JPH03183682A - Single crystal growth method and device - Google Patents

Abstract

PURPOSE:To obtain the good-quality single crystal without breaking a vertical type cylindrical vessel by closing the lower small aperture of the vessel, adding raw materials from the upper small aperture, heating and melting the materials, immersing a seed crystal into the upper part of the melt, closing the upper small aperture with the grown crystal, opening the lower small aperture, and growing the crystal successively from above. CONSTITUTION:The lower small aperture 6 of the vertical type cylindrical vessel 4 is hermetically closed and the raw materials 20 are charged from the upper small aperture 2. The entire part of the vessel 4 is heated to the temp. higher than the m.p. of the raw materials 20 by heaters 7, 8, 9 to melt the raw materials 20. The temp. of the raw material melt 14 in the upper small aperture 2 is held nearly at the m.p. of the raw materials 20 and the temp. of the melt 21 lower than this melt is held at the temp. higher than the m. p. The seed crystal 15 is then immersed into the melt 14 of the upper small aperture 2 and after the upper small aperture 2 is hermetically closed by the grown crystal 22, the lower small aperture 6 is opened so that the excess melt 16 can flow out. The temp. gradient is then moved downward, by which the crystal is solidified and grown successively from above to grow the single crystal. The failure of the vessel 4 is obviated in this way even with the raw materials which expand at the time of the solidification of the melt.

Description

[Detailed description of the invention] (Industrial application field) The present invention is applicable to semiconductors such as Si and Gc, m-v group compound semiconductors such as GaAs and InP, and semiconductors such as Zn5e and CdTe.
- A method and an apparatus for growing Li crystals of group compound semiconductors and oxides such as BSO and LNO under a vertical temperature gradient.

(Prior art) Conventionally, there have been methods for applying a temperature gradient to the raw material melt in an M-shaped container circle and solidifying and growing from one end. For example, J.

CrystaIGrowLh 64 (1983) 285
290 describes a method of growing CdTcfli crystals by the VB method.

In this weighing method, an inverted conical part is provided at the bottom of the vertical 42 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 lj box crystal. ing.

In the second method, the seed crystals are exposed to high temperatures during the preparation of the raw material melt, which may cause the seed crystals to melt and disappear, or the seeding temperature may be too low, resulting in polycrystals. To prevent this, strict temperature control is required. Furthermore, with this method, it is not possible to directly check the state of seeding, so it is not easy to repeatedly carry out predetermined seeding. Furthermore, in this method, all the weight of the upper raw material melt is applied to the growing crystal, so! In some cases, a large number of defects are generated inside the grown crystal, and only crystals with many defects can be grown.

Therefore, in order to eliminate the above-mentioned drawbacks, the present inventor used a vertical cylindrical container with a small opening at the top, immersed the F5 crystal in the raw material melt in the small opening, and fixed it therein to reduce the temperature gradient. The method and apparatus for growing a single crystal by moving it downward and solidifying it from one side and the apparatus therefor were published as Tokuya No. 63-322025.

(Problems to be Solved by the Invention) However, when assimilating the raw material melt, the volume of the 11 crystals expands. is added to the growing crystal, and as with the conventional VIS method and VGF method, this method has disadvantages such as causing defects inside the growing crystal.

Therefore, the present invention solves the above-mentioned drawbacks and makes it possible to easily grow high-quality single crystals even for volume-expanding 111 crystals without damaging the container or applying pressure to the growing crystals. The purpose of the present invention is to provide a single crystal growing method and apparatus that make it possible to do so.

(Means for Solving the Problems) The present invention provides (1) a qt crystal growth method in which a raw material melt in a vertical cylindrical container is solidified and grown from one end under a temperature gradient; The opening is sealed, the raw material is introduced through the small opening at the top, the entire container is heated to a temperature higher than the melting point of the raw material to melt the raw material, and the surface of the raw material melt is kept within the small opening. A temperature gradient is formed so that the temperature of the raw material melt inside the opening is approximately at the melting point of the raw material, and the temperature below that is ij'5 Q below the melting point. After the upper small opening is sealed with the growing crystal, the lower small opening is unplugged to allow excess raw material melt to flow out, and the temperature gradient is adjusted to 1 + -, -.
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(2) A single crystal growth apparatus in which a WC-type cylindrical container containing a raw material melt is placed in a vertical temperature gradient furnace, and the single crystal is solidified and grown from one end, in which the negative part of the container is formed into a substantially conical shape. A neck is formed at the tip with a small opening for the seed, and a charge receiving part for the raw material is connected through the neck, and the excess raw material is melted at the bottom of the container. A vertical or cylindrical container is formed by providing a small opening through which the liquid flows out, and a single axis for supporting a seed crystal is provided for soaking and seeding a seed crystal in the raw material melt at the neck, and for receiving the raw material melt flowing out. receiving m
t is attached to the tip of the lower shaft, a stopper is attached to the center of the receiver 1m for sealing the small opening 1'l at the bottom, and means is provided for moving the temperature gradient downward. j11100 breeding device.

(Function) FIG. 1 is an explanatory diagram of a specific example of an apparatus for carrying out the single crystal growth method of the present invention.
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(h) is a diagram showing a state in which raw materials are melted and seeded, and (c) is a diagram showing a state in which the raw material is melted and seeded, and (c) is a diagram showing a state in which a part of the small opening of the container is sealed by the growing crystal, and a lower small opening is closed. (d) shows the state in which the growing crystal has grown up to the straight body of the container. and,
Figure 2 is a temperature distribution diagram at the center of the furnace, drawn to match the position (1'L) in the vertical axis direction of Figure 1(d).

In the present invention, small crystals are formed along the white walls of a vertical cylindrical container. The container has a receiving part 1 for charging a solid raw material 20 into the container, a hanging part 2 provided with a small opening for engraving, and a substantially conical part 3 for forming an X1 part in the growing crystal. , 11° [It is equipped with a body portion 4, a tail portion 5, and a lower booth opening 6 that allows the raw material melt to flow out. The material of the container is ceramics such as AIN, AItO+, SiC, TiC, magnesia, BN, pnN, Mo,
II, heat-resistant metal such as Ta, carbon, quartz, or
You can choose from among these combinations. In addition, in the 11th class 1, the container is fixed to the chamber 18 using the support 23, but it is fixed to another shaft and the container is fixed to the chamber 18 using the support 23.
It is also possible to set the performance to 11J with 4 drops.

On the other hand, below the container, a receiver 1+1113 for receiving the flowing raw material melt 16 is attached to the tip of the lower shaft II and rearranged, and the receiver IIn! A stopper 12 is provided in the center of the container for sealing the lower opening (6).On the other hand, a seed crystal 15 is supported by the axis IO in the container's neck 2. Seeding is possible by dipping it into the raw material melt 14. Heaters 7.8.9 for forming a t! degree gradient are placed around the container, and a seeding monitor is placed above. A viewing window 19 is attached, and the entire body is housed in a chamber 18.

Next, the order of operations F in the present invention will be explained. First, Figure 1 (a
), insert the small opening rl 6 at the bottom of the vertical cylindrical container into the lower shaft 1.
The solid raw material 20 is filled in a sealed state with the stopper 4 attached to 1, and then the heater 7.8.9 is energized to form a temperature gradient as indicated by the 20th dotted line (■) to melt the solid raw material. ,
As shown by the arrow pointing from the dotted line ■ to the solid line ■ in FIG. 2, the temperature gradient is moved downward while maintaining the temperature gradient, and the temperature of the raw material melt I4 in the neck 2 is maintained at approximately the melting point. , as shown in FIG. 1(b), the seed crystal 1 is
5 is immersed in the raw material melt 14 and seeded while being monitored through the viewing window 19. In this way, seeding in a small opening allows easy crystallization because the raw material melt surface is small, and seeding can suppress crystal defects that sometimes occur. Further, since the seeding situation can be monitored through the viewing window 19, seeding can be easily performed without causing loss of FfI crystals. At the stage where the growing crystal 22 fills the inside of the neck 2 and the small opening of the jaw is sealed, the lower shaft 11
lower the container, remove the small open roller stopper 12 at the bottom of the container,
” While moving the temperature gradient downward, as shown in Figure 1(d)
As shown in the figure, small crystals 22 are grown, and the excess 16 of the raw material melt 2I in the container flows out from the small opening 6 at the bottom of the container into the saucer 13 attached to the lower shaft 11 and is ff1T. At this time, the raw material melt l is heated from the surroundings, so the surroundings become hotter and the solid-liquid interface 10 can be maintained in a downwardly convex state as shown in FIG. 1(d). Various crystal defects that are likely to occur can be eliminated.

In the apparatus shown in FIG. 1, the temperature gradient in the second part is moved by controlling the output of the heater 7.8.9. It is also possible to grow the vocabulary while keeping it fixed.

As described above, the present invention is based on the previously proposed patent application No. 63-32.
Compared to the method of No. 2025, excess raw material melt can be flowed out from the small opening at the bottom of the vertical cylindrical container during the refined product growth process, so even if the raw material melt solidifies and expands in volume, The orientation of the seed crystal can be reliably controlled without damaging the container by applying pressure, and without applying pressure to the growing crystal and causing defects inside the crystal. It is now possible to produce high-quality I1111 parts with a desired shape.

(Example) Ga As 711 seeds were grown using the apparatus d shown in FIG. For vertical cylindrical containers, the inner diameter of the cylindrical part is 50 mm,
Direct torso? =': r size 100111ffi, conical 1
One part has a 16 degree taper of 45", and one part has a small opening with an inner diameter of 8".
mm, i ¥ of the lower small opening is 1 mm, the same length is 5 mm,
A 2g volume was made of pBN-coated carbon with a PI of 5w+a+ for the wall of the container, and was divided into upper and lower halves at the n' (body) to form a 2-g capacity that could be removed by i'(i').

In the chanting container, GaAs polycrystalline product 1 crystal 0g and 11,0
.

100g';:: Immersion L, 18at in the chamber
m of argon gas. Next, the temperature distribution across the furnace width was adjusted using a vertical temperature gradient force so that the temperature gradient near the solid-liquid interface was approximately 10° C./cm. The raw material is melted in a high temperature region, and then moved down the temperature gradient to lower the surface temperature of the raw material melt in the upper small opening to 1240 to 1245 °C, and the seed crystal is immersed in the raw material melt. I sowed the seeds. Since the weighing process could be monitored through a viewing window, it was extremely convenient and reliable. After the upper small opening was sealed with crystals, the lower phase was lowered and the stopper of the lower small opening was removed, and the temperature gradient was gradually moved downward to grow 11 crystals. During this time, excess raw material melt was flowed out through the small opening at the bottom.

In this way, GaAsf11 crystals could be grown with good reproducibility, and cut out from the single crystal]1゛[diameter 2
The average IEP D within the inch wafer surface is 2000 degrees or more, the specific resistance is 5XIO'Ωcm, and the mobility is 5200cm'.
I was able to crystallize a high quality G a As fi1 product.

(Effects of the Invention) The present invention prevents melting and polycrystalization of seed crystals by adopting the structure described in 2.
: Also, even for raw materials that expand when the raw material melt solidifies, seeding can be done in a timely manner without damaging the container and without applying pressure from the raw material melt to the growing crystal. It also suppresses the occurrence of crystal defects during solidification growth, making it possible to grow high-quality moon crystals with a uniform diameter in the straight body.

4.1×1 side I! 'I Ill Explanation 1st [χ1(a
) to ((1) is a conceptual diagram of a device for growing 11 products, which is a specific example of the present invention, and FIG. It is an explanatory diagram showing one example.

Claims (2)

[Claims] (1) In a method for growing a single crystal in which a raw material melt in a vertical cylindrical container is solidified and grown from one end under a temperature gradient, the small opening at the bottom of the vertical cylindrical container is sealed, the raw material is introduced through the small opening at the top, The entire container is heated to a temperature higher than the melting point of the raw material to melt the raw material, the surface of the raw material melt is maintained within the small opening at the top, and the temperature of the raw material melt within the small upper opening is approximately equal to and lower than the melting point of the raw material. A temperature gradient is created that makes the lower part higher than the melting point, and then the seed crystal is immersed in the raw material melt in the upper small opening for seeding.After the upper small opening is sealed with the growing crystal, the stopper in the lower small opening is removed. A method for growing a single crystal, characterized in that the excess raw material melt is allowed to flow out, and the single crystal is solidified and grown from above by moving the temperature gradient downward. (2) In a single crystal growth apparatus in which a vertical cylindrical container containing a raw material melt is placed in a vertical temperature gradient furnace and solidified and grown from one end, the upper part of the container is a substantially conical part, and the tip of the container is solidified and grown from one end. A vertical cylindrical container is formed with a neck portion having a small opening for seeding, a receiving portion for charging raw material is connected through the neck portion, and a small opening is provided at the bottom of the container to allow excess raw material melt to flow out. comprising an upper shaft for supporting a seed crystal for dipping and seeding a seed crystal in the raw material melt in the neck, a receiving tray for receiving the flowing raw material melt at the tip of the lower shaft, and a receiving tray. 1. A single-crystal growth device, comprising: a stopper for sealing a small opening at the bottom in the center thereof; and means for moving the temperature gradient downward.