JPS5988394A - Manufacturing device for gallium arsenide single crystal - Google Patents

Abstract

PURPOSE:To provide a titled device which provides a gallium arsenide single crystal having high quality by providing a blind cylinder in the opening part of a high pressure vessel, and providing a means for blowing arsenic into a melt by sliding a supporting bar fixing an arsenic contg. vessel in the blind cylinder. CONSTITUTION:The opening end of a blind cylinder 15 is airtightly connected to the opening 14 in the upper side wall of a high pressure vessel 1. A supporting bar 18 is provided in the cylinder 5 and an arsenic contg. vessel 16 is fixed to the top end thereof. A permanent magnet 20 is provided to the rear end of the bar 18, and a permanent magnet 19 is fixed externally to the cylinder 15. Raw materials such as Ga, As, B2O3 or the like are put in a crucible 3 and are melted, then the current value is measured to detect the compsn. ratio of the raw materials. If As portion is found to be deficient, the annular magnet 19 fitted to the cylinder 15 is dropped to bring an arsenic vessel 16 to near the crucible 3 so that the top end of a pipe 17 is thrusted into the GaAs melt 7. The As in the vessel 16 is heated to form As vapor which is blown into the melt 7. When the compsn. of the melt is adjusted, a seed crystal 9 is rotated and the pulling-up operation is started.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention utilizes high quality semi-insulating gallium arsenide (G(Li2)).
The present invention relates to an apparatus for producing a single crystal, and more particularly to an apparatus for producing a GaAs single crystal, which is equipped with means for blowing arsenic (A8) vapor into a raw material melt.

1. Among the V group compounds, G (Li2) has a large electron transfer property and is being widely used as a material for high-speed integrated circuits, optical, and electronic devices.GaAs is attracting attention because of its high quality. G (Li2) has high insulation properties with a specific resistance of 1070·α or more, has few defects in the crystal and has a uniform distribution, and can easily manufacture large wafers. G who makes such a request
The method for producing aAs single crystals is the liquid confinement pulling method (
, LEC: method) 8 This liquid sealing pulling method includes a low pressure sealing pulling method and a high pressure sealing pulling method.

The low-pressure sealing and pulling method uses S made in advance using the boat growth method.
Because Gaps polycrystals containing impurities such as It is not necessary to add G, which is a raw material.
a, A8 and sealant B, 0. When they are put into a crucible and heated under high pressure for synthesis, much of the gas with low vapor pressure transpires. Therefore, in order to obtain a Ga, As melt with the desired composition ratio, the amount of As added is increased, but depending on the conditions, As
The amount of GaAs that transpires is different, and the composition ratio of GaAs in the melt varies, resulting in high quality undoped G.
It was difficult to obtain aA3 single crystals with good reproducibility.

The purpose of this invention is to produce high quality semi-insulating additive-free Go, As.
A single crystal manufacturing apparatus capable of manufacturing M' crystal with good reproducibility is provided.

Therefore, in the single crystal manufacturing apparatus according to the present invention,
It is equipped with a means for blowing A8 steam into the crystal raw material melt in the crucible, and when a shortage of KAsO is found during raw material synthesis, As vapor is directly blown into the raw material melt to adjust the GaAs composition ratio to a predetermined value. Crystal growth will be performed later. Therefore, high quality GcLAs single crystals can always be obtained with good reproducibility.

First, the method proposed by the present inventors for measuring the G (LA5 composition ratio) in the crystal raw material melt will be explained with reference to Figure 1. A crucible 3 made of quartz, boron 9ide, etc. covered with a material tag is provided, and the crucible 3 is rotatably supported by a rotary support shaft B. A heater 2 is provided around the crucible 3 to rotate the crucible. The crucible 3 is heated and maintained at a predetermined temperature.A conductive pulling shaft with a seed crystal P attached to the lower end is provided in the upper part of the crucible 3, and the pulling shaft is configured to rotate and move up and down. Then, lead wires 10. // are connected to the support member of the crucible and the seed crystal pulling shaft, respectively.

A predetermined amount of Ga and As as crystal materials and boron oxide (B, Os) as a high-pressure sealing agent are placed in the crucible 3, the inside of the container is pressurized with an inert gas, and a heater is used to heat the container to a temperature above the melting point of the raw materials. When the raw material in the crucible is heated and melted, the pulling axis is lowered to bring the seed crystal 2 into contact with the raw material melt 7 in the crucible 3.

In this state, when an AC voltage is applied from the power supply l to the crucible support ≠ and the pulling shaft j via the lead wires /θ, l/, the GaA3 melt is regarded as a resistor, and the crucible becomes an insulator. Therefore, a capacitor is constructed, and the ammeter 13 displays a current value corresponding to the resistance value of the raw material melt.

The above current value changes depending on the composition ratio of GaAs melted in the crucible. - As an example, when the crucible is heated to about 1260°C, the relationship between the composition ratio of LAS and the current value is
As shown in the figure, Ga is approximately 51°5 inches.

When the composition ratio of A8 to 4B is 7%, the maximum current value is shown, and when the composition ratio increases beyond that, the current value decreases rapidly. Normally, the composition ratio of Ga and 88 in the melt to obtain a high-quality single crystal is said to be in the range of 50% ± 0.2, and the current value can be reduced to 0 by adjusting the composition ratio of GaAs in the melt. .27~0.
After specifying the range of 3 mA (range indicated by the dotted line in the figure), high-quality Gaks can be obtained by performing a crystal pulling operation.
The advantage is that single crystals can be obtained with good reproducibility.

FIG. 6 is a cross-sectional view of the single-crystal manufacturing apparatus shown in FIG.
The open end of the blind part /j is airtightly connected to the opening /lI- made in the upper side wall of the blind part /j. There is a high-pressure container l at the tip inside the blind part/j.
A support rod /f is inserted into the inside, an arsenic storage container /6 is fixed to the tip of the support rod, and a permanent magnet is attached to the rear end of this support rod.
Set 〇. There is an annular permanent magnet on the outer circumferential surface of the blind part/j.
This permanent magnet /9 is connected to the magnet 20 at the rear end of the support rod.
When the permanent magnet 2 is slid along the outer periphery of the blind portion by sandwiching the walls of the blind portion and attracting each other, the support rod 7g also moves back and forth within the blind portion.

This holding of the support rod and the sliding force method may be performed by other methods. One end of the pipe 17 is connected to the vicinity of the fixed end of the support rod of the container/B, and the pipe 17 is bent so that its tip extends toward the front of the container, so that when the support rod descends inside the blind part, the raw material melt in the crucible 3 7. A heater unit is provided on the circumferential surface of the container to heat the inside of the container.

The container, support rod, and blind portion described above are formed of quartz or pyrolithic boron nitride.

How to use a single crystal manufacturing apparatus having the following configuration (To explain this, the storage container /2 is loaded with 88 in advance, the support rod /g is pulled up to the upper end by the annular magnet /2,
The container is kept in the opening lψ. Ga in crucible 3
HAs + Bt (h) is put in, the predetermined pressure and temperature are maintained, and when the raw material in the crucible melts, the seed crystal is lowered and brought into contact with the GaA3 melt 7, and the current value is measured.

If it turns out that A8 is insufficient based on the measured current value, check the blind area/! The annular magnet /2 fitted in the pipe 1 is lowered, and as a result, the container /6 approaches the crucible 3 and the pipe 1
The tip of 7 will rush into the G (LA8 molten liquid 7) in the crucible 3. Since the temperature inside the high-pressure vessel is higher than the melting point of As, As vapor is ejected from the tip of the crucible 17. 88 is blown into the GaAs melt.

If the amount of blown steam is insufficient, the amount of steam blown out can be increased by further actively heating the heater 2/vessel/6. The GaA3 melt in the crucible performs all the lifting operations of the predetermined support rod, the container/B is placed on standby at the opening/g, and normal single crystal production is performed by rotating and pulling up the seed crystal.

When producing a single crystal by rotating and pulling a seed crystal in contact with a GaAs melt, the GaAs in the raw material melt
The composition ratio of ps has a great influence on the quality of the single crystal produced. In particular, As has a lower evaporation temperature than GcL, and when the raw materials are synthesized under high pressure, if the conditions change even slightly, the GaA3 composition ratio of the synthesized melt will change slightly, resulting in a GaA8 melt with the desired composition ratio. It is difficult to synthesize liquids with good reproducibility. However, according to the present invention, it is possible to supply Ase to the GaAs melt in the high-pressure vessel, and since the composition ratio of the melt is adjusted before the crystal pulling operation, high-quality GaAs single crystals can be obtained with good reproducibility. It will be done. Furthermore, during raw material synthesis or crystal pulling, A8
A8 is injected into the high-pressure container from a pipe connected to the storage container, creating an atmosphere containing a large amount of nitric acid. It suppresses evaporation of A8 from the surface and contributes to improving the quality of the single crystal.

Note that the method for measuring the composition ratio of the GaAs melt described in the specification is just one example, and based on the results obtained by other measurement methods, A8 is supplied to the crystal raw material melt using the apparatus of the present invention, Manufacture of single crystal 75: It goes without saying that it is possible.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing an example of an apparatus for producing a crystal of GaAs, which is equipped with a means for measuring the GaAs composition ratio in the melt, and Fig.
A graph showing an example of the relationship between the s composition ratio and the current value, and FIG. 6 is an enlarged sectional view of the A8 supply means of the single crystal manufacturing apparatus according to the present invention. In the figure, l is a high-pressure vessel, c is a heater, 3 is a crucible, j is a pulling axis, 6 is a seed crystal, 7 is a GaAs melt, /3 is an opening, /lI- is a blind part, /j is As 1m storage container, /
6 is a pipe, /7 is a support rod, / is a magnet 1.20
indicates a heater. −nu

Claims (1)

[Claims] A rotating crucible that is heated by a heater to melt raw materials is provided in a high-pressure container, and a pulling shaft that can rotate and move up and down with its lower end facing above the crucible and a seed crystal attached to the lower end. When the raw material in the crucible melts, the pulling shaft is lowered, and the seed crystal at the lower end is brought into contact with the molten liquid in the crucible to rotate and pull the single crystal manufacturing device. A blind part is provided by connecting the ends airtightly, and the rear end of the support rod whose tip protrudes into the high-pressure vessel is indirectly held within the blind part, and the support rod is attached by sliding along the blind part. An apparatus for producing gallium arsenide crystals, characterized in that an arsenic storage container is fixed to the tip of the support rod, and a pipe is provided protruding from the arsenic storage container with the tip facing the crucible.