JPH0442911Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to an apparatus used for growing single crystals, particularly SIC single crystals.

(b) Prior Art SIC (silicon carbide) is attracting attention as an environmentally resistant semiconductor element material due to its physical and chemical properties. It also has many crystal forms with the same composition, and its energy gap is 2.4ev (3c type)
~3.0ev (6H type). Therefore 6H
Type six single crystals are also being put into practical use as materials for blue light-emitting diodes.

Figure 1 is from Journal of Crystal Growth52 (1981)
Y uMTAIROV and VF published in 146-150
The paper “GENERAL” with TSVETKOV
PRINCIPLE OF GROWING LARGE−SIZE
SINGLE CRYSTALS OF VARIOUS
SILICONCARBID POLYTYPES'', in which 1 is a crucible made of graphite, 2 is a SIC raw material stored in the crucible, and 3 is placed so as to close the upper opening of the crucible 1. It is a SIC seed crystal.

In such an apparatus, by heating and sublimating the SIC raw material 2, a SIC single crystal 4 is grown on the surface of the seed crystal 3 facing the raw material 2. However,
When growing a SIC single crystal, the seed crystal 3 can only have a small area, and the horizontal spread of the growth is also restricted by the side walls of the crucible, making it difficult to increase the area. The area around the single crystal that grows under the influence of the side walls of the crucible becomes polycrystalline.

(c) Purpose of the invention The present invention has been made in view of these points, and provides a single crystal growth apparatus that can suppress the generation of polycrystals in the grown crystal and can increase the area of the growing single crystal. We aim to provide the following.

(d) Structure of the invention The structural features of the invention include a crucible in which a raw material is stored, a holding surface for holding a seed crystal, and the holding surface is a holding part disposed opposite to the raw material in the crucible. In the single crystal growth apparatus, which heats and sublimates the raw material to grow a crystal on the seed crystal, a holding surface of the seed crystal of the holding part has substantially the same shape as a crystal growth surface of the seed crystal. It is in.

(E) Embodiment FIG. 2 shows an embodiment of the present invention, and the difference from the conventional device shown in FIG. 1 lies in the holding portion 5 for the seed crystal 3. That is, the holding part 5 is composed of a base part 5a that closes the opening of the crucible 1 and a placing part 5b that hangs down from approximately the center of the base part 5a.
The seed crystal 3 is fixed on the surface 5c (hereinafter referred to as the holding surface) facing the . For such fixing, one side of the L-shaped members 6, 6 is brought into contact with the surface of the seed crystal 3, as shown in FIG.
This is done by fixing the other side to the side wall of the mounting portion 5b with screws 7, 7. Further, as is clear from FIG. 3, the planar shape of the holding surface 5c is substantially the same as that of the seed crystal 3. Furthermore, the holding portion 5, the L-shaped member 6,
6. Screws 7 and 7 are made of carbon. Note that the same parts in FIG. 2 as in FIG. 1 are denoted by the same numbers, and explanations thereof will be omitted.

In such an apparatus, the inner diameter of the crucible 1 can be made sufficiently large regardless of the size of the seed crystal 3, so that the horizontal spread of the single crystal, that is, the size of the seed crystal 3 can be increased.
The growth spreading toward the end with the peak is not restricted by the crucible 1, and there is no fear that polycrystals will grow due to the influence of the side walls of the crucible 1 during growth, and a large-area SIC single crystal can be obtained.

In the device of this embodiment, the holding surface 5c is connected to the seed crystal 3
The holding surface 5c has approximately the same shape as the seed crystal 3.
If the size is larger, a part of the holding surface 5c will be exposed, so SiC polycrystals will be deposited on this exposed part during growth, and this will cause the SiC polycrystals growing on the seed crystal 3 to
When it comes into contact with a single crystal, the contact area becomes polycrystalline,
This is because it is not possible to substantially widen the growth space of the SiC single crystal.

FIG. 4 shows another embodiment of the invention. In this embodiment, since the seed crystal 3 is fixed with an L-shaped member 6 made of carbon in the first embodiment, such L-shaped member 6 is fixed.
Since there is a risk that SIC crystals will grow on the surface of the character member 6 and that the crystals will become polycrystals, the method for fixing the seed crystal 3 to the holding surface 5c has been improved.

Specifically, first, an Si layer 8 (for example, a thin plate cut from a Si single crystal) and a seed crystal 3 are sequentially laminated on the holding surface 5c of the mounting portion 5b (FIG. 5A), and then heated at about 1500°C. By holding the si layer 8 for a long time, the si layer 8 melts.
Good conformability is achieved between the layer 8 and the holding surface 5c and between the Si layer 8 and the seed crystal 3. Then set the holding temperature
Made at 1800℃ or higher. When kept at such a temperature for a long time, c (carbon) and si in the si layer 8 form the mounting portion 5b.
(silicon) and becomes sic (Fig. 5B).
Such SIC conversion gradually progresses from the holding surface 5c side to the seed crystal 3 side, and eventually the entire SI layer 8 becomes a SIC single crystal, and the adhesion between the seed crystal 3 and the mounting portion 5b becomes strong. (Figure 5c).

When the seed crystal 3 is fixed to the holding surface 5c in this way, only a single crystal grows on the surface of the seed crystal 3 because no foreign matter (for example, the L-shaped member 6 in the first embodiment) is present on the surface of the seed crystal 3. , the danger of polycrystal growth is eliminated.

(f) Effects of the invention By using the device of the invention, the growth space can be made wider, so it is possible to prevent the growing single crystal from contacting the side wall of the crucible and crystallizing it. Since the shape is substantially the same as that of the crystal, it is possible to prevent the growing single crystal from coming into contact with the polycrystal deposited on the exposed portion of the holding surface and becoming polycrystalline. Therefore, according to the device of the present invention, a large-area single crystal without polycrystals can be obtained.

[Brief explanation of the drawing]

FIG. 1 shows a conventional example, FIG. 1 is a sectional view, and FIGS. 2 to 4 show embodiments of the present invention.
4 and 4 are cross-sectional views, and FIG. 3 is a perspective view. 1... Crucible, 2... Raw materials, 3... Seed crystal,
5... Holding part, 5c... Holding surface.

Claims (1)

[Scope of utility model registration request] comprising a crucible in which a raw material is stored, and a holding part having a holding surface for holding a seed crystal, the holding surface being disposed in the crucible to face the raw material,
A single crystal growth apparatus for heating and sublimating the raw material to grow a crystal on the seed crystal, characterized in that a holding surface of the seed crystal of the holding section has substantially the same shape as a crystal growth surface of the seed crystal. Single crystal growth equipment.