JPS6041034B2 - Method for manufacturing compound semiconductor crystal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing compound semiconductor crystals, which is generally called the SSD method.

The SSD method for making Gap semiconductor crystals was published in the Special Publication Act in 1978-20.
It is publicly known from Publication No. 106 and the like.

Next, a typical conventional GaP crystal growth method using this SSD method will be explained with reference to FIGS. 1 and 2. A seed crystal 2 is placed at the bottom of a cylindrical crucible 1 made of quartz as shown in FIG.
Put the Ga solution 3 on top of it, and hold the crucible 1 on the support member (
(not shown) and placed on the upper part of the sealed quartz container 4. Further, red phosphorus 5 in an amount of 4 to 5 skins in height is placed at the bottom of a sealed container 4 made of quartz, and the container is vacuum-sealed to about 10-6 tons. Next, this red phosphorus 5 is heated to about 430 qC by the first heater 6 to generate a P vapor pressure of about 1 atmosphere inside the container 4. In addition, the second heater 7 is installed so that the surface of the Ga solution 3 is, for example, 1150 qo, and the portion of the seed crystal 2 is, for example, 1000 qo.
A temperature gradient between P and P2 in FIG. 2 is applied to the Ga solution 3. In this way, Ga on the surface of the Ga solution 3
p is synthesized to form a Gap film 8, this GaP diffuses as a solute in the Ga solution 3 toward the seed crystal 2, and the growth of the Gap crystal 9 on the seed crystal 2 begins. That is, Ga solution 3
The compound GaP synthesized (S skin thesis) in the high temperature part of the surface of the 0a solution 3 diffuses as a solute toward the low temperature part of the surface of the seed crystal 2 or the already grown Gap crystal 9. (Diffusion) and G
An ap crystal 9 grows.

Although the SSD method described above has the disadvantage of slow crystal growth, it has many advantages as shown below. {a}
Unlike the conventionally widely used LEC method, there is no need to grow crystals at high temperatures and pressures, making the manufacturing equipment simple and inexpensive. {b} Manufacturing is easy because crystals are directly formed using the elements constituting the compound semiconductor as starting materials.
[c} Since the shape of the crystal is determined by the shape of the container (crucible), crystals with uniform diameter can be obtained. {d} Since a crystal with few crystal defects can be obtained, a light emitting element with high luminous efficiency can be obtained. However, if a crystal is grown using the conventional SSD method using the apparatus shown in Fig. 1, the crystals shown in Figs. 3 and 4 will grow.
As shown in the figure, many single crystal portions 9a, that is, large single crystal grains were arranged in an unspecified manner, resulting in a crystal 9, that is, a polycrystal.

Therefore, when making a light emitting device using this crystal 9, there are always disadvantages due to the fact that it is polycrystalline. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for manufacturing a compound semiconductor crystal that can obtain a single crystal or a crystal close to a single crystal using the SSD method.

In order to achieve the above object, the present invention includes placing a container containing a solution of component A exhibiting a relatively low vapor pressure in an atmosphere containing the vapor of component B exhibiting a relatively high vapor pressure; The part where the solution contacts the vapor of the component B is a high temperature part that is lower than the melting point of the compound semiconductor AB composed of the component A and the component B, but is relatively high temperature, and the high temperature part of the solution of the component A is A part away from the high temperature part is set as a low temperature part whose temperature is lower than the high temperature part, and the vapor pressure of the component B is made higher than the decomposition pressure of the compound semiconductor AB, and the compound AB synthesized in the high temperature part is converted into the component A. In the method of growing crystals of the compound semiconductor AB in the low-temperature part by diffusing the compound semiconductor AB in a solution, the contact area between the solution of the component A and the vapor of the component B or the diffusion area of the compound A diffusion control object formed to have a smaller area than the surface of the crystal of the compound semiconductor AB in contact with the solution of component A, which is formed in The present invention relates to a method for manufacturing a compound semiconductor crystal, which is characterized by performing crystal growth of a compound semiconductor AB.

In a preferred embodiment of the present invention, the component A is Ga, the component B is the neighbor P, the compound AB is Gap, the high temperature part is around 115,000, and the low temperature part is around 100
It is a part near 0oo, limited by a diffusion control object,
Contact area between the solution of component A and the vapor of component B or compound A
The ratio of the diffusion area of B (the cross-sectional area of the part through which compound AB passes) and the area of the surface of the crystal of compound semiconductor AB in contact with the solution of component A (the area of the crystal growth surface) is preferably within the range 1'
It is 1/3 selected from 1.7 to 1/5.

According to the present invention, the diffusion control object is placed on top of or in the solution of component A to constantly control the diffusion of compound AB, thereby suppressing excessive supply of compound AB and obtaining large single crystals. This makes it possible to make almost the entire ingot a single crystal, or to create a crystal close to a single crystal.

Embodiments of the present invention will be described below with reference to FIGS. 5 to 12.

However, the items indicated by numerals 1 to 9 in Figs. 5 to 12 are substantially the same as those indicated by the same numerals in Figs. 1 to 4, and the basic manufacturing method is also the same. Therefore, the explanation of these will be omitted. In this embodiment, the diffusion control object 1
0 is disposed on the surface of the Ga solution 3, that is, on the upper surface, to advance crystal growth.

This diffusion control object 10' is a donut-shaped float made of graphite having a through hole 11 as shown in FIGS. That is, the area of the upper surface of the Ga solution 3 is limited to about 1/3 of the area of the upper surface of the crystal, which is the contact area between the seed crystal 2 or the growing crystal 9 and the Ga solution 3. In order to reliably maintain this state from the start to the end of crystal growth, a pulling device 1 is provided to pull up the diffusion control object 10 in accordance with changes in the height of the liquid level of the Ga solution 3.
2 is provided. Although not shown, a sealing device is provided to prevent phosphorus P vapor from escaping even if the pulling device 12 is provided. Reference numeral 13 denotes a heat sink made of graphite, which adjusts the temperature gradient in the Ga solution 3.

In this embodiment, the seed crystal 2 is placed directly on the heat sink 13, and the bottomless crucible 1 is used as a container, but the Ga solution 3 does not flow out due to the surface tension of the Ga solution 3. . When the diffusion control object 10 is floated as described above, it becomes possible to reduce the contact area between the Ca solution 3 and the phosphorus P vapor to 1/Mori degree, and the area of the GaP film 8 formed on the surface of the Ga solution 3 to also be reduced to 1 /3, Gap film 8
The amount of Gap that diffuses toward the seed crystal 2 or the growing crystal 9 decreases. Then, from the surface of Ga solution 3, crystal 9
The concentration distribution of GaP in the Ga solution 3 up to the growth surface is the first
This becomes curve A in Figure 0. That is, by providing the diffusion control object 10, the Gap concentration decreases rapidly immediately below this object, and then gradually decreases from there toward the crystal growth surface.
By the way, the saturation concentration of GaP is determined by temperature, and C
When the temperature gradient in solution a is approximately constant, it is represented by a curve arched slightly downward, as shown by curve B in FIG. 10, from experimental data.

As is clear from the comparison between this Cap saturation concentration curve B and the Gap concentration curve A of this example, the Gap concentration of this example is limited to below the saturation concentration in substantially the entire diffusion region. In other words, the concentration distribution is such that no supersaturation occurs. Therefore, even if stimulation such as vibration is applied,
Crystal nuclei that cause polycrystals are less likely to occur, and a large single crystal portion 9a as shown in FIGS. 8 and 9 can be obtained. Although a small amount of polycrystalline portion 9b is formed in the outer peripheral region that contacts the crucible 1, it is much smaller than the single-crystalline portion 9a. Such an effect occurs when the ratio of the contact area or diffusion area between the Ga solution 3 and the P vapor to the area of the crystal growth surface is 1/1.7.
Good results can be obtained in the range of 1'5 to 1'5. If it is larger than 1/1.7, the number of single crystal grains increases, and if it is smaller than 1/5, the crystal growth rate becomes slow, making it impractical. Therefore, a more preferable range is 1'2.5 to 1/4. According to this embodiment, as described above, it is possible to grow the whole into a single crystal, whereas in the conventional method shown in FIG. 1, the growth becomes polycrystalline as shown in FIGS. Naruha is G
This is thought to be because the distribution of Gap concentration in solution 3 becomes like curve C in FIG. 10.

That is, in the case shown in FIG.
If the supply of p is sufficient, the concentration distribution of Gap as a melt from the side of the GaP film 8 with a high concentration to the side of the crystal growth surface with a low concentration will be slightly upward according to Fick's first law. The curve C becomes an arch-like protrusion, and all regions are in a supersaturated state or a state close to this. For this reason, it is thought that stimulation such as vibration tends to generate crystal nuclei that cause polycrystals, resulting in crystals 9 as shown in FIGS. 3 and 4. As is clear from the above, the method of this embodiment provides the following effects.

{A' A single crystal or a Gap crystal close to a single crystal can be easily produced.

{〇'The diffusion control object 10 is made of Ga as crystal growth progresses.
The Ga
Since it is directly on the surface of the solution 3, almost the entire amount of the expensive Ga solution 3 can be used for crystal growth.

Therefore, less material is wasted. Since the diffusion control object 10 is formed in a donut shape, a cylindrical crystal 9 with good uniformity can be obtained. 0 Since the heat sink 13 is provided, the temperature gradient and concentration gradient are ideal, making it possible to stably produce crystals.

FIG. 11 shows a part of an apparatus for explaining another embodiment of the present invention.

In this embodiment, the diffusion control object 10 is floated relying on its own buoyancy without providing the lifting device 12 shown in FIG. Even in this case, a single crystal can be grown in the same way as in the case of FIG. In the case of FIG. 11, the diffusion control object 10 may get caught in the crucible 1 and may not float on the surface of the Ga solution 3 as shown in FIG. 12. Even if such a phenomenon occurs, the amount of Gap supplied from the GaP film 8 or the Gap polycrystal 14 attached to the diffusion control object 10 is limited to one diffusion control object, and the amount of Gap supplied from the GaP film 8 or the Gap polycrystal 14 attached to the diffusion control object 10 is limited. At the bottom, the GaP concentration distribution is similar to that of the method shown in FIG. 5, and a single crystal is formed. Furthermore, the 12th
If the situation shown in the figure occurs, the supply of phosphorus P is temporarily stopped and the GaP polycrystal 14 attached to the diffusion control object 10' is removed.
is melted and used for crystal growth, and the diffusion control object 10 is made of Ga.
It may be floated on the surface of the solution 3 again and the supply of P may be started again. Although the embodiments of the present invention have been described above, the present invention is not limited thereto and can be further modified.

For example, the diffusion control object 10 may have a large number of through holes 11 as shown in FIG. Alternatively, the diffusion control object 10 may be formed of a porous graphite plate or the like, and GaP may be supplied through small holes. Further, the diffusion control object 10 may be held or moved by electric force or magnetic force. In addition, although the seed crystal 2 is essential in order to reliably obtain a single crystal, if a polycrystal close to a single crystal is sufficient, the seed crystal may be omitted. Even in the case where a seed crystal is not used in this way, by providing the diffusion control object 10, it is possible to obtain a polycrystal that is closer to a monocrystal than a similar conventional method. Also heat sink 1
3 serves to form a temperature gradient that prevents the generation of polycrystalline nuclei, but even if this is omitted, a single crystal or a crystal close to this can be obtained due to the effect of the diffusion control object 10. G again
It is not limited to aP crystal, and component A may be Ga, ln, etc., component B may be P, pine, etc., Ga pine, lnP, ln
It is also applicable to the growth of binary compound semiconductors such as pine, or to the growth of ternary compound semiconductors or more multi-component compound semiconductors by making one of component A and component B a mixture of two elements. It can also be applied to epitaxial growth in which a thin single crystal layer is formed on a semiconductor wafer.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing a conventional SSD method equipment, Figure 2 is a temperature distribution diagram showing the temperature distribution of the equipment in Figure 1, Figure 3 is a cross-sectional view of a crystal made with the equipment in Figure 1, Figure 4 is N of Figure 3.
It is a sectional view of a portion corresponding to the -W line. FIG. 5 is a sectional view of a manufacturing apparatus according to an embodiment of the present invention, FIG. 6 is an enlarged plan view of a diffusion control object of the apparatus of FIG. 5, and FIG.
The figure is a cross-sectional view of the skin-to-skin line in Figure 6, Figure 8 is a cross-sectional view of the crystal made by the counterfeiting of Figure 5, Figure 9 is a cross-sectional view corresponding to the line K-K in Figure 8, FIG. 10 is a graph showing the relationship between the position in the Ga solution and the GaP concentration in the apparatus shown in FIG. FIGS. 11 and 12 are cross-sectional views showing a part of an apparatus according to another embodiment of the present invention. FIG. 13 is a plan view showing a modification of the diffusion control object. In the symbols used in the drawings, 1 is a crucible, 2 is a seed crystal, 3 is a Ga solution,
4 is a container, 5 is red phosphorus, 6 is a first heater, 7 is a second heater, 8 is a Gap film, 9 is a GaP crystal, 10 is a diffusion control object, and 11 is a through hole. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 7 Figure 6 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13

Claims (1)

[Scope of Claims] 1. A container containing a solution of component A exhibiting a relatively low vapor pressure is placed in an atmosphere containing vapor of component B exhibiting a relatively high vapor pressure, and the solution of component A is The part that comes into contact with the vapor of component B is a high temperature part that is lower than the melting point of the compound semiconductor AB made of component A and component B, but is relatively high temperature, and the part of the solution of component A that is away from the high temperature part is A low-temperature section is formed whose temperature is lower than the high-temperature section, the vapor pressure of the component B is made higher than the decomposition pressure of the compound semiconductor AB, and the compound AB synthesized in the high-temperature section is diffused into the solution of the component A. In the method of growing crystals of compound semiconductor AB in the low temperature part, the solution of the component A and the component B
A diffusion control object formed so that the contact area with the vapor or the diffusion area of the compound AB is smaller than the area of the surface in contact with the solution of component A of the crystal of the compound semiconductor AB formed at the low temperature. A method for manufacturing a compound semiconductor crystal, characterized in that crystal growth of the compound semiconductor AB is performed by disposing the compound semiconductor AB on the surface of or in a solution of the component A. 2. The method for manufacturing a compound semiconductor crystal according to claim 1, wherein the diffusion control object is a float that is changed to follow changes in the liquid level of the component A.