JPH0558774A - Vessel for silicone carbide single crystal growing device - Google Patents

Abstract

PURPOSE:To uniformly and stably sublime on SiC powder in a crucible in an SiC single crystal growing method making SiC seed crystal grow to obtain an ingot of SiC single crystal by subliming the SiC powder or an SiC granule prepared in the crucible, upper side of which the seed crystal is provided. CONSTITUTION:The bar-shaped graphite 6 is arranged on the bottom 1a of the crucible made from graphite by integrally forming with the crucible 1 or by fixed with screw or calking on the crucible 1. The raw material such as the SiC powder or an SiC granule is added into the crucible 1 and the cover 3 fixed the SiC seed crystal is placed on the opening part 105 of the crucible 1 and argon gas atmosphere is made in the crucible. After that, by heating the crucible 1 and the bar-shaped graphite with the high-frequency induction heating coil provided around the crucible 1, the raw material is sublimed and the SiC seed crystal is grown to form the ingot of the SiC single crystal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a container used in a silicon carbide single crystal growth apparatus used in electronic devices.

[0002]

2. Description of the Related Art Silicon carbide (SiC) is a semiconductor that is physically and chemically stable and has a wide band gap. Therefore, it has attracted attention as a material for environment-resistant semiconductor elements and short wavelength light emitting diodes. ..

For SiC, 3C type, 4H type, 6H type, 1
There are various crystal forms such as 5R form. Of these, 3C type Si
C is considered to be used as an active element that operates in a high temperature environment or a radiation environment. Further, 6H-type SiC has a band gap of about 2.9 eV and is used as a blue light emitting element. Since 4H-type SiC has a bandgap of about 3.2 eV, which is wider than that of 6H-type SiC, it is considered to be used for a blue to violet light emitting diode and other heterojunction devices with crystalline SiC.

As a method of growing a single crystal for a SiC substrate,
Sublimation method utilizing decomposition / sublimation of SiC raw material, or Si
There is an Acheson method for synthesizing a compound and a C compound at high temperature.
However, since the Acheson method is difficult to control the impurities and the crystal size, the sublimation method is often used.

As this sublimation method, for example, Appl. P
hys. Lett. 58 (1), 7 January 1
Pp. 56-58 of 991, "Con
trolled suspension growt
h of single crystal line 4H
-SiC and 6H-SiC and ident
indication of polytypes by
X-ray diffraction "in FIG. Four
Some use the crucible structure shown in. FIG. 5 shows a sectional view of this crucible.

A method of growing a SiC single crystal using the crucible will be described below.

Reference numeral 101 is a crucible made of graphite, and a raw material 102 in the form of SiC powder or granules is prepared in the crucible 101. Reference numeral 3 is a lid made of graphite for mounting and fixing the SiC seed crystal 4 on the inner lower surface, and is placed (disposed) on the opening 105 of the crucible 101.

The inside of the crucible 101 is about 10T.
It is heated to about 2350 ° C. by high frequency induction in an Ar gas atmosphere of about orr. Therefore, the raw material 102 in the crucible 101 is decomposed and sublimated by heat conduction and heat radiation from the crucible 101, fixed on the inner lower surface of the lid 3, and fixed again on the surface of the SiC seed crystal 4 at about 2250 ° C. The SiC single crystal grows by crystallization.

[0009]

Since the crucible 101 having the above-mentioned structure usually has a temperature distribution as shown in FIG. 6 (b), heat conduction and heat radiation from the crucible 101 cause As shown in FIG. 6A, the region where the raw material 102 is sublimated by heating gradually increases from the raw material 102a near the bottom of the crucible 101 and the raw material 102b near the side wall of the crucible 101 to the raw material 10 at the center.
It gradually spreads to 2c.

However, with the expansion of the sublimation region, the raw material 10 near the bottom of the crucible 101 that initially sublimated comes into contact with the raw material 10.
2a and raw material 10 near the crucible 101 surrounding side wall
Since 2b first changes to soot-like powder that is a heat insulating material, heat conduction and heat radiation to the raw material 102c in the central portion are rapidly reduced, and sublimation of the raw material 102c in the central portion is rapidly reduced. Or it will not happen again. As a result, since the growth rate of the SiC single crystal becomes unstable, there is a problem that a good quality SiC single crystal cannot be obtained.

Accordingly, the present invention provides a container for a crystal growth apparatus capable of forming a SiC single crystal at a stable growth rate.

[0012]

A silicon carbide single crystal growth apparatus according to the present invention comprises a crucible for containing raw materials and a lid for mounting and fixing a seed crystal on an inner lower surface and disposing the seed crystal in an upper opening of the crucible. In a container for a silicon carbide single crystal growth device,
The heat conductors are symmetrically installed in the crucible. In particular, the heat conductor is installed on the bottom surface of the crucible.

[0013]

When the heat conductors are symmetrically installed in the crucible as described above, heat is conducted to the center of the raw material by the heat conductor, so that the raw material near the inner wall of the crucible is sublimated and at the same time the raw material in the central portion is located. Also sublimates. Therefore, the sublimation of the central portion of the raw material does not suddenly become unstable or does not occur, so that the growth rate of the SiC single crystal becomes stable and a good quality SiC single crystal can be obtained.

In particular, it is more desirable to dispose the heat conductor at the center of the bottom of the crucible because the heat conduction to the raw material becomes more uniform.

[0015]

Embodiments of the present invention will be described in detail with reference to the drawings. The same parts as those in the conventional example are designated by the same reference numerals and the description thereof will be omitted.

FIG. 1 is a sectional view of a container for a SiC single crystal growth apparatus according to the first embodiment of the present invention.

Reference numeral 1 is made of graphite, for example, has an inner diameter of 40.
mm crucible with a depth of 50 mm. At the center of the bottom surface 1a of the crucible 1, a rod-shaped heat conductor 6 made of graphite and having a height of 30 mm and a diameter of about 10 mm is integrally molded,
Alternatively, the crucible 1 and the heat conductor 6 are fixedly installed by screwing or caulking. Therefore, the heat conductors 6 are symmetrically located in the crucible. A raw material 2 of SiC powder or SiC granules is prepared in the crucible 1.

Further, a container 8 for a SiC single crystal growth apparatus comprising the crucible 1, the lid 3 and the heat conductor 6 is arranged in a reaction tube (not shown) for introducing Ar gas or the like, and is provided around it for high frequency induction heating. The coil is wound.

Next, the SiC seed crystal 4 has a crystal form of 6H.
Using SiC, a SiC single crystal was prepared in the container 8 for a SiC single crystal growth apparatus as in the conventional example.

That is, the inside of the crucible is about 10 Torr.
In a state of Ar gas atmosphere of about 10 ° C., the crucible 1 is heated to about 2350 ° C. by high frequency induction, the raw material 2 in the crucible 1 is decomposed and sublimated by heat conduction and heat radiation from the crucible 1, and the lid 3 Installed and fixed on the inner bottom surface of the
S is recrystallized on the surface of the SiC seed crystal 4 at about 0 ° C.
Grow an iC single crystal.

In this case, a good quality 6H-SiC single crystal having fewer defects than the conventional one was obtained. This is about 10 mm from the crucible peripheral side wall 1b among the raw materials 2 in the crucible 1,
Further, the raw material 2 located within about 15 mm from the bottom surface 1a of the crucible sublimes sufficiently stably by heat conduction and heat radiation from the crucible 1, and the raw material 2 at the center is a heat which is located symmetrically with respect to the inside of the crucible. This is because the heat conduction from the conductor 6 causes the raw material 2 to be sublimated in a stable manner over about 5 mm around the heat conductor 6, so that the raw material 2 is uniformly and stably sublimated.

FIG. 2 is a sectional view of a container for a SiC single crystal growth apparatus according to the second embodiment of the present invention.

Reference numeral 11 is made of graphite, for example, has an inner diameter of 4
It is a crucible with a depth of 0 mm and a depth of 50 mm. Crucible 11
At the center of the bottom surface 11a of the heat conductor 16, for example, a heat conductor 16 is provided which is provided with an inverted conical plate of graphite having a height of 30 mm and a diameter of about 10 mm and having a thickness of 3 to 5 mm formed of graphite around the rod. It is fixedly installed at the etc. Therefore, the heat conductors 16 are symmetrically positioned in the crucible.

Next, S consisting of the crucible 11 and the lid 3 and the like.
Using the container 18 for the iC single crystal growth apparatus, a 6H—SiC single crystal was prepared in the same manner as in the first embodiment. In this case, in addition to the rod made of graphite, heat is conducted not only from the inverted conical plate made of graphite, but the sublimation of the raw material 2 which is more uniform and stable as compared with the first embodiment is performed. As a result, a good quality 6H-SiC single crystal with fewer defects can be obtained as compared with the conventional example and the first example, and the crucible inner diameter can be increased.

FIG. 3 is a sectional view of a container for a SiC single crystal growth apparatus according to a third embodiment of the present invention, which is different from the first and second embodiments only in the shape of the heat conductor.

At the center of the bottom surface 21a of the crucible 21, a heat conductor 26 having a spiral plate made of graphite and having a thickness of 3 to 5 mm provided around a rod having a height of 30 mm and a diameter of about 10 mm is screwed at the center. It is fixedly installed by a built-in type or caulking. Therefore, the heat conductor 26
It will be located symmetrically within the crucible.

Next, S consisting of the crucible 21 and the lid 3 and the like.
Using the container 28 for the iC single crystal growth apparatus, a 6H-SiC single crystal was prepared in the same manner as in the first embodiment. In this case as well, the same effect as in the second embodiment is obtained, a good quality 6H-SiC single crystal with fewer defects is obtained compared to the conventional example and the first embodiment, and the crucible can be enlarged.

As described above, when the heat conductors are installed symmetrically in the crucible, among the raw materials in the crucible, the raw materials in the vicinity of the peripheral side wall of the crucible and in the vicinity of the bottom surface of the crucible can conduct heat conduction and heat radiation from the crucible body. Is sufficiently stable to sublimate, and the raw material in the center of the raw material is sublimated by uniformly heating the region around the heat conductor by heat conduction and heat radiation from the heat conductor. Since it sublimates uniformly and stably over the entire area, it is a high-quality SiC with few defects.
A single crystal is obtained.

In the above embodiment, the heat conductor is installed on the bottom surface of the crucible, but it is also effective to install the heat conductor symmetrically with respect to the inside of the crucible in other parts of the crucible. For example, as shown in FIG. The heat conductor 36 may be symmetrically fixedly installed in the crucible 31 as shown in the top view of FIG. Further, the heat conductor may be formed in various shapes such as a plate shape, a prismatic shape, a conical shape, etc. other than the above-mentioned embodiment.

Further, the heat conductor of the above-mentioned embodiment is constructed so as to have substantially the same height as the raw material prepared in the crucible, but it is effective even if appropriately changed. However, it is more preferable that the heat conductor is higher than the prepared raw material because the heat conduction can be more uniform.

Although a pure SiC single crystal was prepared in the above-mentioned embodiment, p and n type SiC single crystals with few defects can also be prepared by adding impurities such as Al and N ₂ .

Further, in the above embodiment, 6H-SiC single crystal was prepared by using 6H-SiC as a seed crystal, but other crystal form SiC having few defects by temperature control or addition of impurities.
Single crystals can also be created.

Further, the term "symmetrically installing the heat conductors in the crucible" according to the present invention includes the one in which the heat conductors are installed substantially symmetrically in the crucible.

[0034]

According to the present invention, when the heat conductors are symmetrically installed in the crucible, among the raw materials in the crucible, the raw materials in the vicinity of the peripheral side wall of the crucible and in the vicinity of the bottom surface of the crucible are heat conductive from the crucible body, Substantially stable by heat radiation,
Moreover, since the raw material in the center of the raw material is also sublimated stably by heat conduction from the heat conductor, the raw material is sublimated uniformly and stably, so that a good quality SiC single crystal with few defects can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a cross section of a container used in a crystal growth apparatus of a first embodiment according to the present invention.

FIG. 2 is a cross-sectional view showing a cross section of a container used in a crystal growth apparatus of a second embodiment according to the present invention.

FIG. 3 is a cross-sectional view showing a cross section of a container used in a crystal growth apparatus of a third embodiment according to the present invention.

FIG. 4 is a top view of a container used in a crystal growth apparatus of another embodiment according to the present invention.

FIG. 5 is a cross-sectional view showing a cross section of a container used in a conventional crystal growth apparatus.

FIG. 6 is a diagram showing a temperature distribution of the container and a state of raw materials.

[Explanation of symbols]

 1 crucible 1a crucible bottom 1b crucible peripheral side wall 11 crucible 11a crucible bottom 21 crucible 21a crucible bottom 31 crucible 2 raw material 3 lid 4 SiC seed crystal 6 heat conductor 16 heat conductor 26 heat conductor 36 heat conductor 8 single crystal growth device Container 18 single crystal growth apparatus container 28 single crystal growth apparatus container 105 opening

Claims (2)

[Claims] 1. A container for a silicon carbide single crystal growth apparatus comprising a crucible for containing raw materials, and a lid for mounting and fixing a seed crystal on an inner lower surface thereof, the lid being provided in an upper opening of the crucible,
A container for a silicon carbide single crystal growth apparatus, wherein heat conductors are symmetrically installed in the crucible. 2. The container for a silicon carbide single crystal growth apparatus according to claim 1, wherein the heat conductor is installed at the center of the bottom surface of the crucible.