Method for controlling growth of a silicon crystal
First Claim
1. A method for use in combination with an apparatus for growing a silicon single crystal, said crystal growing apparatus having a heated crucible containing a silicon melt from which the crystal is pulled, said melt having a surface with a meniscus visible as a bright area adjacent the crystal as the crystal is pulled from the melt, said method for determining a diameter of the crystal, said method comprising the steps of:
- generating an image with a camera of the interior of the crucible including a portion of the bright area adjacent the crystal, said image including a plurality of pixels, said pixels each having a value representative of an optical characteristic of the image;
defining a central window region of the image at a position corresponding to an approximate center of the crystal, said central window region having an elliptical shape;
processing the image as a function of the pixel values to detect edges within the central window region;
grouping the detected edges to define an object in the image corresponding to the crystal;
determining a dimension of the defined object; and
determining an approximate diameter of the crystal as a function of the determined dimension of the defined object.
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Abstract
A method and system for determining a diameter of a silicon single crystal being pulled from a silicon melt contained in a heated crucible. The melt has a surface with a meniscus visible as a bright area adjacent the pulled crystal. A camera generates an image of the interior of the crucible including a portion of the bright area adjacent the crystal. Image processing circuitry defines a central window region of the image having an elliptical shape at a position corresponding to an approximate center of the crystal and processes the image as a function of its pixel values to detect edges within the central window region. The image processing circuitry further groups the detected edges to define an object in the image corresponding to the crystal, determines a dimension of the defined object and determines an approximate diameter of the crystal as a function of the determined dimension of the defined object.
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Citations
21 Claims
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1. A method for use in combination with an apparatus for growing a silicon single crystal, said crystal growing apparatus having a heated crucible containing a silicon melt from which the crystal is pulled, said melt having a surface with a meniscus visible as a bright area adjacent the crystal as the crystal is pulled from the melt, said method for determining a diameter of the crystal, said method comprising the steps of:
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generating an image with a camera of the interior of the crucible including a portion of the bright area adjacent the crystal, said image including a plurality of pixels, said pixels each having a value representative of an optical characteristic of the image; defining a central window region of the image at a position corresponding to an approximate center of the crystal, said central window region having an elliptical shape; processing the image as a function of the pixel values to detect edges within the central window region; grouping the detected edges to define an object in the image corresponding to the crystal; determining a dimension of the defined object; and determining an approximate diameter of the crystal as a function of the determined dimension of the defined object. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification