KR20120119363A - Apparatus for fabricating ingot - Google Patents

Abstract

PURPOSE: An ingot manufacturing apparatus is provided to minimize defect generation due to difference between a seed holder and a seed holder thermal expansion coefficient. CONSTITUTION: An ingot manufacturing apparatus includes a crucible(100) and a seed holder(170). The crucible accepts raw material(130). The seed holder fixes a seed(190) arranged on the raw material. A buffer layer(160) is formed in the seed holder. The buffer layer and the seed holder include material having the same thermal expansion coefficient.

Description

Ingot manufacturing equipment {APPARATUS FOR FABRICATING INGOT}

The present description relates to an ingot manufacturing apparatus.

In general, the importance of the material in the electrical, electronics industry and mechanical parts field is very high, which is an important factor in determining the characteristics and performance index of the actual final component.

SiC has excellent thermal stability and excellent oxidation resistance. In addition, SiC has an excellent thermal conductivity of about 4.6W / Cm ℃, has the advantage that can be produced as a large diameter substrate of 2 inches or more in diameter. In particular, SiC single crystal growth technology is most stably secured in reality, and industrial production technology is at the forefront as a substrate.

In the case of SiC, a method of growing silicon carbide single crystals by sublimation recrystallization using seed crystals has been proposed. The silicon carbide powder used as a raw material is accommodated in a crucible, and the silicon carbide single crystal which becomes a seed crystal is arrange | positioned on the upper part. By forming a temperature gradient between the raw material and the seed crystal, the raw material in the crucible is diffused to the seed crystal side and recrystallized to grow a single crystal.

In order to proceed with this process, the seed crystals in which the single crystals are grown are attached to a separate member such as a crucible lid, for example, and the seed crystals may have a great influence on the quality of the single crystals grown on the surface. Therefore, the seeding process is very important.

Due to the difference in thermal expansion coefficient and lattice mismatch between the seed crystal and the seed crystal holder, the seed crystal may desorb as the single crystal grows.

Embodiments can grow high quality single crystals.

Ingot manufacturing apparatus according to the embodiment, the crucible for receiving the raw material; And a seed crystal holder for fixing the seed crystal disposed on the raw material, wherein a buffer layer is formed on the seed crystal holder.

In the ingot manufacturing apparatus according to the embodiment, a buffer layer is formed on the seed crystal holder.

The buffer layer may include a material having a same thermal expansion coefficient as a seed crystal to be grown. Therefore, it is possible to minimize the occurrence of defects due to the difference in thermal expansion coefficient between the seed crystal holder and the seed crystal. In addition, it is possible to prevent the seed crystal from being detached during the single crystal growth process due to the thermal expansion coefficient difference.

During the high temperature process of growing a single crystal, a SiC _1-X layer is formed at an interface between the buffer layer and the seed crystal, which may minimize lattice mismatch in the buffer layer and the seed crystal. Thereby, seed crystal adhesion can be improved.

Subsequently, the buffer layer may include at least one grain boundary. The grain boundary can effectively disperse the stress generated as the seed crystal grows. As a result, it is possible to provide a large area high quality single crystal with few defects.

In addition, stability and recovery can be improved in large area single crystal growth.

1 is a cross-sectional view of an ingot manufacturing apparatus according to an embodiment.
FIG. 2 is an enlarged view of a portion A of FIG. 1.
3 is a perspective view of a seed crystal holder and a buffer layer according to an embodiment.
4 to 6 are cross-sectional views illustrating a manufacturing process of the seed crystal holder according to the embodiment.

In the description of embodiments, each layer, region, pattern, or structure may be “on” or “under” the substrate, each layer, region, pad, or pattern. Substrate formed in ”includes all formed directly or through another layer. Criteria for the top / bottom or bottom / bottom of each layer will be described with reference to the drawings.

The thickness or the size of each layer (film), region, pattern or structure in the drawings may be modified for clarity and convenience of explanation, and thus does not entirely reflect the actual size.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 to 5, the ingot manufacturing apparatus according to the embodiment will be described in detail. 1 is a cross-sectional view of an ingot manufacturing apparatus according to an embodiment. FIG. 2 is an enlarged view of a portion A of FIG. 1. 3 is a perspective view of a seed crystal holder and a buffer layer according to an embodiment. 4 to 6 are cross-sectional views illustrating a manufacturing process of the seed crystal holder according to the embodiment.

1 to 3, an ingot manufacturing apparatus according to an embodiment may include a crucible 100, an upper cover 140, a seed crystal holder 170, a buffer layer 160, a focusing tube 180, and a heat insulating material 200. ), A quartz tube 400 and a heat generating induction part 500.

The crucible 100 may accommodate the raw material 130. The raw material 130 may include silicon and carbon. More specifically, the raw material 130 may include a silicon carbide compound. The crucible 100 may contain silicon carbide powder (SiC powder) or polycarbosilane (polycarbosilane).

The crucible 100 may have a cylindrical shape to accommodate the raw material 130.

The crucible 100 may include a material having a melting point higher than the sublimation temperature of silicon carbide.

For example, the crucible 100 may be made of graphite.

In addition, the crucible 100 may be coated with a material having a melting point higher than the sublimation temperature of silicon carbide. Here, it is preferable to use a material chemically inert to silicon and hydrogen at the temperature at which the silicon carbide single crystal is grown as the material to be applied on the graphite material. For example, metal carbide or metal nitride may be used. In particular, a mixture comprising at least two or more of Ta, Hf, Nb, Zr, W and V and a carbide comprising carbon may be applied. In addition, a mixture comprising at least two or more of Ta, Hf, Nb, Zr, W and V and a nitride comprising nitrogen may be applied.

The upper cover 140 may be located on the top of the crucible 100. The upper cover 140 may seal the crucible 100. The upper cover 140 may be sealed to allow a reaction to occur in the crucible 100.

The upper cover 140 may include graphite. However, the embodiment is not limited thereto, and the upper cover 140 may include a material having a melting point higher than the sublimation temperature of silicon carbide.

The seed crystal holder 170 is positioned at the lower end of the upper cover 140. That is, the seed crystal holder 170 is disposed on the raw material 130.

The seed crystal holder 170 may fix the seed crystal 190. The seed crystal holder 170 may include high density graphite.

The buffer layer 160 may be formed in the seed crystal holder 170. In detail, the buffer layer 160 may be located between the seed crystal holder 170 and the seed crystal 190.

The buffer layer 160 may include a material having the same thermal expansion coefficient as that of the seed crystal 190 to be grown. In addition, the buffer layer 160 and the seed crystal 190 may include the same material. For example, during silicon carbide single crystal growth, the buffer layer 160 may include silicon carbide.

Therefore, it is possible to minimize the occurrence of defects due to the thermal expansion coefficient difference between the seed crystal holder 170 and the seed crystal 190. In addition, it is possible to prevent the seed crystal 190 from detaching during the single crystal growth process due to the thermal expansion coefficient difference.

Referring to FIG. 2, the buffer layer 160 may include at least one grain boundary 162. The grain boundary 162 may effectively disperse the stress generated as the seed crystal 190 grows. Thus, the buffer layer 160 may be a polycrystal including at least one crystal grain boundary 162.

As a result, it is possible to provide a large area high quality single crystal with few defects. In addition, stability and recovery can be improved in large area single crystal growth.

The buffer layer 160 may be formed through a polycrystalline growth process.

4 to 6, after loading the raw material 130 and the seed crystal holder 170 in the crucible 100, the buffer layer 160 may be grown. Specifically, after charging the silicon carbide powder 130 and the seed crystal holder 170 in the crucible 100, it can be grown for 1 to 2 hours at a temperature of about 2300 ℃ and a pressure of 15 mbar. .

Referring to FIG. 5, the silicon carbide powder 130 may be sublimed to grow the buffer layer 160 on the surface of the seed crystal holder 170. That is, silicon carbide polycrystals may grow on the surface of the seed crystal holder 170. When the seed crystal holder 170 includes graphite, silicon carbide particles may grow in the seed crystal holder 170 such that the seed crystal holder 170 and the buffer layer 160 may have a high bonding force.

Referring to FIG. 6, a polishing process may be performed to secure a uniform surface of the buffer layer 160.

After the polishing process, the seed crystal 190 may be attached to the buffer layer 160 using an adhesive.

During the high temperature process of growing the single crystal from the seed crystal 190, a SiC _{1 -X} layer is formed at the interface between the buffer layer 160 and the seed crystal 190, which is the buffer layer 160 and the seed crystal ( 190 The grid mismatch can be minimized. In addition, the buffer layer 160 may have a very small particles and thus may have a back-bone of the SiC _{1 -X} layer.

Conventionally, seed crystals 190 are directly attached to the seed crystal holders 170 to grow single crystals. Since the seed crystal holder 170 and the seed crystal 190 are heterogeneously coupled, thermal expansion coefficient difference and lattice mismatch exist. Therefore, pores exist in the single crystal grown from the seed crystal 190, which causes defects.

Subsequently, the focusing tube 180 is located inside the crucible 100. The focusing tube 180 may be located at a portion where the single crystal grows. The focusing tube 180 may narrow the movement path of the sublimated silicon carbide gas to focus diffusion of the sublimed silicon carbide into the seed crystal 190. This can increase the growth rate of single crystals.

Subsequently, the heat insulator 200 surrounds the crucible 100. The insulation 200 maintains the temperature of the crucible 100 at a crystal growth temperature. Since the heat insulating material 200 has a very high crystal growth temperature of silicon carbide, graphite felt may be used. Specifically, the heat insulator 200 may be a graphite felt made of a cylindrical shape of a predetermined thickness by compressing the graphite fiber. In addition, the heat insulating material 200 may be formed of a plurality of layers to surround the crucible 100.

Subsequently, the quartz tube 400 is located on the outer circumferential surface of the crucible 100. The quartz tube 400 is fitted to the outer circumferential surface of the crucible 100. The quartz tube 400 may block heat transferred from the heat generating induction part 500 to the inside of the single crystal growth apparatus. The quartz tube 400 may be a hollow tube. Cooling water may be circulated in the internal space of the quartz tube 400. Therefore, the quartz tube 400 can more accurately control the growth rate, growth size, and the like of the single crystal.

The heat generation induction part 500 is located outside the crucible 100. The heat generating induction part 500 may be, for example, a high frequency induction coil. The crucible 100 and the crucible 100 may be heated by flowing a high frequency current through the high frequency induction coil. That is, the raw material accommodated in the crucible 100 may be heated to a desired temperature.

A central region that is induction heated in the exothermic induction part 500 is formed at a position lower than a central portion of the crucible 100. Therefore, a temperature gradient having different heating temperature regions is formed on the top and bottom of the crucible 100. That is, a hot zone HZ, which is the center of the heat generating induction part 500, is formed at a relatively low position from the center of the crucible 100, and thus the temperature of the lower portion of the crucible 100 is bounded by the hot zone HZ. Is formed higher than the temperature of the top of the crucible (100). In addition, a temperature is formed high along the outer direction at the inner center of the crucible 100. This temperature gradient causes sublimation of the silicon carbide raw material, and the sublimed silicon carbide gas moves to the surface of the seed crystal 190 having a relatively low temperature. As a result, the silicon carbide gas is recrystallized to grow into a single crystal.

The features, structures, effects and the like described in the foregoing embodiments are included in at least one embodiment of the present invention and are not necessarily limited to one embodiment. In addition, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified with respect to other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

In addition, the above description has been made with reference to the embodiments, which are merely examples and are not intended to limit the invention. It will be appreciated that various modifications and applications are possible. For example, each component specifically shown in the embodiments may be modified and implemented. It is to be understood that the present invention may be embodied in many other specific forms without departing from the spirit or essential characteristics thereof.

Claims (8)

A crucible for accommodating raw materials; And
A seed crystal holder for fixing a seed crystal disposed on the raw material,
Ingot manufacturing apparatus in which a buffer layer is formed on the seed crystal holder. The method of claim 1,
The buffer layer is an ingot manufacturing apparatus located between the seed crystal holder and the seed crystal. The method of claim 2,
The buffer layer and the seed crystal are ingot manufacturing apparatus comprising a material having the same coefficient of thermal expansion. The method of claim 3,
The buffer layer and the seed crystal ingot manufacturing apparatus comprising the same material. The method of claim 2,
Wherein said buffer layer comprises at least one grain boundary. The method of claim 5,
The buffer layer is an ingot manufacturing apparatus comprising a polycrystalline. The method according to claim 6,
The buffer layer is an ingot manufacturing apparatus containing silicon carbide. The method of claim 7, wherein
The seed crystal holder is ingot manufacturing apparatus comprising graphite.

Images