JP2014094853A - Method for manufacturing semiconductor single crystal of iii-v group compound, and semiconductor single crystal substrate of iii-v group compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress desorption of a group V element from a growing crystal surface, and to reduce dislocation density in the crystal caused by thermal stress.SOLUTION: A method for manufacturing a semiconductor single crystal of a III-V group compound by a liquid-sealing Czochralski method includes a heating step of putting a raw material containing a III group element and a V group element and a sealant in a crucible and heating the raw material and the sealant, a seeding step of bringing a seed crystal into contact with a melt of the raw material of which the surface is covered with the liquefied sealant, and a pulling-up step of pulling up the seed crystal through the liquefied sealant to grow a semiconductor single crystal of a III-V group compound. In the pulling-up step, at least a side face of the grown semiconductor single crystal of a III-V group is covered with the sealant by increasing a thickness of the liquefied sealant.

Description

  TECHNICAL FIELD The present invention relates to a method for producing a group III-V compound semiconductor single crystal and a group III-V compound semiconductor single crystal substrate, and more particularly, to a method for producing a group III-V compound semiconductor single crystal by a liquid-sealed Czochralski method. The present invention relates to a group III-V compound semiconductor single crystal substrate manufactured by the manufacturing method.

  For example, one of the methods for producing a group III-V compound semiconductor single crystal used as a substrate of a semiconductor device is a liquid encapsulated Czochralski (LEC) method. In the LEC method, a raw material and a sealant are accommodated in a crucible and heated, and the seed crystal is brought into contact with the melt of the raw material whose liquid surface is covered with a liquid sealant, while pulling up the seed crystal. Crystals grow through the sealant. By covering the liquid surface with the sealing agent in this way, crystal growth can be performed while suppressing the detachment of the V group element from the raw material (see, for example, Patent Document 1).

JP 2005-298255 A

  However, in the LEC method, the growing crystal surface continues to be heated at a temperature of 1000 ° C. or higher. For this reason, the group V element is detached from the upper surface and side surfaces of the crystal not covered with the sealant. The group III element remaining in the vicinity of the crystal surface due to the elimination of the group V element erodes the grown crystal and propagates downward. When the group III element reaches the solid-liquid interface, the crystal growth plane orientation is disturbed at the solid-liquid interface, and the crystal is polycrystallized.

For this reason, in the LEC method, for example, the crystal growth rate is increased to 6 mm / h to 12 mm / h. However, in this method, thermal stress is generated by pulling up the crystal at a high speed, and the dislocation density in the crystal exceeds 10,000 / cm ² . As described above, a substrate manufactured from a crystal having a high dislocation density generates a leak current via dislocation, and thus is unsuitable for use in a high-performance semiconductor device.

  An object of the present invention is to provide a method for producing a group III-V compound semiconductor single crystal that can suppress the detachment of a group V element from the crystal surface during growth and can reduce the dislocation density in the crystal due to thermal stress. And III-V compound semiconductor single crystal substrate.

According to a first aspect of the invention,
A method for producing a group III-V compound semiconductor single crystal by a liquid-sealed Czochralski method,
A heating step of containing a raw material containing a group III element and a group V element and a sealing agent in a crucible and heating the raw material and the sealing agent;
A seeding step of bringing a seed crystal into contact with the melt of the raw material whose liquid surface is covered with the sealant that has become liquid;
A pulling step of pulling up the seed crystal and growing a group III-V compound semiconductor single crystal through the sealant that has become liquid;
In the pulling process,
The thickness of the sealing agent that has become liquid is increased, and at least a side surface of the grown group III-V compound semiconductor single crystal is covered with the sealing agent.
A method for producing a group III-V compound semiconductor single crystal is provided.

According to a second aspect of the invention,
In the pulling process,
The III-V group compound semiconductor according to the first aspect, in which the thickness of the sealing agent that has become liquid is increased by allowing the filling member disposed in the crucible to enter the sealing agent. A method for producing a single crystal is provided.

According to a third aspect of the invention,
In the seeding step,
The thickness of the sealant that has become liquid is 30 mm or less,
In the pulling process,
The group III-V according to the first or second aspect, wherein the maximum thickness of the sealant that has become liquid is at least half the total length of the group III-V compound semiconductor single crystal at the end of the pulling step A method for producing a compound semiconductor single crystal is provided.

According to a fourth aspect of the invention,
In the pulling process,
The method for producing a group III-V compound semiconductor single crystal according to any one of the first to third aspects, wherein the growth rate of the group III-V compound semiconductor single crystal is 3 mm / h or less is provided.

According to a fifth aspect of the present invention,
Manufactured by the method for manufacturing a group III-V compound semiconductor single crystal according to any one of the first to fourth aspects,
It has a circular shape with a diameter of 150 mm or more,
The in-plane dislocation density is 10000 / cm ² or less.
A III-V compound semiconductor single crystal substrate is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the III-V compound semiconductor single crystal which can suppress the detachment | desorption of the group V element from the crystal | crystallization surface in the middle of growth, and can reduce the dislocation density in the crystal | crystallization by a thermal stress. And III-V compound semiconductor single crystal substrates are provided.

It is the schematic of the semiconductor single crystal manufacturing apparatus which concerns on one Embodiment of this invention, Comprising: It is a figure which shows the state at the time of a seeding process. It is the schematic of the semiconductor single crystal manufacturing apparatus which concerns on one Embodiment of this invention, Comprising: It is a figure which shows the state at the time of a raising process. It is the schematic of the semiconductor single crystal manufacturing apparatus which concerns on one Embodiment of this invention, Comprising: It is a figure which shows the state by which the sealing agent became the maximum thickness at the time of a raising process.

<One Embodiment of the Present Invention>
The method for producing a group III-V compound semiconductor single crystal according to an embodiment of the present invention is performed using, for example, a liquid-encapsulated Czochralski (LEC) method.

  That is, the III-V group compound semiconductor single crystal manufacturing method according to the present embodiment includes a heating step of heating the raw material and the sealing agent, a seeding step of bringing the seed crystal into contact with the raw material melt, And a pulling step for growing a group III-V compound semiconductor single crystal. In the pulling process, the thickness of the encapsulant that has become liquid is increased so that at least the side surface of the grown III-V compound semiconductor single crystal is covered with the encapsulant.

(1) Semiconductor Single Crystal Manufacturing Apparatus Hereinafter, a semiconductor single crystal manufacturing apparatus that implements the above-described III-V group compound semiconductor single crystal manufacturing method according to the present embodiment will be described with reference to FIG. FIG. 1 is a schematic view of a semiconductor single crystal manufacturing apparatus 20 according to the present embodiment, showing a state during a seeding process.

  As shown in FIG. 1, the semiconductor single crystal manufacturing apparatus 20 includes a high-pressure vessel 21 having a pressure resistance configured to be able to introduce a predetermined gas. For example, a cylindrical crucible 23 whose upper part is opened and whose lower part is closed is provided at a substantially central part in the high-pressure vessel 21. The crucible 23 is made of, for example, pyrolytic boron nitride (PBN) having excellent heat resistance. The crucible 23 is configured to accommodate a raw material 10 m of a group III-V compound semiconductor single crystal (hereinafter also simply referred to as “semiconductor single crystal”), a sealant 11, and the like.

  A cylindrical pulling shaft (upper shaft) 22 used for pulling the semiconductor single crystal is inserted into the high pressure vessel 21 from above the center of the high pressure vessel 21. The lower end of the pulling shaft 22 is configured so that a seed crystal (seed crystal) 22 s can be attached, and is disposed so as to face the crucible 23 in the high-pressure vessel 21. The lifting shaft 22 is configured to be rotatable and liftable by a rotating device and a lifting device (not shown).

  The crucible 23 is supported by a cylindrical pedestal (lower shaft) 25 via a container-type susceptor 24 that accommodates the crucible 23. The pedestal 25 is inserted into the high-pressure vessel 21 concentrically with the lifting shaft 22 from below the center of the high-pressure vessel 21. The pedestal 25 is configured to be rotatable and liftable by a rotating device and a lifting device (not shown). The susceptor 24 is made of graphite (C: graphite), for example, and is fixed to the upper end of the pedestal 25.

  In the high-pressure vessel 21, an upper heater 26 t and a lower heater 26 b that heat the raw material 10 m and the sealant 11 accommodated in the crucible 23 are positioned above and below the crucible 23 so as to surround the crucible 23. Respectively. The upper heater 26t and the lower heater 26b are made of, for example, graphite. The upper heater 26t and the lower heater 26b include a temperature controller (not shown) as temperature control means for controlling the respective temperatures. In addition, a thermocouple 26 c is provided in the upper part of the pedestal 25 as temperature detecting means for detecting the temperature of the raw material 10 m and the sealant 11 in the crucible 23.

The semiconductor single crystal manufacturing apparatus 20 includes a pair of filling members 30 installed in the crucible 23. Each of the pair of filling members 30 is supported by the column 31 and is disposed, for example, in contact with the inner wall of the crucible 23 at a position above the raw material 10m accommodated in the crucible 23 and facing each other. The column 31 for placing the filling member 30 at a predetermined position in the crucible 23 is installed, for example, on the bottom surface of the high-pressure vessel 21 outside the crucible 23, and is inserted into the crucible 23 from above the crucible 23. Is provided with a filling member 30. The filling member 30 and the support column 31 are made of, for example, graphite, alumina (Al ₂ O ₃ ), or the like. The shape of the filling member 30 can be cylindrical or prismatic, and the area of the bottom surface of each filling member 30 is preferably slightly larger than the cross-sectional area of the semiconductor single crystal to be grown, for example.

  With the semiconductor single crystal manufacturing apparatus 20 configured as described above, a single crystal of a III-V group compound semiconductor such as GaAs, GaP, InAs, InP or the like is manufactured using, for example, the LEC method. In the LEC method, the sealant 11 is in a liquid state so as to cover the melt of the raw material 10 m, so that a group V element having a high vapor pressure such as arsenic (As) or phosphorus (P) is decomposed from the raw material 10 m. While suppressing (dissociation) and desorption (evaporation), a III-V group compound semiconductor single crystal can be grown.

(2) Method for Producing III-V Group Compound Semiconductor Single Crystal Below, for example, III-V according to one embodiment of the present invention, which is performed using the LEC method in the semiconductor single crystal production apparatus 20 as described above, for example. A method for producing a group compound semiconductor single crystal will be described with reference to FIGS. FIG. 2 is a schematic view of the semiconductor single crystal manufacturing apparatus 20 according to the present embodiment, and shows a state during the pulling process. FIG. 3 is a schematic view of the semiconductor single crystal manufacturing apparatus 20 according to an embodiment of the present invention, and shows a state in which the sealant has a maximum thickness during the pulling process.

  In the present embodiment, a single crystal made of GaAs as a III-V compound semiconductor is manufactured using a raw material 10m containing gallium (Ga) as a group III element and arsenic (As) as a group V element. To do.

(Heating process)
First, the raw material 10 m containing Ga and As and the sealing agent 11 are accommodated in the crucible 23. For example, boron trioxide (B ₂ O ₃ ) or the like is used as the sealant 11. In addition, arrangement | positioning of the filling member 30 in the crucible 23 is adjusted beforehand according to the quantity of the sealing agent 11 accommodated in the crucible 23 so that the predetermined conditions in the seeding process etc. which are mentioned later may be met.

  Subsequently, the raw material 10 m and the sealant 11 are heated in the crucible 23 to, for example, 1250 ° C. or more and 1350 ° C. or less. At this time, the inside of the crucible 23 is set to an inert gas atmosphere having a pressure of, for example, atmospheric pressure or more, preferably 5 MPa or more and 8 MPa or less.

When the solid raw material 10m is heated in the crucible 23 and reaches the melting temperature, it melts into a melt. Moreover, the sealing agent 11 such as B ₂ O ₃ is solid at room temperature, for example, and when heated in the crucible 23 and reaches the melting temperature, it melts and becomes liquid. Since the sealant 11 has a specific gravity smaller than that of the melt of the raw material 10 m, the liquid surface of the raw material 10 m that has become the melt is covered with the melted sealant 11.

  In this way, while keeping the inside of the crucible 23 at atmospheric pressure or higher and covering the liquid surface of the raw material 10 m with the sealing agent 11 in the form of liquid, the desorption due to decomposition and evaporation from the As raw material 10 m having a high vapor pressure is prevented. Can be suppressed.

Here, a carbon (C) -containing gas such as carbon monoxide (CO) or carbon dioxide (CO ₂ ) may be mixed in the atmospheric gas in the crucible 23. Thereby, C is taken into the GaAs single crystal 10, and the semi-insulating GaAs single crystal 10 can be manufactured.

(Seeding process)
Subsequently, as shown in FIG. 1, a seeding step is performed in which the seed crystal 22 s is brought into contact with the melt of the raw material 10 m whose liquid surface is covered with the liquid sealant 11. That is, the crucible 23 is raised while rotating. Further, the pulling shaft 22 to which the seed crystal 22s is attached is lowered while being rotated, so that the seed crystal 22s is in contact with the melt of the raw material 10m.

  Here, the amount of the sealing agent 11 accommodated in the crucible 23 and the arrangement of the filling member 30 in the crucible 23 are such that the thickness of the sealing agent 11 that has become liquid in the seeding step is, for example, 30 mm or less, Preferably, it is adjusted in advance to be 5 mm to 30 mm, more preferably 22 mm to 30 mm.

  As the possible arrangement of the filling member 30, the lower end portion of the filling member 30 is not in contact with the molten sealant 11 and is located above the sealant 11, Either the contact state or the state of being immersed in the sealant 11 as shown in FIG. That is, initially, the amount of the sealing agent 11 accommodated in the crucible 23 and the arrangement of the filling member 30 in the crucible 23 are such that the sealing agent 11 that has become a liquid has a thickness within the above-described range during the seeding process. It may be adjusted so that.

  Specifically, when the filling member 30 is above the sealant 11 or is in contact with the liquid surface, an amount of the above-described thickness that satisfies the above-described thickness is obtained only by the volume of the melted sealant 11. It is necessary to store the sealant 11. When the lower end portion of the filling member 30 is immersed in the sealing agent 11, the amount of the sealing agent 11 is reduced by the volume of the filling member 30 entering the molten sealing agent 11. be able to.

  By setting the thickness of the sealing agent 11 to 30 mm or less, when the seed crystal 22s is immersed in the liquid of the sealing agent 11 and brought into contact with the melt of the raw material 10m, the seeding state can be easily observed. Therefore, the risk of failing the seeding operation is reduced. Further, the length of the seed crystal 22s can be shortened, and the acquisition and management of the seed crystal 22s are facilitated. In addition, adhesion of the sealant 11 or the like to the pulling shaft 22 can be suppressed.

  Moreover, the sealing agent 11 should just be thick enough to suppress the detachment of As from the raw material 10 m, and the lower limit of the thickness can be set to 5 mm, for example. Furthermore, when the thickness of the sealing agent 11 is set to 22 mm or more, the sealing agent 11 can be increased to a sufficient thickness in a pulling process described later, which is more preferable.

(Pulling process)
Subsequently, as shown in FIG. 2, the seed crystal 22s is pulled up while gradually decreasing the heating temperature of the upper heater 26t and the lower heater 26b. As a result, the GaAs single crystal 10 grows and is pulled up through the sealant 11.

  At this time, as the crystal growth proceeds, the melt of the raw material 10m in the crucible 23 decreases and the liquid level decreases, and the positional relationship between the upper heater 26t and the lower heater 26b and the crystal growth interface (solid-liquid interface). Will change. Therefore, the amount of decrease in the liquid level of the raw material 10 m is calculated from the amount of crystal growth, and the pedestal 25 is gradually raised by controlling the lifting device to correct this, and the position of the crucible 23 is adjusted. Thereby, the liquid level of the raw material 10m is kept substantially constant with respect to the heating zones of the upper heater 26t and the lower heater 26b. Therefore, the melt of the raw material 10 m can be efficiently heated and kept at a substantially constant temperature.

  The GaAs single crystal 10 is, for example, thin and sharp at the beginning, and is pulled up while maintaining a substantially constant thickness after reaching a predetermined thickness. Therefore, the GaAs single crystal 10 has a conical shape with a tip portion extending downward and a straight body portion having a substantially constant thickness (diameter). In addition, the end of the crystal growth becomes tapered again. Therefore, it has a downward convex tail part under the straight body part.

  When the GaAs single crystal 10 is pulled up through the sealant 11 while growing into such a shape, the sealant is equal to the volume of the GaAs single crystal 10 that is passing through the melt of the sealant 11. 11 is pushed away. Therefore, the liquid level of the sealing agent 11 with respect to the liquid level of the melted raw material 10 m initially shows a slight increase.

  Here, in the crystal growth by the conventional LEC method, when the upper end portion of the straight body portion of the GaAs single crystal comes out of the liquid surface of the sealant, the volume of the GaAs single crystal that passes through the melt of the sealant. Becomes substantially constant, and thereafter, the rise in the liquid level of the sealant 11 stops. Therefore, the GaAs single crystal protrudes from the liquid surface of the sealant 11. The side surfaces of the GaAs single crystal exposed to the atmosphere in the crucible 23 are continuously heated at a temperature of 1000 ° C. or higher. As a result, As is detached from the side surface of the exposed GaAs single crystal. When Ga remaining after the desorption of As aggregates and erodes the GaAs single crystal to reach the solid-liquid interface, polycrystallization occurs due to disorder of the crystal growth plane orientation.

  Therefore, in this embodiment, the filling member 30 is provided in the crucible 23 and the height of the liquid level of the sealant 11 is adjusted.

  That is, as the position of the crucible 23 gradually rises, the filling member 30 fixed at a predetermined position by the support column 31 is submerged into the sealant 11, and the depth of entry gradually increases. Go. Thereby, the sealing agent 11 of the volume of the filling member 30 that has entered is pushed away, and the liquid level of the sealing agent 11 with respect to the liquid level of the melted raw material 10 m increases. That is, the thickness of the sealing agent 11 increases.

  As shown in FIG. 3, such an increase in the liquid level of the sealant 11, that is, an increase in thickness, is caused by the entire filling member 30 after the liquid level increase due to the GaAs single crystal 10 stops. Continue until completely immersed in the sealant 11. That is, in the state where the filling member 30 is completely submerged in the sealant 11, the sealant 11 has the maximum thickness.

  As a result, at least the side surface of the GaAs single crystal 10 growing through the melt of the sealing agent 11 is covered with the sealing agent 11. As described above, the thickness of the sealant 11 in the seeding step is preferably adjusted to 22 mm or more, and the bottom surface of the filling member 30 has a slightly larger area than, for example, the cross-sectional area of the GaAs single crystal 10. . Thereby, the liquid level of the sealing agent 11 can be raised to a thickness that can sufficiently maintain the side surface of the GaAs single crystal 10 covered with the sealing agent 11 until the end of crystal growth.

  Specifically, adjustment is made so that the maximum thickness of the sealing agent 11 is, for example, more than half of the total length of the GaAs single crystal 10 at the end of the pulling process in a state where the filling member 30 is completely submerged in the sealing agent 11. Has been. As described above, for example, only the straight body portion of the GaAs single crystal 10 having a conical tip and tail is mainly used for manufacturing a GaAs single crystal substrate or the like. Therefore, if the maximum thickness of the sealant 11 is more than half of the total length of the GaAs single crystal 10, the thickness is sufficient to cover the straight body portion of the GaAs single crystal 10 almost completely. Further, as described above, if the sealing agent 11 covers at least the straight body portion of the GaAs single crystal 10, that is, the side surface, the GaAs single crystal obtained even if the tip portion of the GaAs single crystal 10 is exposed. It hardly affects the characteristics of the substrate.

  More specifically, for example, when manufacturing a GaAs single crystal having a total length of 200 mm having a diameter of about 150 mm (+10 mm), each filling member is formed into a cylindrical shape having a diameter of 170 mm, and the maximum thickness of the sealant The thickness can be 100 mm or more. At this time, in order to reduce the thickness of the sealant in the seeding step to 30 mm or less, the upper limit of the maximum thickness of the sealant in the pulling step is considered to be about 134 mm.

  In the present embodiment, the pulling process can be performed in a state where the growth rate of the GaAs single crystal 10 is reduced to, for example, 3 mm / h or less.

  In the crystal growth by the conventional LEC method, the side surface of the GaAs single crystal is exposed to the atmosphere in the crucible, and As is easily desorbed. Therefore, in order to suppress As desorption as much as possible, the growth rate of the GaAs single crystal is increased to, for example, 6 m / h to 12 mm / h to shorten the exposure time in the crucible atmosphere. For this reason, thermal stress is generated by pulling at a high speed, which may result in a GaAs single crystal having a high dislocation density.

  However, in the present embodiment, the side surface of the GaAs single crystal 10 is covered with the sealing agent 11, and As is not easily detached. Therefore, the growth rate of the GaAs single crystal 10 can be controlled to be 3 mm / h or less, for example, and the dislocation density in the crystal can be reduced.

  As described above, the GaAs single crystal 10 as the III-V group compound semiconductor single crystal is manufactured.

  From the GaAs single crystal 10 thus manufactured, for example, a GaAs single crystal substrate is manufactured according to the following procedure. That is, grinding is performed with a cylindrical grinding blade along the side surface of the cylindrical GaAs single crystal 10. For example, by grinding the thickness from the outermost surface of the GaAs single crystal 10 to about 5 mm inside, even if the As composition ratio of the outermost surface is slightly reduced, the portion can be removed, and the As composition ratio is further increased. A GaAs substrate with good uniformity can be obtained.

  Thereafter, the ground GaAs single crystal 10 is annealed as necessary. Next, the GaAs single crystal 10 is thinly sliced into a substrate shape using a band saw or the like, and one side or both sides and the outer peripheral end are polished.

The GaAs single crystal substrate manufactured as described above is a high-quality substrate with few crystal dislocations. For example, in a circular GaAs single crystal substrate having a diameter of 150 mm or more, the conventional in-plane dislocation density is, for example, more than 10,000 / cm ² , but in this embodiment, for example, 10,000 / cm ² or less. be able to.

(3) Effects According to this Embodiment According to this embodiment, one or more effects shown in Table 1 below are exhibited.

<Other Embodiments of the Present Invention>
As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to the above-mentioned embodiment, It can change variously in the range which does not deviate from the summary.

  For example, in the above-described embodiment, the GaAs single crystal 10 in which the group III element is Ga and the group V element is As has been mainly described, but the contained elements are not limited thereto. For example, the group III element may be indium (In), aluminum (Al), or the like. The group V element may be phosphorus (P), nitrogen (N), or the like. Thereby, a III-V group compound semiconductor single crystal made of not only GaAs but also GaP, GaN, InAs, InP, AlGaInP and the like can be manufactured.

  In the above-described embodiment, the semi-insulating GaAs single crystal 10 is manufactured by adding impurities such as C. However, the present invention is not limited to this configuration. Various impurities that control the conductivity of the semiconductor, such as imparting conductivity such as n-type or p-type, can be used, not limited to imparting semi-insulating properties by adding C or the like. A GaAs single crystal may be manufactured without adding impurities.

  In the above-described embodiment, at least the side surface of the GaAs single crystal 10 is covered with the sealant 11, but the entire GaAs single crystal may be completely submerged in the sealant. Alternatively, even if the side surface of the GaAs single crystal is not completely covered with the sealing agent, a predetermined effect of suppressing As desorption can be obtained.

  In the above-described embodiment, the pair of filling members 30 are provided so as to contact the inner wall of the crucible 23, but the number and arrangement of the filling members are not limited thereto.

  In the above-described embodiment, the filling member 30 is fixed and the crucible 23 is raised to enter the sealing agent 11. However, a movable filling member may enter the sealing agent. . In this case, in the step of pulling up the GaAs single crystal 10, it is possible to grow the crystal while fixing the position of the seed crystal and lowering the crucible instead of growing the crystal while pulling up the seed crystal 22s. At this time, the filling member may be lowered at a lowering speed than the crucible. However, as in the above-described embodiment, by making the filling member 30 fixed, it is not necessary to provide a separate drive mechanism or the like, and a simple and inexpensive apparatus configuration can be achieved.

  That is, the entry of the filling member into the sealant may be made by either one or both movements relative to each other. The pulling of the seed crystal or GaAs single crystal from the crucible in the pulling process also indicates a relative movement.

  In the above-described embodiment, the crucible 23 is made of PBN or the like, and the filling member 30 is made of graphite, alumina, or the like. However, the material is not limited to this as long as the material has excellent heat resistance.

  Moreover, in the above-mentioned embodiment, although the filling member 30 was used for the liquid level adjustment of the sealing agent 11, it is not limited to this structure. The liquid level of the sealing agent may be adjusted, for example, by additionally replenishing the sealing agent during the pulling process. However, in the method using the filling member 30 as in the above-described embodiment, the amount of the sealant 11 used can be suppressed, and the cost can be reduced.

  Next, examples according to the present invention will be described.

First, a GaAs single crystal according to the example was manufactured. That is, 24,000 g of GaAs polycrystal as a raw material and 1800 g of B ₂ O ₃ as a sealant were accommodated in a PBN crucible. At the stage where the GaAs polycrystal and B ₂ O ₃ were heated and melted, the filling member was positioned above without contacting the melt of B ₂ O ₃ .

Next, the crucible was raised while rotating. Initially, rotation of the B ₂ O ₃ melt was observed following the rotation of the crucible. The rotation of the B ₂ O ₃ melt was stopped when the filling member contacted the liquid surface due to the rise of the crucible. Based on the contact point between the liquid level of the sealant and the filling member, the amount of the filling member entering the B ₂ O ₃ was 9 mm. At this time, the thickness of B ₂ O ₃ was 27 mm.

In the pulling process after the seeding process, the growth rate was set to 3 mm / h, and a GaAs single crystal having a diameter of 150 mm (+10 mm) and a total length of 200 mm was obtained. The maximum thickness of B ₂ O ₃ was 110 mm. The above process was repeated to produce a total of five GaAs single crystals, and the following evaluation was performed.

In the visual appearance confirmation, there was no polycrystal. Moreover, these GaAs single crystals were sliced to produce a GaAs single crystal substrate having a diameter of 150 mm, and the dislocation density was measured for every 10 sheets. As a result, the average dislocation density was 5900 / cm ² .

10 GaAs single crystal (III-V compound semiconductor single crystal)
10 m Raw material 11 Sealant 20 Semiconductor single crystal manufacturing apparatus 21 High-pressure vessel 22 Lifting shaft 22s Seed crystal 23 Crucible 24 Susceptor 25 Pedestal 26c Thermocouple 26b Lower heater 26t Upper heater 30 Filling member 31 Column

Claims (5)

A method for producing a group III-V compound semiconductor single crystal by a liquid-sealed Czochralski method,
A heating step of containing a raw material containing a group III element and a group V element and a sealing agent in a crucible and heating the raw material and the sealing agent;
A seeding step of bringing a seed crystal into contact with the melt of the raw material whose liquid surface is covered with the sealant that has become liquid;
A pulling step of pulling up the seed crystal and growing a group III-V compound semiconductor single crystal through the sealant that has become liquid;
In the pulling process,
The thickness of the encapsulant that has become liquid is increased, and at least the side surface of the grown III-V compound semiconductor single crystal is covered with the encapsulant III- A method for producing a group V compound semiconductor single crystal. In the pulling process,
The thickness of the said sealing agent used as the liquid is increased by making the filling member arrange | positioned in the said crucible penetrate | invade in the said sealing agent, The III- of Claim 1 characterized by the above-mentioned. A method for producing a group V compound semiconductor single crystal. In the seeding step,
The thickness of the sealant that has become liquid is 30 mm or less,
In the pulling process,
3. The III according to claim 1, wherein a maximum thickness of the sealing agent that has become liquid is set to be not less than half of a total length of the III-V compound semiconductor single crystal at the end of the pulling process. -Manufacturing method of group V compound semiconductor single crystal. In the pulling process,
The method for producing a group III-V compound semiconductor single crystal according to any one of claims 1 to 3, wherein the growth rate of the group III-V compound semiconductor single crystal is 3 mm / h or less. Manufactured by the method for producing a group III-V compound semiconductor single crystal according to any one of claims 1 to 4,
It has a circular shape with a diameter of 150 mm or more,
A group III-V compound semiconductor single crystal substrate having an in-plane dislocation density of 10,000 / cm ² or less.

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