JP3654314B2 - Manufacturing method of AlGaAs single crystal by flux method and manufacturing apparatus used therefor - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a method for manufacturing a ternary single crystal body using a vertical boat and a manufacturing apparatus therefor, and more particularly, grows crystals while stirring a flux (melt) loaded in the vertical boat. The present invention relates to a method for producing a multicomponent single crystal and an apparatus for producing the same.
[0002]
[Prior art]
Conventionally, as a method for producing a multi-component single crystal, a seed crystal (seed) is put in a raw material melt, and a single crystal attached to this seed crystal is pulled up while rotating, or a cylindrical vertical type A vertical boat method in which a raw material is put into a boat to be melted and then the temperature of the melt is lowered from the bottom of the boat to grow crystals in the boat is widely known.
[0003]
In addition, after generating a raw material composition flux that precipitates the compound semiconductor of the target composition, this is epitaxially grown on a GaAs single crystal seed, or AlGaAs of the target composition is floated on the top of the flux and this is used as a flux. A method of growing an AlGaAs single crystal having a target composition by depositing it at the bottom has also become known.
[0004]
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. However, in the prior art, there is no suitable means for stirring the flux, and the diffusion rate of the raw material into the flux. Is based on natural diffusion control.
[0005]
As one means for solving these drawbacks, the present inventors previously described a rare earth magnet rotation mechanism capable of easily stirring a flux in Japanese Patent Laid-Open No. 6-340490 “Manufacturing method and manufacturing apparatus for multi-component single crystal”. However, this method has been able to achieve a considerable effect.
[0006]
[Problems to be solved by the invention]
However, in the subsequent research, among the multi-component semiconductor compounds, especially in the process of producing AlGaAs ternary single crystals, the segregation of Al during crystal growth significantly reduces the Al content in the flux. Since the solubility in Ga is small, it was found that an AlGaAs single crystal having the target Al / Ga ratio cannot be obtained, and that only a small amount of AlGaAs single crystal can be formed with respect to the flux amount.
[0007]
Therefore, the present invention provides an AlGaAs single crystal manufacturing method and apparatus for manufacturing an AlGaAs single crystal that can solve the above problems and can manufacture a uniform and high-quality AlGaAs single crystal in a large amount in a short time by an inexpensive and simple means. With the goal.
[0008]
[Means for Solving the Problems]
As a result of diligent research to achieve the above-mentioned object, the present inventors stir the flux by inducing electromagnetic induction current in the flux with a rare earth magnet, and after the binary compound is once fluxed, it is insufficient. The present inventors have found that an AlGaAs single crystal having a composition with a desired component ratio can be produced by adding an Al-based compound.
[0009]
That is, according to the first aspect of the present invention, a vertical Bridgman furnace is used to form Ga and GaAs on the seed and on a partition plate having a small hole above the seed in a vertical crucible having a GaAs seed disposed at the bottom. After the raw material is charged, the first step of seeding the flux obtained by melting this with the GaAs seed is added , and then the melt obtained by melting by adding Al grains is added into the flux. after adjusting the Al to a predetermined concentration Te, Ri second step to obtain an AlGaAs single crystal by adding Al particle and the melt which is obtained melted by introducing alternating with GaAs from adult, the rare earth magnet in the production method of the AlGaAs single crystal by the flux method, wherein that you stirring the flux by inducing an electromagnetic induction current in said flux caused to orbit on the outer periphery of the crucible That.
[0010]
A second aspect of the present invention is a method for producing an AlGaAs single crystal on a GaAs seed by a flux method using a vertical Bridgman furnace having a vertical crucible having a GaAs seed disposed at the bottom , and starting growth. It consists of one step, a second step for increasing the Al composition, and a third step for growing a single crystal of the target composition. In the first step, on the seed plate in the crucible and on the partition plate having a small hole above the seed. The GaAs seed is seeded by using a flux composed of Ga and GaAs obtained by melting and obtained without melting and containing Al, and in the second step, it is 1/1000 (weight) or less of the flux amount. the metallic Al was obtained melted was charged at a constant time interval melt were charged in the flux, in the third step so that Al / Ga ratio by weight is the weight ratio of the target composition Metal Al simultaneously or melt which is obtained melted by introducing alternating GaAs be those mixed in the flux, an electromagnetic induction current in said flux caused to orbit the rare earth magnet to the outer periphery of the crucible This is a method for producing an AlGaAs single crystal, characterized in that the flux is stirred by induction .
[0011]
A third aspect of the present invention includes a container (flux charging container) containing Al and GaAs charged with the vertical crucible and a container (crystal growth container) for growing a single crystal of AlGaAs. The flux in both containers is connected through a hole with a diameter of 2 to 5 mm in the partition plate provided at the boundary, and the introduced Al and GaAs at the upper part of the partition plate become a melt and pass through the hole to form the AlGaAs. 3. The method for producing an AlGaAs single crystal according to the first or second aspect, wherein the method enters a container (crystal growth container) for growing a single crystal.
[0012]
A fourth aspect of the present invention is a crystal manufacturing apparatus using a vertical boat having a raw material melting crucible disposed therein and an electromagnetic induction stirring type vertical Bridgman furnace in which a driving mechanism is installed in the crucible. The surrounding area is provided with a rare earth magnet rotation mechanism for rotating the rare earth magnet , and a raw material inlet for introducing Al and GaAs is provided at the top, and a small hole for dividing the flux vertically in the crucible. An apparatus for producing an AlGaAs single crystal, characterized in that a partition plate is provided.
[0013]
[Action]
In the present invention, using the manufacturing apparatus shown in FIG. 1, Ga and GaAs raw materials are charged in advance on the upper and lower sides of the partition plate in the raw material melting crucible 1, and the heaters 13, 14 and 15 at the center, upper and lower portions in the furnace are used. Heat to 1170 ° C. to melt the raw material in the crucible.
[0014]
In this case, when the raw material above and below the partition plate in the crucible begins to melt, the rare earth magnet 4 provided on the outer peripheral portion of the central heater 13 circulates and stirs these melts. Hereinafter referred to as “flux” and enters the crucible 1 through the small holes 12 of the partition plate, while the flux in the crucible is seeded into seeds provided in advance at the bottom of the crucible (first step).
[0015]
Next, Al particles (0.06 g / piece) are charged every 10 minutes from the raw material inlet 16 provided in the upper part of the production apparatus, and the metal Al particles are dropped so that the ratio is 1/1000 or less of the flux amount by weight. Then, a certain concentration of Al is mixed in the flux.
[0016]
Next, while gradually cooling the furnace temperature at a rate of 5 ° C./hr, at the same time, 0.5 g of GaAs is added every 5 minutes and Al particles are added every 10 minutes. The AlGaAs single crystal was grown by operating so as to be mixed, and finally an ingot of the AlGaAs single crystal was manufactured (second step).
[0017]
As described above, in the first step and the second step, an electromagnetic induction current is induced in the flux (melt) by a rare earth magnet, whereby the flux is agitated by the induced electromagnetic induction current and the raw material diffuses into the flux. In addition to increasing the speed, the flux agitation with the electromagnetic induction current does not cause contamination, so that an extremely uniform and high quality AlGaAs single crystal can be produced in a short time.
[0018]
On the other hand, the AlGaAs single crystal manufacturing apparatus of the present invention is a crystal manufacturing apparatus in which a vertical boat and a crucible are equipped with a drive mechanism, but a rare earth magnet rotating around the outer periphery of the central heater. A mechanism is provided. As such a crystal manufacturing apparatus, for example, a conventional vertical Bridgman type multi-component single crystal manufacturing apparatus with a rare earth magnet rotating mechanism installed outside can be used, and thereby a single crystal can be manufactured. it can.
[0019]
One of the other features of this device is that a partition plate having small holes is placed in a crucible provided inside the heater, and the generated flux is attached to the seed and then added from the raw material inlet. The Al particle melt is mixed into the flux little by little through the small holes in the partition plate.
[0020]
As a result, Al segregation during crystal growth, which is a drawback of the conventional method, can be prevented and the flux can be mixed uniformly in the flux.
[0021]
The second feature of the device of the present invention is that a crucible is formed by combining a special material of graphite and Vitrocarbon (a product name of vitreous carbon manufactured by Nippon Carbon Co., Ltd.) instead of the conventional graphite material alone as the crucible material. It has a temperature gradient.
[0022]
This is because a graphite material alone has a thermal conductivity that is too good, and therefore has a property that heat easily escapes. Therefore, a vitro carbon material that has a thermal conductivity of 1/20 to 1/50 that of a graphite material. Is used. Furthermore, it has been confirmed that the outer side of the crucible is provided with a vitro coating of about 0.1 mm to prevent gas leakage in the crucible.
[0023]
EXAMPLES Hereinafter, although this invention is demonstrated in detail with reference to an Example, the scope of the present invention is not limited to these.
[0024]
[Example 1]
Dowa Mining Ltd. Electromagnetic induction stirring type vertical Bridgman furnace shown in FIG. 1 (VGF furnace) using a first charged to a special carbon crucible 2 inch inner diameter and a Ga300g and GaAs580g as raw materials Suruga, in this case first GaAs seed 3 ( After an appropriate amount was charged in the upper part of φ52 × 15t (azimuth [100]), the partition plate 11 was mounted at a fixed position, and the remaining portion was further charged on the partition plate 11 and heated in an argon atmosphere.
[0025]
When the raw material starts to melt to some extent, the rare earth magnet 4 is rotated at a rotational speed of 100 rpm, the generated flux is uniformly mixed with electromagnetic induction stirring, the crucible temperature is set to 1170 ° C., and the obtained flux is used as a GaAs seed. 3 was seeded (first step).
[0026]
Next, metallic Al particles (0.06 g / piece) are charged every 10 minutes from the raw material inlet 16 and melted, and the obtained Al melt is supplied from a plurality of small holes 12 of φ2 to φ5 provided in the partition plate 11. When it is charged into the flux 2 inside the crucible 1 and adjusted to be 1/1000 (weight ratio) or less of the total amount of flux, the furnace temperature is gradually cooled at a rate of 5 ° C./hr. At the same time, 0.5 g of GaAs is added 260 times every 5 minutes and Al particles (0.06 g) are added 130 times every 10 minutes, and the resulting melt is mixed into the flux inside the crucible as above, and finally An ingot containing an AlGaAs single crystal (φ52 × 10 mm) containing 30 to 35% Al was obtained (second step).
[0027]
[Example 2]
Using the apparatus shown in Example 1, the first step was controlled under the same conditions.
[0028]
Next, 100 grains of Al particles were added every 10 minutes to adjust the Al concentration, and then 5% GaAs (0.5 g) was added while lowering the crucible at a rate of 0.25 mm / hr in a temperature gradient of 15 ° C./cm. AlGaAs (0.06 g) was added 260 times per minute and 130 times every 10 minutes and the resulting melt was mixed into the flux inside the crucible, and finally AlGaAs containing 30 to 35% Al. An ingot containing a single crystal (φ52 × 10 mm) was obtained (second step).
[0029]
[Comparative Example 1]
Using the same apparatus as in Example 1, Ga300g, GaAs580g, and Al13.2g were simultaneously placed in the crucible, and the seeding was performed by reacting at 1200 ° C. with the GaAs seed (φ52 × 15t) provided at the bottom of the crucible. (First step).
[0030]
Next, in an atmosphere with a temperature gradient of 15 ° C./cm, cooling was performed by lowering the crucible at a speed of 0.25 mm / hr with electromagnetic induction stirring at 100 rpm, but single crystallization was achieved, but only polycrystalline AlGaAs was obtained. It was.
[0031]
【The invention's effect】
In the conventional method, since it was impossible to produce an AlGaAs single crystal as a means for producing an AlGaAs diode, there was only a means for removing the GaAs substrate by etching after forming an AlGaAs epitaxial layer on the GaAs substrate. AlGaAs single crystals can be manufactured, which greatly contributes to the improvement of 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 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
17 Sample temperature measurement sensor

Claims (4)

Using a vertical Bridgman furnace, after a raw material composed of Ga and GaAs is charged on the seed and on a partition plate having a small hole above the seed in a vertical crucible having a GaAs seed at the bottom, The first step of seeding by bringing the flux obtained by melting the GaAs seed into contact with the GaAs seed, then adding the melt obtained by melting the Al grains into the flux to adjust the Al to a predetermined concentration after the second step to obtain an AlGaAs single crystal by adding Al particle and the melt which is obtained melted by introducing alternating with GaAs, formed Ri from allowed around the rare earth magnet to the outer periphery of the crucible method of manufacturing AlGaAs single crystal by the flux method, wherein that you stirring the flux by inducing an electromagnetic induction current in said flux. This is a method of manufacturing an AlGaAs single crystal on a GaAs seed by a flux method using a vertical Bridgman furnace equipped with a vertical crucible with a GaAs seed placed at the bottom. The first step of starting growth is to increase the Al composition. And a third step of growing a single crystal of the desired composition. In the first step, the crucible is charged on the seed and on a partition plate having a small hole above the seed and melted. The obtained GaAs seed is seeded using a flux composed of Ga and GaAs and containing no Al. In the second step, metal Al of 1/1000 (weight) or less of the flux amount is fixed at regular intervals. in a charged to have been obtained by melting the melt was charged in the flux, the third metallic Al as Al / Ga ratio by weight is the weight ratio of the target composition in the process and Ga simultaneously or melt which is obtained melted by introducing alternating s be those mixed in the flux, thereby inducing an electromagnetic induction current in the flux caused to orbit the rare earth magnet to the outer periphery of the crucible The method for producing an AlGaAs single crystal, wherein the flux is stirred by A partition plate provided at the boundary between the two containers, comprising a container (flux charging container) containing Al and GaAs charged with the vertical crucible and a container (crystal growth container) for growing an AlGaAs single crystal. The container in which the fluxes in both containers are connected through a hole having a diameter of 2 to 5 mm, and the Al, GaAs charged on the upper part of the partition plate becomes a melt to grow the AlGaAs single crystal through the hole ( 3. The method for producing an AlGaAs single crystal according to claim 1, wherein the method enters a crystal growth vessel . In a crystal manufacturing apparatus using a vertical boat with a raw material melting crucible inside and an electromagnetic induction stirring vertical Bridgman furnace equipped with a drive mechanism in the crucible, a rare earth magnet is placed on the outer periphery of the raw material melting crucible. A rotating rare earth magnet rotating mechanism is provided, a raw material inlet for introducing Al and GaAs is provided at the top, and a partition plate having small holes for dividing the flux vertically is provided in the crucible. An apparatus for producing an AlGaAs single crystal.

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