JP2966677B2 - Single crystal growing apparatus and 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 an apparatus for growing a single crystal, in particular, a semiconductor such as Si, Ge, etc. by the vertical Bridgman method.
III-V compound semiconductors such as GaAs and InP, GdT
e, ZnSe and other II-IV compound semiconductors, BGO, L
A single crystal growing apparatus for growing single crystals of oxides such as BO,
And a method for producing a single crystal using the apparatus.

[0002]

2. Description of the Related Art Semiconductors such as S and Ge, GaAs and In
Growing of III-V group compound semiconductors such as P, II-IV group compound semiconductors such as GdTe and ZnSe, and oxide single crystals such as BGO and LBO are usually performed by a vertical Bridgman method, a pulling method or the like. In this vertical Bridgman method, the raw material melt is housed in a vertical container, the container is placed in a furnace with a temperature gradient, and the raw material melt is cooled and solidified from below by moving it downward, thereby obtaining a single crystal. This single crystal growing apparatus by the vertical Bridgman method is used to obtain a good quality crystal by making a desired temperature in the furnace core tube in a necessary range in the length direction of the furnace core tube. In addition, the heating device was composed of a number of heating elements along the longitudinal direction on both sides of the furnace core tube, the heating elements were divided into a plurality of independent heating sections, and each heating section was independently temperature-controlled. One has been proposed (see JP-A-2-221180).

As a factor determining the crystal growth rate in the crystal growth method according to the Bridgman method, it is known that compositional supercooling is likely to occur. It is necessary to increase the temperature gradient in the direction, but it is easy to increase the temperature gradient when the inner diameter of the furnace core tube is small. This includes, for example, 1) dividing the furnace into a plurality of heaters, A method of increasing the set temperature of the heater at a position where the temperature gradient is desired to be increased, a method of installing a heat shielding plate at a position where the temperature gradient is desired to be increased, and a method of cooling the position at which the temperature gradient is desired to be cooled with water, etc. ing. For furnaces with a relatively large furnace core tube, it was also reported that the furnace core tube, crucible base, etc., were all made of quartz and that the temperature gradient was increased by facilitating the escape of radiant heat in the furnace from below the furnace. [See J. Cryst. Growth. 94 (1989) 373-380].

[0004]

In the growth of a single crystal by the Bridgman method, all the raw materials in a vertical vessel housed in a furnace are once melted, and then a temperature gradient is gradually set across the melting point of the single crystal to be grown. Although it is performed by moving downward, industrially it is necessary to grow a large-diameter single crystal in a short time, so it is necessary to increase the temperature gradient at the position where crystal growth is progressing. Needed. Therefore,
An industrially preferred Bridgman furnace is designed to increase the temperature gradient at the inner diameter of the furnace core and at the growing position, and not to raise the temperature of the zone for melting the raw material so much from the melting point. In order to grow large-diameter crystals, it is necessary to adopt a supporting type in which the crucible is placed on a crucible base instead of a method in which the crucible is hung.

However, in this under-supported Bridgman furnace, the inner diameter of the furnace core tube is set to 140 mm so that a crystal having a crystal system of 3 inches or more can be grown.
As described in 221180, the heating device is composed of a large number of heating elements, and the heating element is divided into a plurality of independent heating zones to increase the temperature gradient at the growing position. Temperature gradient of only 8 ° C./cm, and the temperature gradient at the growth position for the furnace core tube and the crucible base made of quartz as described in the above-mentioned document also shows the growth position of the furnace. No remarkable change was seen only by moving upward, the furnace temperature could not be equalized by using quartz, and the quality of the crystal was degraded by the overheating of the raw material, and the appearance of an unfavorable phase caused by the appearance of an undesirable phase. Decreased.

As a method of increasing the temperature gradient, a method of installing a baffle or reflector that blocks radiant heat near the growing position is known.
In this method, it is necessary to enlarge the reflector to a certain extent.Therefore, even if the furnace core tube is enlarged, if the inner diameter of the reflector is small, there is a disadvantage that the crystal that can be grown has a small diameter. There is a problem that a single crystal having a large diameter cannot be manufactured.

[0007]

SUMMARY OF THE INVENTION The present invention relates to an apparatus for growing a single crystal and a method for producing a single crystal which solves such disadvantages and problems. Having heating means provided outside the furnace core tube,
In an apparatus for moving a crucible into the furnace core tube to grow a single crystal material contained in the crucible into a single crystal, a furnace core is provided.
The present invention is characterized in that a plurality of reflectors are provided along the inner wall of the tube , and the method for producing a single crystal is characterized in that a single crystal is grown using the single crystal growing apparatus. .

That is, the present inventors have conducted various studies to develop an apparatus for easily growing various types of single crystals by the vertical Bridgman method. In a vertical Bridgman furnace in which a crucible containing a single crystal material is placed in the furnace core tube, a plurality of reflectors are provided along the inner wall of the furnace core tube. In the part, the heat retention is improved, the temperature gradient can be increased by the reflector, it is found that the optimum distribution is possible as a Bridgman furnace, and it is not necessary to increase the size of individual reflectors, and the inner diameter of the reflector is increased it is possible to, easily the so with Bridgman furnace various large single crystal, and be produced efficiently It was completed with the present invention confirmed that you can. This will be described in more detail below.

[0009]

The present invention relates to a single crystal growing apparatus and a method for producing a single crystal. The single crystal growing apparatus has a cylindrical furnace core tube and heating means provided on the outside thereof, and the crucible is connected to the furnace core. an apparatus for growing a single crystal of the single crystal material that houses moved in a crucible inside the tube, along the inner wall of the furnace core tube
What is intended to characterized in that it comprises a plurality of reflectors, although the single-crystal manufacturing method is characterized in that for growing a single crystal by using the single crystal growing apparatus, in which According to this, the single crystal growing apparatus has the advantage of being able to easily and efficiently produce various single crystals because the distribution of heat is optimized as a Bridgman furnace.

The single crystal growing apparatus of the present invention is, for example, as shown in FIG. FIG. 1 is a longitudinal sectional view of a single crystal growing apparatus according to the present invention, in which a heater 3 is provided outside a furnace core tube 1 and a crucible 4 and a crucible base are provided in the furnace core tube 1. 5 on the inner wall of the furnace core tube 1
A plurality of reflectors 6 are provided along the furnace core 1, and a lid 7 is provided on the furnace core tube 1.

Since the furnace core tube 1 in this apparatus is preferably made of a material having good heat conductivity, for example, one made of high-purity alumina, silicon nitride, or high-purity alumina lined with platinum is used. The lower part is made of a furnace core tube 2 made of quartz. The heater 3 includes a plurality of heaters 3-1, 3-2, and 3-3 for dividing the length direction of the furnace core tube into a plurality of independent heating sections and independently controlling the temperature of each heating section. It is good to have made it. In addition, the crucible 4 may be generally made of a metal material such as platinum, platinum-rhodium, iridium, etc., but the crucible base 5 is made of transparent quartz because it easily releases radiant heat downward. It is good to be made from.

This apparatus is provided with a plurality of reflectors 6 along the inner wall of the furnace core tube. This reflector may be made of any material as long as it is capable of reflecting radiant heat. May be used, and generally, platinum, platinum-rhodium, iridium, nickel, etc. may be used. Although the effect increases as the number of sheets increases, the number of sheets may be set to about 3 to 6 in consideration of material costs and labor for installation.

The apparatus for growing a single crystal according to the present invention is characterized in that a plurality of reflectors are provided along the inner wall of the furnace core tube. Naturally, the reflector functions as a reflector.However, since it is composed of a plurality of reflectors, the heat retention is improved in the high temperature part above the reflector, and the temperature gradient of this Bridgman furnace changes remarkably by the reflector, and the optimal temperature distribution In this case, if high-purity alumina is used as the furnace core tube, the heat conduction is good, so that excessive heating of the raw material is prevented, and if a quartz material is arranged as a crucible base , radiant heat is effectively escaped. Therefore, a larger temperature gradient can be obtained. According to this, semiconductors such as Si and Ge, III-V compound semiconductors such as GaAs and InP, II-IV compound semiconductors such as GdTe and ZnSe,
This provides an advantage that single crystals of oxides such as BGO and LBO can be easily and efficiently manufactured.

[0014]

Next, examples of the present invention and comparative examples will be described. Embodiment A hollow cylindrical furnace core tube 1 made of high-purity alumina having an inner diameter of 140 mm as shown in FIG. 1 and a quartz furnace core tube 2 provided vertically below the furnace core tube 1 are provided vertically. 3-1, heater 3-2, and heater 3-3 are divided and arranged in the longitudinal direction of the furnace core tube.
A 90 mm platinum crucible 4 is placed on a crucible table 5 made of transparent quartz, and is placed near a single crystal growing point in the furnace core tube 1.
Five reflectors 6 made of platinum were mounted along the inner wall of the furnace core tube, and a lid 7 was provided on the furnace core tube 1.

Then, 4,500 g of Bi ₄ Ge ₃ O ₁₂ (hereinafter abbreviated as BGO) polycrystal is inserted into the crucible, and the furnace core tube is heated to about 1,100 ° C. by the heater 3, and the crucible is heated. When the BGO single crystal was grown at a growth rate of up to 1.0 mm / hour by lowering into the tube, the temperature gradient near the single crystal growth point in the longitudinal direction in the furnace core tube became 23 ° C./cm. 3,800 g of the crystal was obtained as a good single crystal having no crystal defects such as cellular inclusions, but the cellular inclusions were contained in the upper part of about 20 mm of the crystal.

Comparative Example A BGO single crystal was grown using the known single crystal growing apparatus shown in FIG. 2 similar to that of Example 1 except that a plurality of reflectors were not provided in the single crystal growing apparatus of Example 1. However, in this case, the temperature gradient near the growth point of the single crystal in the longitudinal direction in the furnace core tube was 8% because there were no plural reflectors.
° C / cm, and thus a single crystal obtained at a growth rate of 0.5 mm / hour had many crystal defects such as cellular inclusions. Also, as will those of the crucible base and the furnace core tube of high purity alumina made quartz
When the temperature gradient was measured instead, the temperature gradient was 9 ° C./cm and no remarkable change was seen only when the growing position was moved 50 mm above the furnace, and the transparency was good because it was made of quartz. As a result, the furnace temperature could not be soaked, and the peak temperature of the furnace increased by 50 ° C. In this case, the entire crystal became reddish in addition to the cellular inclusions.

[0017]

According to the present invention, a single crystal growing apparatus having the above structure is used.
By doing so , the heat retention in the high temperature area above the reflector is improved, and the reflector can increase the temperature gradient near the single crystal growth point in the longitudinal direction in the furnace core tube.
The optimum temperature distribution is obtained for the Bridgman furnace.
Luo, reflector and can be increased inside diameter of the reflector in providing plural, easily various large single crystal, and efficiently, it is possible to obtain a crystal defect single crystal. In addition, the furnace core tube and crucible stand below the growing device
Or make the material of the crucible support tube transparent so that radiant heat can easily pass through
Greater temperature gradient near single crystal growth point by using quartz
Can be heard.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a single crystal growing apparatus of the present invention.

FIG. 2 is a longitudinal sectional view of a known single crystal growing apparatus.

[Explanation of symbols]

 1 ... Alumina furnace core tube, 2 ... Quartz furnace core tube, 3 ... Heater, 4 ... Crucible, 5 ... Crucible stand, 6 ... Reflector, 7 ... Lid.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Toshihiko Nagao 2-1-1 Isobe, Annaka-shi, Gunma Prefecture Shin-Etsu Chemical Co., Ltd. Precision Functional Materials Research Laboratories (56) References JP-B 37-17102 ( JP, B1) (58) Field surveyed (Int. Cl. ⁶ , DB name) C30B 1/00-35/00

Claims (3)

(57) [Claims] 1. A single crystal material comprising a cylindrical furnace core tube and a heating means provided outside the furnace core tube, wherein the crucible is moved into the furnace core tube and the single crystal material stored in the crucible is converted into a single crystal. An apparatus for growing a single crystal, comprising a plurality of reflectors provided along an inner wall of a furnace core tube . 2. The single crystal growing apparatus according to claim 1, wherein a material of a furnace core tube, a crucible base, or a crucible base supporting pipe at a lower portion of the crystal growing apparatus is made of transparent quartz that easily transmits radiant heat. 3. A method for producing a single crystal, comprising growing a single crystal using the apparatus for growing a single crystal according to claim 1.