KR101003075B1 - Method and Apparatus for growth of silicon carbide single crystal - Google Patents

Abstract

The present invention relates to a method and apparatus for growing SiC single crystal with stable reproducibility and stable growth of large-diameter SiC single crystals having a diameter of 3 inches or more by controlling not only the vertical temperature gradient at the top and bottom of the crucible but also the initial-end temperature difference at the bottom of the crucible. In the SiC single crystal growth method according to the present invention, the temperature difference (ΔT _FI ) between the beginning and the end of the process at the bottom of the crucible is controlled by controlling the temperature difference (ΔT _BU ) at the bottom and the top of the crucible and the growth pressure (P _C ) in the crucible. It is characterized by controlling.

SiC, single crystal, growth device, vertical temperature gradient

Description

SiC single crystal growth method and apparatus {Method and Apparatus for growth of silicon carbide single crystal}

The present invention relates to a method and apparatus for growing SiC single crystal, and more particularly, to stably grow a large diameter SiC single crystal having a diameter of 3 inches or more by controlling not only the vertical temperature gradient at the top and bottom of the crucible but also the initial-end temperature difference at the bottom of the crucible. The present invention relates to a method and apparatus for growing SiC single crystal, which is reproducible.

As next-generation semiconductor device materials, broadband semiconductor materials such as SiC, GaN, AlN, and ZnO are expected to be promising. However, among these broadband semiconductor materials, only SiC single crystal materials 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.

Particularly, since SiC has excellent thermal stability at 1500 ° C or lower and excellent stability in an oxidizing atmosphere, and has a large thermal conductivity of about 4.6W / cm ° C, III such as GaAs or GaN is required in an environment requiring long-term stability at high temperature. It is expected to be much more useful than the Group-V compound semiconductor.

Although SiC has a smaller electron mobility than silicon (Si), the energy bandgap is about 2 to 3 times that of silicon and the operating limit temperature is 650 ° C. Compared with this, the operating limit temperature is much higher. In addition, it is possible to manufacture a device that can be used in extreme environments because it is chemically and mechanically strong.

The performance limitations of the device due to the intrinsic physical properties of these materials are such as Johnson's Figure of Merit (JFOM), Keyes' Figure of Merit (KFOM), Baliga's Figure of Merit (BFOM), and Baliga's High Frequency Figure of Merit (BHFFOM). Comparing the various index coefficients can easily identify them. For example, JFOM, which shows the advantages of high frequency and high power applications, compares the power and frequency limits of transistors from breakdown voltage and saturation electron transfer rate, and SiC is over 600 times that of silicon (Si).

As the device using SiC having such excellent physical properties is announced differently each day, the scope of application and its ramifications of SiC are rapidly expanding. For example, SiC is a high temperature integrated circuit such as automobile or aerospace, radiation resistant device, III-V-IV-VI interconnection device, ultra-precision MEMS device, X-ray mask, ultraviolet (UV) probe, It is applied to a blue light emitting element (LED).

On the other hand, in order to be stably applied to the above-described applications and increase the yield, the growth of high-quality single crystals of large diameter of 3 inches or more is required.

In the case of a conventional SiC single crystal growth apparatus, Korean Patent Publication No. 485023 and ' Growth-Induced structure defects in SiC PVT Boules (ICSCRM 2001, Materials Science Forum Vols. 389-393 (2002) pp. 385-390) In the present invention, the SiC raw material is placed in the graphite crucible and the SiC seed is mounted on the graphite crucible so that the SiC single crystal is grown on the SiC seed by raising the temperature of the portion where the SiC raw material is located to be higher than the SiC seed part. I choose.

In such a conventional SiC single crystal growth apparatus, a method of controlling the vertical temperature gradient from the top of the crucible to the bottom is applied as a method of controlling the quality of the SiC single crystal. However, controlling the quality of single crystals by controlling the vertical temperature gradients in the top and bottom of the crucible is suitable for the growth of SiC single crystals with a relatively small diameter of less than 2 inches, but in the growth of SiC single crystals with diameters of 3 inches or more, the polytype domains within the single crystals. It is difficult to solve the problem of defects such as the vertical temperature gradient control alone. This can be said to prove that when a large-diameter SiC single crystal growth of 3 inches or more, in addition to the vertical temperature gradient at the top and bottom of the crucible, another variable control is required.

The present invention has been made to solve the above problems, by controlling the initial-end temperature difference at the bottom of the crucible as well as the vertical temperature gradient of the upper and lower crucibles to stably grow a large diameter SiC single crystal of 3 inches or more in diameter and reproducibility It is an object of the present invention to provide a method and apparatus for growing this SiC single crystal.

SiC single crystal growth method according to the present invention for achieving the above object between the beginning and the end of the process at the bottom of the crucible through the control of the temperature difference (ΔT _BU ) and the growth pressure (P _C ) in the bottom of the crucible It is characterized by controlling the temperature difference ΔT _FI .

The temperature difference ΔT _BU between the bottom and the top of the crucible may be controlled at 0.1 to 50 ° C./cm, and the growth pressure P _C may be controlled to 1 to 100 Torr. In addition, the temperature difference ΔT _FI between the beginning of the process and the end of the process at the bottom of the crucible is characterized by controlling to 0.1 to 10.0 ° C / hr.

SiC single crystal growth apparatus according to the present invention is a SiC single crystal growth apparatus comprising a crucible, a reaction chamber and heating means, wherein the crucible is composed of a plurality of unit crucibles that are selectively removable, each unit crucible vertical Direction cross-sectional area is different from each other, the heating means is provided along the circumference of the reaction chamber is characterized in that the vertical movement of the crucible is possible to move up and down.

The SiC single crystal growth method using the SiC single crystal growth apparatus has a temperature difference (ΔT _FI) between the beginning and the end of the process at the bottom of the crucible by controlling the temperature difference (ΔT _BU ) at the bottom and the top of the crucible and the growth pressure (P _C ) in the crucible. ) Is controlled to 0.1 ~ 10.0 ℃ / hr, the temperature difference (ΔT _BU ) between the lower and the top of the crucible is controlled to 0.1 ~ 50 ℃ / cm, the growth pressure (P _C ) is 1 to 100 Torr Can be controlled.

Each unit crucible is provided in close contact with each other, the thickness of the side and the outer surface of each of the unit crucible may be the same or different, the thickness of the side of each unit crucible is the inner diameter of the unit crucible with the largest cross-sectional area It may be less than 1/2 of. In addition, the thickness of the side or outer surface of each unit crucible is 1 to 100 mm, and the inner diameter of the unit crucible having the smallest cross-sectional area among each unit crucible is larger than 51 mm.

A heating element may be further provided in the SiC raw material of the unit crucible having the smallest cross-sectional area among the unit crucibles, and the heating element has a thickness of 1 to 100 mm and a diameter or length of 1 mm to a crucible inner diameter or less. In addition, the heating element is any one of isotropic graphite, anisotropic graphite, carbon composite material or isotropic graphite coated with SiC, anisotropic graphite coated with SiC, carbon composite material coated with SiC or Ta, Nb Any one of W, Mo, Hf, Zr, V, or a carbide containing one or more of Ta, Nb, W, Mo, Hf, Zr, V or one of Ta, Nb, W, Mo, Hf, Zr, V It may be composed of a nitride containing the above. Here, the heating element may be in the form of a disk, a rod, a polyhedron, a pipe, or the like.

When the heating means moves, the bottom of the crucible does not rise higher than 1/2 of the total vertical distance of the heating means, and when the heating means moves up and down, the vertical distance between the top of the heating means and the top of the crucible is It is contained within 0-150 mm.

The circumference of the crucible is further provided with an upper heat insulating material, a lower heat insulating material and an outer heat insulating material, wherein the upper heat insulating material and the lower heat insulating material are respectively provided on the upper and lower portions of the crucible, and the external heat insulating material is the side of the crucible and the upper heat insulating material and the lower heat insulating material. It is provided to surround the side of the heat insulating material. It is preferable that the lower insulation has a thickness of 1 to 400 mm.

In addition, the SiC single crystal growth apparatus according to the present invention comprises a crucible, a reaction chamber and a heating means, wherein the crucible includes an outermost unit crucible defining an inner space of the crucible, and the outermost crucible. It consists of <one or more unit side member> and <one or more unit lower surface member> selectively detachable in an outer unit crucible, or the said <one or more unit side member> or said <one or more Unit lower surface member> only, the heating means is provided along the circumference of the reaction chamber is characterized in that the vertical movement of the crucible can be moved up and down.

The thickness of each unit side member is less than 1/2 of the inner diameter of the unit crucible having the largest cross-sectional area, and the thickness of each unit side member or unit lower surface is 1 to 100 mm. Further, the inner diameter of the unit side member having the smallest cross-sectional area among the unit side members is larger than 51 mm.

SiC single crystal growth method and apparatus according to the present invention has the following effects.

It is possible to stably grow a large-diameter SiC single crystal of 3 inches or more by controlling the initial temperature-end temperature difference in the lower part of the crucible as well as the vertical temperature gradient in the upper and lower parts of the crucible.

Hereinafter, a method and apparatus for growing SiC single crystal according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Prior to describing the SiC single crystal growth method according to an embodiment of the present invention, a SiC single crystal growth apparatus for implementing the same will be described first. 1 is a cross-sectional view of a SiC single crystal growth apparatus according to an embodiment of the present invention.

As shown in FIG. 1, the SiC single crystal growth apparatus according to the exemplary embodiment includes a crucible 110, a heat insulating material, a reaction chamber 130, and a heating means 140.

The crucible 110 is to provide a reaction space in which SiC single crystal growth occurs, and the bottom of the crucible 110 is provided with a SiC raw material 111 in a powder state, and the top of the crucible 110 is a SiC seed in a single crystal state ( 112 is provided. Here, the crucible 110 may be configured in a form having an internal space of a predetermined length, such as a cylindrical or square barrel in one embodiment, it may be made of a graphite (C) material.

On the other hand, the crucible 110 according to an embodiment of the present invention is composed of a plurality of unit crucibles. Each unit crucible is preferably designed so that the cross-sectional area of the crucible vertical direction is different from each other, so that each unit crucible is embedded in the order of decreasing cross-sectional area in the crucible having the largest cross-sectional area. Taking a cylindrical crucible as an example, it can be seen that unit crucibles 201 having different cross-sectional areas are provided in order of decreasing cross-sectional area in the unit crucible 201 having the largest cross-sectional area as shown in FIGS. 2A and 2B. At this time, each unit crucible 201 is preferably configured to be in close contact with each other, the thickness of the outer wall defining the inner space of each unit crucible 201 can be designed to be the same or different. For example, the outer wall thickness t of each unit crucible 201 may be designed to be 1 to 100 mm within a range not deviating from 1/2 of the inner diameter D of the outermost unit crucible 301. Meanwhile, each of the unit crucibles 201 is selectively detachable, and the smallest unit crucible 201 is preferably designed to have a diameter of 51 mm or more for single crystal growth of 3 inches or more.

Each of the unit crucibles 201 may be configured to have both side and bottom surfaces as shown in FIG. 2. That is, each unit crucible 201 may be made of a combination of the unit side member 310 and the unit bottom member 320, or may be configured of only the unit side member 310 or the unit bottom member 320. Referring to the drawings, as illustrated in FIGS. 3A and 3B, at least one unit side member 310 and at least one unit bottom surface in an outermost unit crucible 301 defining an inner space of the crucible 110. The member 320 has a form provided on the side and bottom of the unit crucible 201, respectively. In this case, the unit side member 310 and the unit lower surface member may be provided only on the side or bottom surface of the unit crucible 201, or the unit side member 310 and the unit lower surface may be provided on both the side and the bottom surface. The face member may be provided. Here, each unit side member 310 and the unit lower surface member may have the same or different thickness, for example, the thickness t of each unit side member 310 is the outermost unit crucible 301 It can be designed from 1 to 100mm within a range not deviating 1/2 of the inner diameter (D), the thickness of each unit lower surface member is within a range not deviating 1/2 of the height of the outermost unit crucible 301 Can be designed from 1 to 100mm. Each of the unit side member 310 and the unit lower surface member may be selectively detached similarly to the unit crucible 201.

As such, the thickness of the side and bottom surfaces of the crucible 110 is selectively adjusted through a method in which the crucible 110 is composed of a plurality of unit crucibles 201 or provided with a unit side member 310 and a unit bottom surface member. The reason is that the temperature inside the crucible 110 is precisely to control the temperature difference ΔT _BU between the upper part T _U and the lower part T _B inside the crucible 110, and the same inside the crucible 110. The control of the temperature difference (ΔT _BU ) between the upper (T _U ) and the lower (T _B ) of is between the beginning of the process (T _I ) and the end (T _F ) at the bottom of the crucible 110, which is one of the key features of the present invention. It is an important factor in controlling the temperature difference (ΔT _FI ). Control of the temperature difference ΔT _FI between the initial stage of the process (T _I ) and the terminal stage (T _F ) under the crucible 110 will be described in detail in the SiC single crystal growth method according to an embodiment of the present invention described later.

On the other hand, the heat insulator serves to absorb the heat of the outside while preventing the heat released to the outside of the crucible 110, in detail the upper heat insulating material 121, the lower heat insulating material 122, the external heat insulating material ( 123). The upper heat insulating material 121 and the lower heat insulating material 122 are provided at the upper and lower portions of the crucible 110, respectively, and the external heat insulating material 123 is the side of the crucible 110 and the upper heat insulating material 121 and the lower part. It is provided to surround the side of the heat insulating material (122). Here, a part of the upper heat insulating material 121 and the lower heat insulating material 122 is provided with through parts 121a and 122a having a predetermined diameter penetrating the upper heat insulating material 121 and the lower heat insulating material 122, which is a crucible 110. ) To measure the temperature of the upper and lower parts. In addition, the lower heat insulating material 122 is variable in thickness control. The reason for setting the thickness of the lower heat insulating material 122 in this way is to control the vertical temperature gradient in the crucible, and the lower heat insulating material 122 is 1 It is preferable to have a thickness of ˜400 mm.

The reaction chamber 130 is to provide a mounting space for the crucible 110 and the heat insulator, in one embodiment it may be composed of a quartz tube, both ends of the temperature of the top and bottom of the crucible 110 A window 131 is provided for measuring. Here, the window 131 may be implemented in a double structure in preparation for contamination.

The heating means 140 is provided along the circumference of the reaction chamber 130 to serve to heat the crucible 110, and may be configured as a high frequency induction coil, etc., although not shown in the drawing Up and down movement is possible through the lifting means. When the vertical movement of the heating means 140, the vertical distance between the top of the heating means 140 and the top of the crucible 110 is preferably controlled within 0 ~ 150mm, the bottom of the crucible 110 is the heating means ( It shall not be raised beyond one half of the total vertical distance of 140). Here, in the embodiment of the present invention, the heating means 140, but described as being implemented as a high frequency induction coil, resistance heating method is equally applicable. When a resistive heating method is applied, the crucible may be moved up and down.

The reason for moving the heating means 140 up and down through the lifting means is to control the temperature in the crucible 110, similarly to the reason that the crucible 110 is composed of a plurality of unit crucibles 201. Ultimately, as a means for performing a temperature difference ΔT _FI control between the initial stage of the process (T _I ) and the terminal stage (T _F ) under the crucible 110, a description thereof will be described later.

The crucible 110, the heat insulating material, the reaction chamber 130, and the heating means 140 constituting the SiC single crystal growth apparatus according to the embodiment of the present invention have been described above, in addition to the above components, a temperature measuring device and a gas supply device. A gas supply control device and a vacuum device are further provided, but detailed description thereof will be omitted.

Next, the operation of the SiC single crystal growth apparatus according to an embodiment of the present invention having the configuration as described above, that is, the SiC single crystal growth method according to an embodiment of the present invention will be described.

A key feature of the SiC single crystal growth method according to the present invention is to control the temperature difference (ΔT _FI ) between the initial process (T _I ) and the end (T _F ) at the bottom of the crucible 110, through which SiC single crystal of 3 inches or more It is possible to implement high quality SiC single crystal growth by minimizing defects such as polytype domains during growth. As described in the description of the prior art, the quality of the SiC single crystal can be controlled only by controlling the vertical temperature gradient in the crucible 110 when growing the SiC single crystal of 2 inches or more, but the vertical temperature gradient is controlled when growing the SiC single crystal of 3 inches or more. It is not possible to guarantee stable quality alone, and thus, through various simulations and experiments, the Applicant, in addition to the vertical temperature gradient, the temperature difference (ΔT _FI ) between the initial process (T _I ) and the end (T _F ) at the bottom of the crucible 110. Was found to be an important factor in the quality of SiC single crystals.

The temperature difference ΔT _FI between the process initiation T _I and the end T _F at the bottom of the crucible 110 is controlled by two factors. One is the temperature difference ΔT _BU between the upper portion T _U and the lower portion T _{B in the} crucible 110, and the growth pressure P _{C in the} crucible 110 is the other. Hereinafter, for convenience of description, the temperature difference between the initial stage of the process (T _I ) and the end (T _F ) at the bottom of the crucible 110 is ΔT _FI , between the top (T _U ) and the bottom (T _B ) inside the crucible 110. The temperature difference of is abbreviated as ΔT _BU .

As described above, ΔT _FI is controlled by the growth pressure P _C and ΔT _BU . First, ΔT _FI control by adjusting the growth pressure P _C will be described.

The growth pressure (P _C ) can be adjusted through a gas supply control device, a vacuum device, etc., and can be adjusted even during the SiC single crystal growth process. When the growth pressure (P _C ) in the crucible 110 is increased, the crucible 110 can be adjusted. The reaction rate of the SiC raw material 111 in the () is slowed, thereby reducing the amount of reaction gas (SiC ₂ , Si, Si ₂ C, Si ₂ ) generated to reduce the carbonization rate of the SiC raw material 111 . As such, as the carbonization rate of the SiC raw material 111 is lowered, ΔT _{FI, which} is a temperature difference between the beginning and the end of the process at the bottom of the crucible 110, becomes small.

On the contrary, when the growth pressure P _C in the crucible 110 is lowered, the reaction rate of the SiC raw material 111 is increased, and accordingly, the amount of the reaction gases SiC ₂ , Si, Si ₂ C, and Si ₂ is increased. Since the carbonization rate of the SiC raw material 111 is increased by increasing the number, the ΔT _FI is increased by increasing the carbonization rate of the SiC raw material 111.

Next, ΔT _FI control through ΔT _BU adjustment will be described.

For SiC single crystal growth, the temperature of the bottom of the crucible 110 in which the SiC raw material 111 is positioned should be set higher than the top of the crucible 110 in which the SiC seed 112 is located, and the vertical temperature gradient of the crucible 110 is increased. Control, that is, the quality of the SiC single crystal is affected by the temperature difference ΔT _BU control between the top and bottom of the crucible 110.

A large ΔT _BU means that the temperature difference between the bottom and the top of the crucible 110 is large, and the reaction temperature of the SiC raw material 111 is increased by the high temperature difference, so that the reaction gas (SiC ₂ , Si, Si ₂ C, Si ₂ ) is increased. ), The amount of ΔT _FI increases with the increase in the carbonization rate of the SiC raw material 111.

On the contrary, the smaller ΔT _BU means that the temperature difference between the lower part and the upper part of the crucible 110 is smaller, and the reaction rate of the SiC raw material 111 is lowered due to the lower temperature difference, thereby causing the reaction gases SiC ₂ , Si, Si ₂ to be reduced. The amount of C and Si ₂ ) decreases, and finally, ΔT _FI decreases with decreasing carbonization rate of the SiC raw material 111.

On the other hand, the control of ΔT _BU can be controlled through the _shangdong of the plurality of unit crucible 201 or the heating means 140 as described above. First, referring to a control method using a plurality of unit crucibles 201, in general, the thicker the thickness of the outer wall of the crucible 110 is, the temperature inside the crucible 110 is increased and the smaller the thickness of the outer wall of the crucible 110 is the crucible 110. The internal temperature has a characteristic of falling, and the present invention utilizes such characteristics to arrange a unit crucible 201 in a portion where a high temperature is required to induce a temperature increase, and a portion of a unit crucible in which a low temperature is required. Minimize the placement of 201) to induce a temperature drop. For example, if the temperature of the lower portion of the crucible 110 is required, the unit crucible 201 having a relatively thick outer wall thickness of the lower surface is disposed or a predetermined number of unit lower surface members are disposed, and the crucible 110 side portion is disposed. If a temperature increase is required, a unit crucible 201 having a relatively thick outer wall thickness may be disposed or a number of unit side members 310 may be arranged to ultimately control the temperature difference between the bottom and the top of the crucible 110. do.

Next, referring to ΔT _BU control through the lifting of the heating means 140, the temperature of the upper portion of the crucible 110 rises as the crucible 110 is positioned relatively at the center of the heating means 140, and the crucible 110 is located. Is relatively located near the upper end of the heating means 140, it is possible to control the temperature difference between the lower and the top of the crucible 110 by using the characteristic that the temperature of the upper portion of the crucible 110 is lowered.

In addition to controlling the ΔT _{BU by} elevating the plurality of unit crucibles 201 and the heating means 140, the ΔT _BU may be controlled by providing a heating element in the SiC raw material 111 in the crucible 110. That is, by providing a heating element in the SiC raw material (111) pile it is possible to increase the temperature of the lower portion of the crucible 110 and ultimately to control the ΔT _BU . In this case, a heating element having a thickness of 1 to 100 mm and a diameter of 1 mm to less than the inner diameter of the crucible 110 may be charged in the SiC raw material 111. The heating element may be isotropic graphite, anisotropic graphite, or carbon composite material. ) Or any one of SiC coated isotropic graphite, SiC coated anisotropic graphite, SiC coated carbon composite material or Ta, Nb, W, Mo, Hf, Zr, V or Ta, Nb It may be composed of a carbide containing at least one of W, Mo, Hf, Zr, V or a nitride containing at least one of Ta, Nb, W, Mo, Hf, Zr, V. Here, the heating element may be in the form of a disk, a rod, a polyhedron, a pipe, or the like. In addition, the ΔT _BU control may also be controlled by adjusting the thickness of the lower insulation 122.

As described above, it can be seen that ΔT _FI has an inverse characteristic in relation to the growth pressure P _C and a proportional characteristic in relation to ΔT _BU . However, this is a characteristic when the growth pressure (P _C ) or ΔT _BU is applied independently, and when the growth pressure (P _C ) and ΔT _BU factors are applied together, ΔT compared to the growth pressure (P _C ) factor and ΔT _BU factor. Inversely, the proportional characteristic of _FI can be slowed down and increased.

The present invention derives the optimal ΔT _FI by selectively controlling the growth pressure (P _C ) and ΔT _BU based on the inverse and proportional characteristics of ΔT _FI relative to the growth pressure (P _C ) factor and ΔT _BU factor. The optimum ΔT _FI according to the invention is 0.1 to 10.0 ° C / hr, at which time the growth pressure P _C is controlled between 1 and 100 Torr and ΔT _BU is controlled between 0.1 and 50 ° C / cm. As described above, the control of the ΔT _BU is controlled through the side and bottom surface thickness adjustment of the crucible 110 by the plurality of unit crucibles 201, the unit side member 310, the unit bottom surface member, or the heating means 140. Control of the heating element in the SiC raw material 111 or the like.

The reason why the upper limit value is set to 10.0 ° _C./hr at the optimal ΔT _FI is that not only polytype domains or cracks occur at the center or edge of the single crystal when ΔT _FI exceeds 10.0 ° C./hr, This is because stress is generated inside the crystal, and defects such as micropipes and dislocations increase.

As described above, the SiC single crystal growth method according to an embodiment of the present invention is characterized in that the high-quality large-diameter SiC single crystal growth is possible by ultimately minimizing the generation of a polytype domain through ΔT _FI control. The correlation between ΔT _BU , ΔT _FI and the generation of polytype domains is as follows. 4 is a graph showing the correlation between ΔT _BU and ΔT _FI and the generation of polytype domains.

As shown in FIG. 4, when both ΔT _BU and ΔT _FI are large, carbonization of the SiC raw material 111 is rapidly performed due to large ΔT _BU , and thus, of the reaction gas supplied to the SiC seed 112 per unit time. The amount is abundant. As a result, the SiC single crystal growth rate is increased and the polytype instability in the crystal is affected, so that the polytype domain is well formed in the center of the crystal (see 'Δ' in FIG. 4).

On the other hand, if both ΔT _BU and ΔT _FI are small, the growth rate is very low because the amount of reaction gas supplied from the SiC raw material 111 to the SiC seed 112 is not sufficient. The reason for this is that the carbonization of the SiC raw material 111 is performed properly and the amount of reaction gas generated per unit time is also appropriate, but due to the low ΔT _BU , the driving force for moving the reaction gas to the top of the crucible 110 is insufficient. . As a result, the growth rate is low and rather reverse sublimation occurs on the surface of the SiC seed 112 so that the surface of the SiC seed 112 is carbonized. Such carbonization of the surface of the SiC seed 112 facilitates the occurrence of defects such as micropipes and the likelihood of generating polytype domains from the micropipes and the like (see the '□' portion of FIG. 4).

Finally, even if ΔT _BU is very high or low, if ΔT _FI is appropriate, large diameter SiC single crystals without polytype domains as shown in FIGS. 5 and 6 can be grown. This proves that the supply of reaction gas is sufficient due to the appropriate ΔT _FI .

As confirmed through the graph of FIG. 4, the relationship between ΔT _BU and ΔT _FI does not have an absolute proportional relationship, but as described above, it is _changed by a factor of the growth pressure P _C , and ΔT _BU and the growth pressure P _It can be seen that the optimal ΔT _FI can be derived by adjusting _C ).

1 is a cross-sectional view of a SiC single crystal growth apparatus according to an embodiment of the present invention.

Figure 2a is an exploded perspective view of the crucible according to an embodiment of the present invention.

2B is a cross sectional view of FIG. 2A;

3a and 3b is a block diagram of a crucible according to another embodiment of the present invention.

4 is a graph showing the correlation between ΔT _BU and ΔT _FI and the generation of polytype domains.

5 and 6 are photographs of SiC single crystals produced by the SiC single crystal growth apparatus according to an embodiment of the present invention.

Description of the main parts of the drawing

110: crucible 111: SiC raw material

112 SiC seed 113 SiC single crystal

121: upper insulation 121a, 122a: through part

122: lower insulation 123: external insulation

130: reaction chamber 131: window

140: heating means

Claims (34)

The temperature difference ΔT _{F -I} between the beginning and the end of the process at the bottom of the crucible is controlled by adjusting the temperature difference ΔT _{B -U at} the bottom and the top of the crucible and the growth pressure P _C in the crucible. SiC single crystal growth method. The SiC single crystal growth method according to claim 1, wherein the temperature difference ΔT _BU between the bottom and the top of the crucible is controlled at 0.1 to 50 ° C / cm. The SiC single crystal growth method according to claim 1, wherein the growth pressure P _C is controlled at 1 to 100 Torr. The SiC single crystal growth method according to any one of claims 1 to 3, wherein a temperature difference (ΔT _FI ) between the beginning and the end of the process at the bottom of the crucible is controlled at 0.1 to 10.0 ° C / hr. In the SiC single crystal growth apparatus comprising a crucible, a reaction chamber and a heating means, The crucible is composed of a plurality of unit crucibles selectively detachable, each unit crucible is different from each other in the cross-sectional area of the crucible vertical direction, The heating means is provided along the circumference of the reaction chamber is capable of vertical movement in the vertical direction of the crucible, SiC single crystal growth apparatus further comprises a gas supply control device or a vacuum device for adjusting the growth pressure (Pc) in the crucible. The SiC single crystal growth apparatus according to claim 5, wherein each of the unit crucibles is provided in close contact with each other. delete delete delete The SiC single crystal growth apparatus according to claim 5, wherein an inner diameter of each of the unit crucibles having the smallest cross-sectional area is greater than 51 mm. The SiC single crystal growth apparatus according to claim 5, wherein a heating element is further provided in the SiC raw material provided in the unit crucible having the smallest cross-sectional area among the unit crucibles. The SiC single crystal growth apparatus according to claim 11, wherein the heating element has a thickness of 1 to 100 mm and a diameter of 1 mm or more and a crucible inner diameter or less. The method of claim 11, wherein the heating element is any one of isotropic graphite, anisotropic graphite, carbon composite or isotropic graphite coated with SiC, anisotropic graphite coated with SiC, carbon composite material coated with SiC Or carbides containing any one of Ta, Nb, W, Mo, Hf, Zr, V or at least one of Ta, Nb, W, Mo, Hf, Zr, V or Ta, Nb, W, Mo, Hf, Zr SiC single crystal growth apparatus, characterized in that consisting of a nitride containing one or more of V. 6. The SiC single crystal growth apparatus according to claim 5, wherein the lowermost part of the crucible does not rise higher than 1/2 of the total vertical distance of the heating means when the heating means moves. The SiC single crystal growth apparatus according to claim 5, wherein the vertical distance between the top of the heating means and the top of the crucible is included within 0 to 150 mm when the heating means moves up and down. In the SiC single crystal growth apparatus comprising a crucible, a reaction chamber and a heating means, The crucible is An outermost unit crucible defining an inner space of the crucible, <1 or a plurality of unit side members> and <one or a plurality of unit lower surface members> which are selectively removable in the outermost unit crucible, or the <one or more unit side members> or the <one or Consists of a plurality of unit lower surface members>, The heating means is provided along the circumference of the reaction chamber is capable of vertical movement in the vertical direction of the crucible, SiC single crystal growth apparatus further comprises a gas supply control device or a vacuum device for adjusting the growth pressure (Pc) in the crucible. The SiC single crystal growth apparatus according to claim 16, wherein the thickness of each unit side member is smaller than half of the inner diameter of the unit crucible having the largest cross-sectional area. The SiC single crystal growth apparatus according to claim 16, wherein the thickness of each unit side member or unit bottom surface is 1 to 100 mm. The SiC single crystal growing apparatus according to claim 16, wherein an inner diameter of the unit side member having the smallest cross-sectional area of each unit side member is larger than 51 mm. The SiC single crystal growth apparatus according to claim 16, further comprising a heating element in a SiC raw material provided in the outermost unit crucible. The SiC single crystal growth apparatus according to claim 20, wherein the heating element has a thickness of 1 to 100 mm and a diameter of 1 mm or more and a crucible inner diameter or less. The method of claim 20, wherein the heating element is any one of isotropic graphite, anisotropic graphite, carbon composite or isotropic graphite coated with SiC, anisotropic graphite coated with SiC, carbon composite material coated with SiC Or carbides containing any one of Ta, Nb, W, Mo, Hf, Zr, V or at least one of Ta, Nb, W, Mo, Hf, Zr, V or Ta, Nb, W, Mo, Hf, Zr SiC single crystal growth apparatus, characterized in that consisting of a nitride containing one or more of V. The SiC single crystal growth apparatus according to claim 16, wherein, when the heating means moves, the lowermost part of the crucible does not rise higher than 1/2 of the total vertical distance of the heating means. The SiC single crystal growth apparatus according to claim 16, wherein the vertical distance between the top of the heating means and the top of the crucible is included within 0 to 150 mm when the heating means moves up and down. The method according to claim 5 or 16, further provided with an upper insulation, a lower insulation and an outer insulation, The upper heat insulating material and the lower heat insulating material are respectively provided on the upper and lower portions of the crucible, the external heat insulating material is SiC single crystal growth apparatus, characterized in that provided to surround the sides of the crucible and the upper heat insulating material, the lower heat insulating material. 27. The SiC single crystal growing apparatus according to claim 25, wherein the lower heat insulating material has a thickness of 1 to 400 mm. In the SiC single crystal growth method using the SiC single crystal growth apparatus of claim 5, SiC single crystal growth characterized by controlling the temperature difference (ΔT _FI ) between the beginning and end of the process at the bottom of the crucible by adjusting the temperature difference (ΔT _BU ) of the lower and upper crucible and the growth pressure (P _C ) in the crucible Way. 28. The method of claim 27, wherein the temperature difference ΔT _BU between the bottom and the top of the crucible is controlled at 0.1 to 50 ° C / cm. The SiC single crystal growth method according to claim 27, wherein the growth pressure P _C is controlled at 1 to 100 Torr. The SiC single crystal growth method according to any one of claims 27 to 29, wherein a temperature difference ΔT _FI between the beginning and the end of the process at the bottom of the crucible is controlled at 0.1 to 10.0 ° C / hr. In the SiC single crystal growth method using the SiC single crystal growth apparatus of claim 16, SiC single crystal growth characterized by controlling the temperature difference (ΔT _FI ) between the beginning and end of the process at the bottom of the crucible by adjusting the temperature difference (ΔT _BU ) of the lower and upper crucible and the growth pressure (P _C ) in the crucible Way. 32. The method of claim 31, wherein the temperature difference ΔT _BU between the bottom and the top of the crucible is controlled at 0.1 to 50 ° C / cm. 32. The method of claim 31 wherein the growth pressure P _C is controlled to 1 to 100 Torr. The SiC single crystal growth method according to any one of claims 31 to 33, wherein a temperature difference ΔT _FI between the beginning and the end of the process at the bottom of the crucible is controlled at 0.1 to 10.0 ° C / hr.

Images