JPH0948700A - Production of group ii-vi or iii-v compound single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a compound single crystal having little crystal defect by coating an outer surface of a seed crystal composed of a group II-Vl single crystal compound, etc., with a coating film composed of a glassy substance and a powdery solid having a melting point higher than that of the compound of polycrystalline state. SOLUTION: The outer surface of a seed crystal composed of a single crystal of a group II-VI or III-V compound is coated with a coating film composed of a glassy substance and a powdery solid having a melting point higher than the melting point of the above compound in polycrystalline state. The coated product is placed on the bottom of a vertically maintained crucible and the remaining part of the crucible is filled with the compound having polycrystalline form. The crucible is inserted into a vertical furnace capable of forming an upper high-temperature region and a lower low-temperature region. The polycrystalline compound is melted while keeping a part of the seed crystal in solid state in the crucible by controlling the position of the crucible and the temperature of the upper high-temperature region. After forming a solid-liquid interface, the furnace and the solid-interface are vertically shifted while maintaining the temperatures in the lower low-temperature region and the upper high-temperature region to obtain the objective single crystal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a II-VI group or III-V group compound single crystal, and more particularly to the field of optoelectronics such as light emitting diodes (LEDs) and laser diodes, and transistors. The present invention relates to a method for producing a II-VI group or III-V group compound single crystal used in the electronic field.

[0002]

2. Description of the Related Art Examples of III-V and II-VI group compound semiconductor single crystals include gallium arsenide (Ga).
As), gallium phosphide (GaP), indium phosphide (InP), and cadmium telluride (CdTe).

Conventionally, these compound semiconductor single crystals have been manufactured by the horizontal Bridgman method (HB method) or the liquid sealing pulling method (LE).
It is known to be manufactured by various industrial methods such as C method), vertical Bridgman method (VB method) and vertical temperature gradient method (VGF method).

Of these methods, for example, the production of a compound semiconductor single crystal by the VB method is performed as follows.

Generally, the VB method uses a vertical furnace having one or more high temperature zones and one or more low temperature zones. These regions provide a temperature profile for the furnace that consists of a relatively high temperature zone of relatively uniform temperature and a low temperature zone of relatively uniform temperature separated by a transition zone having a temperature gradient of about 5-20 ° C / cm. Designed to be.

First, a vertically arranged crucible (usually composed of pBN) suitable for containing a Group II-VI or Group III-V compound is placed in a sealed ampoule. Single crystal growth is proceeded by slowly raising the furnace while holding the crucible-ampoule assembly stationary.

To manufacture a compound semiconductor by the VB method, a step of arranging a single crystal seed crystal at the bottom of a crucible, a step of putting a polycrystalline substance into a crucible, a crucible being placed in an ampoule, and then the ampoule is sealed. And placing the crucible-ampoule assembly on the pedestal inside the vertically arranged furnace, and heating the polycrystalline material and the upper portion of the single crystal seed crystal above its melting point. Moving the furnace upwards by the length of the melt obtained by melting the crystalline material to produce a solid single crystal material.

The II-VI or III-V compound semiconductor single crystal ingot thus produced is then removed from the crucible and sliced into wafers for various electronic or optoelectronic applications.

The VB method constructed as described above is regarded as promising as a method capable of producing a high-quality crystal having a low defect density at a low cost as compared with other methods.

[0010]

However, this V
In the production of the single crystal by the method B, when the seed crystal is placed at the bottom of the crucible, a gap is created between the crucible and the seed crystal. When the raw material melt such as GaAs melt enters the gap, the melt begins to solidify not from the seed crystal side but from the crucible wall surface side, which causes polycrystallization.

An object of the present invention is to industrially produce a II-VI group or III-V group compound single crystal having few crystal defects by solving the above problems and effectively preventing polycrystallization. Is to provide a method that can.

[0012]

According to a first aspect of the present invention, there is provided an information processing apparatus comprising:
A method for producing a single crystal of a group I-VI or group III-V compound is a method for producing a single crystal group II-VI or group III-V from a polycrystalline group II-VI or group III-V compound in a vertically arranged crucible. A method of producing a compound, the outer surface of a seed crystal consisting of a single crystal compound, a powder solid having a melting point higher than the melting point of the polycrystalline compound, and a step of coating with a film composed of a glassy material, , Placing the coated seed crystal at the bottom of the crucible, placing the polycrystalline compound in the rest of the crucible, and placing the seed crystal and the polycrystalline compound in the crucible, Part of the seed crystal in the crucible by arranging in a vertically arranged furnace that can create a zone and a lower temperature zone, and adjusting the position of the furnace and the temperature in the upper temperature zone. Solid state By melting the polycrystalline compound while keeping it, and setting the temperature of the lower low temperature region below the melting point of the single crystal compound, and setting the temperature of the upper high temperature region higher than the melting point, the solid- Growing a single crystal compound by vertically moving the furnace and the solid-liquid interface upward while substantially maintaining the steps of creating the liquid interface and the temperature settings in the lower low temperature region and the upper high temperature region. And steps.

A method for producing a II-VI group or III-V group compound single crystal according to the second aspect of the present invention is the method according to the first aspect, wherein the outer surface of the seed crystal is a coating made of a powder solid and a glassy substance. The step of coating includes applying a mixed solution containing a powder solid and a silanol compound to the outer surface of the seed crystal, and heating the seed crystal to which the mixed solution has been applied on the outer surface of the seed crystal. And forming a coating containing a powdered solid and a glassy material made of silicon oxide.

The vacuum heat treatment after applying the mixed solution to the seed crystal is performed in a range of 500 to 600 in order to prevent decomposition and deterioration of the seed crystal.
30 minutes or more at a temperature of about ℃, more preferably 500 ~
It may be carried out at a temperature of 600 ° C. for 2-3 hours. By this vacuum heat treatment, silanol in the applied mixed liquid is converted into silicon oxide (SiO ₂ ) by the heat polymerization reaction.

The method for producing a group II-VI or group III-V compound single crystal according to the third aspect of the present invention is the method according to the second aspect, wherein the step of applying the mixed solution to the outer surface of the seed crystal is the mixed solution. It is performed by immersing the seed crystal therein.

The method for producing a II-VI or III-V group compound single crystal according to the invention of claim 4 is the method of claim 2, wherein the step of applying the mixed liquid to the outer surface of the seed crystal is By spraying the mixed solution on the outer surface of the.

When the mixed solution is sprayed for use, it is preferable to mix acetone with the mixed solution. Compared to the mixture of acetone, spray coatability is improved,
This is because the internal strain of the film is reduced.

A method for producing a II-VI group or III-V group compound single crystal according to the invention of claim 5 is the method of claim 1, wherein the glassy material has a softening point lower than the melting point of the polycrystalline compound. It is characterized by having.

The method for producing a II-VI group or III-V group compound single crystal according to the sixth aspect of the present invention is the method according to the fifth aspect, wherein the glassy substance is diboron trioxide (B ₂ O).
₃ ) Including.

A method for producing a II-VI group or III-V group compound single crystal according to the invention of claim 7 is the same as that of the invention of claim 5, wherein the glassy substance is B ₂ O ₃ and silicon dioxide (SiO ₂ ). Contains a mixture of.

According to an eighth aspect of the present invention, in the method for producing a II-VI or III-V group compound single crystal according to any one of the first to seventh aspects, the powder solid contains boron nitride.

The method for producing a II-VI group or III-V group compound single crystal according to the ninth aspect of the present invention is the method according to the eighth aspect, wherein the grain size of boron nitride is 0.
It is not less than 05 μm and not more than 10 μm.

This is because if the average particle size is larger than 10 μm, wetting tends to occur and crystal defects are likely to occur.

In this specification, the particle size of boron nitride (BN) is, for example, BN as shown in FIG.
Even when the primary particles 10 are aggregated to form the secondary particles 20, it is defined as the particle size of the primary particles 10.

As the compound in the present invention, gallium arsenide (GaAs), InP, GaP, etc. III-
Examples thereof include group V compounds and group II-VI compounds such as ZnSe and CdTe.

The method for producing a II-VI or III-V group compound single crystal according to the tenth aspect of the present invention is a polycrystalline I crystal.
Single crystal I from a group I-VI or group III-V compound
A method for producing a group I-VI or group III-V compound, wherein the outer surface of a seed crystal composed of a single crystal compound is higher than the melting point of the polycrystalline compound via a binder composed of a glassy substance. Coating with a powdered solid having a melting point, placing the coated seed crystal at the bottom of the crucible, placing a polycrystalline compound in the remainder of the crucible, and seeding and polycrystalline compound in it. Placing the crucible located in the furnace in a vertically arranged furnace capable of creating a hot zone at the top and a cold zone at the bottom,
By adjusting the position of the furnace and the temperature in the upper high temperature region, the step of melting the polycrystalline compound while keeping a part of the seed crystal in the crucible in the solid state, and the temperature in the lower low temperature region to the single crystal By setting the temperature below the melting point of the compound and setting the temperature of the upper high temperature region higher than the melting point,
By moving the furnace and the solid-liquid interface vertically upward while substantially maintaining the steps of forming the solid-liquid interface and the temperature settings in the lower low temperature region and the upper high temperature region, a single crystal compound is obtained. And the step of growing.

According to the present invention, the outer surface of the seed crystal is coated with the coating composed of the powder solid and the glassy substance.

Therefore, when the seed crystal is placed at the bottom of the crucible, there is no gap between the crucible and the seed crystal, so that the raw material melt is prevented from solidifying and polycrystallizing from the wall surface of the crucible.

Furthermore, according to the present invention, the coating is composed of a powder solid and a glassy substance. Therefore, the adhesive force to the seed crystal is high and a uniform film can be formed.

FIG. 13 is a diagram schematically showing the state of the outer surface of the seed crystal 7 coated with the coating composed of the powder solid 3 and the glassy substance 13 according to the present invention, with reference to FIG. According to the present invention, the glassy substance 13a located between the powder solids 3 acting as a lubricant and the glassy substance 13b located between the powder solids 3 acting as a lubricant and the seed crystal 7 are used as binders. As described above, a uniform film having a strong adhesive force to the seed crystal 7 and being formed is formed as described above.

[0031]

EXAMPLE FIG. 1 is a view showing an example of a process for producing a II-VI group or III-V group compound single crystal.

Each step shown in FIG. 1 will be described below. (1) Raw Material Pretreatment Step First, a raw material made of GaAs polycrystal synthesized by the boat method was chamfered. This is to prevent the coating film formed on the inner surface of the crucible from being peeled off by the edge of the raw material.

On the other hand, a seed crystal made of GaAs single crystal was chamfered in the same manner as the polycrystalline raw material. This is to prevent the coating formed on the inner surface of the crucible from being peeled off when the seed is inserted into the bottom of the crucible.

Subsequently, the polycrystalline raw material and the seed that were subjected to the above-mentioned treatment were etched to remove impurities on their surfaces. The etching conditions are
Normal conditions were used as shown below.

Etching condition example 1 (when a sulfuric acid-based etching solution is used) Etching solution composition; sulfuric acid: hydrogen peroxide: water = 3: 1: 1 etching solution temperature; 60 ° C. etching time; 20 minutes for polycrystalline raw material Before and after, 1 to 2 minutes for seed Etching condition example 2 (when aqua regia is used) Etching solution composition; nitric acid: hydrochloric acid = 1: 3 Etching solution temperature; room temperature Etching time; About 20 minutes for polycrystalline raw material, seed About 8 minutes (2) Crucible pretreatment step (Example 1) FIG. 2 is a diagram showing an example of the crucible pretreatment step.

The crucible pretreatment step will be described below with reference to FIG. (A) Preparation of mixed liquid BN powder having an average particle diameter of 10 μm or less was used. The oxygen concentration of these particles was 3% or less. The lower the oxygen concentration of the particles, the more difficult it is to react with the dopant, which is more preferable.

As the silanol compound, O produced by Tokyo Ohka
A CD was used. This OCD is a liquid composed of a silanol compound and a solvent.

In this experiment, the inorganic type 2
(Si (OH) ₄ : 5.9 wt% content, solvent: ethyl acetate) and organic type 7 (RnSi (OH) _4-n ; R
Represents an alkyl group. : 12 wt% content, solvent: methanol) were used. Both Type 2 and Type 7 were usable up to the concentration of 20 wt%.

Using the BN particles and the silanol compound, the mixed solution was mixed as follows.

When the mixed liquid is used in a liquid state (liquid application)

[0041]

[Table 1]

When spraying a mixed solution

[0043]

[Table 2]

As shown in Table 2, when the mixed solution is applied by spraying, it is preferable to mix acetone.

The first reason for mixing acetone in this way is to improve spray coatability. Since ethyl acetate or methanol, which is a solvent for OCD, has low volatility, it becomes liquid when continuously applied, and is easily cracked or mottled after drying. Further, since OCD has a high viscosity, it is difficult for spray particles to become fine mist, and it is difficult to form a uniform film. Therefore, by mixing acetone in this way, it is possible to obtain an effect that the volatility is good and it is difficult to be in a liquid state. Further, since it becomes a fine mist, there is an effect that a uniform film can be obtained.

The second reason for mixing acetone is to reduce the internal strain of the film. If the OCD ratio is high, G
Although it is difficult to get wet with the aAs melt, the film becomes hard and the internal strain becomes large. A film having a large internal strain is easily cracked or cracked and easily peeled off. Therefore, by mixing acetone in this way, the OCD concentration is lowered, so that the internal strain of the film is reduced, and cracks and peeling are less likely to occur.

The results of the examination of the particle size of BN powder and the mixing ratio of acetone in the mixed solution are as follows.
The results are shown in Tables 3 and 4 below. In Tables 3 and 4, the term "defect" refers to the occurrence of dislocations or polycrystals.

[0048]

[Table 3]

[0049]

[Table 4]

(B) Application of the mixed solution to the crucible The application of the mixed solution to the crucible can be carried out by applying the mixed solution to the inner surface of the crucible in a liquid state (liquid application) or by spraying the mixed solution ( Spraying).

FIG. 3 is a view showing a state in which the mixed liquid is sprayed and applied to the crucible. Referring to FIG. 3, when spray-applying the mixed liquid 5 to the pBN crucible 1 using the sprayer 6, the crucible is heated to 50 to 15 by the hand heater 4.
It is advisable to perform it while heating to 0 ° C. This is because the solvent in the spray-applied mixture can be dried quickly to prevent the mixture from dripping.

When spraying from the opening 1a above the crucible during spray coating, the sprayed liquid is repelled by the wall of the crucible. Hateful. Therefore, by suctioning from the seed setting portion 1c side, the adhesion of the mixed liquid 5 to the tapered portion 1b and the seed setting portion 1c is improved.

FIG. 5 is a sectional view showing an example of the crucible used in the present invention. Referring to FIG. 5, this crucible 1
Has fine irregularities formed on its inner surface. By using such a crucible, it is possible to obtain the effect that the coating formed on the inner surface of the crucible is less likely to peel off. As the magnitude of surface irregularities, for example, up to a height R _max is 10 to 150 m, the center line average roughness R _a include the 3~15μm is used may.

Here, "maximum height R _max " means that a portion having an evaluation length Lm is extracted from the cross-section curve in the direction of the average line, and the cross-section curve is sandwiched by two straight lines parallel to the average line. A value obtained by measuring the distance between these two straight lines in the direction of longitudinal magnification.

The "cross-section curve" means the contour that appears at the cut surface when the measurement surface is cut along a plane perpendicular to the average surface of the measurement surface. In addition, the "mean line" is a straight line having the geometric shape of the surface to be measured in the sampling portion of the section curve, and the line set so that the sum of squares of the deviation from that line to the section curve is minimized. Say.

The "center line average roughness R _a " means that the evaluation length Lm is extracted from the roughness curve in the direction of the center line.
When the center line of the extracted portion is the X axis and the direction of longitudinal magnification is the Y axis and the roughness curve is represented by Y (x), it means the value obtained by the following formula.

[0057]

[Equation 1]

The "roughness curve" refers to a curve obtained by a measuring method having a characteristic of removing a low frequency component from a sectional curve. Further, the "center line" means a straight line in which, when a straight line parallel to the average line of the roughness curve is drawn, the areas surrounded by this straight line and the roughness curve are equal on both sides of this straight line.

The above-mentioned indexes of surface roughness are all JIS
According to B0601-1976.

Furthermore, when the mixed solution is applied to the inner surface of the crucible, if it is applied thickly at one time, cracks may occur in the coating or the coating may be easily peeled off. Therefore, it is preferable to apply the mixed solution to the crucible twice or more.

For example, a preferable film thickness for one application is 50 to 500 μm for liquid application, and 50 to 1000 μm for spray application. Therefore, when applying twice, for example, four kinds of applying methods as shown in Table 5 can be considered.

[0062]

[Table 5]

In addition, when the multi-coating is performed twice or more, it is preferable that the film by the first coating is once subjected to a heat treatment at about 1000 ° C. before the second coating. . This heat treatment increases the strength of the film by the first application, and the film is not cracked even when the multiple application is subsequently performed.

(C) Application of the mixed solution to the seeds The application of the mixed solution to the seeds is performed by immersing (immersing) the seed in the mixed solution or spraying (spraying) the mixed solution on the outer surface of the seed. ) Method.

In the case of liquid application, it is preferable to use, for example, the mixed liquid of mixed liquid mixing example 1 shown in Table 1, while in the case of spraying, it is preferable to use, for example, mixed liquid mixing example 2 shown in Table 2. .

Forming a film on the seed in this way is
For the following reasons. That is, if the GaAs melt flows into the space between the seed and the crucible, the melt may be solidified not from the seed side but from the wall surface side of the crucible and polycrystallized. Therefore, by forming a film on the seed in this way, it is possible to prevent a gap from being formed between the seed and the crucible, and prevent the GaAs melt from entering.

FIG. 6 is a diagram showing a state in which the seed is immersed in the mixed solution and the mixed solution is applied to the seed.

With reference to FIG. 6, when the portion of seed 7 excluding tip portion 7a is dipped in mixed solution 5 and installed at the bottom of the crucible, it may be inserted from tip portion 7a.

(D) Vacuum heating of crucible and seed Inorganic OCD is heated in vacuum to remove water from Si (OH) ₄ by a heat polymerization reaction, so that S
It becomes iO ₂ (quartz glass).

On the other hand, when the organic OCD is heated in vacuum, a small amount of graphite remains in addition to SiO ₂ . Since this graphite easily wets the GaAs melt, crystal defects (dislocations) may occur due to wetting.

Table 6 below shows preferable vacuum heating conditions for the crucible and the seed.

[0072]

[Table 6]

If the heating temperature is 500 ° C. or higher, there is no problem in forming SiO ₂ . However, although the pBN crucible can be heated at a high temperature of, for example, about 1500 ° C., it is considered appropriate to heat the GaAs seed at 500 to 600 ° C. in order to prevent decomposition and deterioration of GaAs.

The degree of vacuum does not particularly affect the production of SiO ₂ , and if water can be removed, for example, nitrogen (N ₂ ), argon (Ar)
It is considered to be good even in a gas stream such as.

FIG. 4 is a diagram showing a state in which the crucible to which the mixed liquid is applied is heated in vacuum. With reference to FIG. 4, the mixed solution 5
The crucible 1 having been subjected to is placed in a quartz container 8 and is heated by a heater 14 from the outside while the inside of the quartz container 8 is kept in a vacuum state by a vacuum pump.

FIG. 7 is a diagram showing a state in which the seed applied with the mixed solution is heated in vacuum. With reference to FIG. 7, the seed 7 to which the mixed liquid 5 is applied is heat-treated by the heater 24 in vacuum.

By such vacuum heat treatment, a coating film made of BN powder and SiO ₂ is formed on the inner surface of the crucible and the outer surface of the seed.

(E) Attachment of seed The seed having the coating formed on the outer surface as described above is inserted into the crucible having the coating formed on the inner surface and placed at the bottom of the crucible.

At this time, if there is an edge at the tip of the seed, the coating film formed on the inner surface of the crucible will be peeled off. Therefore, it is preferable to insert the seed into the crucible from the chamfered side.

After the seed is attached, BN or pBN is attached to the bottom of the crucible so that the seed does not drop from the crucible.
It is preferable to attach a cap or stopper 31 made of plastic.

(F) Filling the gap between the crucible and the seed When the seed is attached to the bottom of the crucible as described above, a gap may be formed between the crucible and the seed. If the GaAs melt enters this gap, solidification may start from that portion and polycrystallization may occur.

Therefore, it is preferable to fill the gap between the crucible and the seed as follows. First, the mixed solution is applied to the gap between the crucible and the seed. To apply the mixed solution, drop the mixed solution into the gap with a dropper to fill it, or
It can be performed by a method of spraying the mixed solution into the gap. In the case of spraying, it is necessary to wipe off the mixed solution adhering to the upper end surface of the seed after application. Further, the upper end surface of the seed may be masked in advance before spraying so that the mixed liquid does not adhere.

In the case of dropping and filling, for example, it is preferable to use the mixed liquid of mixed liquid mixing example 1 shown in Table 1, while
In the case of spraying, for example, a mixed liquid mixing example 2 shown in Table 2
The use of is preferred.

FIG. 8 is a sectional view showing a state in which the gap between the crucible and the seed is filled, and FIG. 9 is a partially enlarged sectional view of a portion IX in FIG.

With reference to FIGS. 8 and 9, the mixed liquid 5 is filled in the gap 9 between the crucible 1 having the coating 15 formed on the inner surface thereof and the seed 7 having the coating 75 formed on the outer surface thereof. ing.

(G) Vacuum heating Next, a vacuum heating treatment is carried out to heat and polymerize the filled mixed solution. As an example of the vacuum heating conditions, heating is performed at a temperature of 500 to 600 ° C., which is a temperature that does not damage the seed, for 2 to 3 hours, and a vacuum degree of 10 ⁻⁶ to 10 ⁻⁸ Torr.
It is good to do it under the atmosphere.

By such a vacuum heat treatment, a film made of BN powder and SiO ₂ is formed in the gap between the crucible and the seed.

(Example 2) In the above-mentioned Example 1, the case where the coating film for coating the inner surface of the crucible and the outer surface of the seed was composed of BN in the form of powder solid and only SiO ₂ as the glassy substance was described. , SiO as glassy material
_When only ₂ is used, it does not soften at the melting point of GaAs.

However, when B ₂ O ₃ or a mixture of B ₂ O ₃ and SiO ₂ is used as the glassy substance, softening occurs at the melting point of GaAs. As a result, the glassy substance as the binder does not hinder the movement of the BN particles as the lubricant, so that the effect of the BN powder particles in the present invention as the lubricant can be further enhanced.

Therefore, hereinafter, B _{2 is} used as a glassy substance.
A method of forming a film and its effect will be described for the case of using a mixture of O ₃ or B ₂ O ₃ and SiO ₂ .

When B ₂ O ₃ is used as the glassy substance (a) Method for forming coating (Method 1) First, BN powder is applied to the inner surface of the crucible. Next, the crucible to which the BN powder has been applied in this manner is heated at a temperature of 900 ° C. to 1200 ° C. in an oxygen (O ₂ ) gas or O ₂ mixed gas atmosphere. Then
The surface of the BN powder is oxidized according to the reaction of the formula (1) shown below.

4BN + 3O ₂ → 2B ₂ O ₃ + 2N ₂ (1) As a result, BN powder particles and B ₂ O are formed on the inner surface of the crucible.
_A coating consisting of ₃ and ₃ is formed.

(Method 2) First, BN powder and boric acid (H ₃ B
After mixing with O ₃ ) powder, it is further mixed with water or a solvent such as alcohol to prepare a mixed liquid.

Next, the mixed solution thus prepared is
Apply to the inner surface of the crucible or the outer surface of the seed. Subsequently, the crucible coated with the mixed liquid in this manner is heat-treated at a temperature of 300 ° C. to 1200 ° C. in a nitrogen (N ₂ ) gas, argon (Ar) gas or O ₂ gas atmosphere.
On the other hand, the seed applied with the mixed liquid is heat-treated at a temperature of 300 ° C. to 600 ° C. in an atmosphere of N ₂ gas or Ar gas.

As a result, the inner surface or seed of the crucible
BN powder particles and B on the outer surface of₂ O _Three The coating consisting of
It is formed.

(Method 3) First, BN powder and boron oxide (B
₂ O ₃ ) powder and then further mixed with a solvent such as water or alcohol to prepare a mixed solution. When preparing the mixed liquid, the B ₂ O ₃ powder may be dissolved in water or a solvent such as alcohol in advance and then further mixed with the BN powder.

Next, the mixed solution thus prepared is
Apply to the inner surface of the crucible or the outer surface of the seed. Subsequently, the crucible coated with the mixed liquid in this manner is treated under an atmosphere of N ₂ gas, Ar gas or O ₂ gas at 300 ° C. to 1 ° C.
Heat treatment is performed at a temperature of 200 ° C. On the other hand, the seed applied with the mixed liquid is heat-treated at a temperature of 300 ° C. to 600 ° C. in an atmosphere of N ₂ gas or Ar gas.

As a result, the inner surface or seed of the crucible
BN powder particles and B on the outer surface of₂ O _Three The coating consisting of
It is formed.

(B) Effect As compared with the case where SiO ₂ is used as the glassy substance, there is no possibility that Si is mixed into the raw material melt,
In particular, it is effective in the production of semi-insulating crystals.

B ₂ O ₃ and SiO as glassy substances
_When a mixture with ₂ is used (a) Method for forming coating (Method 1) First, BN powder and a silanol compound are mixed to prepare a mixed solution. As a silanol compound,
For example, the above-mentioned OCD can be used.

Next, the mixed solution thus prepared is
Apply to the inner surface of the crucible. Then, the crucible to which the mixed liquid is applied is subjected to an oxidation treatment. By this oxidation treatment,
The BN powder in the mixed solution is oxidized and a part thereof is changed to B ₂ O ₃ , and the silanol is changed to silicon oxide (SiO ₂ ).

As a result, a coating film composed of BN particles and a mixture of B ₂ O ₃ and SiO ₂ is formed on the inner surface of the crucible.

(Method 2) First, BN powder, B ₂ O ₃ powder and silanol compound are mixed to prepare a mixed solution.
As the silanol compound, for example, the above-mentioned OCD can be used. Also, instead of B ₂ O ₃ powder,
Boric acid (H ₃ BO ₃ ) powder may be used.

Next, the mixed solution thus prepared is
Apply to the inner surface of the crucible or the outer surface of the seed. Subsequently, the crucible to which the mixed liquid is applied is heat-treated at a temperature of 300 ° C. to 1200 ° C. under a nitrogen (N ₂ ) gas, argon (Ar) gas or oxygen (O ₂ ) gas atmosphere. On the other hand, the seed to which the mixed liquid is applied is heat-treated at a temperature of 300 ° C. to 600 ° C. in an N ₂ gas or Ar gas atmosphere.

As a result, a coating film of BN particles and a mixture of B ₂ O ₃ and SiO ₂ is formed on the inner surface of the crucible or the outer surface of the seed.

(Method 3) First, BN powder, SiO ₂ powder and B ₂ O ₃ powder are mixed and then further mixed with a solvent such as water or alcohol to prepare a mixed liquid. In addition, B ₂
Boric acid (H ₃ BO ₃ ) powder may be used instead of the O ₃ powder.

Next, the mixed solution thus prepared is
Apply to the inner surface of the crucible or the outer surface of the seed. Subsequently, the crucible coated with the mixed liquid is heat-treated at a temperature of 300 ° C. to 1200 ° C. under an atmosphere of N ₂ gas, Ar gas or O ₂ gas. On the other hand, for the seed coated with the mixed liquid, under a N ₂ gas or Ar gas atmosphere, 300
Heat treatment is performed at a temperature of ℃ to 600 ℃.

As a result, a coating film of BN particles and a mixture of B ₂ O ₃ and SiO ₂ is formed on the inner surface of the crucible or the outer surface of the seed.

(Method 4) First, BN powder and SiO ₂ powder are mixed and then mixed with a solvent such as water or alcohol to prepare a mixed liquid.

Next, the mixed solution thus prepared is
Apply to the inner surface of the crucible. Subsequently, the crucible coated with the mixed solution is subjected to an oxidation treatment.

As a result, a film composed of BN particles and a mixture of B ₂ O ₃ and SiO ₂ is formed on the inner surface of the crucible.

[0112] As (b) glassy material effect in the coating can be used only B ₂ O _3, although fully effective as a binder is obtained, B ₂ O
₃ is a substance that is easily affected by moisture absorption as shown below.

That is, B ₂ O ₃ changes to boric acid (H ₃ BO ₃ ) due to moisture absorption, and this H ₃ BO ₃ has no adhesive force and has the property of being scattered by heating.

Therefore, when B ₂ O ₃ is changed to H ₃ BO ₃ , the adhesive force of the film is lowered and the film is scattered by heating until the raw material is melted. The glassy substance is deficient and the coating is peeled off. As a result, crystal defects such as generation of twins or micro twins or polycrystallization may occur.

Therefore, by using a mixture of B ₂ O ₃ and SiO ₂ as the glassy substance, the above-mentioned concern is eliminated.

For example, in the production of GaAs single crystal, the added SiO ₂ concentration is 0.1 mol% to 80 m.
ol% is preferred. B ₂ O _{3 has} a softening point of 300 ° C to 35
Since it is 0 ° C. and the softening point of SiO ₂ is around 1500 ° C., when the SiO ₂ concentration is higher than 80 mol%, the softening point of the mixture of B ₂ O ₃ and SiO ₂ is GaAs.
This is because the softening point of is not less than. On the other hand, SiO
_{This is because if} the concentration of ₂ is less than 0.1 mol%, B ₂ O ₃ will be affected by moisture absorption.

The concentration of SiO ₂ added is preferably 1 mol% to 70 mol%, more preferably 5 mo%.
It is good to be 1% -60 mol%.

Further, in manufacturing a GaP single crystal having a melting point higher than that of GaAs, the added SiO ₂ concentration is 0.1.
mol% to 90 mol%, preferably 1 mol% to 80
mol%, more preferably 5 mol% to 70 mol%
Is good.

Further, in the production of an InP single crystal having a melting point lower than that of GaAs, the added SiO ₂ concentration is 0.
1 mol% to 65 mol%, preferably 1 mol% to 5
5 mol%, more preferably 5 mol% to 45 mol
It is good to be%.

Hereinafter, B ₂ O ₃ and S were used as glassy substances.
The advantages of using a mixture with iO ₂ are SiO ₂
The case where the concentration is low and the case where the concentration is high will be described separately.

In a mixture of B ₂ O ₃ and SiO ₂ ,
When the concentration of SiO ₂ is low, that is, when the concentration of B ₂ O ₃ is high, the contamination with Si is small, and therefore it is preferable to apply it when manufacturing a semi-insulating crystal.

On the other hand, in the mixture of B ₂ O ₃ and SiO ₂ , when the SiO ₂ concentration is high, that is, when the B ₂ O ₃ concentration is low, the dopant Si and boron (B) in B ₂ O ₃ are added. Since the substitution reaction of 1 is unlikely to occur, the concentration of Si as a dopant is low and the contamination with boron (B) is small.
Therefore, it is preferably applied when manufacturing Si-doped crystals. Further, when the SiO ₂ concentration becomes high, the change to boric acid (H ₃ BO ₃ ) due to the moisture absorption of B ₂ O ₃ is more effectively prevented, so that the effect as a binder is sufficiently exerted and the adhesion of the coating film is improved. Is improved and H ₃ B is added when heated.
O ₃ is not scattered and the glassy substance as a binder in the coating is not deficient.

(3) Raw Material Charge 5 kg of a GaAs polycrystalline raw material synthesized by the boat method (HB method) was charged in the pBN crucible subjected to the above-mentioned pretreatment. As the dopant, 110 mg of high-purity silicon (Si) wafer was used.

The equilibrium vapor pressure (1a
It is preferable to add 1 g of high-purity arsenic (As) into the crucible together with the GaAs polycrystal raw material in order to keep the temperature at tm).

(4) Vacuum Encapsulation FIG. 10 is a sectional view showing a state in which the quartz ampoule is encapsulated.

The crucible 1 charged with the polycrystalline raw material 12 as described above was placed in the quartz ampoule 50, the quartz cap 51 was capped, and the burner 52 was vacuum-sealed while drawing a vacuum.

The crucible 1 is charged with a GaAs polycrystal raw material 12 and a Si wafer 22 as a dopant accommodated in a recess formed by the polycrystal raw material 12.

(5) Crystal Growth The GaAs crystal growth was performed under ordinary conditions.

The VB method is a method of growing a single crystal by lowering the temperature from the seed crystal side by raising the heater or lowering the ampoule. On the other hand, the VGF method is a method in which the positional relationship between the heater and the ampoule is fixed, and the temperature profile of the heater is changed to lower the temperature from the seed crystal side to grow a single crystal.

An example of the growth conditions by the VB method will be described below. The sizes of the crucible and the quartz ampoule used were as shown in FIGS. 11 and 12, respectively.

First, the heater temperature was raised at a temperature rising rate of 3 to 5 ° C./min or the ampoule was moved to a higher temperature side to melt the polycrystalline raw material. Subsequently, the heater temperature is raised at a heating rate of 5 to 10 ° C /
By raising the temperature at some point, a part of the seed crystal was melted and seeding was performed.

Next, VB growth was performed under the following conditions. High temperature zone temperature: 1245 to 1265 ° C. Low temperature zone temperature: 1000 to 1150 ° C. Temperature gradient: 5 to 10 ° C./cm Heater moving speed: 2 to 7 mm / hour Heater moving distance: around 300 mm After stopping the movement, 5 ~ 180 ℃
Cooling was performed at 1 / hour.

Cooling can be performed, for example, from the temperature at the end of growth to room temperature at a rate of 180 ° C./hour. Further, in order to suppress the generation of crystal defects, the temperature from the temperature at the end of growth to 1000 ° C. is 1000 ° C. at a rate of 10 ° C./hour.
To 800 ° C at a rate of 30 ° C / hour from 800 ° C to 6
Cooling can also be performed at a rate of 50 ° C./hour up to 00 ° C., and at a rate of 100 ° C./hour from 600 ° C. to room temperature.

The characteristics of the crystal thus grown are shown in Table 7.

[0135]

[Table 7]

The shoulder portion, the middle portion and the tail portion in Table 7 are as shown in FIG.

(6) Ampoule indexing After the crystal growth, the ampoule was broken and the GaAs single crystal was extracted.

[0138]

As described above, according to the present invention, polycrystallization is effectively prevented, and the number of crystal defects is II.
A group VI- or group III-V compound single crystal can be produced.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a process for producing a II-VI group or III-V group compound single crystal.

FIG. 2 is a diagram showing an example of a crucible pretreatment process according to the present invention.

FIG. 3 is a diagram showing a state in which a mixed solution is sprayed and applied to a crucible according to the present invention.

FIG. 4 is a diagram showing a state in which the crucible to which the mixed liquid is applied according to the present invention is vacuum-heated.

FIG. 5 is a sectional view showing an example of a crucible used in the present invention.

FIG. 6 is a diagram showing a state in which a seed is immersed in a mixed solution and the mixed solution is applied to the seed according to the present invention.

FIG. 7 is a diagram showing a state in which the seed applied with the mixed solution according to the present invention is heated in vacuum.

FIG. 8 is a cross-sectional view showing a state where a gap between a crucible and a seed is filled according to the present invention.

9 is a partially enlarged cross-sectional view of a portion IX in FIG.

FIG. 10 is a cross-sectional view showing a state in which a quartz ampoule is enclosed.

FIG. 11 is a diagram showing sizes of crucibles used in Examples of the present invention.

FIG. 12 is a diagram showing sizes of quartz ampules used in Examples of the present invention.

FIG. 13 is a diagram schematically showing a state of an outer surface of a seed crystal coated with a coating film composed of a powder solid and a glassy substance according to the present invention.

FIG. 14 is a sectional view showing a crystal grown according to an example of the present invention.

FIG. 15 is a diagram for explaining the particle size of BN particles.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 pBN crucible 1a Opening 1b Tapered part 1c Seed installation part 2 GaAs melt 3 BN powder 5 Mixed liquid 6 Atomizer 7 Seed 8 Quartz container 9 Gap 12 GaAs polycrystalline raw material 13, 13a, 13b, 13c Glassy substance 15,75 Coat 50 Quartz ampoule 51 Quartz cap In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (10)

[Claims] 1. A polycrystalline I in a vertically arranged crucible.
Single crystal II from group I-VI or group III-V compound
A method for producing a Group VI or III-V compound, comprising: an outer surface of a seed crystal composed of a single crystal of the compound, and a glass solid having a melting point higher than that of the polycrystalline compound Coating with a coating of a substance, the coated seed crystal, the step of placing the bottom of the crucible, the rest of the crucible, the step of placing the polycrystalline compound, and the seed crystal Placing the crucible in which the polycrystalline compound is placed in a vertically arranged furnace capable of creating a hot zone at the top and a cold zone at the bottom; By melting the polycrystalline compound while maintaining a part of the seed crystal in the crucible in a solid state by adjusting the temperature of the high temperature region of the single crystal. Setting below the melting point of the compound, and by setting the temperature of the high temperature region of the upper part higher than the melting point, to form a solid-liquid interface, in the low temperature region of the lower part and the high temperature region of the upper part. Growing the single crystal of the compound by vertically moving the furnace and the solid-liquid interface upward while substantially maintaining the temperature setting. II-
A method for producing a Group VI or III-V compound single crystal. 2. The step of coating the outer surface of the seed crystal with a film made of a powdered solid and a glassy substance, the mixture of the powdered solid and the silanol compound is applied to the outer surface of the seed crystal. And a step of forming a coating film containing the glass solid substance made of the powder solid and silicon oxide on the outer surface of the seed crystal by heating the seed crystal to which the mixed liquid is applied under vacuum. II-VI or III according to claim 1, comprising
-Method for producing Group V compound single crystal. 3. The group II-VI or III- according to claim 2, wherein the step of applying the mixed solution to the outer surface of the seed crystal is performed by immersing the seed crystal in the mixed solution. Method for producing group V compound single crystal. 4. The II-V according to claim 2, wherein the step of applying the mixed solution to the outer surface of the seed crystal is performed by spraying the mixed solution onto the outer surface of the seed crystal.
A method for producing a single crystal of a group I or group III-V compound. 5. The glassy material has a softening point lower than a melting point of the polycrystalline compound,
The method for producing a II-VI group or III-V group compound single crystal according to claim 1. 6. The glassy material comprises B ₂ O ₃ .
The method for producing a II-VI group or III-V group compound single crystal according to claim 5. 7. The glassy material is B ₂ O ₃ and SiO _2.
The method for producing a group II-VI or group III-V compound single crystal according to claim 5, comprising a mixture with ₂ . 8. The method for producing a II-VI group or III-V group compound single crystal according to claim 1, wherein the powder solid contains boron nitride. 9. The method for producing a II-VI group or III-V group compound single crystal according to claim 8, wherein the average particle size of the boron nitride is 0.05 μm or more and 10 μm or less. 10. A single crystalline I from a polycrystalline II-VI or III-V compound in a vertically arranged crucible.
A method for producing a group I-VI or group III-V compound, comprising: forming an outer surface of a seed crystal composed of a single crystal compound from the melting point of the polycrystalline compound via a binder composed of a glassy material. Coating with a powdered solid having a high melting point, the coated seed crystals, placing the bottom of the crucible, the rest of the crucible, placing the polycrystalline compound, and the seed Placing the crystal and the crucible in which the polycrystalline compound is placed in a vertically arranged furnace capable of producing an upper hot zone and a lower cold zone; Melting the polycrystalline compound while maintaining a part of the seed crystal in the crucible in a solid state by adjusting the temperature of the upper high temperature region, and the temperature of the lower low temperature region. Is set below the melting point of the compound of the single crystal, and by setting the temperature of the high temperature region of the upper part higher than the melting point, to form a solid-liquid interface, and the low temperature region of the lower part and the upper part. Growing the single crystal of the compound by vertically moving the furnace and the solid-liquid interface upward while substantially maintaining the temperature setting in the high temperature range of II-
A method for producing a Group VI or III-V compound single crystal.