JPS6036396A - Method for growing single crystal - Google Patents

Abstract

PURPOSE:To prevent the failure in the seeding, and to improve the productibity of single crystal, by determining the seeding temperature correctly based on the temperature wherein the dendrite crystal melts and disappears in a molten liquid. CONSTITUTION:In the liquid encapsulated pulling method, a dendrite crystal in formed on the surface of the molten liquid by lowering the temperature of the molten liquid. The temperature of the molten liquid is raised slowly and the temperature wherein the dendrite crystal melts and disappears is determined. The seeding is carried out at a temperature lower than the melting temperature by 3-15 deg.C. The seeding can be achieved without failure, and the productivity can be improved by this process.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid capsule drawing method (Liquij-dEnc
apsulated 0zochraleki Met
hod-, hereinafter referred to as "LEc method". ), especially the seeding method.

The LEO method yields high-purity single crystals with a circular cross section, GaA3, GaP, etc.
Like inorganic compounds consisting of group B and group VB elements,
It has the characteristics of being able to grow single crystals of inorganic compounds containing highly volatile components.

Although the seeding process is important in the LliiO method, ``Traditionally, seeding was done by setting the temperature empirically, so it was difficult to obtain a single crystal in one go, and several trials and errors were required. There was also. If the temperature is too high, the seed crystals will melt, and if the temperature is too low, the crystals will rapidly grow and become polycrystalline.

However, when seeding is repeated, the length of the seed crystal becomes shorter and the state of heat conduction changes as the seeding occurs, making it difficult to set the temperature. Ta.

The present inventors have arrived at the present invention as a result of intensive research into molds for the purpose of developing a method for accurately setting the seeding temperature.

The above-mentioned object of the present invention is to reduce the temperature of the melt to generate dendrite crystals on the surface of the melt in a method for growing a single crystal from a melt by the LEO method. The temperature at which the dendrite melts and disappears is measured by gradually increasing the temperature, and the temperature is reached by seeding at a temperature 3~/J-°C lower than that temperature.

In order to grow a single crystal from a melt by the method of the present invention, as in the usual LEO method, raw materials for the single crystal such as GaAs,
GaP, Si isostatic capsules are added together with some B2O3 and melted by raising the temperature.

When growing a single crystal of GaAs, GaA is placed in the crucible.
s polycrystal or add equivalent amounts of Ga and As, and add B to this.
2O5k plus the melting point of GaAs (/, 237℃)
The container is also heated to a high temperature to melt the contents of the crucible. After the melting is completed, the temperature of the obtained melt is gradually lowered. Although the temperature may be lowered continuously, it is preferable to lower the temperature in stages because it makes it easier to observe the state of dendrite formation. In this case, after lowering the temperature of the 10°0 melt,
It is preferable to repeat the process of stopping and observing the temperature drop for several minutes. Monitor TV while lowering the temperature of the melt.
When the formation of dendritic crystals was observed at the interface between GaAs and B2O3, the temperature was completely stopped, and then the temperature was gradually increased until the temperature at which the dendritic crystals melted and disappeared was reached. Measure precisely. Although the temperature may be raised continuously, it is preferable to raise the temperature in stages because it is easier to measure the temperature at which the dendrites melt and disappear. -2 to 2°C when increasing temperature in stages
After raising the temperature, it is preferable to repeatedly stop the temperature increase for 3 to 7 minutes. Note that the production and disappearance of dendrite crystals may be observed using a monitor TV, or, if a weight sensor is attached to the seed crystal holder, it may be detected by the signal from the sensor. When using a weight sensor, it is necessary to keep the seed crystal in contact with the melt during the temperature-lowering and temperature-raising processes.

For seeding, the temperature at which the above-mentioned dendrites melt and disappear is also 3~
Single crystal growth is performed by seeding at a temperature as low as /l'o, preferably 0 to /θ°C.

The single crystal pulling apparatus used in the present invention may be one that is normally commercially available. Further, other crystal growth conditions may be the same as those of the conventional LEO method.

The growth of GaP and other single crystals can be done in the same way as the GaAS single crystal.

According to the method of the present invention, the seeding temperature can be determined accurately, so seeding will not fail and production efficiency will be improved. Furthermore, since the formation and disappearance of dendrites can be detected by a weight sensor, single crystal growth can be automated.

The present invention will be explained in more detail based on examples.

Example/ LEO growth equipment manufactured by Metal Re5ear in the UK
A "Melbourn" type crystal growth apparatus manufactured by CH Co., Ltd. was used.

PBN crucible a/, g69. As /, Evening!
fj and B2O3θ, s g were added, and then the pressure inside the apparatus was reduced to /θ-' torr, and nitrogen was introduced to increase the pressure to 0 kg/d.

Next, while heating the crucible to synthesize GaAs'i, the temperature drop was measured with a thermocouple placed outside the crucible.
After the temperature started to decrease, the temperature decrease was stopped for 10 minutes, which was repeated twice.

Since the formation of dendrite crystals was observed at the interface between the B2O3 and GaAs melts, the temperature drop was stopped and the temperature was maintained at a constant temperature for 10 minutes. Subsequently, the temperature was raised by 3°C and then completely stopped for 5 minutes, which was repeated twice.

Melting and disappearance of the dendrites was observed, so from the temperature
After cooling down to ℃, seed crystal (10o direction) '1GaAs
Seeding was performed by contacting the melt and holding it for 30 minutes.

Seeding was completed in 7 times. After seeding was completed, single crystal pulling was started.

5 [Example/A total of 70 runs (RUN) Ga
As single crystals were grown, the average number of seedings was /,
The number of runs was 3 times/run, and single crystals were obtained in 9 runs.

When seeding was done by the conventional method, the number of false runs/run was 5, respectively, so it is clear that the productivity was significantly improved when the method of the present invention was used.

Example λ G was grown in a PBN crucible using the same crystal growth apparatus as Example/.
a As polycrystalline Yukg, B2O3θ, 7kg'i were added, and argon was introduced in the same manner as in Example/3! 9 /
The pressure was increased to d. Subsequently, the temperature was raised, and Ga was measured on a monitor TV.
After confirming that As and B2O3 have melted, G
By bringing the aAs melt into contact with the seed crystal (in the 10θ> direction),
While observing the signal from the weight sensor (load cell), the temperature was lowered in the same manner as in Example.

After an increase in the weight of the seed crystal was observed, the temperature was raised in the same manner as in Example. After confirming that the weight of the seed crystal was the same as the original weight, the temperature of the aAs melt was lowered by g'a, held for 20 minutes, and then single crystal growth was performed.

A total of 10 runs of GaAs single crystals were grown in the same manner as in Example 1, but the number of runs in which the single crystals were obtained was ♂ runs.

Patent applicant Mitsubishi Monsanto Chemical Co., Ltd. Mitsubishi Chemical Industries Co., Ltd. Agent Patent attorney Yo Hase - (and 7 others) Procedural amendment (voluntary) February 2, 1920 SG 2 Name of the invention Method for growing single crystals 3 Amendment Relationship with the case of a person who does Detailed Explanation Column 6 of the Specification of Contents of the Amendment, page 2, lines G to J are corrected to the following passage 9.

[PBN crucible la /, 4 to 5, As /
, j j 醇 and B2O30, J 醇, and then inside the above apparatus.

Claims (4)

[Claims] (1) In a method of growing a single crystal from a melt by the liquid capsule pulling method, the temperature of the melt is lowered to generate dendrites on the surface of the melt, and then the temperature of the melt is lowered. A method characterized in that the temperature at which the dendrite crystals melt and disappear is measured by gradually increasing the temperature, and the seeding is carried out at a temperature that is 3 to 10°C lower than the temperature. (2) The method according to claim 1, wherein the single crystal is an inorganic compound single crystal consisting of elements of Groups 1b and 5b of the periodic table. (3) The method according to claim 1, wherein the inorganic compound single crystal is a GaAs single crystal. (4) For seeding, the temperature is lower than the melting temperature of dendrites.
2. The method according to claim 1, wherein the temperature is /θ゛C lower.