JP4850663B2 - Method for producing SiC single crystal and method for producing SiC single crystal substrate - Google Patents

Description

  The present invention relates to a high-quality SiC single crystal substrate, a seed crystal for manufacturing a high-quality SiC single crystal substrate (a seed crystal for growing a SiC single crystal), and a method for manufacturing a high-quality SiC single crystal substrate.

Conventionally, SiC semiconductors using SiC single crystals have been regarded as promising candidates for next-generation power devices that can replace Si semiconductors. Application is also expected as a substrate for blue light emitting diodes and laser diodes.
SiC single crystals are physically and chemically stable, and can withstand high temperatures and radiation, so they are expected to be applied as environmentally resistant semiconductor materials. In addition, SiC power devices are attracting attention as energy-saving devices because they can significantly reduce power loss in devices compared to conventional Si devices.
However, a crystal growth technique that can stably supply a high-quality SiC single crystal having a large area on an industrial scale has not yet been established. Therefore, SiC has not been widely put into practical use despite the semiconductor material having many advantages and possibilities as described above.

  As a method for obtaining a high-quality SiC single crystal having a relatively large diameter, an improved Rayleigh method is known in which sublimation recrystallization is performed using a SiC single crystal substrate as a seed crystal (Non-patent Document 1). In this method, since a seed crystal is used, the nucleation process of the crystal can be controlled, and the crystal growth rate and the like can be controlled with good reproducibility by adjusting the atmospheric pressure with an inert gas. By using the improved Rayleigh method, it is possible to grow a SiC single crystal while controlling the crystal polymorphism (6H type, 4H type, etc.), carrier type, and concentration of the SiC single crystal. Already by this method, SiC single crystals with a diameter of 2 inches (about 50 mm) to 3 inches (about 75 mm) have been manufactured, processed as substrates, and used for epitaxial thin film growth and device trial manufacture. However, currently available SiC single crystal substrates have many problems in terms of quality, and in order to put SiC single crystals and devices into practical use in the future, it is essential to improve the crystal quality.

  In order to realize a SiC power device having high performance and stable characteristics, it is indispensable to overcome instabilities such as leakage current generated in the SiC semiconductor. The causes of these instabilities are thought to be related to the quality of the SiC single crystal substrate. This deterioration in quality is considered to be mainly caused by crystal defects formed in the substrate, that is, micropipe defects, dislocation defects, and the like. Regarding micropipe defects, various efforts have been made particularly to reduce them, and it has been reported that a substrate without micropipe defects has been created, but for the reduction of dislocation defects, Patent Document 1, Patent Document 2, As disclosed in Patent Document 3 and the like, most of the methods are based on a special method such as changing the growth crystal plane, and there is no simple and industrially effective means.

Patent Document 1 discloses a method for obtaining a high-quality SiC single crystal. That is, in the sublimation recrystallization method in which a SiC single crystal is grown on the SiC single crystal substrate of the seed crystal, a crystal plane shifted by an angle of about 60 ° to about 120 ° from the {0001} plane is exposed as the seed crystal. It is considered effective to use a seed crystal composed of a SiC single crystal. In addition, Patent Document 2 newly discloses a first SiC single crystal grown using a crystal plane of an SiC single crystal tilted about 60 ° to about 120 ° from the {0001} plane as a first seed crystal. Discloses a method of taking out a {0001} wafer and using it as a second seed crystal to grow the crystal. Patent Document 3 discloses a method for producing a crystal with few defects. That is, different crystal planes are cut out and grown as seed crystals in the first growth step, the (n-1) th growth step, and the n growth step, respectively.
In the final production of a device, it is generally assumed that a plane near the {0001} plane is used. In the sublimation recrystallization method based on always growing a crystal on a seed crystal, In any case, a method of cutting out different surfaces, growing them as seeds, and finally growing them again on the {0001} surface is considered inappropriate as a process on the premise of mass production.

Therefore, up to now, there is almost no dislocation density less than 8000 / cm ² in the market.
Further, in the growth in the vicinity of the {0001} plane, defects such as dislocation pairs and dislocation arrays in which dislocations are close to each other, which are thought to be formed at high temperatures due to the interaction between dislocations, are thought to particularly affect device characteristics. However, no efficient reduction method has been proposed.

Non-Patent Document 2 describes the evaluation of SiC single crystals. When the defects contained in the crystal are examined by the molten KOH etching, it is said that many etch pits corresponding to dislocations are generated.
JP-A-5-2562599 JP-A-8-143396 JP 2003-119097 Yu. M. Tairov and VF Tsvetkov, Journal of Crystal Growth, vol.52 (1981) pp.146-150 The Institute of Electrical Engineers of Japan Electronic Materials Research Group September 5, 1988 Document No.EFM-88-24 p.24

  As described above, devices using SiC crystal substrates are expected as next-generation power devices to replace Si, but the stability and yield of device characteristics are not sufficient. Micropipes have been the primary cause. However, even if a substrate having no micropipe is used, the stability and yield of device characteristics are not sufficient for widespread use. Moreover, the present condition is that the efficient method is not found also about the reduction | restoration of the dislocation attracting attention as a defect. Also, even if dislocations exist, there are cases where there is no problem in device operation and characteristic stability, and it is not clear what kind of defect is reduced and how effective.

  The present invention has been made in view of such conventional problems, and is intended to improve the yield and stability of devices, a high quality SiC single crystal substrate, a seed crystal for manufacturing a high quality SiC single crystal substrate, and a high quality SiC. It aims at providing the manufacturing method of a single crystal substrate.

The present invention reduces dislocations terminating at the substrate surface, and also reduces dislocation pairs or regions having dislocation rows that are close to each other among dislocations having terminations on the substrate surface. It is possible to improve quality stability and yield.
That is, the present invention
(1) Using a seed crystal in which an etch pit having a maximum diameter of 3 μm or more and 20 μm or less is formed at the surface termination portion of the dislocation on the seed crystal surface having a total dislocation density of 12000 / cm ² or more and 30000 / cm ² or less , A method for producing a SiC single crystal, characterized by growing single crystal SiC by a sublimation recrystallization method ;
(2) The method for producing a SiC single crystal according to (1), wherein the polytype of the seed crystal is 4H type or 6H type,
(3) The method for producing an SiC single crystal according to (1) or (2), wherein the seed crystal has a disk shape, and the diameter of the disk is more than 50 mm.
(4) The method for producing an SiC single crystal according to any one of (1) to (3), wherein the plane orientation of the seed crystal is [0001],
(5) The method for producing an SiC single crystal according to any one of (1) to (3), wherein the plane orientation of the seed crystal has an angle of 0.5 ° to 10 ° from [0001],
(6) The method for producing a SiC single crystal according to any one of (1) to (5), wherein a thickness of the seed crystal is 0.6 mm or more,
( 7 ) A method for producing a SiC single crystal substrate, wherein the SiC single crystal obtained by the method according to any one of (1) to (6) is cut and polished,
It is.

  According to the present invention, it is possible to suppress dislocations from being taken over by a crystal growing on a seed crystal by forming etch pits at locations having dislocation terminations on the surface of the seed crystal. Further, the dislocations that are close to each other can have the etch pits having an appropriate size, so that the terminal portions of the plurality of dislocations can be made into one etch pit. Dislocation pairs or dislocation arrays of crystals grown on the seed crystal can be reduced. That is, in a substrate cut and processed from a crystal manufactured according to the present invention, the dislocation density terminating at the surface can be reduced, and the region without dislocation pairs or dislocation arrays can be expanded. The device manufactured using the can have a stable electrical characteristic and a high yield.

The present invention provides a high quality substrate for manufacturing devices on a SiC substrate. Although a substrate having no defect is ideal, it is extremely difficult to produce industrially, and it becomes a complicated process or a method with extremely low productivity, which is not practical. In particular, micro pipes that greatly contribute to the stability of device characteristics among defects have been able to produce substrates of 0.1 pieces / cm ² or less. By using them as seed crystals, crystals can be grown. The development that can maintain the same micropipe density has progressed. However, the quality stability of the device has not reached a sufficient level even in the absence of micropipes. As a defect of the substrate, dislocation is considered as a problem, but even if there are more than 8 × 10 ³ / cm ² level, the operation may be confirmed depending on the device, and the relationship with deterioration of quality stability Was unknown.

Focusing on nearby dislocation pairs or dislocation arrays by dislocation interactions among the dislocations present in the substrate, reducing the area in which these defects exist is a highly stable device in device manufacturing. It was found that it can be manufactured with a high yield. In particular, it has been found that adjacent dislocation pairs or dislocation arrays of 5 μm or less influence the stability of the device. More preferably, it is considered that device quality stability can be further ensured by reducing the number of adjacent dislocation pairs or dislocation arrays of 10 μm or less. The 5 mm square is used to define the area because a device with a size of about 5 mm square or larger is effective in order to take advantage of the characteristics of a semiconductor manufactured using SiC as a substrate. It is. Even in a device having a size larger than 5 mm square, it is effective that the area of the entire region without dislocation pairs and dislocation arrays is effective. Considering the stability of the device, if the yield is at least about 50% or more, it can be considered as a practical utility that can replace the Si device. Was made a practical substrate. Furthermore, 10% or less is preferable for cost reduction and quality stabilization for accelerating practical application. Considering heat treatment at a high temperature in the device process, dislocation density in the region without dislocation pairs and dislocation arrays. Is 8000 / cm ² or less , more preferably 4000 / cm ² or less.

  In the modified Rayleigh method, a seed crystal is used and a crystal is grown on the seed crystal. Therefore, when a dislocation having a termination exists on the surface of the seed crystal, the dislocation defect is taken over and grown. In addition, new dislocations may occur due to thermal stress during growth. In addition, since dislocations have a stress field, the number of dislocations that are close to each other during growth increases due to the interaction between the dislocations. In the manufacture of a device, when such a dislocation pair or the like is present, if the total number of dislocations is the same, the dislocation pairs or dislocation arrays are evenly distributed and are concentrated in a specific region. However, it is clear that the device yield and stability are improved. In order to reduce the region where dislocation pairs or dislocation arrays exist according to the present invention, the dislocation pairs or dislocation arrays generated by inheriting from the seed crystal are reduced, and at the same time, the dislocations of the growing crystal are moved so as to be dense. It is effective to make it.

As one of the methods for reducing the dislocations generated from the seed crystal, it is effective to use the seed crystal by etching the surface of the seed crystal and forming etch pits corresponding to the dislocation. Since the growth on the crystal plane in the pit is different from the crystal orientation that grows perpendicularly to the plane of the whole seed, it is difficult to take over the dislocation penetrating the surface. Further, by increasing the size of the etch pits, adjacent dislocation pairs or dislocation row pits are merged, and even if dislocations are generated from the dislocation pits, the total number of dislocations to be inherited is reduced. To coalesce the adjacent dislocation pits you the maximum diameter of the pit or more 3 [mu] m. More preferably, it is preferably 5 μm or more. The 20μm greater, since the possibility of causing new defects in the crystal growth in the pit rises, you to 20μm or less. Although the size of the etch pit varies depending on the type of dislocation even under the same etching conditions, it has been found that it is effective to determine the size by paying attention to the maximum diameter. As described above, melt KOH etching is effective for forming pits at positions where dislocations terminate on the substrate surface. The size of the etch pit is controlled by adjusting the etching temperature and time. For example, the temperature of the molten KOH is fixed at 530 ° C., and the immersion time of the seed crystal substrate is set to about 5 minutes, while observing the etch pit size with a microscope and increasing the immersion time to determine the optimum conditions. can do. FIG. 2 shows an example in which the diameter of the etch pit is 2 μm and the interval between the pits is 4 μm. FIG. 3 shows an example in which the diameter of the etch pit is 6 μm and the interval between the pits is 4 μm. An example of a single etch pit is schematically shown.

  As a method of increasing the region having few defects by moving the dislocations during the growth, it is possible to move by controlling the temperature of the crystal being grown. The activation energy of dislocation movement in SiC crystals is extremely high, and sufficient movement cannot be expected simply by increasing the temperature. It is effective for the movement of dislocations during growth that a temperature gradient from the center of the growing crystal to the periphery (high temperature in the periphery) is about 5 to 20 ° C./cm. The temperature of the crystal at that time is preferably 2000 ° C. or higher. The movement of dislocations causes the existing region to be unevenly distributed due to the interaction of dislocations, and at the same time, the dislocation disappearance probability increases, and is effective in reducing the total dislocation density.

The crystal used as the seed crystal, the total dislocation density is preferably 30000 / cm ² Ri der below and dislocation density which is not included in the dislocation pairs or dislocation arrays is 15000 / cm ² or less. However, when the number of dislocations in the crystal becomes extremely small, the maintenance of the crystal structure becomes unstable during crystal growth, and polycrystals and defects having different polymorphism tend to be introduced. In particular, when using a [0001] plane orientation or a seed crystal within 10 ° from the [0001] orientation, for the stable growth, the dislocation density of the finally grown crystal is as follows. The total dislocation density including the row is preferably about 300 / cm ² or more, more preferably about 1000 / cm ² or more, which is suitable as a production method for industrially performing crystal growth. The thickness of the seed crystal is preferably about 0.3 mm or more, more preferably 0.6 mm or more, in order to ensure uniformity of the seed temperature. With thick seed crystals, the conditions for controlling the temperature and heat distribution are different, but there is no particular problem with the seed crystals becoming thicker, and the ingot surface once grown is polished and etched as necessary. Etch pits can be formed and grown as seeds to lengthen the ingot. The upper limit of the thickness of the seed crystal that can be mass-produced is considered to be about the same as the diameter of the seed crystal in consideration of productivity.

On the other hand, in order to ensure the stability of characteristics when a device is manufactured, it is preferable that the dislocation density in the crystal is reduced, and there is no dislocation array and the region has a dislocation density of 8000 / cm ² or less. For example, in devices that are relatively insensitive to defects such as diodes, no significant yield reduction is observed. It is possible to further reduce dislocations by etching a substrate cut out from a crystal manufactured by the method of the present invention to form dislocation etch pits and crystal growth as a seed crystal. Thus, by repeating crystal growth for forming dislocation etch pits in the seed crystal twice or three times or more, the dislocation density and dislocation distribution can be further improved.

In order to obtain the effects of controlling the dislocation arrangement and crystal stability described above, it is more useful that nitrogen atoms are contained as impurities, and that 1 × 10 ¹⁸ cm ⁻³ or more is contained. It is more preferable that 5 × 10 ¹⁸ cm ⁻³ or more is contained. In particular, in the case of producing a 4H-type crystal, the nitrogen atom is contained in an amount of 1 × 10 ¹⁸ cm ⁻³ or more, which is suitable for obtaining the above effect without causing new defects. The upper limit of nitrogen content is 8 × 10 ²⁰ cm ⁻³ or less, and at higher concentrations, the deterioration of crystallinity becomes significant.

  For the production of a crystal power device, a 4H-type crystal is generally used. However, for 6H-type crystals, the same method as described above is effective for controlling dislocation pairs and dislocation arrays. Further, it is excellent in terms of device characteristics that the crystal plane to be used is manufactured with a {0001} plane or a plane tilted within 10 ° from the {0001} plane. From the viewpoint of substrate productivity and industrial production, a crystal with the same crystal orientation is manufactured, and the crystal is almost perpendicular to the growth direction or cut out within 10 ° from the perpendicular to form a seed crystal. Alternatively, repeated seed substrate growth is preferred. In particular, for dislocations where dislocation lines exist in the {0001} basal plane, the end surface of the dislocation is located on the surface by using a surface having an inclination of 0.5 ° or more and 10 ° or less, and etch pits are formed on the surface. It is formed. The tilt angle is preferably 10 ° or less, and more preferably 8 ° or less. If it exceeds 10 °, stable crystal growth on the seed crystal substrate becomes difficult. When forming a device, an epitaxially grown film is usually formed. In that case, a plane with a slight angle from the {0001} plane, that is, a plane with an angle of 0.5 ° to 10 ° is preferable. Since it is possible to cut out most substrates by cutting in parallel to the growth surface, it is preferable to provide a corresponding inclination angle.

  When manufacturing devices, SiC epitaxial thin films are usually formed on the top surface of a substrate, but it is known to take over defects in the substrate, and the dislocation distribution on the surface of the crystal substrate is controlled by the method described above. It is important to keep It is difficult to move or eliminate dislocation pairs and dislocation arrays during epitaxial growth. When manufacturing a device, the thickness of the epitaxial thin film is generally 3 μm to 30 μm.

  The crystal size is preferably large when manufacturing a device and when manufacturing a crystal, because it is easy to realize cost reduction of manufacturing, but it becomes more difficult to control crystal defects. For crystals having a diameter of more than 50 mm, it is particularly effective to improve the quality of the crystals by controlling the above-mentioned dislocation defects, and for crystals exceeding 60 mm, it is difficult to produce crystals having few defects by other methods. Larger crystals of more than 75 mm are prone to distortion during crystal growth, making it difficult to reduce the total dislocation density. Therefore, it is useful to improve the quality of crystals according to the present invention, which focuses on the dislocation distribution. is there. Crystals with a diameter of more than 250 mm introduce crystal defects and are not practical for mass production. Therefore, a crystal size with a diameter of 250 mm or less is effective.

  The length of the crystal grown from the seed crystal is preferably 15 mm or more and 200 mm or less. If it is 15 mm or less, a large amount of the seed crystal used every time is consumed, and the number of times of heating and cooling of the crucible for crystal growth becomes frequent, which is not suitable from the viewpoint of productivity. From the viewpoint of productivity, the longer one is preferable, but if it exceeds 200 mm, it becomes difficult to ensure the stability of the temperature control of the crucible, and the yield is significantly reduced. As the growth time becomes longer, the crystal growth becomes unstable due to sudden anomalies such as instability of supplied power or vibration, and the probability of generating new defects increases.

(Example 1)
A 4H type SiC single crystal substrate having a diameter of 52 mm, a thickness of 1 mm and a {0001} plane was prepared as a seed crystal. The total dislocation density of the seed crystal is about 12000 / cm ² . Etching was performed by immersing the seed crystal in a KOH melt heated to about 530 ° C., and adjusting the etching time so that the maximum diameter of each dislocation pit was about 6 μm. FIG. 3 shows an example of the distribution of etch pits. The pits of dislocations whose ends existed at intervals of 4 μm were merged. Dislocations whose ends are separated by 6 μm or more formed a single etch pit.

  Next, the seed crystal 1 was attached to the inner surface of the lid 4 of the graphite crucible 3 using the apparatus shown in FIG. The graphite crucible 3 was filled with the SiC crystal raw material powder 2 after washing. Next, the graphite crucible 3 filled with the raw material was closed with the lid 4 and covered with the graphite felt 7, and then placed on the graphite support rod 6 and installed inside the double quartz tube 5. After that, after evacuating the inside of the quartz tube, a mixed gas containing about 7% nitrogen gas is introduced into the high-purity Ar gas as an atmospheric gas, and a current is passed through the work coil while keeping the quartz tube internal pressure constant. The raw material temperature was raised to the target temperature of 2400 ° C., and crystals were grown on the substrate. The growth rate averaged about 1 mm / hour. The crucible temperature was measured using a two-color thermometer with an optical path having a diameter of 2 to 4 mm provided at the center of the felt covering the upper and lower parts of the crucible. The temperature at the bottom of the crucible was the raw material temperature, and the temperature at the top of the crucible was the seed temperature. The growth time was about 25 hours and the crystal height was about 25 mm.

From the grown crystal, a substrate having a {0001} plane orientation with a thickness of 0.4 mm was cut with a wire saw, washed and polished. It was confirmed by X-ray diffraction and X-ray topography that the substrates were all 4H type single crystals and no polycrystals were mixed. The polished substrate was etched with KOH, and the dislocation distribution was observed. The area division of the substrate is schematically shown in FIG. The entire substrate was divided into 5 mm squares with the center of the substrate as the center of the central 5 mm square mesh (No. 45). Only the mesh completely contained in the substrate was counted as a region (shaded portion in FIG. 1) except for a portion where the 5 mm square mesh was missing (03, 12 and the like) at the edge of the substrate. Within each region, the number of regions where dislocation pits exist at intervals of 5 μm or less were sequentially accumulated, and the percentage was calculated by dividing by the total mesh (one with no chip at the end). As a result, 9% was found to be a region containing dislocation pairs and dislocation sequences. The average dislocation density in the region without dislocation pairs and dislocation arrays was 3000 / cm ² . The substrate size was almost the same as the seed crystal and the diameter was 52 mm. The region containing the dislocation pairs and dislocation arrays in the seed crystal was 60%.

(Example 2)
As in Example 1, a substrate having a diameter of 70 mm was used as a seed crystal, and a crystal having a large crucible size was prepared and crystal growth was performed. The total dislocation density of the seed crystal is about 14000 / cm ² . The area containing dislocation pairs and dislocation trains was 80%. The seed crystal was immersed and etched in a KOH melt heated to about 530 ° C., and the etching time was adjusted so that the maximum diameter of one dislocation pit was about 10 μm. As a result, by observing the dislocation distribution similar to that in Example 1, it was found that 24% was a region including dislocation pairs and dislocation arrays. The average dislocation density in the region without dislocation pairs and dislocation arrays was 5000 / cm ² . The substrate size was about 72 mm in diameter.

(Example 3)
In the method described in Example 2, a crystal was created, the substrate was cut out from the surface, the surface was polished, and a SiC single crystal film was formed on the substrate surface with a commercially available CVD epitaxial growth apparatus for SiC in about 10 μm in 2 hours. The thickness was formed.
The plane orientation of the substrate was grown at an angle of 4 ° with respect to <0001>. The dislocation distribution on the surface of the epitaxially grown film was observed in the same manner as described in Example 1. As a result, 26% was found to be a region containing dislocation pairs and dislocation sequences. The average dislocation density in the region without dislocation pairs and dislocation arrays was 5500 / cm ² . The values for the dislocation pair and dislocation array regions were almost the same level as the dislocation distribution of the substrate, and the dislocation density in the portion without the dislocation array was slightly increased, but was almost the same value.

(Example 4)
The stability of 4H polytype during crystal growth was examined by changing the nitrogen content to be introduced by the method described in Example 1. The nitrogen content of single crystal SiC substrate was investigated by secondary ion mass spectrometry. Growth was performed 5 times under each condition. The number of times that crystalline polytypes other than 4H were observed in each case was one when the nitrogen atom was (1-4) × 10 ¹⁸ cm ^-3 and the nitrogen atom was (5-9). The case where ^{x10 18} cm ^{−3 was} contained was 0 times, and the case where nitrogen atoms were contained (1 to 9) × 10 ¹⁹ cm ⁻³ was once. Moreover, the conversion of the crystal type was not seen by the frequency | count. When the nitrogen atom was (5-9) × 10 ¹⁷ cm ⁻³ , it was 3 times.

(Example 5)
A substrate having a thickness of 1.1 mm with an inclination of 2 ° from the {0001} plane orientation was cut out from the crystal obtained by the method described in Example 1, and after polishing the surface, the surface was etched in the same manner to obtain the maximum pits. Conditions were set so that the diameter was 6 μm. Crystal growth was performed under the same conditions as in the example. From the grown crystal, a substrate having a {0001} plane orientation with a thickness of 0.4 mm was cut with a wire saw, washed and polished. As a result of evaluating the dislocation distribution by the same method, it was found that the region containing dislocation pairs and dislocation trains was 6%. The average dislocation density in the region without dislocation pairs and dislocation arrays was 1200 / cm ² . It was revealed that the dislocation distribution and dislocation density of the crystal can be further improved by repeating the crystal growth using the seed crystal in which the etch pits are formed a plurality of times.

(Comparative Example 1)
As a comparative example, a seed crystal was polished and then not etched (no etch pit) was used, and the crystal was grown in the same manner as in Example 1. Since the seed crystal uses the substrate adjacent to the seed crystal used in Example 1, the dislocation density and the dislocation distribution are considered to be almost the same level. From the grown crystal, a substrate having a {0001} plane orientation with a thickness of 0.4 mm was cut with a wire saw, washed and polished. As a result of observing the dislocation distribution in the same manner, the region containing the dislocation pairs and dislocation arrays on the substrate was 60%, which was almost equivalent to the initial state. The dislocation density in the region not including the dislocation pair and dislocation train was also 8000 / cm ² . Crystal growth was performed in the same manner as in Example 1. However, when etch pits were not formed in the seed crystal, almost no improvement in dislocation distribution was observed.

The figure explaining area division in the present invention The figure explaining formation of the etch pit in this invention The figure explaining coalescence of the adjacent etch pit in this invention Configuration diagram showing an example of a single crystal growth apparatus used in the manufacturing method of the invention

Explanation of symbols

1 Single crystal SiC seed crystal
2 Raw material for SiC powder
3 Graphite crucible
4 Graphite crucible lid
5 Double quartz tube
6 Support rod
7 Graphite felt
8 Work coil
9 Ar gas piping
10 Ar gas mass flow controller
11 Nitrogen gas piping
12 Mass flow controller for nitrogen gas
13 Vacuum exhaust system

Claims (7)

Sublimation recrystallization using a seed crystal in which etch pits having a maximum diameter of 3 μm or more and 20 μm or less are formed at the end of dislocations on the surface of the seed crystal having a total dislocation density of 12000 / cm ² or more and 30000 / cm ² or less. A method for producing a SiC single crystal, comprising growing single crystal SiC by a method . The method for producing a SiC single crystal according to claim 1, wherein the polytype of the seed crystal is 4H type or 6H type. The method for producing a SiC single crystal according to claim 1 or 2, wherein the seed crystal has a disc shape, and a diameter of the disc is more than 50 mm. The method for producing a SiC single crystal according to any one of claims 1 to 3, wherein a plane orientation of the seed crystal is [0001]. The method for producing a SiC single crystal according to any one of claims 1 to 3, wherein a plane orientation of the seed crystal has an angle of 0.5 ° to 10 ° from [0001]. The method for producing a SiC single crystal according to any one of claims 1 to 5, wherein the seed crystal has a thickness of 0.6 mm or more. A method for producing a SiC single crystal substrate, comprising cutting and polishing a SiC single crystal obtained by the method according to any one of claims 1 to 6.

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