JP2810975B2 - Single crystal manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a single crystal. More specifically, the present invention relates to a method for producing a single crystal, which can easily produce a high-quality single crystal with few defects by a pulling method.

[0002]

2. Description of the Related Art As a method for growing a single crystal such as an oxide from a melt, a pulling method is conventionally known. In this pulling method, it is common to use a seed crystal having the same composition and crystal structure as the target single crystal. However, when there is no suitable single crystal as the seed crystal, for example, a platinum wire or the like is used. After the polycrystal is generated by using the polycrystal, the polycrystal is repeatedly necked to form a single crystal.

However, in this case, since the solid-liquid interface tends to be unstable at the polycrystalline stage, it is difficult to control the shape, and the necking requires skill. Further, the polycrystalline portion was easily broken at the grain boundary, and the sample often dropped during the growth of the single crystal. On the other hand, a single crystal is prepared in advance by a Bridgman method, a floating zone melting method, or the like, and is used as a seed crystal.In this case, when the seed crystal is immersed in the melt, Crystal defects such as dislocations are likely to occur at the center of the crystal, and it was actually difficult to obtain a high-quality single crystal. Some crystals are difficult to apply to the Bridgman method, the floating zone melting method, and the like.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made to solve the drawbacks of the conventional method for producing a single crystal and to easily produce a high-quality single crystal with few defects by a pulling method. It is an object of the present invention to provide a method for producing a single crystal that can be performed.

[0005]

SUMMARY OF THE INVENTION The present invention, as to solve the above problems, in producing a single crystal by the pulling method, immersing the pipe in the melt, then pulling the pipe upwards, the pipe first polycrystalline the after was crystallized this multi-crystal by single crystal single crystal seed crystal to create in
Then, the present invention provides a method for producing a single crystal, characterized in that crystal growth is continued in a pipe to produce a single crystal.

In the method for producing a single crystal according to the present invention,
After immersing the pipe in the melt, the pipe is pulled upward and crystallized in the pipe to initially crystallize a polycrystal. Then
While the polycrystal grows in the pipe, it is monocrystallized to produce a single crystal. Then, this single crystal is used as a seed crystal as it is, and a single crystal of a desired size is produced from the melt by a pulling method.

FIGS. 1A and 1B are schematic cross-sectional views showing a method of manufacturing a single crystal according to the present invention in the order of steps.
In the case of producing a single crystal, first, as shown in FIG. 1a, a pipe (1) is immersed in a melt (2) from above. Then, the melt (2) rises in the pipe (1) by capillary action, and crystallization starts in a low-temperature portion in the pipe (1). At this point, polycrystals crystallize.

Next, as shown in FIG. 1B, when the pipe (1) is pulled upward, the interface between the crystallized polycrystal and the melt moves downward in the pipe (1) with this movement. Move, during which time the polycrystal single crystallizes. This single crystal is used as a seed crystal, and a single crystal of a desired size is formed following the production of the single crystal seed crystal. The finally crystallized single crystal is separated from the lower end of the pipe (1), and is crystallized in the same manner as in a normal pulling method. A single crystal of the desired size is produced.

As described above, in the method for producing a single crystal according to the present invention, the production of the seed crystal and the production of the single crystal can be performed continuously. In the preparation of a single crystal seed crystal, shape control is easy, the polycrystalline portion does not break at the grain boundaries, and there is no problem of dropping the sample. Also, skill such as necking is not required. Furthermore, since the produced single crystal is used as a seed crystal as it is, crystal defects such as dislocations are suppressed. Seed crystals can also be produced for crystals for which it is difficult to apply the Bridgman method, the floating zone melting method, or the like. A high-quality single crystal with few defects can be easily manufactured by a pulling method. In the case of the present invention, even when there is no suitable single crystal as a seed crystal, a single crystal can be effectively produced together with the single crystal seed crystal, and as is clear from the above, no special device is used. In addition, the present invention can be applied as it is to a conventionally used lifting device.

[0010]

EXAMPLES Examples are shown below to produce a single crystal of the present invention.
The method will be described in more detail.Example 1 In the lifting device, platinum with a diameter and height of 50 mm
BaB in the crucible_TwoO _FourIs melted (melting point 1095 ° C) and the diameter is
2mm, 0.1mm thick, 50mm long platinum pipe holder
Immersed in the melt from above while rotating at 20 rpm
did. Platinum is BaB_TwoO_FourIt did not react with and wet well.

The melt rises about 10 mm from the lower end of the platinum pipe by capillary action due to capillary action, and crystallization starts at a low temperature portion in the pipe (polycrystal crystallization). Thereafter, as the pipe was pulled upward at 2 mm / h, the interface between the crystallized polycrystal and the melt moved downward in the pipe, during which the polycrystal was single-crystallized. Using this single crystal as a seed crystal, crystal growth was subsequently continued. The single crystal finally crystallized was separated from the end of the pipe, and the single crystallization proceeded in the same manner as in a normal pulling method, whereby a single crystal having a diameter of 20 mm and a length of 50 mm could be produced.

In the above description, the polycrystalline portion is inside the pipe.
The sample does not break at the grain boundaries during growth
Was.Example 2 In the lifting device, platinum with a diameter and height of 50 mm
BaB in the crucible_TwoO _FourIs melted (melting point 1095 ° C) and the diameter is
2mm, 0.1mm thick, 100mm long platinum pipe holder
Immersed in the melt from above while rotating at 20 rpm
did. Then, put the platinum pipe 30mm from near the bottom of the crucible.
Lowered to the point.

The melt rose in the platinum pipe by about 40 mm from the lower end of the pipe due to capillary action, and crystallization started at a low temperature portion in the pipe (crystallization of polycrystal). Thereafter, as the pipe was pulled upward at 2 mm / h, the interface between the crystallized polycrystal and the melt moved downward in the pipe, during which the polycrystal was single-crystallized. When the crystal was grown by 20 mm or more in a pipe, crystal defects such as dislocations at the center of the crystal generated in the first crystallization escaped from the crystal.

Using this single crystal as a seed crystal, the crystal growth was continued. The single crystal finally crystallized was separated from the end of the pipe, and the single crystallization proceeded in the same manner as in a normal pulling method, whereby a single crystal having a diameter of 20 mm and a length of 50 mm could be produced. In the above, the polycrystalline portion was in the pipe, and the sample did not break at the grain boundaries and fall during growth. In addition, crystal defects such as dislocations in the center of the crystal generated in the first crystallization were reduced, and a high-quality single crystal was obtained.

Of course, the present invention is not limited by the above examples. It goes without saying that various aspects are possible for details such as the type and size of the single crystal, the material and shape of the pipe, and the like.

[0016]

As described in detail above, according to the present invention, a single crystal can be easily produced by a pulling method, and even if there is no suitable single crystal as a seed crystal, a single crystal having a desired size can be obtained. Can be manufactured. Since seed crystal production and single crystal production can be performed continuously, and a conventional pulling apparatus can be applied, the efficiency of single crystal production is improved. It is also possible to produce a high-quality single crystal with few defects. For example, it is suitable for a nonlinear optical material that is useful in the optical field such as a single crystal laser element and a wavelength conversion element.

[Brief description of the drawings]

FIGS. 1a and 1b are schematic cross-sectional views showing a method of manufacturing a single crystal according to the present invention in the order of steps.

[Explanation of symbols]

 1 pipe 2 melt

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C30B 15/00 C30B 15/36 C30B 28/00-35/00

Claims (1)

(57) [Claims] In producing a single crystal by 1. A pull-up method, immersing the pipe in the melt, then pulling the pipe upwards, first <br/> polycrystalline after crystallized this in a pipe polycrystalline was single-crystallized create a single crystal seed crystal, followed by the method for producing a single crystal, characterized by producing a single crystal by continued crystal growth in the pipe.