JPH0437683A - Producing device for compound semiconductor single crystal - Google Patents

Abstract

PURPOSE:To enhance quality by introducing a raw material into a boat for growing single crystal and encapsulating this boat and a volatile component into an ampoule tube and arranging this ampoule tube into a furnace body which has both a high-temp. region and a low-temp. region and relatively moving the furnace body and the ampoule tube. CONSTITUTION:A raw material of a III-V compd. semiconductor such as GaAs compd. is introduced into a boat 22 for growing single crystal. This boat 22, a volatile component 23 such as As single substance, a diffusion barrier and a dopant added in accordance with necessity are encapsulated into an ampoule tube 21. This vacuumized ampoule tube 21 is placed in the inner walls 31, 32 of a furnace body 11. Then the raw material in the boat 22 is heated and melted at m.p. or more of single crystal in a high-temp. region 11a made of SiC, etc. On the other hand, the volatile component 23 is heated in a low-temp. region 11b made of Al2O3, etc., so that the vapor pressure of the component 23 is held constant. In this state, when the furnace body 11 is gradually moved to one direction, movement of the ampoule tube 21 is inhibited by a supporting rod 51. This ampoule tube 21 is relatively moved for the furnace body 11. Melt is the boat 22 is gradually solidified from seed crystal to produce compound semiconductor single crystal.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to an apparatus for manufacturing compound semiconductor single crystals such as m-v group by a boat method such as a horizontal Bridgman method and a gradient-end freeze method.

"Prior Art" As methods for manufacturing compound semiconductor single crystals by the boat method, the horizontal Bridgman method (HB method) and the gradient end freeze (GF) method are known. The horizontal Bridgman method is a method in which an ampoule tube (reaction tube) containing a boat is moved through a furnace with a predetermined temperature gradient, and the gradient-end freeze method is a method in which the ampoule tube is not moved but the temperature profile is moved. It is. m-v by boat method
Various studies have already been carried out on manufacturing methods and apparatus for group compound semiconductor single crystals, such as Japanese Patent Publication No. 52-19192.
No., Utility Model Application Publication No. 1-129273, etc. are disclosed.

■- Among group V compound semiconductor single crystals, for example, GaAs
As a method for manufacturing crystals by the horizontal Bridgman method, the following method is adopted for boat fishing.

A quartz single crystal growth boat having a GaAs single crystal seed crystal at one end and a diffusion barrier are placed in a quartz ampoule tube, and a stoichiometric amount of GaAs compound or Ga is placed as a raw material. Put the simple substance and As simple substance,
Further, a sufficient amount of As alone to maintain the inside of the ampoule tube at approximately one pressure in the furnace and, if necessary, a dopant that imparts desired electrical characteristics are added, followed by vacuum sealing.

The ampoule tube obtained in this way was used to obtain a melt of GaAs single crystal, which has a melting point of 1238°C.
A high temperature region maintained at a temperature above, preferably around 1250°C, a low temperature region maintained at around 610°C to maintain arsenic gas at approximately atmospheric pressure inside the ampoule tube, and a gentle temperature range between these temperature regions. Place in a furnace with a gradient temperature profile.

Next, the part of the ampoule tube where the boat is placed is placed in the high temperature region of the furnace to heat the raw material in the boat,
Let it be a melt of As. By moving the ampoule tube and the furnace relatively, the ampoule tube is gradually moved to a lower temperature region, and the temperature is gradually lowered from the seed crystal side at one end of the boat, solidifying the GaAs melt. to obtain a single crystal.

In this case, as a method for relatively moving the ampoule tube and the furnace body, the method shown in FIG. 3 or 4, for example, has been proposed.

In the method shown in FIG. 3, a furnace core tube 3 is arranged by penetrating the inside of the furnace body 1, and both ends of the furnace core tube 3 are protruded from both ends of the furnace body 1 and supported on the floor surface. is movable along the axial direction of the furnace core tube 3, the ampoule tube 2 is placed inside the furnace core tube 3, and the ampoule tube 2 is gradually moved to a low temperature region by moving the furnace body 1, This is a method in which the melt filled in the boat in the ampoule tube 2 is solidified from the end.

Furthermore, the method shown in FIG. Place tube 2. By moving the furnace body 1 in the axial direction, the ampoule tube 2 is gradually moved to a low temperature region, and the melt in the boat in the ampoule tube 2 is solidified from the end.

3 and 4, a quartz boat 6 and a volatile component 7 are sealed in the ampoule tube 2. As shown in FIG. Volatile component 7 maintains the vapor pressure of the element that evaporates more easily, since crystal defects occur in compound semiconductors made of elements with different vapor pressures due to the different amounts of evaporation of the elements at high temperatures. established for the purpose of For example, in the production of GaAs single crystals, As alone is used as the volatile component 7.

The furnace body 1 is divided into a high-temperature region 1a where the temperature is higher than the melting point of the target compound, and a low-temperature region b for controlling the vapor pressure of the volatile components. The part of the ampoule tube 2 in which the boat 6 is accommodated is located in the high temperature region 1a, and the part of the ampoule tube 2 that accommodates the boat 6 is
The part where the volatile components 7 are accommodated is the low temperature area 1b.
will be placed in

As mentioned above, for example, in the production of a GaAs single crystal, the high temperature region 1a is the melting point of the GaAs single crystal of 1238
The temperature is maintained at ℃ or higher, preferably around 1250℃,
The low temperature region 1b is maintained at around 610° C. in order to maintain the inside of the ampoule tube with arsenic gas at approximately one atmosphere.

``Problems to be Solved by the Invention'' However, in conventional compound semiconductor single crystal manufacturing equipment, in many cases, a common furnace core tube 3 or furnace The internal body wall 8 is used. For this reason, the furnace core tube 3 or the furnace inner wall 8 is subjected to a sharp temperature gradient between the high temperature region la and the low temperature region 1b, and cracks are likely to occur due to the difference in thermal expansion, resulting in a very short service life. It was short.

Furthermore, the constituent materials of the furnace core tube 3 and the furnace inner wall 8 must be inert to quartz, which is normally used as a constituent material of the ampoule tube 2, and must be a highly pure material that does not contaminate the single crystal. Therefore, expensive materials such as SiC are used. Therefore, the furnace core tube 3 and the furnace inner wall 8 are very expensive, and as mentioned above, they are easy to break and have a short lifespan, which is a factor that increases the manufacturing cost of compound semiconductor single crystals.

Furthermore, in the conventional manufacturing apparatus, the heat in the high temperature region 1a is transferred to the low temperature region 1b through the furnace core tube 3 and the furnace inner wall 8, so that the single crystal in the high temperature region 1a and the low temperature region 1b is grown. This made delicate temperature control difficult.

Therefore, an object of the present invention is to provide an apparatus for manufacturing compound semiconductor single crystals that can reduce the cost of the furnace core tube, extend its life, and further prevent the furnace core tube from affecting temperature control. It's about doing.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an apparatus for manufacturing a compound semiconductor single crystal by a boat method, in which a single crystal growth boat containing at least a raw material and a volatile component are enclosed. a furnace body having an ampoule tube for controlling the temperature, a high temperature region having a temperature equal to or higher than the melting point of the crystal, and a low temperature region for controlling the vapor pressure of the volatile component; means for relatively moving the ampoule tube and the ampoule tube, and the furnace wall is divided between the high temperature region and the low temperature region, and is composed of a plurality of parts. do.

Hereinafter, the present invention will be explained in more detail by giving preferred specific examples.

In the present invention, compound semiconductor single crystals include GaAs,
InAs, GaP, InP, Ga+-
xInxP (0<x<1)In+-XGa, As(
0<x<1), etc.

In the present invention, raw materials, single crystal growth boats, volatile components, ampoule tubes, furnace bodies, etc. for producing compound semiconductor single crystals are usually used when producing compound semiconductor single crystals by the horizontal Bridgman method. The same one used will be adopted.

For example, when obtaining a GaAs single crystal, a stoichiometric amount of a GaAs compound or Ga and As as raw materials is put into a quartz boat, and this boat is placed in the same (quartz ampoule tube). After adding a sufficient amount of As as a volatile component to maintain the inside of the ampoule tube at approximately one pressure, and adding a dopant that imparts desired electrical properties as necessary, a diffusion barrier is placed inside. , vacuum-seal the ampoule tube.

In addition, the furnace body is heated to 1238°C, which is the melting point of GaAs single crystal.
A high temperature region where the above temperature is maintained, preferably around 1250°C, a low temperature region where the ampoule tube is maintained at around 610°C to maintain almost one atmosphere of As gas, and a gentle temperature range. The structure is such that it can be heated to have a temperature profile connected by a temperature gradient. However, the furnace body is not limited to one having the above-mentioned temperature profile (for example, one in which the high temperature region is further divided into a plurality of temperature regions can also be used).

A feature of the present invention is that the inner wall of the furnace is composed of a plurality of parts separated into a high-temperature region and a low-temperature region.

In this case, the inner wall of the furnace has a part corresponding to the high temperature area,
It may be composed of two parts, one corresponding to the low temperature region (and, if the high temperature region is further divided into multiple temperature regions, three or more parts corresponding to each temperature region). It may be composed of.

In a more preferred embodiment of the present invention, the furnace inner wall disposed in the high temperature region and the furnace inner wall disposed in the low temperature region are formed of different materials. Particularly preferably, the inner wall of the furnace disposed in the high temperature region is made of SiC, which is a highly pure material that is inert to quartz, which is normally used as a material for ampoule tubes, and does not contaminate the single crystal being grown. Al2O, which has a certain degree of heat resistance and is a cheaper material, is used for the inner wall of the furnace placed in the low temperature region.
3 is used. These ceramics may be stacked in block form on the inner surface of the furnace body, or may be in the form of a tube.

In the present invention, the means for arranging the ampoule tube within the furnace body and relatively moving the furnace body and the ampoule tube is as follows:
There are no particular limitations (and various structures can be adopted.

As a preferable example, the ampoule tube is placed directly in the furnace body, a support rod is inserted into the furnace body from the low temperature region side of the furnace body,
Connect the end of the support rod to the cold end of the ampoule tube. Then, fix the ampoule tube with a support rod,
Either move the furnace body or keep it fixed.
A structure is adopted in which the ampoule tube is moved by a support rod.

"Function" In the present invention, since the furnace inner wall is composed of a plurality of parts separated between the high temperature region and the low temperature region, the furnace inner wall is heated between the high temperature region and the low temperature region. Since stress due to expansion differences is no longer applied, cracks and the like are prevented from occurring, and the life of the furnace inner wall can be improved.

Moreover, even if damage or deterioration occurs, only one of the parts needs to be replaced, so the running cost of the furnace body can be reduced.

Furthermore, the inner wall of the furnace located in the high temperature region is made of a material that is less likely to be contaminated with crystals by impurities even under high temperatures, such as SiC, and the inner wall of the furnace located in the low temperature region is made of an ampoule tube. Since there are almost no problems with reactivity with oxidants and crystal contamination, relatively inexpensive materials such as A-A can be used.
IgOs or the like can be used, and the cost of the inner wall of the furnace can be reduced as a whole.

In addition, since the furnace wall is separated into the high-temperature region and low-temperature region of the furnace body, the problem of temperature fluctuations in each region through the inner wall, which makes it difficult to control the temperature of the furnace body, is solved. Ru.

Note that Fig. 2 of Japanese Patent Publication No. 52-19192 discloses an example in which the furnace core tube is divided into two, but in this example, the furnace core tube is not fixed to the furnace body, and the furnace core tube is not fixed to the furnace body. The main point is that there is a considerable gap between the core tube and the furnace core tube, and the ampoule tube is only supported at both ends by the two furnace core tubes and is essentially exposed from the furnace core tube. It is different from invention. Moreover,
In the above example, since the furnace core tube is disposed between the inside of the furnace and the outside of the furnace, it is impossible to prevent cracks from occurring due to temperature differences.

Embodiment FIG. 1 shows an embodiment of the apparatus for manufacturing a group III-V compound semiconductor single crystal containing a volatile component according to the present invention. An example applied to the HB method will be shown below, but the present invention can also be applied to the GF method.

The furnace body 11 is composed of an integrated structure as a whole, and includes a high-temperature region 11a for heating the raw material put into the boat 22 in the ampoule tube 21 to a temperature higher than its melting point to form a melt, and a The low temperature region 11b is heated so as to keep the vapor pressure of the volatile component 23 constant.

Note that the high temperature region 11a has a portion where the temperature decreases with a gentle slope toward the low temperature region 11b so that the melt can be solidified and a single crystal can be grown.

High temperature region 11a and low temperature region 1 of this furnace body 11], b
Furnace inner walls 31.3 each constructed separately on the inner periphery of
2 is fixed. That is, the furnace inner walls 31 and 32 are separated between the high temperature region 11a and the low temperature region 11b. In this embodiment, the furnace inner wall 31 fixed in the high temperature region 11a is made of SiC, and the furnace inner wall 32 fixed in the low temperature region 11b is made of A1□0.

The furnace body 11 has carts 41 and 42, and can be moved at a precise speed by a drive mechanism (not shown).

The ampoule tube 21 is placed directly on this furnace inner wall 31,32. A single crystal growth port 22 containing a raw material and a volatile component 23 are sealed in the ampoule tube 21, and in some cases, a diffusion barrier is placed between them to further improve desired electrical properties. The dopant to be given is encapsulated. At least at the beginning of the manufacturing process, the portion of the ampoule tube 21 where the boat 22 is placed is placed in the high temperature region 11a of the furnace body 11, and the portion where the volatile component 23 is placed is placed in the low temperature region 11b. Ru.

A support rod 51 made of stainless steel and inserted through an opening in the furnace wall 32 is connected to the end of the ampoule tube 21 located on the low temperature region 11b side. The end of the support rod 51 that protrudes outside the furnace is supported by a fixed base 52. Note that ceramic powder is interposed between the ampoule tube 21 and the inner walls 31 and 32 of the furnace body in order to reduce frictional resistance during relative movement, which will be described later.

Next, a method for manufacturing a III-V group compound semiconductor single crystal using this manufacturing apparatus will be described.

First, after placing the ampoule tube 21 within the furnace inner wall 31.32 as shown in the figure, the port 21 is placed in the high temperature region 11a.
Make the raw materials in 2 into a melt. Further, heating is performed so that the vapor pressure of the volatile component 23 becomes constant in the low temperature region 11b.

In this state, the furnace body 11 is gradually moved in the direction of the arrow in the figure. In this case, since the ampoule tube 21 is prevented from moving by the support rod 51, the ampoule tube 21 and the furnace inner wall 3
1.32, the ampoule tube 21 slips between the furnace body 1
It moves relative to 1.

As a result, the boat 22 inside the ampoule tube 21 gradually enters a lower temperature region from the right end in the figure, and the port 2
The melt in 2 gradually solidifies from the right end, and a single crystal is grown. By solidifying all of the melt in the port 22 in this manner, an m-v group compound semiconductor single crystal can be obtained.

In addition, in the above embodiment, the high temperature region 11 of the furnace body 11
As the material of the furnace inner wall 31 fixed to a, 5isN4 can also be used in addition to SiC. In addition, the furnace body 1
As the material of the inner wall 32 of the furnace body fixed in the low temperature region 11b, other than A1□03, low-purity SiC or quartz glass can also be used.

In addition, the gap between the furnace inner wall 31 and the furnace inner wall 32 is set to 17 mm, which is the length of the single crystal growth port 22, in consideration of heat dissipation, etc.
It is preferable to set it to 2 or less.

Furthermore, the high temperature region 11a of the furnace body 11 may be divided into smaller temperature bodies, and in that case, a different furnace wall may be arranged for each temperature body. That is, in the present invention, the inner wall of the furnace body can be divided into three or more parts.

FIG. 2 shows another embodiment of the compound semiconductor single crystal manufacturing apparatus of the present invention.

This apparatus has substantially the same configuration as the manufacturing apparatus shown in FIG. 1, but the furnace body is divided into a furnace body 12 for a high temperature region and a furnace body 13 for a low temperature region. The points are different. Then, a furnace inner wall 31 is attached to each furnace body 12.13.
．． 32 are fixed respectively.

Example A GaAs single crystal was manufactured using the manufacturing apparatus shown in FIG.

Note that the tubular furnace inner wall 31 was formed of SiC, and the tubular furnace inner wall 32 was formed of Al2O. In addition, the support rod 51
A stainless steel rod with a length of 1 m was used.

A GaAs polycrystal 4 is placed in the quartz single crystal growth port 22.
A GaAs seed crystal was placed at one end of the boat 22. The boat 22, a diffusion barrier, and about 50 g of As needed to maintain the inside of the ampoule tube 21 at one pressure as a volatile component 23 were placed in a quartz ampoule tube 21 and sealed in vacuum.

This ampoule tube 21 was placed directly within the furnace wall 31, 32 of the furnace body 11. In the high temperature region 11a of the furnace body 11, G
The temperature required to turn the aAs polycrystal into a melt, that is, 1
There are a portion maintained at around 250° C. and a portion having a temperature gradient that gently solidifies the melt. Further, the low temperature region 11b of the furnace body 11 is maintained at around 610° C. in order to maintain the inside of the ampoule tube 21 with arsenic gas at approximately one atmosphere. Further, the aforementioned support rod 51 was connected to the end of the ampoule tube 21 on the low temperature side.

Then, the furnace body 11 is gradually moved to the left in the figure.
The melt in the boat 22 maintained at around 50° C. was gradually solidified from the seed crystal side at the right end to obtain a GaAs single crystal.

Comparative Example For comparison, the furnace inner wall 31 of the manufacturing apparatus shown in FIG.
．． A GaAs single crystal was manufactured in the same manner as in the above example except that 32 was replaced with a continuous tubular SiC inner wall of the furnace body.

As a result, in an example using the device of the present invention,
Compared to the comparative example using an apparatus configured with one inner wall of the furnace, temperature control was more stable and single crystals could be grown better.

In addition, in the apparatus of the present invention, even if the single crystal manufacturing process was repeated 30 times, no cracks occurred on the furnace inner wall 31, 32, but in the comparative example apparatus, after 10 times of use, cracks did not occur on the furnace inner wall 31. Cracks occurred at the boundary between the high temperature region and the low temperature region.

Furthermore, when comparing the single crystal obtained with the apparatus of the present invention and the single crystal obtained with the apparatus of the comparative example, no significant differences were observed in all of the crystal defects, electrical properties, purity, and photoluminescence properties. There wasn't.

That is, according to the semiconductor single crystal manufacturing apparatus of the present invention,
Single crystals with the same quality as single crystals obtained by conventional methods can be obtained through stable temperature control, are inexpensive to manufacture, and can be manufactured using a highly durable furnace wall. It was possible to reduce the manufacturing cost of single crystals.

"Effects of the Invention" As explained above, according to the present invention, a high temperature for growing a compound semiconductor single crystal having at least a part thereof in a temperature range equal to or higher than the melting point of a compound semiconductor single crystal such as a group III-V compound semiconductor is provided. The furnace body has a temperature region and a low temperature region for controlling the vapor pressure of volatile components, and separate walls of the furnace body are fixed in each temperature region, so that materials can be adjusted according to the temperature of each temperature region. The inner wall of the furnace body can be constructed using a relatively low-temperature part, so that the manufacturing cost of the inner wall of the furnace body can be reduced. In addition, since it is not affected by the sudden temperature gradient from the high-temperature section to the low-temperature section, the usable life of the furnace inner wall is long (furthermore, even when it is damaged or deteriorated and needs to be replaced, Since this can be done in a number of steps, running costs can also be reduced.

Further, since the temperatures in the high temperature region and the low temperature region can be prevented from influencing each other on the inner wall of the furnace, temperature control for single crystal growth is stabilized. As described above, according to the present invention, it is possible to reduce the cost of the furnace body and, in turn, reduce the manufacturing cost of compound semiconductor single crystals, and also to obtain high-quality single crystals, thereby improving industrial performance. The significance is extremely large.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing one embodiment of the compound semiconductor single crystal production apparatus of the present invention, FIG. 2 is a schematic diagram showing another embodiment of the compound semiconductor single crystal production apparatus of the present invention, and FIG. 4 is a schematic diagram showing an example of a conventional manufacturing device, and FIG. 4 is a schematic diagram showing another example of the conventional manufacturing device. In the figure, 11 is a furnace body, lla is a high temperature region, Ilb is a low temperature region, 12 is a furnace body for high temperature region, 13 is a furnace body for low temperature region, 21 is an ampoule tube, 22 is a port, 23 is the volatile component, 31.32 is the inner wall of the furnace, 41.42 is the trolley,
51 is a support rod, and 52 is a fixing base. 'l'=:- Figure Figure

Claims (3)

[Claims] (1) An apparatus for manufacturing a compound semiconductor single crystal by a boat method, which includes: a single crystal growth boat containing at least a raw material; an ampoule tube enclosing a volatile component; a high temperature region above the melting point of the crystal; A furnace body having a low temperature region for controlling the vapor pressure of volatile components, and means for arranging the ampoule tube within the furnace body and relatively moving the furnace body and the ampoule tube, An apparatus for producing a compound semiconductor single crystal, characterized in that the inner wall of the furnace is divided into a plurality of inner walls between the high-temperature region and the low-temperature region. (2) The compound semiconductor single crystal manufacturing apparatus according to claim 1, wherein the furnace body walls fixed to the high-temperature region and the low-temperature region of the furnace body are made of different materials. (3) The furnace inner wall fixed in the high temperature region of the furnace body is S
3. The compound semiconductor single crystal production apparatus according to claim 2, wherein the furnace body is made of iC, and the inner wall of the furnace body fixed in the low temperature region of the furnace body is made of Al_2O_3.