segments the evaluation process into distinct steps: capturing specular reflection image, detecting EBR line position, defining judgment band, and comparing position with band. This segmentation allows efficient processing of each step independently, improving overall inspection productivity while maintaining comprehensive evaluation capability.
3Measurement precision
If complex image processing and mapping are used to generate edge maps, then detailed edge analysis can be performed, but the system becomes complicated and optimization verification becomes necessary
Solution Approach 1:
The patent extracts only the essential edge information by detecting the EBR line position and comparing it with the judgment band, rather than generating complex edge maps. This approach achieves accurate edge defect detection while avoiding the complexity of mapping and comprehensive image processing systems.
Solution Approach 2:
Instead of generating an edge map from the entire image and then analyzing it, the patent inverts the approach by directly detecting the EBR line position from the captured image and comparing it with the judgment band. This inversion simplifies the system while maintaining detection accuracy.
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 enables efficient and accurate evaluation of the coating film edge line quality, simplifies the detection process, and allows for precise judgment of edge defects even in cases of substrate misalignment, improving processing efficiency and accuracy.
Implementation Method 1
a photoelectric converter that receives specularly reflected light from the surface of the substrate and captures an image of a scanning line
Data Source
AI summary
A substrate inspection apparatus for detecting a condition of an EBR line at a substrate edge, comprising a turntable for rotating a substrate having a film coated thereon, a light irradiator and a photoelectric converter that receives specularly reflected light from the substrate and outputs a captured image signal. A two-dimensional image is generated by adding detection values of electrical signals corresponding to one radial scan from a center of the substrate for one turn of a rotator, and a changing point is judged using a judgment band set along one direction of the two-dimensional image.