Czochralski method-based crystal growth interface shape detection method and device

A technology of crystal growth and detection method, applied in the direction of crystal growth, single crystal growth, self-melt pulling method, etc.

Active Publication Date: 2021-09-21

SUN YAT SEN UNIV

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AI-Extracted Technical Summary

Problems solved by technology

[0005] Based on the above discussion, it can be concluded that the technology of real-time detection of crystal growth interface shape is of great help to crys...

Abstract

The invention relates to a czochralski method-based crystal growth interface shape detection method and device. The method comprises the steps that: a seed crystal temperature T and an interface electromotive force U at the same time in a crystal growth process are collected, and a T-U curve of the interface electromotive force U changing with the seed crystal temperature T is obtained; the change trend of the shape of a crystal growth interface in real time is judged by observing the deviation between the T-U curve and a reference line, wherein the reference line is a straight line passing through the starting point of the T-U curve, and the slope of the straight line is the Seebeck coefficient of the crystal. The invention also relates to a device used by the method. The detection method provided by the invention can detect the change trend of the shape of the crystal growth interface in real time in the crystal growth process, and can be applied to Czochralski method growth equipment for various single crystals such as lithium niobate, lithium tantalate, sapphire, yttrium aluminum garnet and the like.

Application Domain

By pulling from melt

Technology Topic

Seed crystalSapphire +7

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Examples

Experimental program(1)

Example Embodiment

[0047] Example 1

[0048] Using the detection method and apparatus of the present invention, real-time detection of growth interface in lithium niobate crystal growth process, combined figure 1 with figure 2 Be explained.

[0049] via figure 1 The four-numeral A, B, C, and D is taken out of the wire, and the electrical signal of the seed temperature and the interface electromotive force is taken out in the constant rotation and rising high temperature seed crystal end, and displayed in real time in the temperature meter and voltage meter. , Record, summary, drawing figure 2 (T-U curve of the horizontal axis, the interface electromotive force u is the longitudinal axis. The full range of talent crystal growth includes: warming, lower crystal, shoulder, equilate, pullery, cooling, a total of six stages, the detection method of the present invention is primarily applied to the two key stages of the auxiliary shoulder and the equation. . The specific operation is as follows:

[0050] (1) Since the lower crystal operation (seed crystal immersion high temperature melt), the crystal rotation speed is selected from 25 rpm. The data of the seed temperature T and the interface electromotive force u after 0.5 to 1 h showed a smooth state in the time series, and the data of the seed temperature T and the interface electromotive force u did not significantly undertake, there is no obvious move in the TU curve. At small range, this is the starting point ( figure 2 S-point in the middle. The slope is drawn from the starting point of the lithium niobate crystal Saffbeck coefficient, and the ray is defined as a reference line.

[0051] (2) Afterwards, it will enter the shoulder stage, and the pulling speed taken in this example is 2.4 mm / h according to the preset growth rate, and the pulling speed taken is 2.4 mm / h, and the maximum cooling speed is 2 ° C / h. The initial stage of the shoulder should not be lowered or lowered, and the diameter is increased to 2 to 3 times the diameter of the seed crystal, and then the temperature will cool down. The diameter of the crystal is gradually greater, and the target diameter is proximally reduced or stopped. The target diameter of this embodiment is 4 cm.

[0052] The detection method of the present invention is applied in real time to determine the change of the crystal growth interface, and the method is as follows: figure 2 As shown, in the early stage of the shoulder, the crystal diameter is small, and the growth interface has no significant change, and there is no significant deviation between the T-U curve and the reference line or even completely coincident. In the late stage, the TU curve gradually deviates from the baseline, the relationship between the TU curve and the reference line gradually changes "upper part", which means that the interface transition speed is greater than the three-phase pocket transition speed, the growth interface tends to become convex (crystal convex " Melt). The shoulder stage is close to the target diameter, and the interfacial tendency is slow, but the trend has not changed.

[0053] (3) The crystal gradually enters the equation stage, and the crystal diameter is maintained by controlling the cooling rate, and the maximum cooling rate at which the maximum cooling rate is 1 ° C / h. The principle of operation is that the crystal diameter is expanded to reduce the cooling rate, and the crystal diameter reduction increases the cooling rate.

[0054] The detection method of the present invention is applied in real time to determine the change of the crystal growth interface, and the method is as follows: figure 2 As shown, the initial T-U curve in this stage intersects the reference line, and the intersection marks the termination of the interface shape and the maximum position of the interface shape projections. Thereafter, the relationship between the T-U curve and the reference line gradually becomes "off" means that the interface has less than the three-phase pocket transition speed, and the interface tends to change the concave (crystal post). With the increase in the length of the crystal, the degree of increasing is increased, the stronger the tendency of the crystal changes.

[0055] The crystal growth is forcibly ended until the target isotropic is reached. In the crystal growth stage, the trend of the growth interface shape is observed in real time through the T-U curve.

PUM

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