Method and apparatus for semiconductor wafer alignment
First Claim
1. A wafer alignment system, comprisingA. a rotatable platform,B an image acquisition device having a field of view that includes at least a portion of a wafer on the platform,C. an illumination source that illuminates at least a portion of the wafer,D. an image processor that is coupled to the image acquisition device and that processes an at least two-dimensional image showing one or more characteristics of the wafer in a first frame of reference, the image processor determining therefrom a position and/or orientation of the wafer, or a portion thereof, in a second frame of reference,E. the image processor including a mapping element that maps coordinates in the first frame of reference to coordinates in the second frame of reference at each of a plurality of angles of rotation of the platform,F. wherein the mapping element maps coordinates in the image of the wafer on the platform to the second frame of reference as a function of the angle of rotation of the platform.
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Abstract
The invention provides, in some aspects, a wafer alignment system comprising an image acquisition device, an illumination source, a rotatable wafer platform, and an image processor that includes functionality for mapping coordinates in an image of an article (such as a wafer) on the platform to a “world” frame of reference at each of a plurality of angles of rotation of the platform.
315 Citations
21 Claims
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1. A wafer alignment system, comprising
A. a rotatable platform, B an image acquisition device having a field of view that includes at least a portion of a wafer on the platform, C. an illumination source that illuminates at least a portion of the wafer, D. an image processor that is coupled to the image acquisition device and that processes an at least two-dimensional image showing one or more characteristics of the wafer in a first frame of reference, the image processor determining therefrom a position and/or orientation of the wafer, or a portion thereof, in a second frame of reference, E. the image processor including a mapping element that maps coordinates in the first frame of reference to coordinates in the second frame of reference at each of a plurality of angles of rotation of the platform, F. wherein the mapping element maps coordinates in the image of the wafer on the platform to the second frame of reference as a function of the angle of rotation of the platform.
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16. A method of wafer alignment comprising
A. acquiring an at least two-dimensional image of a wafer that is disposed on a rotatable platform, the image showing one or more characteristics of the wafer in a first frame of reference, B. processing the image to determine therefrom a position and/or orientation of the wafer, or a portion thereof, in a second frame of reference, C. the processing step including determining the position and/or orientation by using a mapping element that maps coordinates in the first frame of reference to coordinates in the second frame of reference at each of a plurality of angles of rotation of the platform, D. mapping coordinates in the image of the wafer on the platform to the second frame of reference as a function of the angle of rotation of the platform, E. using the portion and/or orientation determined in step (B) to position the wafer for any of processing and inspection.
Specification