How the positioning slots of a wafer are determined？
Determination of the wafer positioning slot is an important part of the semiconductor manufacturing process, which involves precise positioning and alignment operations of the wafers. Based on the search results provided, here are some methods for determining the wafer positioning slot:
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Utilising edge images and notch images
By acquiring at least three edge images and edge notch images of a wafer, acquisition can be performed in the platform coordinate system. By setting a reference point and performing a mirroring operation, the difficulty of edge extraction can be reduced, and template matching can be completed quickly so as to determine the circular centre position of the wafer.
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Determining the centre of the circle and the centre of the notched area
By determining the position of the centre of the wafer and the centre of the notched area in the edge notch image, the angle of deflection of the wafer relative to the stage coordinate system can be determined. This aids in accurately determining the orientation of the wafer and completes the accurate alignment of the wafer by rotating the sample motion stage to eliminate the pinch angle.
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Using the template matching technique
By matching the template image with the edge image, reference points and their matching points can be determined, which need not be located on the same edge arc of the same radius on the wafer, thus improving the accuracy of the positioning.
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Determining the deflection angle
The deflection angle of a wafer can be determined by calculating the angle between the line connecting the centre of the circle to the centre of the notch area and the platform coordinate system. If the notch is located in the y-axis direction of the platform coordinate system, the angle with the y-axis is used; if it is located in the x-axis direction, the angle with the x-axis is used.
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Use of a preset missing slot image
By template matching at least one of the predetermined missing slot template images with an edge missing slot image, a missing slot region can be determined and the centre position of the predetermined missing slot image can be used as the centre position of the missing slot region.
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Determination of the deflection line by straight line fitting
By identifying at least one circular arc in the notched area and finding the midpoints of the arcs, a straight line can be fitted using the centre of the wafer and these midpoints to determine the deflection line, and accordingly the angle of deflection of the wafer.
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High-precision positioning technology
Precise wafer positioning during the wafer fabrication process can be achieved with high-precision manipulators and positioning systems such as Notch slot inspection technology.
