JP2589985B2 - Method for growing compound semiconductor crystal - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for growing a binary or ternary III-V group compound semiconductor crystal used for an electronic device or an optical device. More specifically, the present invention relates to the improvement of bulk crystal growth technology represented by the liquid-sealing Bridgman method or the liquid-sealing temperature gradient solidification method. Crystal growth technology to prevent furnace contamination due to solidification and deposition in low-temperature parts in airtight containers, facilitate furnace cleaning work, and obtain high-quality compound semiconductor crystals with uniform controlled crystal composition Is provided.

(Prior Art) Hereinafter, a case of growing a GaAs crystal, which is a typical binary III-V compound semiconductor crystal, will be described as an example.

FIG. 3 is a schematic view of the inside of a furnace showing GaAs crystal growth by a conventionally known liquid-sealed vertical Bridgman method. In FIG. 3, 1 is a seed crystal, 2 is a grown GaAs crystal, 3 is Ga
As melt, 4 is a liquid sealant, 5 is a crucible, 6 is a crucible holder, 7 is a crucible shaft, 8 is a heating element composed of a single or a plurality of combinations, and 9 is an airtight container. In such an in-furnace configuration, normal crystal growth is performed by, first, seed crystal 1 and solid raw material in crucible 5 as already known.
Filled with GaAs single crystal or polycrystal, solid-state liquid sealant, etc., then heated to a high temperature with a heating element, softened liquid sealant, melted raw material GaAs, and started crystal growth after seeding Thus, a crystal growth state as shown in FIG. 3 is realized.

(Problems to be Solved by the Invention) In the above-described conventional crystal growing method, a large amount of highly volatile As dissociates and evaporates in the raw material crystal melting process or crystal growth process and passes through the liquid sealant 4. And solidifies and deposits at a low temperature portion in the airtight container 9. Recently, especially for GaAs crystals, it has become necessary to grow crystals from excess As melt in order to satisfy the required characteristics. Crucible 5
As the crystal growth starts (increasing the solidification rate), the pressure inside the furnace and the temperature distribution in the melt are adjusted to control the amount of As evaporation artificially. Liquid As
A method of keeping the excess constant is adopted. In such a case,
In the crystal growing process as well as in the raw material melt synthesis process, a large amount of As continuously evaporates, and the contamination in the airtight container 9 becomes remarkable. Such contamination not only significantly impairs the reproducible growth of crystals whose characteristics are precisely controlled, but also causes a large amount of harmful substances such as As and / or As in the cleaning operation of the airtight container 9 after the completion of the crystal growth process. This is a major drawback of the conventional technology, such as extreme difficulty in terms of treatment of As oxide dust.

(Object of the Invention) The present invention solves the above-mentioned drawbacks of the prior art, and performs continuous As evaporation control necessary for growing a crystal having uniform characteristics, and contaminates an airtight container with As dust or the like. It is an object of the present invention to provide a crystal growth method that is extremely effective in practical use and has a reduced number of crystals.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention relates to a group IIIb element and a group IIIb element which are melted or synthesized in a container such as a crucible having a cylindrical shape or various shapes. Covering the surface of the compound semiconductor crystal raw material melt comprising the Vb group element with a liquid sealing body,
In addition, in a crystal growing method in which a single crystal or a polycrystal having a desired composition and characteristics is obtained by gradually solidifying the solution by disposing the solution in a high pressure container, at least one or more pressure balancing pores and a volatilization inside Compared to the dissociation pressure of the strong Vb group element from the raw material melt, the cylinder or various shapes are formed in the easy-to-close enclosure having a low-temperature portion such that the vapor pressure of the Vb group element alone becomes sufficiently low. A container such as a crucible having a raw material of the Vb group element is heated, and the container such as a crucible having a cylindrical shape or various shapes containing the raw material of the Vb group element is heated to melt the raw material of the Vb group element, and the melt is evaporated. An object of the present invention is to provide a method for growing a compound semiconductor crystal, characterized in that a crystal is grown by flowing an object into a low temperature part.

Thus, according to the present invention, the entire crucible on which crystal growth is performed is housed in a high-temperature closed container, and the vapor pressure of simple As in a part of the closed container is sufficiently lower than the As dissociation pressure of the GaAs melt. Providing a temperature region (low temperature portion, volatile element deposition portion), providing pores in a part of the closed container for balancing the pressure in the closed container and the pressure of the whole hermetic container 9; Further, the present invention is characterized in that the conductance with respect to the vaporized gas is made larger in the portion communicating with the volatile element deposition portion, and the pressure balance pore portion is made smaller. By the above-described means, most of As evaporated during the production of the raw material melt and during the crystal growth is solidified and deposited only in the low-temperature portion of the closed vessel, and as a result,
This makes it possible to prevent the airtight container 9 from adhering to the inner wall.

Next, examples of the present invention will be described. It should be noted that the embodiments are merely examples, and it is needless to say that various changes or improvements can be made without departing from the spirit of the present invention.

(Example 1) FIG. 1 is a schematic view of a crystal growth state showing one example of the present invention.

In the figure, 1 is a seed crystal, 2 is a grown GaAs crystal,
3 is a GaAs melt, 4 is a liquid sealant, 5 is a crucible, 6 is a crucible holder, 7 is a crucible shaft, 8 is a heating element composed of a single or a plurality of combinations, and 9 is an airtight container. Reference numeral 10 denotes a closed lid according to the present invention, which constitutes a closed container for storing the crucible 5 connected to the crucible holder 6 for storing the crucible 5 and the fitting portion 11. In addition, a low-temperature room 12
Is connected to the inside of the crucible holder 6 through the communication hole 13 to communicate with the atmosphere. On the other hand, reference numeral 14 denotes pressure balance pores provided in a part (upper side wall in the figure) of the crucible holder 6, and the internal pressure of the closed container according to the present invention and the external pressure of the closed container, that is, the internal pressure of the airtight container 9, This prevents the sealed container from being broken by a large pressure difference. Further, reference numeral 15 schematically shows As solidified and deposited inside the low-temperature chamber 12, and according to the present invention, most of As evaporated during synthesis of the raw material melt and during crystal growth is solidified and deposited in the low-temperature chamber 12. Was confirmed. Further, in FIG. 1, reference numeral 16 schematically shows a state in which As vapor moves as bubbles in the liquid sealant 4 during crystal growth.

 Hereinafter, an example of crystal growth to which the above embodiment is applied will be described.

The pBN crucible 5 having a diameter of 80 mm, the seed crystal 1 having a diameter of 5mm length 30 mm, metal Ga1050g, metal As1200g, filled with B ₂ O ₃ 350g, were synthesized and melt the raw material melt is heated to a high temperature by the heating elements 8 Thereafter, crystal growth was started from one part of the seed crystal, and the entire melt was single-crystallized through the crystal growth state shown in FIG. 1 to complete crystal growth. The pressure in the hermetic container 9 during the preparation of the raw material melt was maintained at about 50 atm, and the pressure during crystal growth was maintained at about 2.5 atm. The temperature of the low-temperature section 12 of the hermetic container was kept at a low temperature of 450 to 500 ° C. throughout the preparation of the raw material melt and the growth of the crystal.

After completion of the crystal growth, the weight of As15 solidified and deposited inside the low-temperature part 12 of the closed vessel was measured, and as a result, was about 67 g. Since the amount of As evaporating during the above-mentioned raw material melt production was confirmed to be about 10 g from the results of experiments conducted separately,
It is estimated that the amount of As evaporated during subsequent crystal growth is about 50 g. On the other hand, the total weight of As (or an oxide of As) attached to the inner wall of the hermetic container 9 through the pressure balancing pores 14 in the above-described crystal growth process is 1 g or less, and there is almost no contamination in the furnace. It turns out. This is because the conductance for vaporized As is small communicating with the pores 14, and the communicating holes
In FIG. 13, since the size is increased, most of the As reaches the low-temperature portion (the deposited portion of the volatile element) 12 through the communication hole 13 and is solidified and deposited.
The low-temperature portion 12 is sufficiently separated from the high-temperature molten liquid 3 and solidifies here. Further, since the path is narrowed through the communication hole 13, it is possible to prevent the once solidified As from being separated from the low-temperature portion, falling, and being mixed again.

Example 2 FIG. 2 is a schematic view of a crystal growth state showing another example of the present invention. In this figure, reference numerals 1 to 11 represent the same as those in FIG.

In this case, the low temperature chamber 12 is provided below the crucible holder 6, and the dissociated and evaporated As vapor is a cylindrical communication hole provided between the outside of the crucible holder 6 and the inside of the sealing lid 10.
It reaches the low temperature chamber 12 through 13 and solidifies and deposits. Even in the preparation of the raw material melt and the crystal growth according to the present embodiment, most of the dissociated and evaporated As was solidified and deposited in the low-temperature chamber 12 as in the case of Example 1, confirming the effect of the present invention. Further, since the low-temperature portion (portion where the volatile element is deposited) is located below the melt 3, it is easier to lower the temperature than in the first embodiment, and an additional effect of easy temperature control can be obtained.

In the embodiments of the present invention described above, the case of growing a GaAs crystal has been described. However, the present invention can be applied to the growth of other binary or more compound semiconductor crystals containing an element having a high vapor pressure. 10 configuration, temperature of each part, airtight container 9
It is needless to say that the same effects as in the present embodiment can be obtained by appropriately selecting the internal pressure and the like.

(Effects of the Invention) As described above, according to the present invention, a group IIIb element and a group Vb element formed by melting or synthesizing in a container such as a crucible having a cylindrical shape or various shapes. Crystal growth method of covering the surface of a compound semiconductor crystal raw material melt with a liquid sealing body and disposing the same in a high pressure container to gradually solidify the solution to obtain a single crystal or polycrystal having a desired composition and characteristics In at least one or more pressure balancing pores, the vapor pressure of the Vb group carbon alone becomes sufficiently lower than the dissociation pressure of the highly volatile Vb group element from the raw material melt. A container such as a crucible having the cylindrical shape or various shapes is accommodated in the easy seal having a low temperature portion.
The container such as the crucible or the like having the cylindrical shape or the various shapes accommodating the raw material of the Vb group element is heated to melt the raw material of the Vb group element, and the evaporate of the melt is caused to flow into a low-temperature portion to grow the crystal. This prevents the elements with high vapor pressure, which have been evaporated at random during the preparation of the raw material melt or the crystal growth, from dissipating, solidifying and accumulating in the hermetic container, and contaminating the hermetic container. Is significantly reduced.
In particular, in the case where a crystal having a uniform composition is grown with good reproducibility from a biased substantially constant melt composition while continuously evaporating an element having a high vapor pressure along with crystal growth, by applying the method of the present invention, A great effect can be expected.

[Brief description of the drawings]

FIG. 1 is a schematic view of a main part showing an embodiment of the present invention, FIG. 2 is a schematic view of a main part showing another embodiment of the present invention, and FIG. 3 is a conventionally known liquid-sealed vertical Bridgman method. FIG. 2 is a schematic view of the inside of a furnace showing GaAs crystal growth by the method shown in FIG. DESCRIPTION OF SYMBOLS 1 ... Seed crystal 2 ... GaAs crystal 3 ... GaAs melt 4 ... Liquid sealing agent 5 ... Crucible 6 ... Crucible holder 7 ... Crucible shaft 8 ... Heating element 9 ... Airtight container 10 ... Sealing lid 11… Mating part 12… Low temperature chamber 13… Communication hole 14… Pore for pressure balancing 15… As solidified and deposited 16 Air bubbles of As vapor

Continuation of the front page (72) Inventor Hiroki Koda 3-1 Morinosato Wakamiya, Atsugi-shi, Kanagawa Prefecture, Japan Atsugi Telecommunications Research Institute, Inc. (56) References JP-A-48-12984 (JP, A)

Claims (1)

(57) [Claims] 1. The surface of a melt of a compound semiconductor crystal raw material composed of a Group IIIb element and a Group Vb element, which is formed by melting or synthesizing in a container such as a crucible having a cylindrical or various shapes. In a crystal growth method of obtaining a single crystal or a polycrystal having a desired composition and properties by covering with a sealing body and arranging in a high pressure container to gradually solidify the solution, at least one pressure-balancing thin film is used. Compared with the dissociation pressure of the pores and the highly volatile Vb group element from the raw material melt.
The container containing the cylindrical or crucibles having various shapes is accommodated in the easy seal having a low temperature portion such that the vapor pressure of the elemental group element alone is sufficiently low, and the cylinder accommodating the raw material of the Vb group element. Heating a container such as a crucible having a shape or various shapes to melt the raw material of the Vb group element, and allowing the vaporized product of the melt to flow into a low-temperature portion for crystal growth. Training method.