Wafer notch detection

Abstract

Notch detection methods and modules are provided for efficiently estimating a position of a wafer notch. Capturing an image of specified region(s) of the wafer, a principle angle is identified in a transformation, converted into polar coordinates, of the captured image. Then the wafer axes are recovered from the identified principle angle as the dominant orientations of geometric primitives in the captured region. The captured region may be selected to include the center of the wafer and / or certain patterns that enhance the identification and recovering of the axes. Multiple images and / or regions may be used to optimize image quality and detection efficiency.

Description

[0001] Related Application Cross Reference [0002] This application claims the benefit of US Provisional Patent Application Serial No. 61 / 939,131, filed February 12, 2014, which is hereby incorporated by reference in its entirety. technical field [0003] The present invention relates to the field of semiconductor technology, and more particularly, to the identification of the location of a wafer notch. Background technique [0004] Typically, the orientation of the wafer is conveyed by the location of the notch, which is indicative of the crystallographic orientation of the wafer. In the prior art, wafer orientation calculation based on notch orientation is time consuming since it requires an exhaustive search in the full angular range of 360 degrees. Typically, notch-only wafer orientation results are limited in accuracy and require an additional step of time-consuming "fine alignment". To avoid long mechanical movements, some of the existing solutions require addition...

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