Wafer Notch Detection via Contour Analysis
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Solution Overview
Problem
Existing notch detection methods for crystalline wafers often fail to accurately distinguish between intended notches and unintentional indentations, leading to incorrect orientation and processing failures during wafer processing.
Innovation Solution
A notch detecting method that involves capturing images of the wafer's outer circumference while rotating, calculating contour data, determining irregular areas, and using multiple criteria such as distance, pointedness, and similarity analysis to differentiate between notches and indentations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If simple image-based notch detection is used, then detection speed is improved, but detection accuracy deteriorates due to misidentification of indentations as notches
Solution Approach 1:
The patent applies parameter changes by analyzing multiple geometric parameters of detected irregular areas including area size, shape factors, and positional relationships. By evaluating these parameters against predetermined thresholds and criteria, the system distinguishes genuine notches from machining indentations, thereby improving detection accuracy while maintaining automated processing speed
Solution Approach 2:
The patent implements feedback mechanisms by comparing detected irregular areas against multiple verification criteria. The system provides feedback loops where detection results are validated through parameter analysis, and only irregular areas meeting all criteria are confirmed as notches. This multi-stage verification feedback process eliminates false positives while preserving efficient automated detection
2Reliability
If multiple detection criteria are applied to improve accuracy, then detection reliability is improved, but processing complexity increases
Solution Approach 1:
The patent manages complexity by systematically evaluating multiple geometric parameters (area, shape factors, position) with clearly defined thresholds. Each parameter serves a specific discrimination function, and the structured parameter analysis approach maintains algorithmic clarity while achieving high detection reliability through comprehensive parameter evaluation
Solution Approach 2:
The patent applies segmentation by dividing the detection process into distinct analytical stages: initial irregular area detection, parameter extraction, threshold-based filtering, and final verification. This segmented approach breaks down complex multi-criteria evaluation into manageable sequential steps, reducing overall system complexity while maintaining high reliability
Data Source
AI summary
A notch detecting method for detecting a notch defined in an outer circumferential portion of a wafer includes a placing step of placing the wafer on a rotary table, an image capturing step of acquiring an image of the outer circumferential portion of the wafer, a contour data acquiring step of acquiring contour data including coordinates of a contour of the wafer, a hypothetical circle calculating step of calculating a hypothetical circle that approximates the contour of the wafer, an irregularly shaped area determining step of determining whether an irregularly shaped area exists in the outer circumferential portion of the wafer or not, and a first notch determining step of determining whether the irregularly shaped area is the notch or not.