System for finding the orientation of a wafer
First Claim
1. Apparatus for determining the orientation of a semiconductor wafer having an orientation feature, a center point, a perimeter, and a principal radius extending from the center point to the perimeter, the apparatus comprising:
- means for acquiring an image of at least a portion of said wafer including an image of at least a portion of said orientation feature;
means for acquiring knowledge of the position of said center point, and of the radial distance of a point on said orientation feature from said center point;
means for using said knowledge to define a curved image-partitioning band having a curved inner boundary, a curved outer boundary, and a curved angular displacement scale, such that said image of at least a portion of said orientation feature is disposed between said inner and outer boundaries to provide a curved band image;
polar-to-cartesian coordinate conversion means for transforming said curved band into a straight band image including a longitudinal position scale;
means for determining knowledge of the longitudinal position along said longitudinal position scale of said image of at least a portion of said orientation feature; and
means for converting said knowledge of said longitudinal position into knowledge of the corresponding angular displacement along said curved angular displacement scale, so as to provide knowledge of the orientation of said semiconductor wafer.
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Accused Products
Abstract
The invention can be used to find the orientation of a semiconductor wafer without wafer handling, i.e., in a non-contact manner. The invention uses knowledge of the position of a semiconductor wafer, and the position of an orientation feature of the wafer, to find the orientation of the wafer. According to the invention, a curved band image is formed that includes an image of an orientation feature. The curved band image is then transformed into a straight band image. The longitudinal position of the orientation feature is then determined in the coordinate system of the straight band image, which longitudinal position is then converted into an angular displacement in the coordinate system of the curved band image to provide the orientation of the wafer.
143 Citations
31 Claims
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1. Apparatus for determining the orientation of a semiconductor wafer having an orientation feature, a center point, a perimeter, and a principal radius extending from the center point to the perimeter, the apparatus comprising:
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means for acquiring an image of at least a portion of said wafer including an image of at least a portion of said orientation feature; means for acquiring knowledge of the position of said center point, and of the radial distance of a point on said orientation feature from said center point; means for using said knowledge to define a curved image-partitioning band having a curved inner boundary, a curved outer boundary, and a curved angular displacement scale, such that said image of at least a portion of said orientation feature is disposed between said inner and outer boundaries to provide a curved band image; polar-to-cartesian coordinate conversion means for transforming said curved band into a straight band image including a longitudinal position scale; means for determining knowledge of the longitudinal position along said longitudinal position scale of said image of at least a portion of said orientation feature; and means for converting said knowledge of said longitudinal position into knowledge of the corresponding angular displacement along said curved angular displacement scale, so as to provide knowledge of the orientation of said semiconductor wafer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. Apparatus for determining the orientation of a semiconductor wafer having an orientation feature, a center point, a perimeter, and a principal radius extending from the center point to the perimeter, the apparatus comprising:
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means for acquiring an image of at least a portion of said wafer including an image of at least a portion of said perimeter, and at least a portion of said orientation feature; means for acquiring knowledge of the position of said center point, and of the radial distance of a point on said perimeter from said center point; means for using said knowledge to define an outer circular boundary in substantially concentric relationship with said perimeter, said outer circular boundary having a radius greater than a radial distance of a point on said perimeter; means for using said knowledge to define an inner circular boundary in substantially concentric relationship with said outer circular boundary, said inner circular boundary having a radius less than said radial distance of said point on said perimeter; means for using said knowledge to define a circular angular displacement scale; polar-to-cartesian coordinate conversion means for transforming a circular band image that is bounded by said inner and outer boundaries;
into a straight band image, said circular band image including an image of at least a portion of said perimeter, an image of at least a portion of said orientation feature, and a longitudinal position scale;means for determining knowledge of the longitudinal position along said longitudinal position scale of said image of at least a portion of said orientation feature; and means for converting said knowledge of said longitudinal position into knowledge of the corresponding angular displacement along said curved angular displacement scale, so as to provide knowledge of the orientation of said semiconductor wafer.
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25. A method for determining the orientation of a semiconductor wafer having an orientation feature, a center point, a perimeter, and a principal radius extending from the center point to the perimeter, the method comprising the steps of:
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acquiring an image of at least a portion of said wafer including an image of at least a portion of said orientation feature; acquiring knowledge of the position of said center point, and of the radical distance of a point on said orientation feature from said center point; using said knowledge to define a curved image-partitioning band having a curved inner boundary, a curved outer boundary, and a curved angular displacement scale, such that said image of at least a portion of said orientation feature is disposed between said inner and outer boundaries to provide a curved band image; transforming said curved band image into a straight band image, including a longitudinal position scale, using a polar-to-cartesian coordinate transform; determining knowledge of the longitudinal position along said longitudinal position scale of said image of at least a portion of said orientation feature; and converting said knowledge of said longitudinal position into knowledge of the corresponding angular displacement along said curved angular displacement scale, so as to provide knowledge of the orientation of said semiconductor wafer. - View Dependent Claims (26, 27, 28, 29, 30, 31)
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Specification