JP2899692B1 - Crystal growth method and apparatus - Google Patents

Abstract

A crystal growth method capable of easily obtaining a crystal having a desired composition is provided. A method for growing a crystal (13) from a crystal solution (4), comprising supplying a component solution (6) comprising at least one constituent element of the crystal (13) to be grown to the crystal solution (4) by ultrasonic waves. 4. A method comprising growing a crystal 13 from Step 4. By changing the output of the ultrasonic vibration, the amount of the component solution supplied to the crystal solution can be changed, and the composition can be changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for growing a crystal, and more particularly to a method and an apparatus for growing a crystal having a desired composition or impurity concentration.

[0002]

2. Description of the Related Art Bulk mixed crystal semiconductors such as InGaAs and InGaSb are extremely important as substrate materials for growing crystal thin films for light emitting and light receiving devices. This is because, when the composition of the mixed crystal semiconductor is changed, its lattice constant changes. Therefore, by matching the lattice constant of the crystal thin film, it is possible to suppress the introduction of crystal defects due to lattice mismatch into the thin film. .

Conventionally, as a method of changing the composition of a bulk mixed crystal semiconductor, when growing this semiconductor crystal, a component solution comprising at least one constituent element of the mixed crystal semiconductor is prepared by:
2. Description of the Related Art Supplying a mixed crystal semiconductor crystal solution through a small hole is performed. By changing the size of the small holes, the amount of the component solution supplied to the crystal solution can be changed, so that mixed crystal semiconductor crystals having different compositions can be grown.

However, with this method, it is not easy to obtain a mixed crystal semiconductor crystal having a desired composition. Normally, in order to determine the optimal pore size for obtaining a desired composition, it is necessary to determine in advance the correspondence between the pore size and the crystal composition. Is complicated. In other words, it is necessary to grow the crystal many times using small holes of different sizes, measure the composition of each of the grown crystals, and obtain the correspondence.

On the other hand, as a method for introducing a doping impurity element such as B (boron) into a semiconductor crystal such as Si (silicon), a solution of the impurity element is supplied to the semiconductor crystal solution through a small hole as described above. Meanwhile, it has been attempted to grow a semiconductor crystal from a crystal solution. Since the supply amount of the impurity solution can be changed by changing the size of the small holes, semiconductor crystals having different impurity concentrations can be grown.

However, even with this method, it is not easy to obtain a semiconductor crystal having a desired impurity concentration. also,
Change the size of the pores in advance and grow the crystal many times,
This is because unless the impurity concentration is measured for each of the grown crystals, it is not possible to determine the optimal size of the small hole for obtaining the desired impurity concentration.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a crystal growth method and apparatus capable of easily obtaining a crystal having a desired composition, and a crystal having a desired impurity concentration easily. It is to provide a possible crystal growth method and apparatus.

[0008]

In order to solve the above problems, in the present invention, a component solution is supplied to a crystal solution while applying ultrasonic vibration when growing a crystal.

By changing the output of the ultrasonic vibration, the amount of the component solution supplied to the crystal solution can be changed without changing the size of the small holes. Therefore, if the ultrasonic output is changed stepwise during crystal growth, a crystal whose composition changes stepwise along the growth direction can be grown. If the composition at each stage is measured and made to correspond to the ultrasonic output at each stage, the correspondence between the composition and the ultrasonic output can be immediately obtained. Based on this correspondence, the optimal ultrasonic output level for obtaining the desired composition is determined, and the crystal having the desired composition can be easily formed by growing the crystal while applying ultrasonic waves of this output from the beginning. It is possible to obtain. That is, the crystal growth and measurement performed in advance need only be performed once.

Similarly, a solution of the impurity element is supplied to the crystal solution while applying ultrasonic vibration when growing the crystal. By changing the output of the ultrasonic vibration, the amount of the impurity element solution supplied to the crystal solution can be changed without changing the size of the small holes. Therefore, by changing the ultrasonic output stepwise during the crystal growth, it is possible to grow a crystal whose impurity concentration changes stepwise along the growth direction. By measuring the impurity concentration at each stage and making it correspond to the ultrasonic output at each stage,
The correspondence between the impurity concentration and the ultrasonic output can be immediately obtained. Based on this correspondence, the optimum size of the small holes for obtaining the desired impurity concentration can be determined. That is, it is possible to easily obtain a crystal having a desired impurity concentration by performing crystal growth and measurement only once in advance.

That is, according to the present invention, there is provided a method for growing a crystal from a crystal solution, wherein a component solution comprising at least one constituent element of the crystal to be grown is supplied to the crystal solution by ultrasonic waves. A method is provided for growing a crystal from a crystal solution.

Further, according to the present invention, there is provided a method for growing a crystal from a crystal solution, wherein an impurity solution comprising an impurity element to be introduced into the crystal to be grown is supplied to the crystal solution by ultrasonic waves. A method is provided for growing a crystal from a crystal solution.

In the present invention, while a component solution comprising at least one constituent element of the crystal to be grown together with the impurity solution to be introduced into the crystal to be grown is further supplied to the crystal solution by ultrasonic waves,
It is preferable to grow crystals from the crystal solution.

Further, according to the present invention, a first container for growing a crystal from a crystal solution and a component solution which communicates with the first container and is composed of at least one constituent element of the crystal to be grown are accommodated. A crystal growth apparatus, comprising: a second container for generating a component solution; and an ultrasonic generator for generating ultrasonic waves so as to send the component solution from the second container to the first container. Is done.

Further, according to the present invention, a first container for growing a crystal from a crystal solution and an impurity solution which is in communication with the first container and which contains an impurity element to be introduced into the crystal to be grown are accommodated. And a first ultrasonic generating means for generating ultrasonic waves to send the impurity solution from the second container to the first container. An apparatus is provided.

In the present invention, a third container which communicates with the first container and contains a component solution comprising at least one constituent element of a crystal to be grown, and a third container to a first container It is preferable to further include a second ultrasonic wave generating means for generating an ultrasonic wave so as to send the component solution to the ultrasonic wave.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

In the crystal growth method according to the present invention, a crystal is grown by a pulling method or the like from a crystal solution prepared by melting a crystal or the like.

According to the present method, a crystal having a desired composition and a crystal having a desired impurity concentration can be grown. The respective crystal growth methods will be described below.

First, a method for growing a crystal having a desired composition will be described.

The crystal grown in this method is a binary compound having a variable composition, and is not particularly limited to a semiconductor or an insulator. For example, InGaSb, I
ternary mixed crystal semiconductor such as nGaAs, YBa ₂ Cu ₃ O _x
And the like for high-temperature superconductors.

A crystal having a desired composition is grown from the crystal solution while a component solution prepared by melting or the like from at least one constituent element of the crystal to be grown is supplied to the crystal solution by ultrasonic waves having a predetermined output.

The crystal solution may be prepared from the crystal to be grown itself, or may be prepared from some components of the crystal to be grown.

For example, when growing an InGaSb crystal, the crystal solution may be prepared from the InGaSb crystal itself, or a part of the InGaSb crystal, for example, In, Ga, Sb, or GaSb,
It may be created from InSb.

The component solution is selected according to the crystal to be grown, the desired crystal composition, and the crystal solution.

For example, when a crystal solution prepared from InGaSb is used for growing an InGaSb crystal, the component solution can be selected as follows. For example, when growing an InGaSb crystal having a different In composition ratio, In or Ga is used as a component solution.
Select a solution consisting of Sb. In with different Ga composition ratio
In the case of a GaSb crystal, Ga or InSb is selected as the component solution.

When a crystal solution prepared from some components of the InGaSb crystal is used for growing the InGaSb crystal, the component solution can be selected as follows.

For example, InGaSb with a different In composition ratio
When growing a crystal, In can be selected as a crystal solution and GaSb or InGaSb can be selected as a component solution, or GaSb can be selected as a crystal solution and In or InGaSb can be selected as a component solution.

Further, for example, InG with a changed Ga composition ratio is used.
When growing an aSb crystal, Ga is used as a crystal solution.
And InSb or InGaSb as a component solution
Alternatively, InSb can be selected as the crystallization solution, and Ga or InGaSb can be selected as the component solution.

In the present method, the composition of the crystal can be changed by changing the output of the ultrasonic vibration applied when growing the crystal.

That is, if the ultrasonic power is increased, the amount of the component solution supplied to the crystal solution increases, and the composition ratio of the elements constituting the component solution in the crystal increases. Conversely, if the output of the ultrasonic wave is reduced, the amount of the component solution supplied to the crystal solution is reduced, and the composition ratio of the elements constituting the component solution in the crystal is reduced. Thus, the composition of the crystal can be changed by changing the ultrasonic output.

In this method, first, a crystal is grown from a crystal solution while changing the output of the ultrasonic wave applied during the crystal growth stepwise or continuously. By growing in this manner, a crystal whose composition changes stepwise or continuously along the growth direction is obtained.

The grown crystal is taken out, and its composition is measured at each stage or at a plurality of predetermined locations along the growth direction. Then, by associating with the ultrasonic output applied at each stage or at a plurality of predetermined locations, the correspondence between the crystal composition and the ultrasonic output can be immediately obtained. Based on this correspondence, an optimal ultrasonic output level for obtaining a desired composition can be obtained.

Next, the crystal having the desired composition can be obtained with good reproducibility by re-growing the crystal while applying ultrasonic vibration of the optimum output determined in this way from the beginning.

As described above, in the present method, it is possible to easily obtain a crystal having a desired composition by performing crystal growth and measurement only once in advance.

Next, a method for growing a crystal having a desired impurity concentration will be described.

The crystal grown by this method is a crystal into which impurities can be introduced in order to optimize its electrical characteristics and the like. For example, Si, GaAs, and I
nGaSb and the like.

While supplying an impurity solution prepared by melting from an impurity element to be introduced into the crystal to be grown into a crystal solution prepared by melting or the like from the crystal to be grown by a predetermined ultrasonic wave, the desired impurity is removed from the crystal solution. Grow crystals with concentration.

The impurity element is selected according to the crystal to be grown.

For example, when growing a Si crystal,
B (boron), As (arsenic), P
(Phosphorus) and Sb (antimony). For example, when growing a GaAs crystal,
Examples of the impurity element include Cr (chromium), Si, Te (tellurium), and Zn (zinc). In the case of InGaSb, for example, Te, Zn, or the like is used.

In this method, the concentration of the impurity element in the crystal can be changed by changing the output of the ultrasonic vibration applied when growing the crystal.

That is, if the ultrasonic power is increased, the amount of the impurity solution supplied to the crystal solution increases, and the concentration of the impurity element in the crystal increases. Conversely, if the output of the ultrasonic wave is reduced, the amount of the impurity solution supplied to the crystal solution is reduced, and the impurity concentration is reduced.

In this method, first, a crystal is grown from a crystal solution while changing the output of the ultrasonic wave applied during the crystal growth stepwise or continuously. When grown in this manner, a crystal whose impurity concentration changes stepwise or continuously along the growth direction is obtained.

The grown crystal is taken out, and the impurity concentration is measured at each stage or at a plurality of predetermined locations along the growth direction. Then, by associating with the ultrasonic output applied at each stage or at a predetermined location, the correspondence between the impurity concentration and the ultrasonic output can be immediately obtained. Based on this correspondence, it is possible to determine the optimum magnitude of the ultrasonic output for obtaining a desired impurity concentration.

Next, the crystal having the desired impurity concentration can be obtained with good reproducibility by growing the crystal again while applying the ultrasonic vibration of the optimum output determined in this way from the beginning.

As described above, in the present method, it is possible to easily obtain a crystal having a desired impurity concentration by performing crystal growth and measurement only once in advance.

The method of growing a crystal having a desired impurity concentration described above may be used in combination with the method of growing a crystal having a desired composition described above.

That is, a crystal having a desired impurity concentration and composition may be grown from the crystal solution while supplying the above-mentioned component solution together with the impurity solution to the crystal solution by ultrasonic waves having a predetermined output.

At this time, using two ultrasonic generating means,
Ultrasonic waves for supplying the impurity solution to the crystal solution and ultrasonic waves for supplying the component solution to the crystal solution may be separately applied.

If ultrasonic waves can be separately applied, the correspondence between the impurity concentration of the crystal and the ultrasonic output, and the correspondence between the crystal composition and the ultrasonic output can be separately obtained in advance. From each correspondence relationship, an optimum ultrasonic output for obtaining a desired impurity concentration and a desired composition is separately determined, and a crystal is grown while applying each of the determined optimum ultrasonic outputs, thereby obtaining a desired crystal. A crystal having an impurity concentration and a desired composition can be obtained.

Next, a crystal growth apparatus for performing each of the above two methods will be described.

First, an apparatus for growing a crystal having a desired composition will be described with reference to FIG. FIG.
Is a schematic sectional view showing an example of such an apparatus.

This apparatus is a crystal growth apparatus using a double crucible for pulling a single crystal. The apparatus includes an inner crucible 1, an outer crucible 2, and an ultrasonic generator 3.

The inner crucible 1 is for containing the crystal solution 4. The inner crucible 1 is made of, for example, carbon and has a small hole 5 on the bottom surface.

The inner crucible 1 is inserted into the outer crucible 2.

The outer crucible 2 is made of, for example, carbon, and accommodates a component solution 6 to be supplied to the crystal solution 4 during crystal growth and a component material 7 for forming the component solution 6 by melting or the like. The component material 7 is composed of at least one constituent element of the crystal to be grown. The component solution 6 can be supplied from the outer crucible 2 to the inner crucible 1 during crystal growth through the small holes 5 at the bottom of the inner crucible 1.

The inner crucible 1 has a weight 9 through a wire 8.
The weight 9 is suspended from the outside of the outer crucible 2.

Further, a crystal pulling shaft 10 that can move up and down is suspended above the inner crucible 1. A seed crystal holder 12 for mounting a seed crystal 11 is attached to the lower end of the crystal pulling shaft 10. The single crystal 13 can be grown by bringing the seed crystal 11 into contact with the crystal solution 4 and pulling it up.

The ultrasonic generator 3 is attached to the bottom of the inner crucible 1. The ultrasonic generator 3 generates an ultrasonic wave for sending the component solution 6 into the crystal solution 4. The ultrasonic generator 3 includes an ultrasonic vibration unit 31 and a cooling unit 32.

As the ultrasonic vibrator 31, for example, a vibrator made of nickel or ferrite with a coil wound and connected to a horn is used. A current is passed through the coil to drive the vibrator to generate ultrasonic waves. The oscillation frequency of the ultrasonic wave is, for example, 10 kHz, the oscillation output is, for example, a maximum of 150 W, and the amplitude is, for example, 1 μm.

The tip of the ultrasonic vibrating section 31 is connected to the connecting screw 3
3 is connected to the bottom surface of the outer crucible 2. When the ultrasonic vibration unit 31 is driven, an ultrasonic wave is generated, and the generated ultrasonic wave passes through the bottom surface of the outer crucible 2 and travels toward the upper inner crucible 1. By this ultrasonic wave, the component solution 6 of the outer crucible 2 is sent through the small holes 5 toward the surface of the crystal solution 4 of the inner crucible 1.

The cooling section 32 is connected to the other end of the ultrasonic vibration section 31. A cooling water inlet 35 for flowing cooling water 34 for cooling the ultrasonic vibration unit 31 and a cooling water outlet 36 are connected to the cooling unit 32.

In the crystal growth apparatus according to the present invention, the arrangement of the inner crucible 1, the outer crucible 2, and the ultrasonic generator 3 is such that the component solution 6 of the outer crucible 2 is subjected to the ultrasonic wave to the crystal of the inner crucible 1. The arrangement is not particularly limited as long as it can be supplied to the solution 4.

That is, in the apparatus of FIG. 1, the outer crucible 2 is provided below the inner crucible 1 and the ultrasonic generator 3 is connected to the bottom surface of the outer crucible 2, but other arrangements are also possible. For example, the outer crucible 2 may be arranged next to the inner crucible 1 and the ultrasonic generator 3 may be mounted beside the outer crucible 2 so that the ultrasonic waves are transmitted in the horizontal direction.

The outer crucible 2 and the ultrasonic generator 3
May be arranged plurally. For example, a first outer crucible is arranged below the inner crucible 1, a first ultrasonic generator is attached to the bottom of the first outer crucible, and a second outer crucible is provided beside the inner crucible 1. A second ultrasonic generator may be mounted beside the second outer crucible. Then, the first and second ultrasonic generators are driven, and the component solutions contained in each of the first and second outer crucibles are passed through small holes 5 provided on the bottom and side surfaces of the inner crucible 1. May be supplied to the crystal solution 4 of the inner crucible 1.

When there are a plurality of outer crucibles 2, each of the outer crucibles 2 can contain, for example, a component solution composed of different constituent elements of a crystal to be grown.

The inner crucible 1, the outer crucible 2, and the ultrasonic generator 3 are hermetically housed in a quartz tube 40.

The quartz tube 40 has an atmosphere in which the single crystal 13 is not oxidized, for example, an atmosphere of high-purity hydrogen or a mixed gas of nitrogen and hydrogen. The crystal pulling shaft 10 moves up and down while being airtightly connected to the quartz tube 40. The ultrasonic vibrating section 31 is also hermetically connected to the quartz tube 40 so that the cooling section 32 goes out of the quartz tube 40. Quartz tube 40
A high frequency coil 41 for inductively heating the inner crucible 1 and the outer crucible 2 is wound around the outer periphery of.

Next, an apparatus for growing a crystal having a desired impurity concentration will be described. As an example of such an apparatus, an apparatus using the same configuration as the apparatus shown in FIG. That is, the configuration includes the inner crucible 1, the outer crucible 2, and the ultrasonic generator 3.

More specifically, in the apparatus shown in FIG. 1, a crystal solution 4 is accommodated in an inner crucible 1. The outer crucible 2 contains an impurity solution instead of the component solution 6 and an impurity element instead of the component raw material 7. An impurity solution is prepared by melting the impurity element. Then, the ultrasonic generator 3 is driven during the crystal growth, and the impurity solution is supplied from the outer crucible 2 to the surface of the crystal solution 4 of the inner crucible 1 through the small holes 5 of the inner crucible 1. Other configurations are the same as those in FIG.

In this apparatus, as described above, the arrangement of the inner crucible 1, the outer crucible 2, and the ultrasonic generator 3 is similar to that described above. The arrangement is not particularly limited as long as it can be supplied to the crystallization solution 4.

As described above, there may be a plurality of outer crucibles 2 and a plurality of ultrasonic generators 3, respectively.

When there are a plurality of outer crucibles 2, each outer crucible can contain, for example, an impurity solution containing a different impurity element to be introduced into a crystal to be grown. Then, the ultrasonic generators connected to the respective outer crucibles can be driven to supply impurity solutions composed of different impurity elements to the crystal solution 4.

Alternatively, when there are a plurality of outer crucibles 2, the impurity solution and the above-mentioned component solution may be stored in the respective outer crucibles. Then, the ultrasonic wave generator attached to each outer crucible 2 may be driven to supply the component solution to the crystal solution 4 together with the impurity solution.

It is to be noted that the impurity solution and the component solution are accommodated in one outer crucible, and the ultrasonic generator attached to the outer crucible is driven to supply the component solution to the crystal solution 4 together with the impurity solution. good.

Next, using each of the above-described devices,
A method for growing a crystal will be described.

First, a method for growing a crystal having a desired composition will be described.

As an example, a method for growing a single crystal of an InGaSb ternary mixed crystal semiconductor having a desired In composition ratio by using the apparatus shown in FIG. 1 will be described. However, for InGaSb crystals having different compositions,
Needless to say, other crystals such as nGaAs and YBa ₂ Cu ₃ O _x can be similarly grown to have a desired composition.

(1) First, GaSb as the component material 7 is put into the outer crucible 2. As described later, InGa
By supplying a GaSb solution to the Sb solution and changing the GaSb concentration in the InGaSb solution, the growing InGaSb
The In composition ratio of the crystal can be changed.

Next, InGaSb is charged on the GaSb 7, the inner crucible 1 is further placed thereon, and the weight 9 is hung outside the outer crucible 2.

(2) A current is passed through the high-frequency coil 41,
The inner crucible 1 and the outer crucible 2 are induction heated. Heating is
The temperature of both crucibles is the melting point of GaSb (about 712 ° C) and the temperature of InS.
It is performed so that the temperature is between the melting points of GaSb (about 525 ° C. to 712 ° C.). By such heating, only the InGaSb raw material is melted to form an InGaSb crystal solution 4,
Collects on aSb7.

(3) The inner crucible 1 sinks in the InGaSb solution 4 by the weight 9 suspended from the inner crucible 1. As a result, the InGaSb solution 4 passes through the small hole 5 and the inner crucible 1
Also accumulate inside. Thus, the InGaSb through the small hole 5
By storing the solution 4 in the inner crucible 1, slag such as an oxide generated when InGaSb is melted is prevented from being mixed into the inner crucible 1.

The GaSb 7 of the outer crucible 2 is made of InG
The GaSb solution, which is the component solution 6, is gradually dissolved at the portion in contact with the aSb solution 4.

(4) The ultrasonic vibrator 31 is operated while being cooled with water to generate ultrasonic waves. The generated ultrasonic waves are introduced from the bottom surface of the outer crucible 2 toward the inner crucible 1.
By the introduced ultrasonic waves, the GaSb solution 6 in the outer crucible 2 is transported through the small holes 5 to near the surface of the InGaSb solution 4 in the inner crucible 1.

(5) The GaSb seed crystal 11 attached to the lower end of the crystal pulling shaft 10 is brought into contact with the surface of the InGaSb solution 4. While keeping the temperature of the InGaSb solution 4 constant, the InGaSb single crystal 13 is grown by pulling up the GaSb seed crystal 11 while rotating it.

The output of the ultrasonic wave is changed continuously or stepwise while growing the crystal.

When the output of the ultrasonic wave is increased, InGaS
The amount of the GaSb solution 6 supplied in the b solution 4 increases. In particular, InGaSb in contact with GaSb seed crystal 11
Ga supplied to the surface of the solution 4, that is, in the vicinity of the growth interface
The amount of Sb solution 6 increases. GaSb solution 6 to be supplied
Increases the amount of InGa that grows from the growth interface.
The In composition ratio of the Sb single crystal 13 decreases. in this way,
Increasing the ultrasonic output decreases the In composition ratio.

On the contrary, when the output of the ultrasonic wave is reduced,
As is clear from the above description, the In composition ratio increases.

As described above, by changing the output of the ultrasonic wave, the In composition ratio of the InGaSb single crystal 13 can be changed without changing the size of the small hole 5.

As described above, by changing the ultrasonic output continuously or stepwise during the crystal growth, a crystal whose In composition ratio changes continuously or stepwise along the growth direction can be grown. .

(6) InG grown as described above
The aSb single crystal 13 is taken out, and the In composition ratio is measured at each stage along the growth direction or at a plurality of predetermined locations. The correspondence between the In composition ratio and the ultrasonic output can be immediately obtained by associating the ultrasonic output with the ultrasonic output applied at each stage or at a plurality of predetermined locations.

From this correspondence, it is possible to determine the optimum magnitude of the ultrasonic output for obtaining the InGaSb single crystal 13 having a desired In composition ratio.

(7) Using the optimum ultrasonic output obtained in this way, the InGa is again obtained according to the above (1) to (5).
The Sb single crystal 13 is grown. At this time, the output of the ultrasonic vibration applied during the crystal growth is the optimum output obtained as described above. Thus, an InGaSb single crystal 13 having a desired In composition ratio can be obtained.

As described above, in this method, it is possible to easily obtain a crystal having a desired composition by performing crystal growth and measurement only once in advance.

Also, if the InGaSb single crystal 13 is grown while changing the ultrasonic output based on the correspondence between the In composition ratio and the ultrasonic output obtained as described above, I with the In composition ratio arbitrarily changed by
It is also possible to grow the nGaSb single crystal 13.

In particular, in the case of growing the InGaSb crystal solution 4 while supplying the GaSb component solution 6 as described above, the output of the ultrasonic wave is gradually increased along with the growth of the crystal, so that the growth direction is increased. It is possible to improve the uniformity of the composition along. Usually, when no ultrasonic wave is applied or when the ultrasonic wave output is constant, InGaS
In a b-crystal or the like, the composition ratio of the In element tends to increase along the growth direction. The reason for the increase is that the segregation coefficient of In is smaller than that of Ga or Sb.
This is because the In concentration in the crystal solution 4 gradually increases.
Here, the segregation coefficient indicates the ratio of the In concentration in the crystal 13 to the In concentration in the crystal solution 4. Therefore, if the ultrasonic output is gradually increased along with the growth of the crystal to increase the supply amount of GaSb, it is possible to suppress the increase in the In composition ratio and improve the uniformity of the In composition.

In the apparatus shown in FIG.
The correspondence between the composition ratio and the ultrasonic output naturally depends on the size of the small hole 5. That is, as the size of the small holes 5 increases, the amount of GaSb element supplied by the ultrasonic vibration having the same output increases, and the In composition ratio further decreases.
As the size of the small holes 5, one having an occupancy of about 2.5% is usually used. Here, the occupancy refers to the ratio of the area of the small hole 5 to the bottom area of the inner crucible 1.

Next, a method for growing a crystal having a desired impurity concentration will be described.

As an example, a method for growing a Si single crystal having a desired B concentration using an apparatus having the same configuration as the apparatus shown in FIG. 1 will be described. However, when other impurities are introduced into Si, GaAs or I
It is needless to say that a crystal having a desired impurity concentration can be similarly grown when an impurity is introduced into another crystal such as nGaSb.

(1) First, B as an impurity element is put into the outer crucible 2. Charge Si on B, and
Place the inner crucible 1 on these and attach the weight 9 to the outer crucible 2
And hang it outside.

(2) A current is passed through the high-frequency coil 41,
The inner crucible 1 and the outer crucible 2 are induction heated. Heating is
The temperature of both crucibles is set so as to be between the melting point of B (about 2300 ° C.) and the melting point of Si (about 1414 ° C.). By such heating, only Si is melted to form a Si crystal solution 4, which accumulates on B.

(3) The inner crucible 1 sinks into the Si solution 4 by the weight 9 suspended from the inner crucible 1. As a result, the Si solution 4 accumulates in the inner crucible 1 through the small holes 5. Further, B of the outer crucible 2 gradually dissolves at a portion in contact with the Si solution 4 to form a B solution as an impurity solution.

(4) The ultrasonic vibrator 31 is operated while being cooled with water to generate ultrasonic waves. The generated ultrasonic waves are introduced from the bottom surface of the outer crucible 2 toward the inner crucible 1.
By the introduced ultrasonic waves, the B solution in the outer crucible 2 is transported through the small holes 5 to near the surface of the Si solution 4 in the inner crucible 1.

(5) The Si seed crystal 11 mounted on the lower end of the crystal pulling shaft 10 is brought into contact with the surface of the Si solution 4. S
By keeping the temperature of the i solution 4 constant and pulling up while rotating the Si seed crystal 11, the single crystal Si single crystal 1
Grow 3.

The output of the ultrasonic wave is changed continuously or stepwise while growing the crystal.

When the output of the ultrasonic wave is increased, the Si solution 4
The amount of B solution supplied therein can be increased.
In particular, the amount of the B solution supplied to the surface of the Si solution 4 in contact with the Si seed crystal 11, that is, the vicinity of the growth interface increases. As the amount of the supplied B solution increases, the B concentration of the Si single crystal 13 growing from the growth interface increases. As described above, when the ultrasonic output is increased, the B concentration increases.
Conversely, when the output of the ultrasonic wave is reduced, the B concentration is reduced.
In this manner, by changing the output of the ultrasonic wave, the B concentration of the Si single crystal 13 can be changed without changing the size of the small hole 5.

Thus, by changing the ultrasonic output continuously or stepwise during the crystal growth, the Si single crystal 13 whose B concentration changes continuously or stepwise along the growth direction can be grown. Can be.

(6) The Si single crystal 13 grown as described above is taken out, and the B concentration is measured at each stage along the growth direction or at a plurality of predetermined locations.
Then, the correspondence between the B concentration and the ultrasonic output can be immediately obtained by associating the ultrasonic output with the ultrasonic output added at each stage or at a plurality of predetermined locations. From this correspondence, it is possible to determine the optimum magnitude of the ultrasonic output for obtaining the Si single crystal 13 having the desired B concentration.

(7) Using the optimum ultrasonic output thus obtained, the Si single crystal 13 is grown again according to the above (1) to (5). At this time, the output of the ultrasonic vibration applied during the crystal growth is the optimum output obtained as described above. In this way, S having a desired B concentration
An i single crystal 13 can be obtained.

As described above, also in this method, it is possible to easily obtain a crystal having a desired concentration by performing crystal growth and measurement only once in advance.

Further, if the Si single crystal 13 is grown while changing the ultrasonic output on the basis of the correspondence between the B concentration and the ultrasonic output obtained as described above, along the growth direction, It is also possible to grow a Si single crystal 13 in which the B concentration is arbitrarily changed.

In particular, B, As, P and Sb
When an impurity such as is introduced, the uniformity of the impurity concentration along the growth direction can be improved by gradually reducing the output of the ultrasonic wave as the crystal grows. Usually, when no ultrasonic wave is applied or when ultrasonic vibration is constant, the impurity concentration of the Si crystal tends to increase along the growth direction. The reason for the increase is that the segregation coefficient of the above-mentioned impurity element is smaller than 1 during the crystal growth.
This is because the impurity concentration in the Si crystal solution 4 gradually increases. Here, the segregation coefficient refers to the ratio of the impurity concentration in the crystal 13 to the concentration of the impurity element in the crystal solution 4. Therefore, if the ultrasonic output is gradually reduced as the crystal grows and the supply amount of the impurity element is reduced, the increase in the impurity concentration can be suppressed and the uniformity of the impurity concentration can be improved.

In the apparatus shown in FIG. 1, the correspondence between the concentration of impurities such as B and the output of ultrasonic waves naturally depends on the size of the small holes 5. That is,
As the pores 5 are larger, the amount of the B element supplied by the ultrasonic vibration of the same output increases, and the B concentration decreases. As the size of the small holes 5, one having an occupancy of about 2.5% is usually used. Here, the occupancy refers to the ratio of the area of the small hole 5 to the bottom area of the inner crucible 1.

In the above-described method for growing a crystal having a desired composition and a method for growing a crystal having a desired impurity concentration according to the present invention, ultrasonic vibration is introduced during crystal growth. There is also an effect that the crystal can be grown while stirring the crystal solution 4 by ultrasonic vibration. Agitation during crystal growth can suppress the occurrence of compositional supercooling near the interface between single crystal 13 and crystal solution 4. Since the generation of polycrystals is suppressed by suppressing the compositional supercooling, a single crystal having fewer defects can be obtained.

[0115]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings.

Using the apparatus shown in FIG. 1, an InGaSb single crystal was grown while supplying a GaSb solution by ultrasonic waves according to the method for growing a crystal having a desired composition described above. In the inner crucible 1, the occupancy of the small holes 5 is 2.5%.
Was used.

At the start of the crystal growth, the ultrasonic generator 3 was not operated, and the ultrasonic generator 3 was operated when the solidification rate reached about 2%. The solidification rate refers to the crystallization solution 4
InGaSb in single crystal 13 with respect to InGaSb content
It refers to the ratio of the amount of b. The output of the ultrasonic vibration was 30 W and the frequency was 10 kHz.

The crystal growth was stopped when the solidification rate reached about 7%. With respect to the extracted InGaSb single crystal 13, the In composition ratio was measured at a plurality of locations along the growth direction. The measurement was performed by EPMA. FIG. 2 shows the measurement results.

As is clear from FIG. 2, the GaSb solution 6 is supplied by introducing ultrasonic waves, and InGaS
The In composition ratio of the b single crystal 13 decreases stepwise.

The correspondence between the In composition ratio and the ultrasonic output was determined based on the results shown in FIG. Figure 3 shows the results.

From the correspondence shown in FIG. 3, the value of the ultrasonic output for obtaining InGaSb having a desired In composition ratio was determined. Then, the InGaSb single crystal was grown again while applying the determined ultrasonic output from the start of the crystal.

When the InGaSb single crystal that was grown again was measured for the In composition ratio along the growth direction, it was confirmed that the desired In composition ratio was uniform along the growth direction.

[0123]

As described in detail above, according to the present invention, a crystal growth method and apparatus capable of easily obtaining a crystal having a desired composition, and a crystal having a desired impurity concentration can be easily obtained. A possible crystal growth method and apparatus are provided. As a result, it is possible to easily obtain a crystal having a desired composition or impurity concentration only by performing crystal growth and measurement only once, and to achieve effects such as a reduction in crystal manufacturing cost.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a crystal growth apparatus according to the present invention.

FIG. 2 is a diagram showing a result of measuring a change in an In composition ratio with respect to a solidification rate in the present example.

FIG. 3 is a diagram showing a correspondence relationship between an In composition ratio and an ultrasonic output in the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Inner crucible 2 ... Outer crucible 3 ... Ultrasonic generator 4 ... Crystal solution 5 ... Small hole 6 ... Component solution 7 ... Component raw material 8 ... Wire 9 ... Weight 10 ... Crystal pulling shaft 11 ... Seed crystal 12 ... Seed crystal holder DESCRIPTION OF SYMBOLS 13 ... Single crystal 31 ... Ultrasonic vibration part 32 ... Cooling part 33 ... Connection screw 34 ... Cooling water 35 ... Cooling water inlet 36 ... Cooling water outlet 40 ... Quartz tube 41 ... High frequency coil

Continuation of front page (58) Fields investigated (Int. Cl. ⁶ , DB name) C30B 15/02 C30B 15/12 C30B 28/00-35/00 CA (STN)

Claims (6)

(57) [Claims] 1. A method for growing a crystal from a crystal solution, wherein the crystal is grown from the crystal solution while a component solution comprising at least one constituent element of the crystal to be grown is supplied to the crystal solution by ultrasonic waves. The method characterized by making it. 2. A method for growing a crystal from a crystal solution, wherein the crystal is grown from the crystal solution while an impurity solution comprising an impurity element to be introduced into the crystal to be grown is supplied to the crystal solution by ultrasonic waves. The method characterized by making it. 3. The method according to claim 1, wherein a component solution comprising at least one component element of the crystal to be grown together with the impurity solution to be introduced into the crystal to be grown is further supplied to the crystal solution by ultrasonic waves. 3. The method according to claim 2, wherein the crystal is grown. 4. A first container for growing a crystal from a solution of crystals, and a second container in communication with the first container for containing a component solution comprising at least one constituent element of the crystal to be grown. A crystal growth apparatus comprising: a container; and an ultrasonic wave generating means for generating ultrasonic waves so as to send the component solution from the second container to the first container. 5. A first container for growing a crystal from a crystal solution, and a second container communicating with the first container for containing an impurity solution comprising an impurity element to be introduced into the crystal to be grown. A crystal growth apparatus comprising: a container; and first ultrasonic wave generating means for generating ultrasonic waves so as to send the impurity solution from the second container to the first container. 6. A third container communicating with the first container and containing a component solution comprising at least one constituent element of a crystal to be grown, and a component solution from the third container to the first container. 6. The apparatus according to claim 5, further comprising second ultrasonic wave generating means for generating an ultrasonic wave so as to send the ultrasonic wave.