Nkk Corporation

Akihiro Kawashima

Tatsuo Sato

Toshio Okawa

Yuji Naka

A method of controlling the diameter of a silicon single crystal. In the course of manufacturing a silicon single crystal by pulling the silicon single crystal while rotating it relative to a crucible, a comparison between a measured diameter value of the pulled single crystal measured by optical means and a desired diameter value is made to determine a deviation so that the resulting deviation is subjected to an incomplete differential PID processing or the Smith method processing to calculate a pull rate and the pull rate is applied to a motor controller of a crystal pulling apparatus thereby performing the diameter control of the pulled single crystal through the manipulation of the pull rate. An apparatus for controlling the diameter of a silicon single crystal includes input means for receiving a measured diameter value of a pulled single crystal measured by optical means, incomplete differential PID computing means for making a comparison between a measured diameter value of the pulled single crystal and a desired diameter value a plurality of times at intervals of a unit rotational period to calculate a pull rate, and output means for applying the pull rate to a motor controller of a crystal pulling apparatus.

Method and apparatus for controlling the diameter of a silicon single

A method for rectification includes steps of supplying raw materials to a rectifying column from a raw material feed pipe; returning a refluent fluid from a refluxing pipe to the column; leading a hold-up liquid from a bottom tank having a higher surface to a bottom tank having a lower surface of a liquid in a bottom portion of the column; heating the hold-up in each of bottom tanks; exchanging heat by bringing a vapor produced by heating the bottoms into counter-current contact with the reluent liquid returned to the rectifying column on plates arranged in the rectifying column, taking out a vapor from the top of the rectifying column, and taking out bottoms from the bottom tank. An apparatus for rectification includes a rectifying column having a raw material feed pipe, an offtake pipe for taking out the vapor, a reflux pipe for returning the refluent liquid to the inside of the column in the upper portion of the rectifying column and plates for exchanging heat by bringing the vapor into contact with the refluent liquid. The bottom portion is divided into at least two bottom tanks having surfaces of liquid different in height, in the bottom portion of rectifying column. The bottoms in each of the bottom tanks are heated and an offtake pipe takes out the bottoms.

Method for rectification and apparatus therefor

A method of measuring the diameter of a silicon single crystal. At intervals of a given rotational period of a pulled single crystal being pulled by the CZ method, optical means samples the luminance distribution of a fusion ring to obtain measured diameter values of the pulled single crystal so that the measured diameter values are processed by a low-pass filter to generate filter output values converted to time series diameter data and the filter output values are subjected to moving averaging to calculate a diameter value. Also, an apparatus for measuring the diameter of a silicon single crystal includes optical means whereby at intervals of a given rotational period of a pulled single crystal being pulled by the CZ method the luminance distribution of a fusion ring is sampled and measured to generate measured diameter values of the pulled single crystal, a low-pass filter for filtering the low-frequency components of the measured diameter values to generate filter output values converted to time series data, and computing means for subjecting the filter output values to moving averaging to calculate a diameter value of the pulled single crystal.

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Tokyo, Japan

Akihiro Kawashima