| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a silicon single crystal which has a diameter of at least 200 mm over a length of at least 200 mm and is free of dislocations. <P>SOLUTION: The atmosphere of inert gas and nitrogen in a receptacle has a pressure of 1.5-2.2 bar, and the atmosphere is continuously exchanged. In this case, at least twice of the volume of the receptacle is exchanged per hour. A flat coil with an external diameter of at least 220 mm is used in order to melt a stock ingot. The single crystal is pulled at a rate in a range of 1.4-2.2 mm/min and is periodically rotated through a sequence of rotation angles. The direction of rotation is changed after each rotation by a rotation angle belonging to the sequence. For example, the single crystal is first of all rotated clockwise through the angleα1 at a rotational speed N1. Then a change in the direction of rotation is performed and a rotation in the counterclockwise direction through the angleα2 is performed at a rotational speed N2, followed by periodically recurring rotations throughα1 andα2. A high quality single crystal stable in the shape can be obtained by optimally performing selection of rotation angle. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
