JPS60180988A - Crucible for single crystal growth by bridgman- stockburger method - Google Patents

Abstract

PURPOSE:To obtain an excellent temp. distribution, and to obtain an excellent crystal having low dislocation density by inserting an inner cylinder coaxially into the inside of the bottomed cylindrical main body while keeping a minute clearance between the main body and the inner cylinder. CONSTITUTION:An inner cylinder 2 made of a thin plate is coaxially inserted into the inside of a bottomed cylindrical main body 1. And a minute clearance 3 is provided between the main body 1 and the inner cylinder 2. An excellent temp. distribution consisting of isothermal surfaces vertical to the axis can be obtained at the inside of the crucible, and less strains are given to the crystal by using said crucible. Accordingly, the excellent crystal having low dislocation density can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The Bridgman-Stockberger method for growing single crystals usually uses a vertical furnace to grow the upper part at a temperature about 50 to 10 Gl'O higher than the melting point of the crystal. In addition, the lower part is kept at a lower temperature to the same extent, and the cylindrical Ruriho containing the crystal melt is rotated at a slow speed and gradually moved from the upper part of the furnace to the lower part. First, a crystal nucleus forms at the bottom of the tsubo, and as the tsubo descends, it gradually grows toward the bottom.The material for the tsutsuba is made of high-purity graphite, or perhaps platinum. any metal,
Glass, quartz, alumina, etc. can be selected freely (two choices are possible, but in order to extract the obtained crystal, it must be a material with poor wettability). It is possible to grow a very wide range of single crystals, such as large crystals, ferrite-related crystals, calcium fluoride, lithium fluoride, etc. ◎ However, crystals that cause volumetric expansion due to the addition of strain In order to obtain even better single crystals, it is desirable that the temperature distribution inside the crystal forms a plane perpendicular to its axis. However, the conventional rutsuho does not have sufficient performance in these respects.Furthermore, if only one crystal is formed at the bottom of the rutsuho, there is a problem. Nuclei are generated at the same time and each one begins to grow, so in order to obtain a large single crystal, a small hole is formed in the axial direction at the bottom of Haruho, and a small one is further constricted into the small hole. Making parts is being done.

However, it is effective for obtaining Kuresha single crystals.
When taking out a mature crystal, the expensive embedding must be destroyed, which is extremely uneconomical.Accordingly, in the present invention, the isothermal blood inside the embedding has a good temperature in which the plane is perpendicular to the axis. It is possible to obtain a good crystal with a low N dislocation density, with less strain on crystals that undergo volume expansion during solidification, and to form fins in the bottom holes. In this way, the crystal can be taken out without destroying the L mold.

FIG. 1 is a longitudinal cross-sectional view of an embodiment of the present invention, and is a cross-sectional view taken along the line A-A in FIG. In this way, the rutsuho of the present invention coaxially fits the inner @ 2 formed of a thin plate inside the bottomed cylindrical main body l, so that a microscopic part is formed between the main body l and the inner cylinder 2. Interval I1
3, and is used for growing single crystals by the Bridgman and Stockberger methods. In other words, calcium fluoride (OaFm) used in optical circuits, etc. is grown from single crystals such as lithium fluoride (L=y). It is made of graphite, and a collar is formed on the outer upper end of the main body 1, and it is fitted into the main body 1. Furthermore, the upper end 1 of the inner cylinder 2 is fitted with the lid body 5, and fixed with screws 6. be. The bottom surfaces of the main body 1 and the inner cylinder 2 are formed into a conical shape, and the main body 1 has a narrow (deep hole) in the axial direction at the apex of the cone, and a deep hole is formed at the apex of the inner cylinder 2. ), and the length of the cylindrical part is set to be, for example, about half the depth of the hole.
is supported by the main body 1 at its Efs and one end, and the distance @ 3 is kept uniform at each part, and the hole 7 is connected to the Fi cylindrical part 8 [
〈Fin 9, i.e., a small diameter part, is formed◎Pour the crystal raw material into such a tube (as mentioned above, bring the C11 part to a higher temperature than the l!J! point, and lower the lower part to the catfish temperature ζ −
When the crucible is rotated at a slow speed and lowered in the state of the opening ξ where the raw materials are melted by installing it in the L part of the vertical furnace, the temperature of the bottom of the hole becomes lower than the melting point. A crystal nucleus is formed. However, generally several nuclei are formed at the same time, and each begins to grow.
``laI is like this (; This is an enlarged view of the hole part in Figure 1 in a state where each of the six nuclei has grown. Five nuclei have started to grow at the same time and each is a separate crystal a.

6. The OL pores that form e, d, and a are extremely thin, and there is a constriction 9 in the middle, so the crystal that passes through the constriction and reaches E side is d. Only one single crystal is formed and the single crystal C grows.At this time, the crevice 3 inside the furnace, which is filled with vacuum or a suitable gas atmosphere, is also vacuumed. However, in any case, the molten raw material and For the grown crystal, the heat propagates only in the axial direction, and the radial propagation can be seen virtually.Therefore, inside the crystal, the axis is perpendicular to An isothermal blood consisting of flat planes is formed, and therefore an extremely good single crystal grows.In addition, by making the inner cylinder 2 as thin as possible, even if the volume expands when the raw material crystallizes, the expansion is prevented. Since this is compensated for by the bending of the inner cylinder, there is no fear of applying large strain to the crystal, and for this reason, a good single crystal can be obtained.Next, after the growth of the single crystal is completed, it is taken out. (Secondly, by first pulling out the crystal together with the inner cylinder 2 from the main body l, and then cutting the crystal, that is, the core part, which protrudes from the cylindrical part 8 at the lower end of the inner cylinder, the inner cylinder 2 is also removed. In other words, the crystals that have grown inside can be pulled out without destroying the Ruriho. body 10
・The cross-sectional opening of the bottom in the case where the bottom vJb is formed with 1
Fit these together coaxially and insert fl l mm between them.
15112 is provided between the degrees. and each cylindrical body 10+
At the apex of the conical bottom surface of No. 11, a small-diameter cylindrical portion 1311.4 that fits together with difficulty is formed. The hook 16 is formed by bending the tip of the cylindrical portion 13 inward. In other words, by forming the toothpick inner cylinder 2 with mI & cylindrical bodies and providing a distance of 91 g between them, the thermal conductivity at the inner wall of the crucible is further reduced. The effect of growing a good single crystal with the plane perpendicular to the axis is further increased.In addition, by providing the collar 16 as described above, the bottom hole (=
(In addition to the fins 9, fins 9 and 216 are also formed, making it possible to grow only the crystals of the fins more reliably.

The crucible of the present invention, which has been arranged in a single manner, has been selected because the temperature difference in the direction perpendicular to the axis is extremely small and it is possible to grow a good single crystal. By forming such a constricted part, growth can be inhibited, and the crystal can be taken out without destroying the crucible, and large strain forces can be prevented from being applied to the grown crystal, resulting in a low dislocation. Single crystals with good precision are produced at low cost.Furthermore, even if a seed crystal is inserted at the bottom of the small hole C2, it has excellent effects such as being able to grow a good crystal size in the center. Some 0

[Brief explanation of drawings]

Figure @1 is a longitudinal cross-sectional view of an embodiment of the present invention, Figure @2 is a cross-sectional view taken along line A-A of Figure 1, and Figure 83 is a diagram showing the crystal grown in the crucible shown in Figure @1 and Figure 2. Vertical view of the bottom of the brim,
FIG. 4 is a vertical sectional view of the bottom of another embodiment ζ2 of the present invention. In addition, when the book is set, l is the main body, 2-digit inner cylinder, 3,
12 is the gap ~ 4 is the collar 15 is the lid body, 6Vi screw, 1'
The i-hole 8113114 has a cylindrical part S9 16 which is constricted, 1
0.11 is a cylindrical body, 15 is a brim. O Patent applicant Rigaku 11L4IA Kogyo Co., Ltd. Agent Patent attorney Kadagaki Masuda'
:ITsol

Claims (1)

[Scope of Claims] (1) An inner cylinder formed of a thin plate is coaxially fitted inside a bottomed cylindrical main body, and a narrow gap is provided between the main body and the inner cylinder. Bridgeman features. Bridgman according to claim (1), in which the inner cylinder of the tube (2) for single crystal growth using the Stockberger method comprises a plurality of cylindrical bodies coaxially fitted one after another through minute gaps. ,
The crucible used for single crystal growth using the Stockberger method (3) has a main body and an inner cylinder whose bottom surfaces are formed into a conical shape, an axial hole is formed at the apex of the conical bottom surface of the main body, and a hole is formed at the apex of the conical bottom surface of the inner cylinder. A cylindrical portion is formed which fits tightly into the hole and has a length shorter than the depth of the hole. (The inner cylinder consists of a plurality of cylindrical bodies coaxially fitted one after another through minute gaps, and the apex of the conical bottom surface of each cylindrical body C2 (-) Short cylindrical parts are formed and they are tightly fitted, and C=the tip of the cylindrical part of the outer cylindrical body is bent inward to form a brim (Claim 3). Bridgeman
Brim for single crystal growth using the Stockberger method