JPH02167882A - Growth of single crystal and apparatus therefor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention applies to semiconductors such as Si and Ge, GaAs, and InP.
Group V compound semiconductors such as Zn5e, CdTe, etc.
- A method and apparatus for growing single crystals of Vt group compound semiconductors and oxides such as BSO and LNO under a vertical temperature gradient.

(Prior art) Conventionally, a method of applying a temperature gradient to a raw material melt in a vertical container and solidifying and growing it from one end is called the vertical Bridgman method (
VB method) and vertical temperature gradient method (VGF method). For example, J. Crystal Growth 6
4 (1983) 285-290, CdT was prepared by the VB method.
A method for growing efll crystals is described.

In this type of method, an inverted conical part is provided at the bottom of the vertical container to suppress the generation of crystal nuclei, and a seed crystal is placed at the tip of the inverted conical part to grow a specified single crystal. It is being said.

In addition, Kyrobolus (Kyropo
ulos) method is also known (J, CrystalG
rowth 5g (1982) 455-459).

(Problem to be Solved by the Invention) In the method using the seed crystal described above, the seed crystal is exposed to high temperature during preparation of the raw material melt, so the seed crystal may melt and disappear. requires strict temperature control. In the VB method and the VGF method, it is not possible to directly check the weighing state, so it is not necessarily easy to repeatedly carry out predetermined seeding. In addition, since the chiroporous method allows crystal growth to progress rapidly,
Twins and polycrystals are likely to occur, and only crystals with many defects such as translocation f and '7 can be grown.

The present invention aims to solve the above-mentioned problems and provide a method and apparatus for growing single crystals with good reproducibility in a vertical container.

(Means for Solving the Problems) The present invention provides (1) a method for growing a single crystal in which a raw material melt in a vertical container is solidified and grown from one end under a temperature gradient;
- Fill a vertical container with a substantially inverted conical part in one part and a small opening at its tip with the raw material melt. After stabilizing the raw material melt under the above temperature gradient, the seed crystal is placed in a small opening [J A method for growing a single crystal, characterized in that the material is immersed in a melted limb of the internal material for seeding, and solidified and grown from above by moving a temperature gradient, and (2) storing the material melt in a vertical temperature gradient furnace. In an apparatus for growing a single crystal in which a vertical container is arranged and solidified and grown from one end thereof, a substantially inverted conical part and a small opening are provided at the top of the vertical container and a small opening is provided at the tip of the vertical container, and a seed crystal is placed in the raw material melt in the small opening. This is a single crystal growing apparatus characterized by being provided with a seed crystal support shaft for dipping and weighing the seed crystal, and a means for moving the temperature gradient.

(Function) FIG. 1 is a conceptual diagram of the i single crystal growth apparatus, which is a specific example of the present invention, and FIG. FIG. A vertical container 4 is supported by a lower shaft 6 in the center of the chamber 9, and a heater 7.7'7'' and a heat insulator 8 are arranged around it.Vertical container 4
is the small frontage 11 for mounting the pillar from above, and the crystal a′ [
It has a substantially inverted conical part 12 for expanding the diameter, and a cylindrical part 13 for growing a straight crystal, and its material is AI.
N, AI, Oz, SiC, TiC, v Gunesh 7, 8N
.

It can be selected from ceramics such as pBN, heat-resistant metals such as Mo, F, Ta, carbon, quartz, or a combination thereof. The raw material is put into this vertical container 4 and solidified with a heater at a temperature of T11. It is heated to a higher temperature Tm to melt it. The temperature distribution formed by the heater is assimilated temperature T as shown in FIG. A temperature gradient region decreasing at dT/dZ is provided above the region of higher temperature Tm. After thermally stabilizing the raw material melt I, raise the vertical container 4 a little to open the booth l! The surface temperature of the raw material melt is the solidification temperature Tm.

The seed crystal 3 attached to the upper shaft 5 is lowered and immersed in the raw material melt for seeding. Since the surface of the raw material melt is small, seeding in a small opening can easily produce a single crystal, and seeding can greatly suppress crystal defects that sometimes occur. Further, by providing a viewing window 14 for monitoring above the chamber 9, seeding can be performed reliably. After the scale is attached, the upper and lower axes are simultaneously raised at a constant speed to grow the single crystal 2.

At this time, since the raw material melt I is heated from the surroundings, the surroundings become hotter and the solid-liquid interface 10 can be maintained in a downwardly convex state as shown in the figure, and various types of materials that are easily generated from the surroundings can be maintained. Crystal defects can be eliminated. In this way, reliable weighing is carried out with a small opening, the diameter of the crystal is gradually expanded in the approximately inverted circular ζIL-shaped portion, and a single crystal with a predetermined diameter can be obtained in the cylindrical portion. The orientation of these 43 pieces is controlled by seed crystals,
High-quality single crystals with significantly reduced crystal defects can be obtained.

(Example) A GaAs single crystal was grown using the apparatus shown in FIG.

The vertical container has an inner diameter of 551 mm, a height of 100 mm,
The taper angle of the inverted conical part is 45°, and the inner diameter of the small opening is 10°.
A pBN-coated carbon material having a thickness of 11 and a thickness of l10ffl1 was used. 1.0 kg and 13.0.100 g of GaAs raw materials were accommodated in the vertical 1 () chamber, and the chamber was filled with 20 atm of nitrogen gas. Then, in a vertical temperature gradient furnace, the assimilation temperature Tm, Tm higher than I238°C
The high temperature region of 1245-1250°C and the upper region (dT
/dz) formed a temperature gradient region of about 20'C/am. After the raw material is melted in a high temperature area, the vertical 2-size container is slightly raised and the surface of the raw material melt in the small opening is /! ! degree 1240-1
The temperature was lowered to 245°C, and the seed crystal was immersed and pressed into the raw material melt, and then the -L lower axis was simultaneously moved upward at a speed of 10 mm/hr to solidify and grow. Since seeding could be monitored through a viewing window, it was extremely easy and reliable.

These experiments were repeated 6 times, and in each case, 111 crystals were obtained.
+m Ueno) in-plane EI'D is 3000-6000
Is there a very small range of (showed that.

(Effects of the Invention) The present invention ensures the reproducibility of seeding by adopting the configuration described below, suppresses the occurrence of seeding defects during pressing and solidification growth, and reduces the diameter of the straight body. It has made it possible to grow 11 crops of uniform and high quality.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of a small crystal growth apparatus which is a specific example of the present invention, and FIG. 2 is an explanatory diagram showing an example of the temperature distribution within the growth apparatus.

Claims (2)

[Claims] (1) In a single crystal growth method in which a raw material melt in a vertical container is solidified and grown from one end under a temperature gradient, the raw material is placed in a vertical container having an approximately inverted conical portion at the top and a small opening at the tip. After filling the melt and stabilizing the raw material melt under the above temperature gradient, a seed crystal is immersed in the raw material melt in a small opening for seeding, and solidified and grown from above by moving the temperature gradient. A method for growing single crystals. (2) In a single crystal growth device in which a vertical container containing a raw material melt is arranged in a vertical temperature gradient furnace and solidified and grown from one end, there is a substantially inverted conical portion at the top of the vertical container and a portion at the tip thereof. Single crystal growth characterized by providing a small opening, providing a seed crystal support shaft for seeding by immersing the seed crystal in the raw material melt in the small opening, and having means for moving the temperature gradient. Device.