Control method of crystal growth by crystal pulling method

Abstract

The invention relates to a control method for crystal growth by Czochralski method. A weight signal of a growing crystal is obtained by the sampling of a computer and is converted, according to a signal processing method, to a crystal diameter feedback signal independent of the growth rate; the crystal diameter feedback signal is compared with the preset crystal diameter value to acquire a signal error, and then the calculated value of a mechanical pulling speed for the control of a seed crystal is gained by the PID calculation of the signal error; the calculated value of the mechanical pulling speed is compared with the preset mechanical pulling speed value to get a new signal error, and the temperature (or power) is controlled through the PID calculation of the new signal error. The pulling speed is controlled by a primary control circuit while the temperature is controlled by a secondary control circuit; the constant diameter control of the growing crystal is realized by the synergism of the pulling speed circuit and the temperature circuit. The control method has the advantages of rapid response speed, good constant diameter control effect, smoother crystal surface, higher crystal growth rate and production efficiency, and the using of the control method is not affected by the material of the crystal and can be applied to most growing processes of Czochralski method.

Description

technical field [0001] The present invention relates to a method for manufacturing a semiconductor single crystal by a pulling method, in particular to a method for controlling the growth diameter of a pulling method crystal by changing the pulling speed under the condition that the weight or weight change rate or diameter signal is obtained by a weighing method, that is, Diameter control method with variable pulling speed. Background technique [0002] The pulling method crystal growth method (Czochralski Method, Czochralski Method) is a main method for obtaining single crystals, such as silicon single crystals, laser crystals, and nonlinear optical crystals. Its working principle is that the raw material is first melted, and then the seed crystal (usually single crystal) is brought into contact with the liquid level of the melt from above at a suitable temperature, and the seed crystal is slowly pulled up. While the crystal is pulled up, the temperature of the melt is con...

AI Technical Summary

Problems solved by technology

However, camera or infrared tracking is limited by the crystal material itself. For example, it can be successfully used in silicon single crystal, but it is difficult to track the solid-liquid interface of most other crystals (laser crystals, nonlinear optical crystals).

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