JPH0219967B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for growing crystals, and particularly to a method for growing crystals of compound semiconductors such as - group semiconductors.

- Group compound semiconductor devices such as GaAs and InP have become essential for optical communication microwave devices, but since compounds are a combination of two or more elements with different properties (multi-element system), their crystal growth is difficult. It is very difficult, and it is not easy to make the composition ratio uniform.

However, in order to improve the performance of semiconductor devices, it is desired to overcome these difficulties and grow high-quality crystals with a uniform composition.

[Prior art and problems to be solved by the invention] Conventionally, when trying to obtain a multi-component bals crystal or a multi-component epitaxial crystal, the solute elements constituting the compound on the high melting point side are As the crystal dries up in the growth solution, the crystal composition gradually shifts, making it difficult to grow crystals with a uniform composition.

For example, in Gax, In _1-x As crystals, as the growth progresses, the solute element Ga that makes up GaAs, a high melting point compound, dries up in the growth solution and gradually
Gax In _1-x As crystals with low Ga content grow and cannot grow into crystals with uniform composition.

The same applies to the pull growth method for growing multi-element bulk crystals and the liquid phase epitaxial growth method for growing multi-element epitaxial crystals.

Figure 4 shows a schematic diagram of the conventional pulling growth method (bulk crystal growth method), where 1 is a container (crucible);
2 is a growth solution, 3 is a seed crystal, 4 is boron oxide (B ₂ O ₃ )
5 is a rotating pulling rod, 6 is a heating element, and the membrane is made of B ₂ O ₃
The film 4 is a coating film for suppressing volatile matter evaporated from the growth solution, and this growth method is also called the LEC method (liquid encapsulated Czochalski method). Growth liquid 2 with heating element 6
is heated, the seed crystal 3 is pulled up while rotating with the rotating pulling rod 5, and the desired crystal is placed on the seed crystal in the growth solution 2.
This is a method of precipitating from.

In that case, for example, in the above embodiment, Ga gradually decreases in the growth solution 2, and a Gax In _1- xAs crystal with a changed Ga composition grows.

The term "growth solution" here refers to both a solution for growth and a melt for growth. A solution is a solution in which a solute is dissolved in a solvent, and a melt is a solution in which a solute is dissolved in a solvent. Same composition (for example, in InGaAs, the composition of In + Ga and As are the same)
It refers to the liquid. This example will be explained below using a solution as an example, but the same applies to a melt.

In view of the above-mentioned drawbacks, the inventor recently proposed a crystal growth method aimed at uniformizing the composition of the grown crystal (see Japanese Patent Application No. 171174/1982).

FIG. 5 shows an example of this, and this example is a schematic diagram of the pulling growth method. The same members as in Figure 4 are given the same symbols, but in the container, 11 is an insulator made of boron nitride (BN: boron nitride), 12 is a source material, and 13 is a container that holds a growth solution. A carbon electrode 14 also serves as a container and is connected to the source material. In this way, the carbon electrode 13 is connected to the + power source S ⁺ , the carbon electrode 14 is connected to the − power source S ^- , and a direct current is passed from the growth solution 2 toward the source material 12 to generate heat, and the amount of heat is generated according to the amount of current. Dissolve the source material in the growth solution.

Then, as the crystal grows, the source material is dissolved in the growth solution, reducing changes in the solution composition and making the composition of the grown crystal uniform. and,
When a direct current is passed from the solution to the compound source, the heating due to the resistance heat generation (Joule heat) of the source material itself and the heat generation due to the Peltier effect at the interface between the source material and the growth solution combine to produce the most efficient method. heated.

However, on the other hand, when the solute element dissolved from the source material moves through the solution and reaches the growing crystal (seed crystal), the movement of the solute element is caused by electromigration effects, diffusion effects due to concentration differences, and specific gravity. This results in a complex form in which many movement effects, such as the convection effect (levitation effect) due to differences, are combined, and it becomes very difficult to control the movement state of solute elements in this growth liquid.

The present invention is capable of replenishing such a multi-component growth solution (solution or melt) with a compound containing one or more constituents of a multi-component crystal with good controllability, and at the same time precipitating the growing crystal with good control of solute elements. This paper proposes a growth method that will make the plant grow.

[Means for solving the problem] The purpose is to bring a source material containing one or more elements constituting a multi-element compound semiconductor crystal into contact with a growth solution for the multi-element compound semiconductor crystal, and to This is achieved by a crystal growth method in which a direct or alternating current is passed through the crystal to generate heat, and a source material corresponding to the amount of current is dissolved in the growth solution to control the composition of the growth solution.

[Operation] That is, in the present invention, a direct current or an alternating current is passed only through the source material to generate heat, and the source material is dissolved in the growth solution, thereby maintaining the composition of the growth solution constant.

This simplifies the structure of the container (such as a crucible), and at the same time eliminates the movement effect due to electromigration, making it easier to control the movement of solute elements dissolved from the source material into the growth solution.

[Examples] Hereinafter, examples will be described in detail with reference to the drawings.

FIG. 1 shows a schematic diagram of one embodiment of the pulling growth method among the crystal growth methods according to the present invention. In the figure, the same members as those in FIG. One side of the source material is in contact with the growth solution, and carbon electrodes 13 are connected to both sides of the source material 12. Then, at the same time as the growth liquid 2 is heated by the heating element 6, a DC current is passed between the carbon electrodes 13 by the DC power sources S ⁺ and S ^- , and the source material 12 is heated by its own resistance heating (jul). heat).

According to such a structure, the source material is heated only by Joule heat, and the Bertier effect is not added. On the other hand, when solute elements dissolved from the source material move through the growth solution and reach the growing crystal (seed crystal), the only movement of the solute elements is the diffusion effect due to the concentration difference and the convection effect (floating effect) due to the specific gravity difference. , and the effect of electromigration is removed. Therefore, it becomes easy to control the movement of solution elements in the growth solution.

Examples of applying this method include:
The source material 12 is the same material as the growth container. For example, if the solute is a solution of Ga and As, the source material is a GaAs compound.

Incidentally, in the growth method of the present invention, the same effect can be achieved even if the DC power source is replaced with an AC power source and an alternating current is passed, and an AC/DC current power source can be applied in the above embodiments and the following examples. In the figure, the AC power source is indicated by a dotted line.

Next, the example of the pulling growth method shown in FIG. 2 is an example showing a method for adjusting this method with higher precision. That is, in this example, the heating element 6' is adjusted to increase the temperature gradient between the lower part and the upper part of the growth liquid. Since the temperature in the vicinity of the upper seed crystal 3 is constant, the lower part is made to have a higher temperature, and this is adjusted by, for example, making the number of turns of the heater or coil denser in the lower part. In this case, in addition to the concentration difference in the above example, the temperature difference becomes large, so that diffusion and convection effects become large, and the growth material can be quickly replenished in the growth solution. This effect can more accurately and effectively create a temperature difference in the growth solution by heating the source material itself. In this way, the composition of the grown crystal can be made more uniform by increasing the effects of diffusion and convection, but the controllability of the solute elements moving in the growth solution is different from that of the conventional growth method explained in Figure 5. In comparison, this example is much easier.

Furthermore, in FIG. 2, a contact metal 15 is interposed between the source material 12 and the carbon electrode 13. It consists of source material 12 and carbon electrode 13
This is provided to reduce the contact resistance since the contact with the
In metal etc. are used. Further, in the figure, an AC power source is indicated by a dotted line, which has the same effect as a DC power source.

Note that it is also possible to adopt a method of accommodating two or more source materials or accommodating and replenishing two or more types of source materials. For example, for solution growth of InGaAsP quaternary bulk crystal using In solvent,
Ga, As, P depending on the source material of GaAs and InP
This includes replenishing solute elements and adjusting solution components.

Next, FIG. 3 shows a schematic diagram of the liquid layer epitaxial growth method. In the figure, 20 is a growth solution;
21 is boron nitride (BN), 22 is a source material, 23 is a carbon electrode, 31 is a BN boat, 24 is a carbon slide, and 24 is a growth substrate. Similar to the example in Figure 1, DC power supplies S ⁺ , S ^-
, a direct current is passed between the carbon electrodes 13 and the source material 12 is heated by its own Joule heat. Further, in the figure, an AC power source is shown by a dotted line, which has the same effect as a DC power source.

At this time, when the solute element dissolved from the source material moves through the growth liquid and reaches the growing crystal (seed crystal), the movement of the solute element is caused by the diffusion effect due to the concentration difference and the convection effect due to the specific gravity difference (floating effect) The effect of electromigration is removed. Therefore, the controllability of movement of solution elements in the growth solution is improved.

Although the heating body is not shown in FIG. 3, this is because the entire body is inserted into a heating furnace.

Therefore, according to the present invention, the solute is replenished in the vicinity of the growing crystal (seed crystal) with good controllability, and the composition of the growing crystal is made uniform.

[Effects of the Invention] As is clear from the above description, according to the present invention, in the growth method of bulk crystals and liquid phase epitaxial crystals, the movement of solute elements in the growth solution can be easily controlled, and the growth of the grown crystal can be easily controlled. The composition is homogenized,
This has a remarkable effect on improving the performance of compound semiconductor devices.

[Brief explanation of drawings]

1 and 2 are schematic diagrams of the pulling growth method according to the present invention, FIG. 3 is a schematic diagram of the liquid phase epitaxial growth method according to the present invention, and FIGS. 4 and 5 are schematic diagrams of the conventional pulling growth method. FIG. In the figure, 1 is a container, 2 and 20 are growth liquids, and 3
is a seed crystal, 4 is a B ₂ O ₃ film, 5 is a rotating pulling rod, 6,
6' is a heating element, 11 and 21 are BN, 12 and 22 are source materials, 13, 14 and 23 are carbon electrodes,
15 is a contact metal, 31 is a BN boat, 24 is a carbon slider, and 25 is a growth substrate.

Claims (1)

[Claims] 1. The elements constituting the multi-compound semiconductor crystal are 1.
A source material containing at least one source material is brought into contact with the growth solution for the multi-component compound semiconductor crystal, a direct current or an alternating current is passed through the source material itself to generate heat, and the source material according to the amount of current is grown in the growth solution. A crystal growth method characterized by controlling the composition of a growth solution by dissolving it in a solution. 2. The crystal growth method according to claim 1, wherein the multi-compound semiconductor crystal is a bulk crystal. 3. The crystal growth method according to claim 1, wherein the multi-compound semiconductor crystal is a liquid phase epitaxial crystal. 4 The growth solution is located below the growth substrate,
4. The crystal growth method according to claim 3, wherein the surface of the growth substrate and the surface of the growth liquid are in contact with each other. 5. A patent characterized in that the source material contacts the growth solution at an arbitrary position, and the composition of the growth solution is controlled by diffusion of the source material due to a concentration difference in the growth solution. A crystal growth method according to claim 1. 6. Claim 1, wherein the source material is located below and in contact with the growth solution, and the composition of the growth solution is controlled by the floating effect of the source material. crystal growth method. 7. The crystal growth method according to claim 1, characterized in that a plurality of the source materials are arranged.