JPS58167499A - Preparation of single crystal of gallium arsenic - Google Patents

Abstract

PURPOSE:To obtain a single crystal of GaAs having high specific resistance and electrical semi-insulating properties in high yield, by crushing high-purity GaAs crystal prepared by high-pressure crystal pulling method, melting it under heating, growing a crystal by crystal pulling method under pressure <= middle pressure. CONSTITUTION:Ga, As and B2O3 having >=1,200ppm water content are put in the crucible 3, it is placed in the container 1, and heated under high pressure of >=50atm., to form melt comprising the B2O3 melt 8 as an upper layer and the GaAs melt 7 as a lower layer. The seed crystal 6 is brought into contact with the GaAs melt 7 and pulled up to form a GaAs crystal. The prepared GaAs crystal is crushed, subjected to etching treatment to remove impurities, the crushed GaAs material and B2O3 as a sealing compound are fed to the crucible 3 again, melted under pressure <= middle pressure of 10-20atm. under heating, the seed crystal 6 is brought into contact with the GaAs melt 7, and pulled up, to give the desired GaAs single crystal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a semi-insulating gallium arsenide (GaAy) single crystal having a resistivity of 10"Ω·1 or more.

High-purity GdA single crystal is semi-insulating with a resistivity of 1060.1 or higher), and this GdA crystal is used as an element substrate for optoelectronic integrated circuits by integrating optical devices and electronic devices. With this, stray capacitance due to wiring etc. can be reduced, and separation between elements can be made easier, and integration density can be increased.

Until now, methods for producing semi-insulating GaA single crystals include the mate growth method, the low-pressure single-pull method, and the high-pressure seal-pull method (direct synthesis method from Ga and A7). &−
) The growth method can be performed under atmospheric pressure, but silicon from the quartz boat material is mixed into the material, lowering the resistivity. For this reason, chromium is usually added to make it semi-insulating. However, there are problems such as variations in properties due to uneven distribution of chromium and changes in properties during the heat treatment process), and the adduction position distribution of the nine crystals obtained has a U-shape. There is a tendency to show. In addition, in the low-pressure sealed pulling method, the raw material is 〇mkl polycrystals produced by the boat molding method, so the purity of the raw material is low and the addition of chromium is required. The high-pressure sealing method does not require the addition of chromium, but since crystals are created under high pressure, defects are likely to occur in the crystals due to the influence of the thermal environment due to pressure, and liquid sealants and gas convection (The manufacturing process is complicated due to the influence of the above), and the adduction position distribution of the obtained crystalline sea urchin tends to show a W-shape.

Therefore, it is difficult to create a high-quality semi-insulating single crystal, but it is easy to create a high-purity polycrystal because the amount of molten liquid splashed into the furnace is small.

This invention is a semi-insulating GgA with a resistance value of 10'Ω・1 or more without adding impurities such as chromium.
#1! The aim is to provide a method for producing crystals with high bulk yield and good reproducibility.G and A# are produced by a high-pressure method using wet oxide (!It's) with a high water content as a sealant.
F) It is characterized in that a crystal is synthesized, the crystal is crushed, the crushed GgAz crystal is heated and melted under low pressure of 20 atmospheres or less, and a GaAz single crystal is obtained by a pulling method.

This invention will be explained based on the attached drawings. FIG. 1 shows an example of a single crystal manufacturing apparatus by the pulling method, / is a high-pressure container, and a crucible J is installed in this high-pressure container l. The crucible is rotatably supported by a supporting member tray and heated to a predetermined temperature by nine heaters provided around the crucible. A round pulling shaft 3 with a seed crystal number at its tip is provided at the top of the crucible, and this pulling shaft is configured to rotate and move up and down.

In the present invention, the crucible J can be made of either quartz or pyrolyte boron nitride, but the latter can prevent rounding and impurity contamination since it does not contain silicon. Inside this crucible are gallium (Ga) and arsenic (A,?
) are added in such proportions as to obtain a single crystal with the desired composition ratio. Then, as a sealant, B, 0. Melt the bath 7
At the time of t, insert a hole that will form a hole with a thickness of 1 cm or more. The graph in Figure 2 is B, 0. The relationship between the ground water wheel and the resulting G, A, and single crystal resistivity is shown, and B, 0. It is clear that the higher the moisture content of , the greater the gettering effect of impurities due to moisture, and the water content of K to obtain a GQkl single crystal with a resistivity of 106 Ω is 1200 ppwL.
It is sufficient to use the above Ueno) B, O, and so on.

As mentioned above, when the crucible is charged with a predetermined voltage G(1+A#+J
After adding OG, place the crucible in a high-pressure container and press inert gas such as argon or nitrogen to create a high pressure of 50 atmospheres or more.
Heat to approximately 1260 C) or higher.

Then, inside the crucible, a GaA melt layer 7 is formed at the bottom, and a layer 820. A melt layer t is formed, and the 8101 layer acts as a high-pressure sealant to prevent G, A, and the melt from evaporating. At this time, since B*Osk with high moisture content is used,
G, Aj Impurities in the melt, such as silicon, are gettered and the melt is highly purified. In this state, the seed crystal 6 is brought into contact with the G-AI melt 7 and pulled up.

Create a crystal. In the above-mentioned pulling process, the crucible or the pulling shaft j is rotated and stirred at an appropriate speed in order to maintain G, A, and the melt homogeneously as required. Further, since a single crystal is not manufactured, the pulling speed of the seed crystal may be 5 to 20 m+/A 9 degrees.

The crystalline product thus obtained is ground to a size of 151 squares or less by an appropriate method in order to facilitate melting. Next, a rounding etching process is performed to remove impurities attached to the pulverized material. This etching treatment is carried out using sulfuric acid, hydrochloric acid, nitric acid, hydrogen peroxide, etc., but sulfuric acid is effective for removing organic matter adhering to the surface of the pulverized material, while hydrochloric acid and nitric acid are effective for removing heavy metals.

The GaA# crystals crushed and purified in this way can be used as a sealant in OB! 0. The mixture is then placed in the crucible again, and the inside of the high-ratio container is heated with an inert gas under a medium pressure of 10 to 20 atmospheres or lower to WIm G, A, crystals and B, O, and the seed crystal is By bringing it into contact with Ga I solution and raising it at a rate of about 1 to 5 #/, the specific resistance becomes 10'Ω・1
The above GaA single crystal can be obtained. BO added to the above
1 can be used in either wet type or dry type. In addition, when pulling up the seed crystal, the crucible and the shaft are rotated at an appropriate speed as necessary.

As is clear from the above description, the present invention is directed to B, 0. A wet type with a high water content is used to create an AAHZ crystal from which impurities are removed by the gettering effect, and this crystal is remelted and then pulled up under pressure below medium pressure. A GaA single crystal with no crystal defects and a specific resistance of 1060·1 or more can be obtained reproducibly. Furthermore, the moisture content is 1500 pp
By using B, O, of rm or more, and controlling the pulling speed of the seed crystal, the specific resistance is 10 Ω·1 or more,
GaAy single crystals with practically uniform resistance distribution within the crystal can also be easily obtained.

Next, examples of the present invention will be described.

Using a single-crystal manufacturing apparatus having the structure shown in the diagram, raw material Gα with a purity of 6N and ~500 f were placed in a B01J-chik boron nitride crucible with an inner diameter of 109 mm and a height of Zoo ■, and then the water content was reduced to 2000 mm. ppm B, O, 1
I put 6Of. This crucible was placed in a high-pressure container, and argon gas was pressurized to create a pressure of about 50 atmospheres, while the crucible was heated to about 1300'CK using a heater. As a result of the above heating, in the crucible, the upper layer contains B and Os melt, and the lower layer contains KG.
aA# Melt forms a circle.

After the aaha is completely melted in the crucible, the seed crystal is
A, #The melt was brought into contact with 'II&' and pulled up at a rate of 15%/h. During this pulling operation, the crucible was rotated 20 times per minute, and the seed crystal was rotated 5 times in the opposite direction to the crucible.

The diameter is approximately 50mm due to the above-mentioned lifting process. , length about 100
m, 900 t of GaA by weight, ? A round crystal is obtained.

Next, this GaA# crystal was crushed to a size of 1 flaw angle or less, and Ht 804 : He Ot ; Ht O was 5:1.
Etching treatment was performed for 5 minutes using a mixed solution of :1:Hct:HNO,:H,O was 1:1 after washing thoroughly with water.
After etching treatment 1 to 9 again for 3 minutes with a 1:1 mixture,
Washed thoroughly with pure water. In this way, the 90a Az crystal is crushed and refined and becomes B again! 0. Place the crucible in a crucible, place the crucible in a high-pressure container, pressurize argon gas,
Set the pressure to 0 atmospheric pressure and heat the crucible to about 1300℃.9. When the GaAz in the crucible was completely melted, a seed crystal was brought into contact with the Gaam I melt and pulled up at a rate of 5-. At this time, the crucible was rotated at a rate of 20 times per minute, and the seed crystal was rotated at a rate of 6 @ in the opposite direction to the crucible. By the above pulling operation, a cylindrical GaA with a diameter of about 50 cm and a length of about Zoo-
A single crystal was obtained.

Next, the shoulder part and the middle part of this cylindrical GaAt single crystal were cut out, and the resistivity was measured from one end of each uni I to the other end through the diameter.9. The specific resistance of the shoulder wafer is shown in Figure 1M3 (Fg), and the specific resistance of the body wafer is shown in Figure 3(A). As is clear from the graph above, 1
The specific resistance of both the shoulder and body wafers exceeded 1080, and the resistance distribution was almost uniform at all points.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of a single crystal manufacturing apparatus, and FIG. 2 is a graph showing the relationship between the water content of B, O, used for capsule cutting in the present invention, the GaA obtained, and the specific resistance of the single crystal. Figure 3 is a graph showing the specific resistance of a 90gA# single crystal obtained by the method of the present invention. In the figure, / is a high-pressure container, C is a heater, 3 is a crucible, 6 is a seed crystal, 7 is G, A, a melt, and l is a 101 melt.

Claims (3)

[Claims] (1) Gallium, arsenic and water content, rate 1200 ppm
The above boron oxide is heated under high pressure to a temperature higher than the melting temperature of gallium arsenide to form a melt in which the upper layer is boron oxide/melt and the lower layer is gallium arsenide melt, and seed crystals are added to the skeleton gallium arsenide solution. The gallium arsenide crystals are brought into contact and pulled up to create gallium arsenide crystals. A method for producing a gallium arsenide single crystal, characterized by pulling it. (2) The method for producing a gallium arsenide single crystal according to claim 1, wherein the pressure is 50 atmospheres or more. (3) Claim 1 characterized in that the intermediate pressure is 10 to 20 atmospheres! A method for producing a gallium arsenide single crystal according to JIEI or 2.