System and control method for drawing crystal bar

Abstract

The invention provides a system and a control method for drawing a crystal bar. The system comprises: a first control unit which is used for controlling the drawing speed of the drawn crystal bar to be constant; an obtaining unit which is used for obtaining a distance between a solid-liquid interface and a reference surface, wherein the solid-liquid interface is an interface between a crystal liquid and the current crystal bar; a crucible used for containing the crystal liquid; a heating device used for heating the crucible; a second control unit used for adjusting the crucible lifting ratio under the condition that the distance is different from the preset distance in order to make the distance reach the preset distance, wherein the crucible lifting ratio is the ratio of the crystal growth rate to the crucible lifting rate; and a third control unit connected with the heating device and used for controlling the heating power of the heating device to make the diameter of the crystal barat each position is within a preset range. The system makes the ratio v/G of the drawing speed of the drawn crystal bar to the temperature gradient of the solid-liquid interface kept unchanged, so that the defect concentration of the drawn crystal bar is reduced.

Description

technical field [0001] The present application relates to the field of semiconductors, in particular, to a system and control method for pulling crystal ingots. Background technique [0002] With the rapid development of semiconductor chip technology, the minimum line width of devices is getting smaller and smaller, and the requirements for the size and concentration of essential defects in polished silicon wafers are also becoming stricter. Traditional low-density defect polished silicon wafers have been unable to meet the advanced semiconductor process with a minimum line width below 30nm. [0003] According to Voronkov's theory, the type and concentration of intrinsic defects in the crystal are determined by v / G, where v is the growth rate and G is the average axial temperature gradient between the solidification temperature and about 1300 °C at the central axis. When v / G is greater than a certain critical value, the defects in the crystal tend to be void, and the larger...

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Problems solved by technology

Too high a pull speed will lead to easy wire breakage, and too slow a pull speed will lea

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