JPH09110577A - Production of aluminum-gallium-arsenic single crystal by flux method and production unit therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mass-produce a three-component single crystal in a short time by inexpensive and simple means by fluxing a stock comprising Ga and GaAs followed by adding Al being in shortage to the flux to grow an AlGaAs single crystal having a required composition. SOLUTION: The upper and lower spaces of a partition plate 11 having a tiny hole 12 in a longitudinal crucible 1 for melting stocks are first charged with Ga and GaAs stocks which are then heated and melted into a flux 2 which is agitated by rotating a rare earth metal magnet 4. (1) The Al-free flux is brought into contact with a GaAs seed 3 to effect seeding. (2) Al granules are charged in an amount <=1/1,000wt. times that of the flux via a stock inlet 16 into the flux at specified time intervals to adjust the amount of the Al in the flux to a specified concentration. (3) The flux is charged with Al granules and GaAs granules alternately or simultaneously so that the weight ratio Al/Ga comes to that with the aimed composition; thereby the objective AlGaAs single crystal having a target composition is grown to produce an ingot of single crystal form.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a ternary single crystal body using a vertical boat.
More specifically, the present invention relates to a method and an apparatus for manufacturing a multi-component single crystal in which crystals are grown while stirring a flux (melt) loaded in a vertical boat.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a multi-component single crystal, a choral sulky method in which a seed crystal (seed) is put into a raw material melt and the single crystal attached to this seed crystal is pulled while rotating, A vertical boat method in which a raw material is put into a cylindrical vertical boat to melt it and then the temperature of the melt is lowered from the bottom of the boat to grow crystals in the boat is widely known.

In addition to the above, a method of generating a flux having a raw material composition such that a compound semiconductor having a desired composition is deposited and then epitaxially growing the flux on a GaAs single crystal seed, or floating AlGaAs having a desired composition above the flux, This is deposited in the lower part of the flux and the target composition of A
A method for growing an lGaAs single crystal has also become known.

However, according to these conventional crystal growth methods, there is a problem that the crystal growth rate is extremely slow. This is because the crystal growth rate depends on the rate at which the raw material diffuses into the flux, but in the prior art there is no suitable means for stirring the flux, and the rate of diffusion of the raw material into the flux is Because it was based on natural diffusion control.

As a means for solving these drawbacks, the present inventors have previously disclosed in JP-A-6-340489 "Method and apparatus for producing a multi-component single crystal body" in which a rare earth which can easily stir a flux is used. Although a magnet rotating mechanism has been disclosed, this method has been able to achieve a considerable effect.

[0006]

However, in the subsequent research, among the multi-component semiconductor compounds, particularly AlGaA
Since the segregation of Al during crystal growth during the process of producing a ternary single crystal reduces the Al content in the flux and the solubility of the AlGaAs compound in Ga is small, the target Al / Ga ratio is With Al
It was found that a single crystal having a GaAs composition cannot be formed and only a small amount of AlGaAs single crystal can be produced with respect to the flux amount.

Therefore, the present invention solves the above-mentioned problems and provides a method and an apparatus for producing an AlGaAs single crystal body capable of producing a uniform and high-quality AlGaAs single crystal in a large amount in a short time by an inexpensive and simple means. The purpose is to provide.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, the flux is agitated by inducing an electromagnetic induction current in the flux with a rare earth magnet, and the binary It has been found that an AlGaAs single crystal having a desired composition ratio can be manufactured by adding a deficient Al compound after fluxing the compound to provide the present invention.

That is, the first aspect of the present invention is that GaAs is formed on the bottom.
A first step of seeding by placing a raw material consisting of Ga and GaAs in a crucible in which a seed body is placed, and then melting the resulting material to bring it into contact with a GaAs sheet body for seeding, and then using Al particles as the above flux A second step of obtaining AlGaAs single crystal by alternately adding Al grains and GaAs after adjusting Al to a predetermined concentration by adding Al in the inside to produce AlGaAs single crystal by the flux method. Regarding the method.

A second aspect of the present invention is a method for producing an AlGaAs single crystal on a GaAs seed crystal by a flux method using a vertical crucible, the first step of starting the growth, A
l The second step of increasing the composition and the third step of growing a single crystal of the target composition are included.
Seeding is performed on a GaAs seed using a flux that is composed of aAs and does not contain Al. In the second step, 1/1000 (weight) or less of the flux amount of metallic Al is introduced into the flux at regular time intervals. The present invention relates to a method for producing an AlGaAs single crystal, characterized in that, in the third step, the metal Al and GaAs are simultaneously or alternately introduced into the flux so that the Al / Ga weight ratio becomes the weight ratio of the target composition.

A third aspect of the present invention comprises a container (flux charging container) for containing Al and GaAs in which the vertical crucible is charged and a container for growing a single crystal of AlGaAs (crystal growth container). The flux in both containers is connected through a hole having a diameter of 2 to 5 mm provided at a boundary between the Al and the Al according to the second aspect.
The present invention relates to a method for manufacturing a GaAs single crystal.

A fourth aspect of the present invention is a crystal manufacturing apparatus comprising a vertical boat having a raw material melting crucible provided therein and a driving mechanism provided in the crucible, wherein a rare earth magnet is circulated around the outer periphery of the raw material melting crucible. A rare earth magnet rotating mechanism is provided, and the raw material melting crucible is made of two kinds of materials having different thermal conductivities, and a partition plate having a small hole for vertically dividing the flux is provided in the crucible. The present invention relates to an apparatus for producing an AlGaAs single crystal, which is characterized in that

[0013]

In the present invention, using the manufacturing apparatus shown in FIG. 1, Ga and GaAs raw materials are charged in advance above and below the partition plate in the raw material melting crucible 1, and the central, upper and lower heaters 1 in the furnace are charged.
The materials in the crucible are melted by heating to 1,170 ° C. in 3, 14, and 15.

In this case, when the raw materials above and below the partition plate in the crucible begin to melt, the rare earth magnet 4 provided on the outer peripheral portion of the central heater 13 orbits to agitate these melts, and the raw material above the partition plate It becomes a melt (hereinafter referred to as a flux) and enters the crucible 1 through the small holes 12 of the partition plate, while the flux in the crucible is seeded on a seed body previously provided at the bottom of the crucible (No. 1). One step).

Next, Al particles (0.06 g / one piece) are charged from the raw material charging port 16 provided at the upper part of the manufacturing apparatus every 10 minutes, so that the weight ratio of the metallic Al is 1/1000 or less. Grains are dropped to mix a certain concentration of Al in the flux.

Next, while gradually cooling the furnace temperature at a rate of 5 ° C./hr, 0.5 g of GaAs was introduced every 5 minutes and Al particles were introduced every 10 minutes, and the flux obtained was GaAs under the partition plate. The AlGaAs single crystal was grown by operating so as to mix with the main flux, and finally an ingot of the AlGaAs single crystal was manufactured (second step).

As described above, in the first step and the second step, the electromagnetic induction current is induced in the flux (melt) by the rare earth magnet, the flux is agitated by the induced electromagnetic induction current, and the raw material is in the flux. In addition to increasing the diffusion speed, the contamination of the flux due to the electromagnetic induction current does not cause contamination, so that an extremely uniform and high quality AlGaAs single crystal can be manufactured in a short time.

On the other hand, the AlGaAs single crystal production apparatus of the present invention is a crystal production apparatus having a vertical boat and a driving mechanism provided in a crucible. A rare earth magnet is circulated around the outer periphery of the central heater. A rare earth magnet rotating mechanism is provided. As such a crystal production apparatus, for example, a conventional vertical Bridgman-type multi-component single crystal production apparatus provided with a rare earth magnet rotation mechanism outside can be used, whereby a single crystal can be produced. it can.

Another feature of this apparatus is that a partition plate having small holes is arranged in a crucible provided inside a heater,
After the generated flux is attached to the seed body, a melt of Al particles obtained by adding it from the raw material charging port is mixed little by little into the flux through the small holes of the partition plate.

This makes it possible to prevent Al segregation during crystal growth, which is a drawback of the conventional method, and to mix the flux uniformly in the flux.

The second feature of the apparatus of the present invention is that the crucible is made of a special material of graphite and vitro carbon (trade name of vitreous carbon manufactured by Nippon Carbon Co., Ltd.) instead of the conventional graphite material alone. To form a temperature gradient.

Since the graphite material alone has a too high thermal conductivity, it has a property that heat easily escapes. Therefore, the thermal conductivity is 1/20 to 1/5 that of the graphite material.
It uses the zero carbon material, vitro carbon. Furthermore, it has been confirmed that it is effective to coat the outside of the crucible with a Vitro coating of about 0.1 mm to prevent gas leakage in the crucible.

The present invention is described in detail below with reference to examples, but the scope of the present invention is not limited to these.

[0024]

Example 1 An electromagnetic induction stirring vertical Bridgman furnace (VGF furnace) manufactured by Dowa Mining Co., Ltd. shown in FIG.
300 g of a and 580 g of GaAs are loaded into a special carbon crucible having a 2-inch inner diameter. In this case, first, an appropriate amount is loaded on the upper part of the GaAs seed body 3 (φ52 × 15t: orientation [100]), and then the partition plate 11 is fixed. , And the rest was placed on the partition plate 11 and heated in an argon atmosphere.

When the raw material begins to melt to some extent, the rare earth magnet 4 is circulated at a rotation speed of 100 rpm, the flux produced is uniformly mixed under electromagnetic induction stirring, the crucible temperature is set to 1170 ° C., and the obtained flux is obtained. To G
The aAs seed body 3 was seeded (first step).

Next, metal Al particles (0.06 g / piece) are charged from the raw material charging port 16 every 10 minutes to be melted, and the obtained Al melt is provided in the partition plate 11 and a plurality of small particles of φ2 to φ5 are provided. After charging through the hole 12 into the flux 2 inside the crucible 1 and adjusting so as to keep mixing and to be 1/1000 (weight ratio) or less of the total amount of flux, the furnace temperature is set at 5 ° C./hr. Gradually cool and simultaneously add 0.5 g of GaAs every 5 minutes to 2
60 times, Al particles (0.06 g) are charged 130 times every 10 minutes, and the obtained melt is mixed with the flux inside the crucible in the same manner as above, and finally AlGaAs containing 30 to 35% of Al is added. An ingot containing a single crystal (φ52 × 10 mm) was obtained (second step).

[0027]

Example 2 Using the apparatus shown in Example 1, the first step was controlled under the same conditions.

Next, 100 Al grains were introduced every 10 minutes to adjust the Al concentration, and then GaAs was lowered in a temperature gradient of 15 ° C./cm at a rate of 0.25 mm / hr while lowering the crucible.
(0.5 g) 260 times every 5 minutes, Al particles (0.06 g)
Was added 130 times every 10 minutes to mix the resulting melt with the flux inside the crucible, and finally the Al
AlGaAs single crystal containing 30 to 35% (φ52 × 10
mm) was obtained (second step).

[0029]

Comparative Example 1 Using the same apparatus as in Example 1, 300 g of Ga, 580 g of GaAs, and 13.2 g of Al were simultaneously placed in the crucible and reacted at 1200 ° C. with a GaAs seed body (φ52 × 15 t) provided at the bottom of the crucible. Seeding was performed (first step).

Then, a single crystallization was attempted by cooling the crucible at a rate of 0.25 mm / hr in an atmosphere with a temperature gradient of 15 ° C./cm while electromagnetically stirring the mixture at 100 rpm to obtain a single crystal. I couldn't get it.

[0031]

According to the conventional method, since it was impossible to manufacture an AlGaAs single crystal as a means for manufacturing an AlGaAs diode, there was only means for removing the GaAs substrate by etching after forming the AlGaAs epitaxial layer on the GaAs substrate. , Al according to the method of the present invention
It is possible to manufacture a GaAs single crystal, which largely contributes to improvement in productivity.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a manufacturing apparatus according to the present invention.

[Explanation of symbols]

 1 crucible bottom (graphite) 1'crucible side (vitrocarbon) 2 flux 3 GaAs seed body 4 rare earth magnet 5 upper heater sensor 6 central heater sensor 7 crucible cradle sensor 8 lower heater sensor 9 heat insulating material 10 water cooling jacket 11 partition plate 12 Small hole 13 Central heater 14 Upper heater 15 Central heater 16 Raw material inlet

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[Procedure amendment]

[Submission date] November 22, 1995

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 1

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction contents]

That is, the first aspect of the present invention is that GaA is formed on the bottom.
After the raw material consisting of Ga and GaAs was charged into the crucible in which the s seed was placed, the flux obtained by melting it was used.
First step of seeding by contacting with GaAs seed , then adding Al grains into the above flux to adjust Al to a predetermined concentration, and then alternately adding Al grains and GaAs to obtain an AlGaAs single crystal body The present invention relates to a method for producing an AlGaAs single crystal by the flux method, which comprises the second step.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction contents]

In this case, when the raw materials above and below the partition plate in the crucible begin to melt, the rare earth magnet 4 provided on the outer periphery of the central heater 13 orbits to agitate these melts, so that the raw material above the partition plate It becomes a melt (hereinafter referred to as a flux) and enters the crucible 1 through the small holes 12 of the partition plate, while the flux in the crucible is seeded with a seed previously provided at the bottom of the crucible (first). Process).

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction contents]

Another feature of the present apparatus is that a partition plate having small holes is arranged in a crucible provided inside a heater, the generated flux is attached to a seed , and then added from a raw material charging port. The melt of the Al particles obtained in this way is mixed little by little into the flux through the small holes of the partition plate.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0024

[Correction method] Change

[Correction contents]

[0024]

Example 1 An electromagnetic induction stirring vertical Bridgman furnace (VGF furnace) manufactured by Dowa Mining Co., Ltd. shown in FIG.
300 g of a and 580 g of GaAs are loaded into a special carbon crucible with an inner diameter of 2 inches.
Over de 3: After an appropriate amount charged to the top of (φ52 × 15t orientation [100]), equipped with a partition plate 11 in position, further charged with the remainder on the partition plate 11, and heated in an argon atmosphere.

[Procedure correction 6]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction contents]

To some extent, when the raw material begins to melt, the rare earth magnet 4 is circulated at a rotation speed of 100 rpm, the flux produced is uniformly mixed while stirring with electromagnetic induction, the crucible temperature is set to 1170 ° C., and the obtained flux is obtained. To
The GaAs seed 3 was seeded (first step).

[Procedure amendment 7]

[Document name to be amended] Statement

[Name of item to be corrected] 0029

[Correction method] Change

[Correction contents]

[0029]

Comparative Example 1 Using the same apparatus as in Example 1, 300 g of Ga, 580 g of GaAs, and 13.2 g of Al were simultaneously placed in the crucible, and the GaAs sheet provided at the bottom of the crucible was used.
De reacted with (φ52 × 15t) and 1200 ° C. which was subjected to seeding (first step).

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] Explanation of sign

[Correction method] Change

[Correction contents]

[Explanation of Codes] 1 Crucible bottom (graphite) 1'Cruise side (vitro carbon) 2 Flux 3 GaAs seed 4 Rare earth magnet 5 Upper heater sensor 6 Central heater sensor 7 Crucible cradle sensor 8 Lower heater sensor 9 Insulating material 10 Water cooling Jacket 11 Partition plate 12 Small hole 13 Central heater 14 Upper heater 15 Central heater 16 Raw material inlet 17 Sample temperature measuring sensor

[Procedure amendment 10]

[Document name to be amended] Drawing

[Correction target item name] Fig. 1

[Correction method] Change

[Correction contents]

FIG.

Claims (4)

[Claims] 1. A crucible having a GaAs seed body at the bottom thereof is charged with a raw material made of Ga and GaAs, and the flux obtained by melting the raw material is brought into contact with a GaAs sheet body for seeding. Step, then add Al particles into the above flux to adjust Al to a predetermined concentration,
A method for producing an AlGaAs single crystal by a flux method, which comprises a second step of alternately adding Al grains and GaAs to obtain an AlGaAs single crystal. 2. A method for producing an AlGaAs single crystal on a GaAs seed by a flux method using a vertical crucible, which comprises a first step of starting growth, a second step of increasing Al composition and a single composition of a target composition. A third step of growing a crystal is used. In the first step, seeding is performed on a GaAs seed using a flux composed of Ga and GaAs and containing no Al. Metal Al of 1000 (weight) or less is charged into the flux at regular time intervals, and in the third step, Al is used.
Metal Al so that the weight ratio of / Ga becomes the weight ratio of the target composition.
And a method of manufacturing an AlGaAs single crystal, wherein GaAs and GaAs are simultaneously or alternately introduced into the flux. 3. A container (flux charging container) for accommodating Al and GaAs in which the vertical crucible is charged, and Al
It is composed of a container for growing a single crystal of GaAs (crystal growth container) and has a diameter of 2 to 5 m provided at the boundary between both containers.
The method for producing an AlGaAs single crystal according to claim 2, wherein the fluxes in both containers are connected through a hole of m. 4. A crystal production apparatus comprising a vertical boat having a raw material melting crucible arranged therein and a driving mechanism in the crucible, wherein a rare earth magnet rotating mechanism for rotating a rare earth magnet around an outer periphery of the raw material melting crucible. In addition, the raw material melting crucible is composed of two kinds of materials having different thermal conductivities, and a partition plate having a small hole for vertically dividing the flux is provided in the crucible. An AlGaAs single crystal manufacturing apparatus.