Wafer Edge Bead Removal Line Detection via Dark Field Imaging
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Solution Overview
Problem
Existing methods for detecting edge bead removal lines on wafers are not effective in distinguishing these lines from other structural elements, leading to ambiguity in identifying edge bead removal lines due to overlapping photoresist layers and underlying structures.
Innovation Solution
A method involving dark field imaging and comparison of structures on either side of detected lines to determine if they represent edge bead removal lines, utilizing the transparency of photoresist in the visible spectrum to identify correlations and standardize intensity profiles, thereby distinguishing edge bead removal lines from other features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If dark field imaging is used to detect lines on the wafer edge, then the detectability of lines is improved, but the ability to unequivocally identify edge bead removal lines among multiple detected lines deteriorates
Solution Approach 1:
The method segments the analysis by dividing the wafer edge into multiple line areas and analyzing each detected line separately. For each line, a first line area and second line area are defined on either side, allowing individual comparison of structures across each line to identify which ones are edge bead removal lines versus other structural elements
Solution Approach 2:
The patent uses the transparency of photoresist in the visual spectrum as an intermediary property. This transparency allows underlying structures to be visible through the photoresist layer, enabling the comparison of structures on either side of detected lines to determine if they are edge bead removal lines, thus resolving the ambiguity among multiple detected lines
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 method allows for the unequivocal classification of detected lines as edge bead removal lines, improving detectability and reducing false positives by correlating structures across the wafer edge, ensuring accurate identification.
Implementation Method 1
the edge of the wafer is imaged on a detector, in particular using dark field imaging onto a suitable detector
Implementation Method 2
This makes use of the fact that photoresists are transparent in the visual range of the spectrum so that the underlying structures are visible
Data Source
AI summary
To determine an edge bead removal line (17) on a wafer (10), first lines or edges (38, 40, 42, 44) in the edge area (19) of the wafer (10) are detected. A first line area (48) and a second line area (50) are defined on either side of these lines (38, 40, 42, 44). The structures (36) present in these edge areas (48, 50) are compared to each other. From the result of the comparison it is determined whether or not an edge bead removal line (17) is present.