JPH08208386A - Device for pulling up compound semiconductor single crystal - Google Patents

Abstract

PURPOSE: To obtain a device for pulling up a compd. semiconductor single crystal with which the precision control of a vapor pressure is made possible by suppressing the reaction of a high melting metallic material and a high-dissociation pressure component without deterioration of the hermeticity of a hermetic vessel, thereby preventing the deterioration of the material and preventing the deterioration in the purity of the high-dissociation pressure component. CONSTITUTION: This device has the hermetic vessel 1, a crucible 13 which is installed in the hermetic vessel 1 and in which a raw material melt 28 is stored, a pulling-up mechanism 24 which pulls up a seed crystal, heating means 15a, 15b which heat the crucible 13 together with the hermetic vessel 1, a vapor pressure control section 21 which controls the pressure of the high-dissociation pressure component in the hermetic vessel 1 and a temp. control means which controls the temp. of the vapor pressure control section 21. The hermetic vessel 1 and the vapor pressure control section 21 consist of carbon formed with a ceramic coating layer 5b of a high-purity III-V compd. on its inner peripheral surface and/or the high melting metal. Ceramic inside walls 31 to 33, 21c consisting of the high-purity III-V compd. are arranged in proximity to the inner side of the hermetic vessel 1 and the vapor pressure control section 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compound semiconductor single crystal pulling apparatus suitable for growing a III-V group compound semiconductor single crystal such as GaAs used as a laser element, an IC substrate or the like.

[0002]

2. Description of the Related Art Conventionally, for growing a III-V group compound semiconductor single crystal such as GaAs used as a laser device, an IC substrate, etc., a single crystal pulling apparatus as shown in FIG. 6 has been used. There is. (For example, Japanese Patent 1490
No. 669, Japanese Patent Application No. 2-332781, etc.) This apparatus is for producing a III-V group compound semiconductor single crystal by the Czochralski method (CZ method),
In FIG. 6, reference numeral 1 is a closed container for hermetically sealing the internal space and enclosing a high dissociation pressure component in the internal space for growing a compound semiconductor single crystal.
Is configured to be separable by a container upper part 2 and a container lower part 3.

The upper part 2 of the container is made of, for example, Mo, W, N.
It is composed of a metal such as b and one or more of these alloys. The lower part 3 of the container is, for example, Mo,
A material bottom plate 4 made of a metal such as W or Nb and one or more of these alloys, and a highly pure and dense BN (PBN) having a thickness of about 250 μm on the inner wall surface of the tubular body 5a made of carbon or the like. , AlN and the like, and a side wall portion 5 on which a coating layer 5b made of a III-V group compound is formed. A seal member 7 is interposed at a joint portion 6 between the container upper portion 2 and the container lower portion 3 and a joint portion (not shown) between the bottom plate portion 4 and the cylindrical body 5a at the container lower portion, and the container lower portion 3 is pushed up. A stress buffer mechanism 9 is attached to the shaft 8,
The structure is such that the stress applied to the joint 6 is maintained at an appropriate value.

On the other hand, a crucible 13 which is supported by the susceptor 11 and stores the raw material melt is arranged inside the closed container 1. The crucible 13 is rotated by a lower shaft 14 and is closed by heaters 15a and 15b. It is designed to be heated together with the container 1. Further, a vapor pressure control unit 21 for controlling the amount of the high dissociation pressure component in the closed container 1 is provided on the top plate portion of the container upper portion 2, and the vapor pressure control unit 21 has a temperature of the inner wall surface 21a thereof. Temperature control heater 21 for controlling the temperature of the inner wall of the closed container 1 to the lowest and appropriate constant temperature.
b is provided, and the temperature control heater 21b controls the temperature of the inner wall surface 21a of the vapor pressure control unit 21 to be the lowest and appropriate constant temperature on the inner wall of the closed container 1, so that the high dissociation pressure component condensed there. Is adjusted to control the pressure of the high dissociation pressure component in the closed container 1 to control the composition of the grown compound semiconductor single crystal 22.

A view lot 23 for observing the growing portion of the single crystal 22 is provided through the top plate of the closed container 1, and the pull-up shaft 24 and the lower shaft 14 each have a penetrating portion.
A rotary seal 25 filled with a liquid sealant such as B ₂ O ₃ is provided. The entire configuration described above is housed in the outer container 26 in a sealed state.

Next, a method for growing a GaAs single crystal using the above apparatus will be described. In this case, the high dissociation pressure component is As and the other raw material components are Ga (melting point: 29.
78 ° C.). First, a Ga raw material is stored in the crucible 13 and a predetermined amount of As is placed on the bottom plate portion 4 of the closed container 1.
Then, after the entire inside of the outer container 26 is evacuated, the lower shaft 8 is pushed up and the closed container 1 is sealed. Next, after heating the inner wall of the closed container 1 excluding the bottom plate part 4 with the heater 15a, the bottom plate part 4 of the closed container 1 is gradually heated with the heater 15b to heat As placed on the bottom plate part 4. While being sublimated, the crucible 13 is heated together with the closed container 1 to about 1200 to 1300 ° C.
a. As sublimated As is absorbed into the crucible 13 and Ga
The As melt 28 is synthesized.

During the synthesis work, an inert gas such as Ar gas or N ₂ gas is introduced into the outer container 26 to balance the pressure inside and outside the closed container 1. At the time of completion of the synthesis, the temperature distribution in the closed container 1 is controlled by the vapor pressure control unit 21 to be lower than the other parts and at a predetermined temperature, and the As sublimated As.
Is condensed 27 only in the vapor pressure control unit 21 and is not condensed in other parts in the closed container 1. GaAs melt 28
After completion of the above synthesis, the seed crystal (not shown) at the lower end of the pull-up shaft 24 is immersed in the GaAs melt 28, and the pull-up shaft 24 is rotated and pulled up while the heaters 15a and 15b are being pulled up.
The single crystal 22 is grown while gradually lowering the temperature.

The amount of the raw material As is the GaAs melt 28
The amount required for the synthesis is set to be more than that required, and after the synthesis of the GaAs melt 28 is completed, the closed container 1 is filled with As gas at a constant pressure during the growth process by the excess As condensed in the vapor pressure control unit 21. To do. Further, the vapor pressure control unit 21 has a volume and a structure that can store As solids until the crystal growth is completed, in consideration of the amount of As lost during crystal growth.

[0009]

By the way, in the above single crystal pulling apparatus, the closed container 1 for growing the single crystal 22 is used.
The internal temperature is high, and the molecular motion of the As gas sealed in the closed container 1 is also extremely vigorous. Therefore, there is a problem in that the PBN layer 5b of the closed container 1 is eroded by the As gas and holes are formed, and the life of the closed container 1 is shortened. If holes are formed in the PBN layer 5b, As
The gas easily passes through the cylindrical body 5a through this hole and leaks to the outside of the closed container 1. So PBN
Although it was considered to increase the thickness of the layer 5b,
Since the carbon constituting the a and the PBN layer 5b have different thermal expansion coefficients, when the thickness is increased, a new problem arises in that the PBN layer 5b is cracked due to thermal stress during temperature increase and temperature decrease. .

Further, the closed container 1 or the vapor pressure control unit 2
The part made of refractory metal material of No. 1 is A at high temperature.
Because it is exposed to s gas, it reacts with As gas from the inside,
This will produce various arsenides and solid solutions. Such a reaction occurs in a wide temperature range and deteriorates the material, leading to deterioration in mechanical strength and dimensional accuracy. Further, when the vapor pressure control unit 21 is made of a refractory metal, As condensed in this portion is kept in a high temperature state for a long time, so that it causes mutual diffusion with the metal wall material, thereby increasing the purity of As. The problem of changing it arises. In this case, even if the temperature of the vapor pressure control unit 21 is kept constant, the vapor pressure of As itself gradually changes, so that the composition of the single crystal cannot be precisely controlled.

The present invention has been made in view of the above circumstances, and there is no possibility that the PBN layer of a closed container is eroded to open holes and deteriorate airtightness, and a high melting point metal material and a high dissociation pressure component are used. The reaction of is suppressed to prevent the deterioration of the material, and the deterioration of the purity of the high dissociation pressure component is prevented, and the precise control of the vapor pressure is enabled. Therefore, the reliability of the closed container is improved,
It is an object of the present invention to provide a compound semiconductor single crystal pulling apparatus that can have a long life.

[0012]

In order to solve the above problems, the present invention employs the following compound semiconductor single crystal pulling apparatus. That is, the compound semiconductor single crystal pulling-up apparatus according to claim 1, wherein the internal space is hermetically sealed, and a high dissociation pressure component is sealed in the internal space, which can be opened and closed, and the closed container of the closed container. A crucible rotatably provided inside for storing a raw material melt, a pulling mechanism for immersing a seed crystal in the raw material melt to pull up a single crystal, a heating means for heating the crucible together with the closed container, and A vapor pressure control unit for controlling the pressure of the high dissociation pressure component in the closed container, the space being in communication with the internal space of the closed container; and a temperature control unit for controlling the temperature of the vapor pressure control unit. In the compound semiconductor single crystal pulling apparatus for pulling a compound semiconductor single crystal from a raw material melt in the crucible, the closed container and the vapor pressure control unit have high purity III at least on the inner peripheral surface thereof.
A high purity group III-V compound which is made of carbon and / or a high melting point metal on which a ceramic coating layer made of a group V compound is formed, and which is close to the inside of the closed container and the vapor pressure control unit. The ceramic inner wall is arranged.

A compound semiconductor single crystal pulling apparatus according to a second aspect is the compound semiconductor single crystal pulling apparatus according to the first aspect, in which the interval between the ceramic coating layer and the ceramic inner wall is 0.5 to 3 mm. Is.

[0014]

In the apparatus for pulling up a compound semiconductor single crystal according to claim 1 of the present invention, the closed vessel and the vapor pressure control section are provided with a ceramic coating layer made of a high-purity III-V group compound on at least the inner peripheral surface thereof. It is made of formed carbon and / or a high melting point metal, and is of high purity III close to the inside of the closed container and the vapor pressure control unit.
-By arranging the ceramic inner wall made of a group V compound, the ceramic coating layer on the inner peripheral surface of the closed container is protected from the attack of the components of high dissociation pressure that violently convection, and the ceramic coating layer formed on the inner peripheral surface. Eliminates the risk of problems such as erosion of the
There is also no risk of the high dissociation pressure component leaking to the outside. As a result, the reliability of the hermetically sealed container is increased and the life is extended.

Further, it is possible to suppress the permeation of the high dissociation pressure component into the surfaces of the closed container and the vapor pressure control section members made of a high melting point metal and the reaction with the surfaces. In the vapor pressure control unit, since the internal temperature is controlled to be uniform, most of the condensation of the high dissociation pressure component occurs inside the ceramic inner wall, and the surface of the vapor pressure control unit and the high dissociation pressure are controlled. Interdiffusion with the components is prevented by the ceramic inner wall.

In the apparatus for pulling up a compound semiconductor single crystal according to the second aspect, the gap between the ceramic coating layer and the ceramic inner wall is 0.5 to 3 mm, so that even if there is a temperature distribution in this gap. However, convection due to this temperature difference does not occur. As a result, the impact force of the high dissociation pressure component on the ceramic coating layer is relaxed, and perforation due to erosion of these ceramic coating layers is prevented.

[0017]

1 is a sectional view showing an apparatus for pulling up a compound semiconductor single crystal according to an embodiment of the present invention, and FIG. 2 is a partially enlarged sectional view showing an essential part thereof. The single crystal pulling apparatus is an improvement of the conventional single crystal pulling apparatus, and the same components as those in FIG. 5 are designated by the same reference numerals.

In FIG. 1, reference numeral 31 is arranged close to the inside of a ceramic coating layer (hereinafter, simply referred to as a coating layer) 5b made of high-purity and dense PBN (pyrolytic boron nitride) of the closed container 1. And cylindrical P
It is a ceramic cylinder (ceramic inner wall) made of BN and having a thickness of 1 mm, and the gap t with the coating layer 5b is 0.5 to.
The outer diameter is set so as to be in the range of 3 mm. The size of this gap is preferably as small as possible, but is determined in consideration of the processing accuracy of the coating layer 5b and the ceramic cylinder 31 and the difference in the coefficient of thermal expansion. This ceramic tube 31
It is manufactured by stacking PBN thickly on the outside of a graphite cylindrical mold by a thermal CVD method and then extracting the mold.

The upper flange 2, the lower flange 4 and the vapor pressure controller 21 of the closed container 1 are made of Mo (molybdenum).
The upper flange 2 is made of a refractory metal such as
Also, a PBN inner wall (ceramic inner wall) 32 and a PBN bottom plate (ceramic inner wall) 33 are arranged close to the inside of each of the lower flanges 4, and a PBN inner cylinder (ceramic inner wall) is arranged near the inside of the vapor pressure control unit 21. ) 21c is provided. All of these members are PB with a wall thickness of 1 mm.
The upper flange 2, the lower flange 4 and the inner wall of each of the vapor pressure control portions 21 are made of N-peel material and are set to have a clearance of 0.5 to 3 mm. This gap is preferably small, but is set in consideration of dimensional changes due to the reaction of these members with As gas (high dissociation pressure component), differences in thermal expansion coefficient, and the like.

In this apparatus for pulling a single crystal, the ceramic cylinder 31 is arranged close to the inside of the coating layer 5b of the closed container 1, so that the coating layer 5b on the inner peripheral surface of the closed container 1 is protected by the ceramic cylinder 31. To be done. The ceramic cylinder 31 is eroded by As gas having high kinetic energy to generate a small hole. On the other hand, since the coating layer 5b on the inner peripheral surface of the closed container 1 and the ceramic cylinder 31 are arranged sufficiently close to each other, the As gas sandwiched therebetween is suppressed from convection, and the coating layer 5b is eroded. There is no risk of holes being created by Further, the holes formed in the ceramic cylinder 31 do not impair the airtightness, but retain the more important airtightness of the closed container 1. As described above, the reliability of the closed container 1 is significantly increased and the life is extended, so that there is no risk of As gas leaking out of the closed container 1.

Further, the reaction between the upper flange 2, the lower flange 4 of the closed container 1 and the high melting point metal such as Mo which constitutes the vapor pressure control section 21 and As gas is caused by the arrangement of the PBN inner wall 32. The supply is mainly based on diffusion, and the reaction is suppressed as compared with the case where the PBN inner wall 32 is not provided, and the deterioration of the refractory metal can be delayed by that amount.

In this embodiment, since the vapor pressure control section 21 is made of a high melting point metal, the P arranged on the inner peripheral portion of the vapor pressure control section 21.
The BN inner wall 32 plays an important role. That is, the condensation of As gas also occurs in the gap between the inner peripheral portion of the vapor pressure control unit 21 and the PBN inner wall 32, but if this gap is filled, further condensation will occur in the PBN inner wall 32. It occurs inside. As condensed in this part is the refractory metal and PBN.
Since they are separated by the inner wall 32, A due to mutual diffusion
s is not contaminated. Most of the As condensed in this way can give a constant vapor pressure to the temperature of the vapor pressure control unit 21.

In this single crystal pulling apparatus, the PBN cylinder 31 is arranged close to the inside of the PBN layer 5b of the closed container 1, but the closed container 1 has a high purity II on the inner peripheral surface.
It is sufficient that a ceramic coating layer made of a IV compound is formed, and a ceramic cylinder made of a high-purity III-V compound is arranged in the vicinity of the inside of the ceramic coating layer, regardless of the above configuration. Various configurations are possible.

For example, as shown in FIG. 3, P of the cylindrical body 5a is
High-purity and dense AlN close to the inside of the BN layer 5b
The (aluminum nitride) cylinder 41 may be arranged, or, as shown in FIG. 4, the inner peripheral surface 42 of the cylinder 5a.
A highly pure and dense AlN layer 43 is formed on the
The AlN cylinder 41 may be arranged close to the inside of the layer 43.

In each of the above embodiments, the GaAs single crystal was grown, but the compound semiconductor single crystal of interest may be a single crystal containing a high dissociation pressure component,
The present invention is not limited to the III-V group compound semiconductor single crystal. Furthermore, the ceramic cylinder 31 of the present embodiment can be applied to other compound semiconductor processing apparatus for sealing high dissociation pressure components, for example, vertical semiconductor single crystal growing apparatus by the Bridgman method, heat treatment apparatus and the like.

[0026]

As described above, according to the first aspect of the present invention.
According to the described compound semiconductor single crystal pulling apparatus, the hermetically sealed container and the vapor pressure control unit have carbon on which a ceramic coating layer made of a high-purity III-V group compound is formed on at least the inner peripheral surface thereof, and / or Since a ceramic inner wall made of a high-melting metal and arranged close to the inside of the closed container and the vapor pressure control section and made of a high-purity III-V group compound, the ceramic coating layer on the inner peripheral surface of the closed container. Can be protected from the attack of high dissociation pressure components that violently convection, eliminating the risk of problems such as erosion of the ceramic coating layer formed on the inner peripheral surface and the formation of holes, resulting in high dissociation. There is also no risk of the pressure component leaking to the outside. Therefore, the reliability of the closed container can be improved and the life can be extended.

Further, the permeation of the high dissociation pressure component into and the reaction with the surface of each of the closed vessel and the vapor pressure control section made of a material of carbon or a refractory metal is suppressed to suppress the vapor. It is possible to prevent mutual diffusion between the surface of the pressure control unit and the condensed solid of high dissociation pressure component.

In the compound semiconductor single crystal pulling up apparatus according to the second aspect, the gap between the ceramic coating layer and the ceramic inner wall is 0.5 to 3 mm. Therefore, even if there is a temperature distribution in this gap. It is possible to prevent convection due to this temperature difference, reduce the impact force of the high dissociation pressure component on the ceramic coating layer, and prevent perforation and the like due to erosion of these ceramic layers.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a compound semiconductor single crystal pulling apparatus of one embodiment of the present invention.

FIG. 2 is a partially enlarged cross-sectional view showing a main part of a compound semiconductor single crystal pulling apparatus according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a modified example of the compound semiconductor single crystal pulling apparatus of one embodiment of the present invention.

FIG. 4 is a cross-sectional view showing another modified example of the compound semiconductor single crystal pulling apparatus of one embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a conventional compound semiconductor single crystal pulling apparatus.

[Explanation of symbols]

 1 Closed Container 2 Upper Container 3 Lower Container 4 Bottom Plate 5 Side Wall 5a Cylindrical 5b PBN Coating Layer 6 Joint 7 Sealing Material 8 Push Down Lower Shaft 9 Stress Buffer Mechanism 11 Susceptor 13 Crucible 14 Lower Shaft 15a, 15b Heater 21 Steam Pressure Control part 21a Inner wall surface 21b Temperature control heater 22 Compound semiconductor single crystal 23 Viewlot 24 Pulling shaft 25 Rotating seal 26 Outer container 27 Condensed solid of high dissociation pressure component 31 Ceramic cylinder (ceramic inner wall) 32 PBN inner wall (ceramic inner wall) 33 PBN bottom plate (ceramic inner wall) 41 AlN (aluminum nitride) cylinder 42 inner peripheral surface 43 AlN layer t gap

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Sasa 1-297 Kitabukurocho, Omiya City, Saitama Prefecture Mitsubishi Materials Corporation Central Research Laboratory

Claims (2)

[Claims] 1. An openable and closable closed container in which an internal space is hermetically sealed and a high dissociation pressure component is sealed in the internal space, and a raw material melt rotatably provided inside the closed container. A crucible to be stored, a pulling mechanism for immersing a seed crystal in the raw material melt to pull up a single crystal, a heating means for heating the crucible together with the closed container, and an internal space communicating with the internal space of the closed container. A vapor pressure control unit for controlling the pressure of the high dissociation pressure component in the closed container, and a temperature control means for controlling the temperature of the vapor pressure control unit are provided, and the compound semiconductor is removed from the raw material melt in the crucible. In a compound semiconductor single crystal pulling apparatus for pulling a single crystal, the closed container and the vapor pressure control unit have carbon on which a ceramic coating layer made of a high-purity III-V compound is formed on at least the inner peripheral surface thereof. And / or a high melting point metal, and a ceramic inner wall made of a high-purity III-V group compound is arranged close to the inside of the closed container and the vapor pressure control section. Lifting device. 2. The compound semiconductor single crystal pulling apparatus according to claim 1, wherein the interval between the ceramic coating layer and the ceramic inner wall is 0.5 to 3 mm.