KR20060095268A - Growing method of high-quality sic single crystal with low defects - Google Patents

Abstract

The present invention relates to a method for growing high quality silicon carbide single crystals using the internal structure of a crucible used for growing silicon carbide single crystals, and its purpose is to minimize stress in radial direction by using a temperature control pipe inside the crucible. It is to provide a method for suggesting a stable process to remove and grow high quality single crystals and a method for increasing production efficiency by growing uniform crystals. To this end, the present invention comprises the steps of supplying SiC raw material to the crucible; Placing and SiC seed; And growing a SiC single crystal on the seed by heating the raw material. In this case, a method relating to the internal structure and related functions of the crucible for SiC single crystal growth is proposed.

      Silicon Carbide, High Quality Monocrystalline, Temperature Controlled Pipe, Stress

Description

Growing method of high-quality SiC single crystal with low defects

1 to 2 are cross-sectional views each showing a crystal growth apparatus used in the present invention,

FIG. 3 is a plan view of a single crystal direction from a side view and a bottom view of mounting two or more temperature control pipes used in the present invention around the seed and on the inner surface of the crucible,

4 is a side view of a crucible generally used,

Figure 5 (a) is a plan view and a temperature gradient graph determined in the radial direction when using two or more temperature control pipes proposed in the present invention,

Figure 5 (b) is a plan view and a temperature gradient graph determined in the radial direction seen in a typical crucible structure.

<Symbol Representation in Drawing>

10: crucible 11: crucible lid

12: insulation 13: induction coil

14: single crystal seed 30: seed bonding portion

31: temperature controlled pipe 32: silicon carbide single crystal

33: silicon carbide raw material

The present invention relates to silicon carbide crystal growth, and more particularly, to a method for growing high quality SiC single crystal with few defects.

As next-generation semiconductor device materials, broadband semiconductor materials such as SiC, GaN, AIN, and ZnO are expected to be promising. However, among these broadband semiconductor materials, only SiC single crystal material can be produced as a single-crystal ingot growth technology and can be produced as a large diameter substrate having a diameter of 2 inches or more.

In particular, SiC has excellent thermal stability at 1500 ° C or lower, excellent stability in an oxidizing atmosphere, and has a large thermal conductivity of about 4.6W / cm ° C. It is expected to be much more useful than III-V compound semiconductors.

  Although SiC has a smaller electron mobility than silicon, its band gap is 2-3 times higher than that of silicon, so the operating limit temperature is 650 ° C, and thus the operating limit temperature is much higher than that of Si having an operating limit temperature of 200 ° C or less. . It is also chemically and mechanically strong, making it possible to fabricate devices that can be used in extreme environments.

The performance limitations of the device due to the intrinsic physical properties of these materials can be easily compared by comparing various surface coefficients such as JFOM, KFOM, BFOM and BHFFOM. For example, JFOM, which shows the advantages of high frequency and high power applications, is a comparative coefficient derived from the breakdown voltage and the saturation electron moving speed of the transistor's power and frequency limits, and SiC is 600 times higher than that of Si.

As the device using SiC having such excellent physical properties is announced differently every day, the scope of application of SiC and its ripple effect are widening at a very high speed.

For example, SiC is a high temperature integrated circuit, a radiation resistant device, a III-V-IV-VI associated device, an ultra-precision MEMS device, an X-ray mask, an ultraviolet (UV) detector, a blue light emitting device (such as an automobile or aerospace). LED) and the like.

Such applications require large diameter silicon carbide single crystal wafers and high quality wafers with few defects. High-quality wafers with few defects generally refer to a small number of micropipes and dislocations per unit area in silicon carbide single crystals. These defects are related to stresses generated during crystal growth, and these stresses are generated radially. It is related to the temperature gradient that occurs.

Therefore, the silicon carbide single crystal is grown using a sealed graphite crucible. In general, the induction heating method of direct heating of the crucible or the resistance heating method of indirect heating type has a disadvantage in that the temperature difference between the walls of the crucible and the center of the crucible is very large. see. This temperature difference (temperature gradient) becomes larger as the diameter of the silicon carbide single crystal to be grown increases.

Therefore, the present invention proposes a method of growing a single crystal by mounting two or more temperature controlled pipes between the crucible wall and the grown silicon carbide single crystal to reduce the large temperature gradient in the radial direction, which is critical for defect formation, thereby reducing the defects of high quality SiC. A single crystal growth method is proposed.

The present invention proposes a method of growing a single crystal by mounting two or more temperature controlled pipes between a crucible wall and a growing silicon carbide single crystal to reduce the large temperature gradient difference in the radial direction, which is critical for defect formation, thereby reducing the defects of high quality SiC single crystal. Provide a way to grow.

Another object of the present invention is to provide a method that can be applied to a mass production and a large-diameter SiC wafer manufacturing method.

In order to achieve the object as described above, the present invention comprises the steps of supplying a SiC raw material to the crucible; Placing a plurality of SiC seeds; And growing a SiC single crystal on the seed by heating the raw material.

According to the present invention, the SiC single crystal may have a SiC single crystal seed of 8 inches or less.

The seed is preferably a single crystal having any one of a hexagonal structure, a cubic structure and a rhombohedral structure.

The face of the seed from which single crystal growth starts when the seed has a hexagonal structure has an orientation of any one of 0001, 1100, 1120, and 0338, and the face of the seed from which the single crystal growth starts when the seed has a cubic structure is 100, 110. , And 111 may have an orientation of any one of 100, 110, and 111, wherein the face of the seed in which the single crystal growth starts when the seed is a lambohydral structure.

It is preferable that the seed is plate-like, such as square, semicircle, and round.

SiC single crystals can be grown by either sublimation or chemical vapor deposition (CVD).

When the SiC single crystal is grown by the sublimation method, the seed may be disposed on the top of the crucible including the inner surface of the crucible or on the bottom surface of the crucible.

When SiC single crystals are grown by chemical vapor deposition, the seeds can be placed on all inner surfaces, including the top, bottom and sides of the crucible.

In the step of growing the SiC single crystal, the temperature of the seed portion where the SiC single crystal is grown is preferably 1700-2400 ° C, and the temperature of the raw material part is preferably 1800-2500 ° C.

In the present invention, the SiC single crystal is grown by sublimation or chemical vapor deposition (CVD), and the source material and apparatus used as the SiC raw material are appropriately changed according to each method.

For example, when growing SiC single crystals by sublimation, SiC powder can be used as a raw material, and when CVD is used, a hydrocarbon gas such as C3H8 or C2H4 can be supplied with a transport gas such as He or H2 as a carbon source. As a silicon source, a gas such as SiH4 may be supplied together with a transport gas such as He.

The SiC single crystal system of the present invention includes a crucible. Crucibles are generally cylindrical, but need not necessarily be cylindrical, but may be manufactured in other shapes. In particular, using two or more temperature-controlled pipes can control the number of pipes used and the thickness of the pipes according to the diameter to be grown.

The crucible and the temperature controlled pipe mounted inside the crucible are made of a material having a melting point higher than the sublimation temperature of SiC, and may be made of, for example, graphite or a high temperature resistant metal and a metal compound. Related materials include Ta, Hf, Nb, Zr, W, V metals and metal carbides or metal nitrides, in particular Ta, Hf, Nb, Zr, W, V, and carbides formed by a mixture of two or more of them, carbon, Ta, Hf, Nb, Zr, W, V, among which there are nitrides of two or more mixtures and nitrogen.

The final diameter of a single grown SiC single crystal can be grown up to 8 inches. The seed can be produced in a plate shape as SiC seed crystals in which single crystal growth starts. Such seeds use SiC single crystals having any one of a hexagonal (6H, 4H, 2H) structure, a cubic (3C) structure, and a rhombohedral (15R) structure. If the seed has a hexagonal structure, the seed face on which single crystal growth begins has an orientation of 0001, 1100, 1120, and 0338. When the seed has a cubic structure, The orientation of any one of 100, 110, and 111, and when the seed is a lombohydral structure, the surface of the seed from which single crystal growth starts has the orientation of any of 100, 110, and 111.

Insulation may be installed to surround the periphery of the crucible.

The top and bottom of the crucible may be installed with a device for measuring the temperature.

For example, around a cylindrical crucible, a donut-shaped insulator may surround the crucible with several layers having the same central axis as the crucible, in which case the bottom surface and the center of the cover surface of the crucible are exposed without enclosing the insulator. This exposed portion allows the temperature of the bottom and cover of the crucible to be measured.

The SiC single crystal growth system of the present invention includes a heater that heats the crucible to form a temperature gradient.

The present invention proposes a method of growing a single crystal by mounting two or more temperature controlled pipes between a crucible wall and a growing silicon carbide single crystal to reduce the large temperature gradient difference in the radial direction, which is critical for defect formation, thereby reducing the defects of high quality SiC single crystal. Provide a way to grow.

Another object of the present invention is to provide a method that can be applied to a mass production and a large-diameter SiC wafer manufacturing method.

Claims (5)

Supplying SiC raw materials to the crucible; Placing a SiC seed; And Heating the raw material to grow a SiC single crystal on the seed SiC single crystal growth method comprising a. The method of claim 1, How to use a pipe to control the temperature gradient in the crucible in the radial direction The method of claim 1, How to use more than one temperature controlled pipe The method of claim 3, wherein The method grows by applying a seed having any one of a hexagonal (6H, 4H, 2H) structure, a cubic (3C) structure, a rhombohedral (15R) structure having a diameter of 8 inches or less. Way The method of claim 4, wherein The face of the seed from which the single crystal growth starts when the seed has a hexagonal structure has any one of 0001, 1100, 1120, and 0338, and the face of the seed from which the single crystal growth starts when the seed has a cubic structure The SiC single crystal growth method having any one of 100, 110, and 111, and the face of the seed having the orientation of the single crystal growth when the seed has a lombohydral structure has one of 100, 110, and 111.

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