JPH031485Y2 - - 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) Conventional technology SiC (silicon carbide) is physically
Due to its chemical properties, it is attracting attention as a material for environmentally resistant semiconductor devices. It also has many crystal forms with the same composition, and its energy gap varies from 2.4eV (3C type) to 3.0eV (6H type). Therefore, 6H type SiC single crystal is also being put into practical use as a material for blue light emitting diodes.

Figure 3 is from Journal of Crystal Growth52 (1981)
Yu.M.TAIROV and VF published in 146−150
TSVETKOV's paper "DENERAL PRINCIPLE"
OF GROWING LARGE−SIZE, SINGLE
CRYSTALS OF VARIOUS SILICON
1 is a crucible made of graphite, 2 is a SiC raw material stored in the crucible, and 3 is a device of this kind disclosed in "CARBID POLYTYPES".
is a SiC seed crystal placed so as to close the upper opening of the crucible 1.

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 grow a large area. The area around the single crystal that grows under the influence of the sidewalls becomes polycrystalline.

In view of this, an apparatus capable of producing a single crystal without being affected by the crucible side wall was proposed in Utility Model Application No. 59-22015.

(c) Problems to be solved by the invention However, in the device proposed in Utility Application No. 59-22015, there is a problem that the growth rate is slow because the heated and sublimated SiC raw material is not directed toward the seed crystal efficiently.

In addition, SiC raw materials are generally Si ₂ C, SiC ₂ , Si,
It is sublimated as gases such as Si ₂ , among which Si,
Si ₂ gas does not contribute to SiC. Moreover, since Si gas has a higher vapor pressure than other gases, it occupies most of the sublimated gas. Therefore, the small proportion of the gas that contributes to growth among the sublimated gases is also a factor in slowing down the growth rate.

(d) Means for solving the problems The present invention has been made in view of the above, and aims to provide a crystal growth apparatus that can efficiently guide heated and sublimated SiC raw materials toward the seed crystal direction. This device is characterized by a device for sublimating the raw material in the crucible to grow a desired crystal on the seed crystal, and a control means for guiding the sublimated raw material only to the surface of the seed crystal. It's about being prepared.

(E) Effect When such a device is used, the heated and sublimated SiC raw material is concentrated on the seed crystal by the control means, and the sublimated Si gas or Si ₂ gas reacts with the carbon atoms of the control means. Si ₂ C gas, SiC ₂ gas,
Since the amount of gas that contributes to the growth of SiC increases, crystal growth can be performed efficiently.

(f) Example FIG. 1 shows an example of the present invention, 11 is a crucible in which a SiC raw material 12 is stored in the bottom,
The crucible is made of graphite. 13 is the above crucible 11
The lid is made of graphite and is arranged so as to close the opening on the top surface of the lid, and an opening is bored in the approximate center of the lid. Seed crystal 14 is arranged so as to face . Reference numeral 15 denotes a control means for directing the heated and sublimated raw material 12 in the direction of the seed crystal, and the control means includes a base 16 that vertically separates the inside of the crucible 11 into two chambers.
A small hole connecting the two chambers and a heated sublimated SiC raw material directed upward from the small hole are placed in the seed crystal 14.
It consists of a cylindrical portion 17 that is oriented in the direction. The control means 15 is made of graphite, and as is clear from FIG.
It is arranged so that it is located on the lower chamber side separated by.

The background vacuum of such equipment is 1×10 ^-2
Placed in a vacuum of ² Torr to 10 Torr, SiC seed crystal 14
By maintaining the SiC raw material 12 at 2000°C and 2400°C, the SiC raw material 12 is heated and sublimated, and the SiC single crystal 18 grows on the seed crystal 14. At this time, the SiC heated and sublimated by the control means 15
It is clear that since the raw material is efficiently directed onto the seed crystal 14, the crystal growth rate is higher than when the control means 15 is not present.

In addition, SiC raw materials are generally Si ₂ C, SiC ₂ , Si,
It is sublimated as gases such as Si ₂ , among which Si,
Si ₂ gas does not contribute to SiC growth. but,
In the device of this embodiment, the control means 15 is made of graphite C, so when the Si and Si ₂ gases come into contact with the control means 15, they react with and combine with the carbon atoms of the control means 15. The gas becomes Si ₂ C and SiC ₂ gas and is guided to the seed crystal 14 . Therefore, in the apparatus of this embodiment, the amount of Si ₂ C and SiC ₂ gases that contribute to the growth of SiC increases, so that the growth rate further increases.

FIG. 2 shows a second embodiment of the present invention, in which 21 is a crucible with an open top, and a SiC raw material 22 is stored in the bottom of the crucible. Reference numeral 23 denotes a control means disposed above the top surface of the crucible 21, and the control means has a diameter comparable to that of the top surface open portion on the surface in contact with the crucible 21, and A communication hole 24 having a small diameter is formed. Reference numeral 25 denotes a substrate holder disposed on the control means 23. The holder has a bottom surface open to communicate with the communication hole 24, and protrudes inward from the top surface so that its tip is connected to the control means 23. It has protrusions 26 that are adjacent to each other.

Further, a SiC seed crystal 27 is fixed to the tip of the convex portion 26 so that one main surface thereof faces the SiC raw material 22. In addition, the crucible 21, the control means 23,
Both substrate holders 25 are made of graphite.

This device is placed in a vacuum with a background vacuum of 1×10−2 ² Torr to 10 Torr like the device of the first embodiment, and the SiC seed crystal 27 is heated at 2000° C. to 2200° C.
When the SiC raw material 22 is held at 2400°C, the SiC raw material 22 is heated and sublimated in the same manner as in the first embodiment, and the sublimated raw material is transferred to the seed crystal 2 by the control means 23.
Furthermore, the Si and Si ₂ gases react with the carbon atoms of the control means 23 and the Si ₂ C and SiC ₂ gases increase, so that SiC is efficiently deposited on one main surface of the seed crystal 27. A single crystal grows.

(g) Effects By using the crystal growth apparatus of the present invention, all heated and sublimated raw materials are directed in the direction of the seed crystal, and
Since SiC ₂ and Si ₂ C gases that contribute to SiC crystal growth increase, efficient crystal growth can be performed and undesired crystal growth can be suppressed.

[Brief explanation of drawings]

1 and 2 are sectional views showing an embodiment of the present invention, and FIG. 3 is a sectional view showing a conventional example. 11, 21... Crucible, 12, 22... Raw material, 1
4, 27... Seed crystal, 15, 23... Control means.

Claims (1)

[Scope of utility model registration request] An apparatus for growing a desired SiC crystal on a seed crystal by sublimating a SiC raw material in a crucible, the apparatus comprising a control means made of graphite for guiding the sublimated raw material only to the surface of the seed crystal. A crystal growth device featuring: