Memc Electronic Materials, Inc.

Robert H Fuerhoff

Steven Lawrence Kimbel

Mohsen Banan

John D Holder

Joseph C Holzer

Zheng Lu

A method of continuously measuring an elevation and shape of an unmelted polycrystalline silicon island during a silicon meltdown process. The method comprises projecting a focused bright light on the silicon island to produce a bright dot on the silicon island. The method also includes electronically determining an elevation and a shape of the silicon island by tracking the bright dot during the meltdown process.

Method and device for continuously measuring silicon island elevation

A method and apparatus for controlling the diameter of a monocrystalline ingot as it is being pulled from a melt by changing the temperature of the melt. The ingot is pulled from the melt at a target rate that substantially follows a predetermined velocity profile. A temperature model represents variations in the melt temperature in response to variations in power supplied to a heater for heating the melt. In generating a temperature set point representing a target melt temperature, an error between a target diameter and a measured diameter of the ingot is determined and proportional-integral-derivative (PID) control is performed on the error signal. The PID control generates the temperature set point as a function of the error signal. In turn, the temperature model determines a power set point for the power supplied to the heater as a function of the temperature set point generated by the PID control and the power supplied to the heater is adjusted according to the power set point.

Method and apparatus for controlling diameter of a silicon crystal in a locked seed lift growth process

A method and apparatus for preparing molten silicon melt from polycrystalline silicon in a crystal pulling apparatus entails loading an amount of polycrystalline silicon loaded into the crucible less than a predetermined total amount of polycrystalline silicon to be melted. The crucible is heated to form a partially melted charge in the crucible having an island of unmelted polycrystalline silicon exposed above an upper surface of melted silicon. Granular polycrystalline silicon is fed from a feeder onto the island of unmelted polycrystalline silicon until the predetermined total amount of polycrystalline silicon has been loaded into the crucible. The position of the island relative to the crucible side wall is electronically determined as granular polycrystalline silicon is fed onto the island. The feed rate at which granular polycrystalline silicon is fed from the feeder onto the island of unmelted polycrystalline silicon is controlled in response to the determined position of the island relative to the crucible side wall.

Method for preparing molten silicon melt from polycrystalline silicon charge

A method and system for determining melt level and reflector position in a Czochralski single crystal growing apparatus. The crystal growing apparatus has a heated crucible containing a silicon melt from which the crystal is pulled. The crystal growing apparatus also has a reflector positioned within the crucible with a central opening through which the crystal is pulled. A camera generates images of a portion of the reflector and a portion of a reflection of the reflector visible on the top surface of the melt. An image processor processes the images as a function of their pixel values to detect an edge of the reflector and an edge of the reflection in the images. A control circuit determines a distance from the camera to the reflector and a distance from the camera to the reflection based on the relative positions of the detected edges in the images. The control circuit determines at least one parameter representative of a condition of the crystal growing apparatus based on the determined distances and controls the apparatus in response to the determined parameter.

Method and system for controlling growth of a silicon crystal

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.

Method for controlling growth of a silicon crystal

System and method for determining the diameter of a silicon crystal being pulled from a silicon melt for controlling a silicon crystal growing apparatus. The melt has a surface with a meniscus which is visible as a bright ring adjacent the crystal. A camera generates an image pattern of a portion of the bright ring adjacent the crystal. Image processing circuitry detects a characteristic of the image pattern and defines an edge of the bright ring as a function of the detected characteristic. The image processing circuitry further defines a generally circular shape including the defined edge of the bright ring. The diameter of the crystal is then determined based on the diameter of the defined shape for use in controlling the crystal growing apparatus.

System for controlling growth of a silicon crystal

System for determining the diameter of a silicon crystal being pulled from a silicon melt for controlling a silicon crystal growing apparatus. The melt has a planar surface including a meniscus that is visible as a bright ring adjacent the crystal. A camera positioned above the melt surface and away from the crystal includes an image plane that is generally parallel to the melt surface and responsive to light from the bright ring for generating an image pattern of a portion of the bright ring. As such, the camera compensates for distortion of the image pattern caused by the position of the camera relative to the crystal. Image processing circuitry detects a characteristic of the image pattern and defines an edge of the bright ring as a function of the detected characteristic. The image processing circuitry further defines a generally circular shape including the defined edge of the bright ring. The diameter of the crystal is then determined based on the diameter of the defined shape for use in controlling the crystal growing apparatus.

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St. Charles, MO, United States of America

Robert H Fuerhoff