JPS60226491A - Single crystal growth unit - Google Patents

Abstract

PURPOSE:The titled unit in which a liquid sealer is fitted between the air-tight crystal-growing vessel and the single crystal-pulling up shaft as well as the crucible-supporting shaft so that air-tightness is kept in the pressure vessel, thus being easy to handle and prolonged in the life of the shaft sealer. CONSTITUTION:In a double-chamber type of single crystal growing unit which is composed of the air-tight crystal-growing vessel 2 made of, e.g., quartz provided with crucible 3 made of pBN that is supported rotatably with the shaft 7 and including the starting materials for single crystal, the heater 4 for the crucible and the shaft for pulling up the single crystal and of the pressure vessel made of stainless steel which includes the above-stated crystal-growing vessel inside and has air tightness, two shaft sealers 9 and 12 which have liquid traps 10 on the shafts 8, 9 and the inner tubes 11 on the vessel 2 to keep air-tight. The sealing liquid used in the traps is suitably the melt of B2O3 or Ga with low vapor pressure and the maximum length of the inner tube wall dipping in the liquid is required to be larger than the moving distance of both shafts 7, 8, when the single crystal is pulled up.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a double-chamber single crystal pulling apparatus using a liquid sealing device as a shaft sealing device.

Periodic table 1 [group b and v of GaAs, GaP, etc.
Inorganic compound single crystals consisting of group b elements are semiconductor lasers,
It is used to manufacture various semiconductor devices such as light emitting diodes and field effect transistors.

The temperature gradient method (Gradei) is used to manufacture these single crystals.
ent Freeze method), horizontal frifusiman method (Ho
boat growth method such as rizontal Bridgeman method) or liquid capsule rotational pulling method (LiquidF
incnps+λl ated CzOchralek
i method, hereinafter referred to as "LEc method". ) is manufactured by.

2. Description of the Related Art In these inorganic compounds, group Vb elements tend to volatilize at high temperatures, so in the boat growth method, the vapor pressure of the group Vb elements, which is proportional to the dissociation pressure of the compound, is applied9. In this method, a method of stopping with Ar and N2 is used.

However, the conventional single crystal growth apparatus using the LEO method has a heater for heating the crucible inside the single crystal growth container, and a so-called cold wall that cools the wall of the crystal growth container. (Col
d Wall) method, an extremely steep temperature gradient occurs within the crystal growth container, and as a result, arsenic condenses on the walls of the container, so it is necessary to maintain an arsenic vapor pressure equivalent to the dissociation pressure of GaA+3 to decompose GaAs. It is difficult to suppress
In order to maintain the arsenic vapor pressure, Ar or other inert gas was used to prevent the field of GaA by applying a pressure of qg/.

As a method to solve these problems, a device consisting of a crystal growth container equipped with a crucible, a single crystal pulling shaft, etc., and a pressure-resistant container covering it is used, and the vapor pressure of Group Vb elements is applied inside the crystal growth container. How to do it (JP-A-Sho! 9-/369/ issue,
Patent application 1939-. 232!67) has been proposed.

Problems to be Solved by the Invention When a single crystal is grown by the LEC method using these double-chamber single crystal growth apparatuses, a crucible support shaft that supports the crucible for one rotation, a single crystal pulling shaft, etc. The part where the rotating part penetrates the crystal growth container is kept airtight, and -? It is important to have a shaft seal that completely prevents the leakage of vapors such as , As, etc. It is necessary to use materials that can withstand high temperatures and are chemically stable, and it is necessary to maintain airtightness over a wide temperature range.

Conventionally, mechanical shaft sealing devices such as ceramic seals, O-rings made of heat-resistant rubber, etc. have been used. However, these methods have problems in material selection, structure, lifespan, etc.

Purpose of the Invention The present inventors have solved the above problems, and have developed a double-chamber single unit that is easy to handle, has a long life, and has a shaft sealing device that allows for easy replacement of the atmosphere inside the crystal growth container. The present invention was achieved as a result of intensive research aimed at developing a crystal growth apparatus.

Means for Solving the Problems The above-mentioned object of the present invention is to provide a crucible rotatably held by a crucible support shaft, a crucible heater for heating the crucible, and an airtight crystal growth system equipped with a single crystal pulling shaft. In a double-chamber single crystal growth apparatus consisting of a container and an airtight pressure-resistant container containing the crystal growth container inside, an airtight or liquid sealing device between the single crystal pulling shaft, the crucible support shaft, and the crystal growth container. The liquid reservoir of the liquid sealing device is attached to the single crystal pulling shaft and the crucible support shaft, respectively, and the weir is attached to the crystal growth container. This is achieved by an apparatus characterized in that the maximum length of the overlapping portion of the liquid and the weir is greater than the distance that the single crystal pulling axis and the crucible support axis move during single crystal pulling.

Ru A voltage detection device according to the present invention will be explained based on the drawings.

FIG. 1 is a vertical cross-sectional front model view of an example of a single crystal growth apparatus according to the present invention.

In FIG. 1, / is a pressure vessel. The container/container is preferably made of stainless steel and preferably can be water-cooled with a jacket or the like. The pressure-resistant container must be able to withstand an internal pressure of at least about 10 kg/cd, preferably about 0 kg/d. If the withstand pressure is as small as 70 kg/crll, it will be dangerous during crystal growth.

λ is the crystal growth vessel. The container is heated to a high temperature (10θθ・
It has sufficient strength even at temperatures ranging from ~/da θθ°C).

and is manufactured using chemically active materials such as quartz or tantalum (Ta).

3 is the crucible. The crucible 3 is made of pBN (pyrolytic boron nitride), quartz, or the like. The crucible 3 stores polycrystals such as GaAs, GaP, and InP, which are raw materials for single crystal growth, and B2O3, which is a capsule if necessary.

DA is a heater that heats the crucible 3.

j is a container for storing group Vb elements such as As and P. 6 is a heater that heats the container j.

Although the heater 6 is placed outside the container in the drawing,
It can be placed inside. Container for heater 6! By heating the Group Vb group contained in the.

The vb is equal to the dissociation pressure (oaA, in case of 3/atm) near the melting point of inorganic compounds such as GaAs and GaP.
Generates vapor pressure of group elements. In this case, the capsule can be omitted. If a capsule is not used, the elements of group 1b and group yb can be reacted directly in the container 2. 7 is a crucible support shaft that supports the crucible 3. l is the single crystal pulling axis. The shafts 2 and 2 are movable up and down and rotatable, and when growing a single crystal, they usually pull up the single crystal while rotating in opposite directions. For shaft sealing between the shaft and male and pressure-resistant container/.

Ceramic seals, O-ring seals, etc. are used. wa is a liquid sealing device installed on the single crystal pulling shaft.

IO is a liquid reservoir of the liquid sealing device 9. The liquid reservoir 10 is attached to the single crystal pulling shaft l. If the liquid reservoir 10 is attached to the shaft, the structure becomes simple. jl is a weir of the liquid sealing device 9. Weir/
l is attached to the container. /2 is a liquid sealing device provided on the crucible support shaft. /3 is a liquid sealing device/-20 liquid reservoir.

Further, /& is a weir of the liquid sealing device 12. The liquid reservoir 13 is attached to the crucible support shaft 7, and the weir/4t is attached to the container. The maximum length of the overlap between the weir // of the liquid sealing device 9 and the sealing liquid in the liquid reservoir 10 is normally the maximum length of the overlap between the weir // of the liquid sealing device 9 and the sealing liquid in the liquid reservoir when the base is not immersed in the liquid. The depth corresponds to t) shown in Figure 1, but if there is a problem in which the single crystal pulling axis cannot be pulled, such as when the height of the liquid reservoir is greater than the length of the hanging part of the weir, becomes smaller. Is this value the single crystal pulling axis when pulling a single crystal? It is necessary that the distance traveled by the robot is also large. If it is smaller than this, it will not be possible to maintain the airtightness of the crystal growth container, so this is appropriate.

The distance traveled with respect to the axis usually corresponds to the length of the single crystal to be pulled.

If the length of the overlap between the weir // and the liquid is shorter than the above distance,
The container cannot be kept airtight during the entire period of single crystal growth.

In the liquid sealing device 12 as well, it is necessary that the crucible support shaft 7 be immersed in the liquid for at least a length that is substantially the same as the distance that the crucible support shaft 7 moves during single crystal pulling.

Liquid sealing device? The sealing liquid used in 7.2 and 7.2 needs to be a liquid at the #I temperature and have a low vapor pressure, and a melt such as B2O2+ Ga is preferable.

In the case of directly synthesizing GaAs, GaP, etc. using a capsule, a device for injecting Va vapor of group Va elements such as As and P is used as shown in the longitudinal cross-sectional front model diagram of Fig. 2. It is preferable to use an apparatus having

FIG. 2 shows an example of a single crystal manufacturing apparatus using the direct synthesis method.

In FIG. 1, /j is a group Vb element vapor blowing device provided in the container λ. Blowing device/! is placed so that it can be moved up and down.

In the case of direct synthesis, the 1st b such as Ga, n etc.
Accommodate the family with B2O3, blowing device/! is inserted into the group Vb element and the group Vb element is blown into Ga.
Synthesize compounds such as As.

Blowing device/! The airtightness between the and the container is provided by a liquid sealing device
Let's do good. The overlap between the weir of the liquid sealing device/6 and the liquid needs to be equal to or longer than the vertical movement distance of the blowing device/6.

Effects of the Invention In the single crystal growth apparatus according to the present invention, the shaft sealing device of the crystal growth container does not wear out and can withstand high temperatures and corrosive atmospheres.

In addition, by lowering the liquid reservoir of the liquid sealing device such as the crucible support shaft and removing the liquid from the weir, the airtightness between the pressure vessel/crystal growth vessel is broken, so the atmosphere in both vessels is changed to argon (Ar) at the same time. ) etc., which facilitates the operation.

Furthermore, since it is a double chamber, the temperature gradient within the crystal growth container can be reduced, and as a result, crystal defects in the resulting single crystal can be reduced. Furthermore, since crystal growth can be performed in an atmosphere of group YB elements, h ”2
The method of the present invention will be explained in more detail based on Examples.

Example/ A single crystal of GaAB was pulled using the apparatus shown in FIG.

The pressure vessel 7 is made of stainless steel, and the crystal growth vessel λ is made of tantalum.

Liquid sealing device? In 7.2 and 7.2, boron oxide (B203) was heated to above its melting point using a heating tag and Otsu, and used as a liquid seal. The movable distance of the single crystal pulling shaft was 20 Crn.

Polycrystalline Si-doped GaAS is placed in a quartz crucible 3.
og and boron oxide θo'g were placed in the container 2. In addition, As was added in the evening as an evaporation source. (/θθ) Is the seed crystal a single crystal pulling axis? After the container was attached to the container, the inside of the container was evacuated to /×70″torr.

At this time, by lowering the crucible support shaft 2 downward, the υ liquid sealing device/2 was released, and the inside of the container λ was able to be evacuated. Then fill the container with argon gas at s kg/c
rl, and further heated until the boron oxide in each liquid seal device was melted. Then, the crucible support shaft 2 was raised upward to shut off the container/and 2.

In addition, the As pressure was controlled by heating the cylinder Asj and the container. The pressure between the container and the container was controlled to be the same by monitoring the temperature inside the container.

The diameter of the pulled (/00) GaAs single crystal is SO-crystal weight is tooog. The length was 75 mouths. Etch-bit density (FjPD) is Y x 703 cm at the front and x 103 (7) at the tilt.
-2 and the E of GaAs single crystal produced by the usual LEC method.
It was about 7 orders of magnitude lower than the PD level.

Also, the Si carrier concentration is at the front! ×/θ17
crn-3, 3 x 10I8B-3 in the tail.

Example λ A single crystal of GaAs was pulled by a direct synthesis method using the apparatus shown in FIG. Note that the movable distance of the single crystal pulling shaft of this device was 20 m. Boron oxide was used as the sealing liquid used in each liquid sealing device, and tantalum was used as the material for the container 3.

PBNi was used as the crucible material, and Ga of /θθθI and boron oxide of 3oθI were placed in the crucible. AS blowing device/! Add As of /10θI to the container again! I put AS in jOg.

After the inside of the reactor was evacuated to /x/θ-' torr, 70 kg/cI/I of argon gas was introduced, and the inside of the system was heated by a heating tag and a heater. Place the blowing device/-5' into the PBN crucible and blow Ga and As.
After directly synthesizing GaAs from (/θθ), undoped GaAs was crystal-pulled.

The diameter of the undoped GaAs crystal obtained is 0A, N
The amount was 7900 g, and the length of the single crystal was /3 t'm. The specific resistance is /, 3 x 108Ω-(
7), showed good semi-insulating properties with /, / x /θ8Ω-1 at the till part. Also, the EPD is 2X /
03crn-2, ', 2 X / 0' l at tail part
It was m-2.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional front model diagram showing an example of a single crystal growth apparatus according to the present invention. FIG. 2 is a vertical cross-sectional front model diagram showing another example of the single crystal growth apparatus according to the present invention. /...Pressure vessel λ...Crystal growth vessel 3...Crucible 2...Crucible support shaft! ......Single crystal pulling shaft 9, /2, /...Liquid sealing device 10, /
j・River・・・Liquid sump／／、／gu・・・・・・Weir

Claims (2)

[Claims] (1) A crucible rotatably held by a crucible support shaft, an airtight crystal growth container equipped with a heater for heating the crucible, a single crystal pulling shaft, and an airtight container containing the crystal growth container inside. In a double-chamber single crystal growth apparatus consisting of a pressure-resistant container, airtightness between the single crystal pulling shaft, the crucible support shaft, and the crystal growth container is maintained by a liquid sealing device, and the liquid reservoir of the liquid sealing device is are attached to the single crystal pulling shaft and the crucible support shaft, respectively, and the weir is attached to the crystal growth container, and the maximum length of the portion where the sealing liquid and the weir overlap is equal to A device characterized in that the distance traveled by the crystal pulling shaft and the crucible support shaft is greater than the distance traveled during single crystal pulling. f1 (2) The device according to claim 1, wherein the sealing liquid is a melt of boron oxide or gallium.