Semiconductor Edge Inspection via Tangential and Dark-Field Illumination
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Solution Overview
Problem
Conventional edge and bevel inspection techniques for semiconductor structures suffer from blurry images due to low contrast, especially in transition regions, and fail to detect defects accurately.
Innovation Solution
The proposed inspection system employs a tangential imaging setup with back-light tangential illumination and a dark-field imaging setup, enabling high-contrast imaging of contour outlines, interfaces, and transition regions, and detecting abnormalities within these regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional front-side illumination and bright-field imaging mode are used, then the inspection process is simple and fast, but the acquired images suffer from low contrast and blurry appearance, especially in transition regions
Solution Approach 1:
The patent applies parameter changes by switching from conventional bright-field imaging mode to dark-field imaging mode, and from normal illumination to tangential illumination geometry. These parameter changes in the imaging system enable high-contrast visualization of edge and bevel features, particularly in transition regions, by capturing scattered light at specific angles that highlight surface topography and defects.
Solution Approach 2:
The patent introduces a new dimension to the imaging approach by implementing multi-angle illumination and detection geometries. By using tangential illumination from the side and detecting scattered light at multiple angles, the system creates three-dimensional information about the edge and bevel surfaces, enabling clear differentiation of transition regions that appear blurry in conventional single-angle imaging.
2Reliability
If conventional imaging approaches are used, then the inspection setup is straightforward, but defects in edge and bevel regions cannot be properly detected or located
Solution Approach 1:
The patent uses scattered light as an intermediary to detect defects. By illuminating the edge and bevel regions at tangential angles and capturing the scattered light pattern, the system indirectly reveals defect locations and characteristics. The scattered light acts as a mediator that highlights surface irregularities and defects that are invisible in conventional reflection-mode imaging.
Solution Approach 2:
The patent applies local quality by using zone-specific imaging strategies针对不同 regions of the edge and bevel. Different illumination angles and detection geometries are optimized for specific zones (e.g., top bevel, apex, bottom bevel, transition regions), allowing each region to be inspected with the most appropriate imaging parameters for maximizing defect detection sensitivity in that particular area.
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 provides accurate definition of contour outlines and interfaces, determination of bevel angles, and effective detection and classification of defects along the edge profile of semiconductor structures.
Implementation Method 1
a tangential illumination unit configured and operable to provide back-light tangential illumination towards the contour region
Implementation Method 2
a dark-field illumination unit configured and operable to direct dark-field illumination towards the contour region... providing collection of scattering of a response of the contour region to the dark-field illumination
Data Source
AI summary
An inspection system and method are presented for edge and bevel inspection of a semiconductor structure using and an optical system defining: a tangential imaging providing back-light tangential illumination propagating along a tangential illumination path with respect to a contour outline of a contour region of an edge of the structure and substantially along a detection path of a tangential imaging sensor unit which detects at least a part of said back-light tangential illumination and generates image data indicative of a tangential image of the contour outline to enable detection of defect data of the edge, and at least dark-field imaging setup directing dark-field illumination towards the contour region along at least one dark-field illumination path and providing collection of scattering of a response of the contour region to the dark-field illumination, to enable detection of a dark-field image indicative of location of defects along said profile of the edge.