JP2012136376A - Unit for liquid phase epitaxial growth of single crystal silicon carbide, and method for liquid phase epitaxial growth of single crystal silicon carbide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost required for liquid phase epitaxial growth of single crystal silicon carbide.SOLUTION: Each of the feed material 11 and the seed material 12 has a surface layer including polycrystalline silicon carbide whose crystal polymorph is 3C. Through Raman spectroscopic analysis, where the excitation wavelength of the surface layer is set at 532 nm, an LO (longitudinal optical) peak derived from polycrystalline silicon carbide whose crystal polymorph is 3C, is observed for each of the feed material 11 and the seed material 12. The absolute value of the shift amount from 972 cm-1 of the LO peak is smaller for the feed material 11 than that of the seed material 12.

Description

  The present invention relates to a unit for liquid crystal epitaxial growth of single crystal silicon carbide and a method for liquid phase epitaxial growth of single crystal silicon carbide using the same.

  Silicon carbide (SiC) can realize high temperature resistance, high voltage resistance, high frequency resistance, and high environmental resistance that cannot be realized by conventional semiconductor materials such as silicon (Si) and gallium arsenide (GaAs). It is believed that. For this reason, silicon carbide is expected as a semiconductor material for next-generation power devices and a semiconductor material for high-frequency devices.

  Conventionally, as a method for growing single crystal silicon carbide, for example, the following Patent Document 1 proposes a sublimation recrystallization method (an improved Rayleigh method). In this improved Rayleigh method, a seed material made of single-crystal silicon carbide is disposed in the low temperature side region in the crucible, and a raw material powder containing Si as a raw material is disposed in the high temperature side region. And after making the inside of a crucible into inert atmosphere, the raw material powder arrange | positioned in the high temperature side area | region is sublimated by heating to the high temperature of 1450 to 2400 degreeC. As a result, silicon carbide can be epitaxially grown on the surface of the seed material disposed in the low temperature region.

  However, the improved Rayleigh method is a method of growing silicon carbide crystals by providing a temperature gradient in the gas phase. For this reason, when the improved Rayleigh method is used, a large apparatus is required for epitaxial growth of silicon carbide, and process control of silicon carbide epitaxial growth becomes difficult. Therefore, there is a problem that the manufacturing cost of the silicon carbide epitaxial growth film is increased. Also, silicon carbide epitaxial growth in the gas phase is non-equilibrium. For this reason, there are problems that crystal defects are likely to occur in the formed silicon carbide epitaxially grown film and that the crystal structure is likely to be rough.

  As an epitaxial growth method of silicon carbide other than the modified Rayleigh method, for example, there is a metastable solvent epitaxy (MSE) method proposed in Patent Document 2 or the like, which is a method of epitaxially growing silicon carbide in a liquid phase. .

  In the MSE method, a seed material made of crystalline silicon carbide such as single crystal silicon carbide or polycrystalline silicon carbide and a feed material made of silicon carbide are opposed to each other with a small interval of, for example, 100 μm or less, and Si is interposed therebetween. A molten layer is interposed. And silicon carbide is epitaxially grown on the surface of the seed material by heat treatment in a vacuum high temperature environment.

  In this MSE method, it is considered that a silicon carbide epitaxial growth film is formed by the concentration gradient of carbon dissolved in the Si melt layer due to the difference between the chemical potential of the seed material and the chemical potential of the feed material. It has been. For this reason, unlike the case of using the improved Rayleigh method, it is not always necessary to provide a temperature difference between the seed material and the feed material. Therefore, when the MSE method is used, the silicon carbide epitaxial growth process can be easily controlled with a simple apparatus, and a high-quality silicon carbide epitaxial growth film can be stably formed.

In addition, an advantage that a silicon carbide epitaxial growth film can be formed on a seed substrate having a large area, and since the Si melt layer is extremely thin, carbon from the feed material is easily diffused, and the temperature of the epitaxial growth process of silicon carbide can be reduced. There is also an advantage.

  Therefore, the MSE method is considered to be an extremely useful method as an epitaxial growth method of single crystal silicon carbide, and research on the MSE method is actively conducted.

Japanese Patent Laid-Open No. 2005-97040 JP 2008-230946 A

  As described above, in the MSE method, it is considered that the feed material and the seed material need to be selected so that the free energy of the feed material is higher than the free energy of the seed material. For this reason, for example, Patent Document 2 describes that the free energy is made different between the feed substrate and the seed substrate by making the crystal polymorph of the feed substrate and the seed substrate different. Specifically, it is described that when the feed substrate is constituted by a polycrystalline 3C-SiC substrate, the seed substrate is constituted by a single crystal 4H-SiC substrate having a lower free energy than that of the 3C-SiC substrate. .

  Here, the polycrystalline 3C-SiC substrate can be easily manufactured by a CVD method. For this reason, as described in Patent Document 2, by using a 3C—SiC substrate as a feed substrate, the formation cost of the silicon carbide epitaxial growth film can be kept low.

  However, among silicon carbide substrates such as 4H—SiC substrates and 3C—SiC substrates, 3C—SiC substrates have the highest free energy. For this reason, it has been considered that a 3C—SiC substrate cannot be used as a seed substrate that requires low free energy. Therefore, in Patent Document 2, a single crystal 4H—SiC substrate that is difficult to manufacture and is expensive is used as a seed substrate, and there is a problem that the formation cost of the silicon carbide epitaxial growth layer is high.

  This invention is made | formed in view of the point which concerns, The objective is to reduce the cost required for the liquid phase epitaxial growth of a single crystal silicon carbide.

  As a result of diligent research, the present inventor has found that there are two types of polycrystalline silicon carbide materials whose crystal polymorph is 3C. It has been found that liquid phase epitaxial growth of single-crystal silicon carbide can be suitably performed by using as a seed material a material that does not easily elute into the silicon melt and as a feed material that easily elution into a silicon melt layer. As a result, the present inventor came to make the present invention.

That is, the single crystal silicon carbide liquid phase epitaxial growth unit according to the present invention is a unit of a seed material and a feed material used in a liquid crystal epitaxial growth method of single crystal silicon carbide. Each of the feed material and the seed material has a surface layer containing polycrystalline silicon carbide whose crystal polymorph is 3C. In each of the feed material and the seed material, an L0 peak derived from polycrystalline silicon carbide whose crystal polymorph is 3C is observed by Raman spectroscopic analysis with an excitation wavelength of 532 nm on the surface layer. The absolute value of the shift amount of the L0 peak from 972 cm ⁻¹ is smaller in the feed material than in the seed material. For this reason, while the seed material of the single crystal silicon carbide liquid phase epitaxial growth unit according to the present invention is relatively less likely to elute into the silicon melt layer, the feed material is relatively less likely to elute into the silicon melt layer. Are likely to occur. Therefore, by using the unit for single crystal silicon carbide liquid phase epitaxial growth according to the present invention, liquid phase epitaxial growth of single crystal silicon carbide can be suitably performed.

  In the present invention, since both the seed material and the feed material have a surface layer containing polycrystalline silicon carbide having a crystal polymorph of 3C, each of the seed material and the feed material is formed by CVD (Chemical It can be produced easily and inexpensively by the Vapor Deposition method.

  Therefore, according to the present invention, for example, compared with the case where the seed material has a surface layer made of 4H—SiC, 6H—SiC, or single crystal silicon carbide, the formation cost of the single crystal silicon carbide epitaxially grown film is reduced. Can be reduced.

In addition, when the absolute value of the shift amount from 972 cm ^{−1 of} the L0 peak is large, the elution to the silicon melt layer is difficult to occur because the internal stress in the surface layer increases and the surface layer becomes dense. it is conceivable that. On the other hand, when the absolute value of the shift amount is small, elution into the silicon melt layer is likely to occur because the internal stress in the surface layer becomes small and the denseness of the surface layer becomes low.

  Further, according to the present invention, it is possible to form an epitaxially grown film of hexagonal single crystal silicon carbide having excellent characteristics. This is because, by using a seed substrate with a high surface density, many of the crystal faces exposed on the surface of the surface have a shape similar to the hexagonal (0001) crystal face, and the hexagonal single crystal carbonization This is probably because the epitaxial growth of silicon proceeds suitably.

  In the present invention, the “liquid phase epitaxial growth method” means that a concentration gradient of graphite melted in the silicon melt layer is formed by heating the seed material and the feed material facing each other through the silicon melt layer. In addition, a single crystal silicon carbide is epitaxially grown on the seed material by the concentration gradient.

In the present invention, the “L0 peak derived from polycrystalline silicon carbide” is a peak derived from a longitudinal optical mode among optical modes that vibrate between two Si—C atoms in a silicon carbide crystal. In the case of 3C polymorphism, it is a peak that appears at 972 cm ⁻¹ .

  In the present invention, a “feed material” refers to a member that supplies a material for epitaxial growth of single crystal silicon carbide such as Si, C, and SiC. On the other hand, the “seed material” refers to a member in which single crystal silicon carbide grows on the surface.

From the viewpoint of enhancing the liquid-phase epitaxial growth rate of the single crystal silicon carbide, in the present invention, it is preferable absolute value of the shift amount from the L0 peak of 972 cm ^-1 in the feed material is less than 4 cm ^-1. It is preferable absolute value of the shift amount from the L0 peak of 972 cm ^-1 in the seed material is ^{4 cm -1} or more.

Moreover, it is preferable that the half value width of the L0 peak in the feed material is 7 cm ⁻¹ or more. It is preferable that the half width of the L0 peak in the seed material is 15 cm ⁻¹ or less.

In addition, when the half width of the L0 peak in the feed material is 7 cm ⁻¹ or more, the liquid phase epitaxial growth rate of the single crystal silicon carbide can be increased more as the half width of the L0 peak is larger. It is considered that the elution from the surface layer is more likely to occur because the crystallinity of the crystalline silicon carbide is low or the impurity concentration is high. On the other hand, when the full width at half maximum of the L0 peak in the seed material is 15 cm ⁻¹ or less, the liquid phase epitaxial growth rate of single crystal silicon carbide can be further increased because the smaller the full width at half maximum of the L0 peak, This is probably because the crystallinity of the crystalline silicon carbide is high or the impurity concentration is low, so that elution from the surface layer is less likely to occur.

  In at least one of the feed material and the seed material, the surface layer preferably contains polycrystalline silicon carbide having a crystalline polymorph of 3C as a main component, and is substantially made of polycrystalline silicon carbide having a crystalline polymorph of 3C. It is preferable to become. According to this configuration, the epitaxial growth rate of single crystal silicon carbide can be further effectively increased.

  In the present invention, the “main component” refers to a component contained by 50% by mass or more.

  In the present invention, “substantially consists of polycrystalline silicon carbide whose crystal polymorph is 3C” means that it contains no components other than impurities other than polycrystalline silicon carbide whose crystal polymorph is 3C. To do. Usually, the impurity contained in the case of “substantially consisting of polycrystalline silicon carbide whose crystal polymorph is 3C” is 5% by mass or less.

  At least one of the feed material and the seed material may include a support material and a polycrystalline silicon carbide film that is formed on the support material and forms a surface layer. In that case, the thickness of the polycrystalline silicon carbide film is preferably in the range of 30 μm to 800 μm.

  Further, at least one of the feed material and the seed material may be made of a polycrystalline silicon carbide material including polycrystalline silicon carbide whose crystal polymorph is 3C.

  The single-crystal silicon carbide liquid phase epitaxial growth method according to the present invention is a single-crystal silicon carbide liquid phase epitaxial growth method using the single crystal silicon carbide liquid phase epitaxial growth unit according to the present invention. In the liquid crystal epitaxial growth method of the single crystal silicon carbide according to the present invention, the single crystal is formed on the surface of the seed material by heating the surface layer of the seed material and the surface layer of the feed material with the silicon melt layer facing each other. Silicon carbide is epitaxially grown.

  According to this method, an epitaxially grown film of single crystal silicon carbide can be formed at low cost. Further, it is not always necessary to provide a temperature difference between the seed material and the feed material. Therefore, the single crystal silicon carbide epitaxial growth process can be easily controlled with a simple apparatus, and a high-quality single crystal silicon carbide epitaxial growth film can be stably formed.

  According to the present invention, the cost required for liquid phase epitaxial growth of single crystal silicon carbide can be reduced.

It is a schematic diagram for demonstrating the epitaxial growth method of the single crystal silicon carbide in one Embodiment of this invention. It is a schematic sectional drawing of the feed board | substrate in one Embodiment of this invention. 1 is a schematic cross-sectional view of a seed substrate in an embodiment of the present invention. It is a schematic sectional drawing of the feed board | substrate in a modification. It is schematic-drawing sectional drawing of the seed substrate in a modification. It is a graph showing the Raman spectroscopic analysis result of the surface layer of samples 1-4. It is a graph showing the shift amount (Δω) of the L0 peak from 972 cm ⁻¹ and the full width at half maximum (FWHM) of the L0 peak in samples 1 to 4. It is a graph which shows the growth rate of the single crystal silicon carbide epitaxial growth film in samples 1, 2 and 4. 5 is a graph showing the growth rate of single crystal silicon carbide epitaxial growth films in samples 3 and 4. FIG. It is a SEM photograph of a seed substrate (sample 3) after execution of a liquid phase epitaxial growth experiment in an example.

  Hereinafter, an example of the preferable form which implemented this invention is demonstrated. However, the following embodiments are merely examples. The present invention is not limited to the following embodiments.

  FIG. 1 is a schematic diagram for explaining an epitaxial growth method of single crystal silicon carbide in the present embodiment.

  In the present embodiment, an example of forming an epitaxially grown film of single crystal silicon carbide using the MSE method will be described.

  In the present embodiment, as shown in FIG. 1, a single crystal silicon carbide liquid phase epitaxial growth unit 14 having a seed substrate 12 as a seed material and a feed substrate 11 as a feed material in a container 10 is replaced with a seed substrate. The 12 main surfaces 12a and the main surface 11a of the feed substrate 11 are arranged to face each other with a silicon plate interposed therebetween. In this state, the seed substrate 12 and the feed substrate 11 are heated to melt the silicon plate. By doing so, the seed substrate 12 and the feed substrate 11 are opposed to each other with the silicon melt layer 13 therebetween. By maintaining this state, raw materials such as silicon, carbon and silicon carbide are eluted from the seed substrate 12 side into the silicon melt layer 13. As a result, a concentration gradient is formed in the silicon melt layer 13. As a result, single crystal silicon carbide is epitaxially grown on main surface 12a of seed substrate 12, and single crystal silicon carbide epitaxial growth film 20 is formed. In addition, the thickness of the silicon molten layer 13 is very thin, for example, can be about 10 μm to 100 μm.

  FIG. 2 shows a schematic cross-sectional view of the feed substrate 11. FIG. 3 shows a schematic cross-sectional view of the seed substrate 12. Each of the feed substrate 11 and the seed substrate 12 has a surface layer containing polycrystalline silicon carbide whose crystal polymorph is 3C. Specifically, as shown in FIGS. 2 and 3, in this embodiment, each of the feed substrate 11 and the seed substrate 12 includes a support material 11b, 12b made of graphite, and a polycrystalline silicon carbide film 11c, 12c. And have. The support materials 11b and 12b made of graphite have high heat resistance that can sufficiently withstand the epitaxial growth process of silicon carbide. Further, the support materials 11 b and 12 b made of graphite have a thermal expansion coefficient similar to that of the single crystal silicon carbide epitaxial growth film 20. Therefore, the silicon carbide epitaxial growth film 20 can be suitably formed by using the support materials 11b and 12b made of graphite.

  Specific examples of graphite include natural graphite, artificial graphite, petroleum coke, coal coke, pitch coke, carbon black, and mesocarbon. Examples of the method for producing the support material 12b made of graphite include the production method described in JP-A-2005-132711.

The polycrystalline silicon carbide films 11c and 12c are formed so as to cover the main surfaces and side surfaces of the support materials 11b and 12b. Polycrystalline silicon carbide films 11c and 12c contain polycrystalline silicon carbide. By the polycrystalline silicon carbide films 11c and 12c, the feed substrate 11 or the seed substrate 1
Two surface layers are formed. Note that the polycrystalline silicon carbide films 11c and 12c in the present embodiment preferably include polycrystalline 3C—SiC as a main component, and are preferably substantially composed of polycrystalline 3C—SiC. That is, in the present embodiment, each surface layer of the feed substrate 11 and the seed substrate 12 preferably contains polycrystalline 3C—SiC as a main component, and is preferably substantially made of polycrystalline 3C—SiC. By doing so, the growth rate of the single crystal silicon carbide epitaxial growth film 20 can be increased.

  Each of thicknesses t11 and t12 of polycrystalline silicon carbide films 11c and 12c is preferably in the range of 30 μm to 800 μm, more preferably in the range of 40 μm to 600 μm, and in the range of 100 μm to 300 μm. More preferably. If the thicknesses t11 and t12 of the polycrystalline silicon carbide films 11c and 12c are too thin, the support material 12b made of graphite is exposed when the single crystal silicon carbide epitaxial growth film 20 is formed, and is caused by elution from the support materials 11b and 12b. In some cases, a suitable single crystal silicon carbide epitaxial growth film 20 cannot be obtained. On the other hand, if the thicknesses t11 and t12 of the polycrystalline silicon carbide films 11c and 12c are too thick, cracks may easily occur in the polycrystalline silicon carbide film 12c.

  The method for forming the polycrystalline silicon carbide films 11c and 12c is not particularly limited. The polycrystalline silicon carbide film 12c can be formed by, for example, a CVD (Chemical Vapor Deposition) method or a sputtering method. In particular, in this embodiment, since the polycrystalline silicon carbide films 11c and 12c contain polycrystalline 3C-SiC, the dense polycrystalline silicon carbide films 11c and 12c can be easily and inexpensively formed by the CVD method.

In this embodiment, the absolute value of the shift amount from 972 cm ⁻¹ of the L0 peak derived from polycrystalline silicon carbide whose crystal polymorph is 3C, which is observed by Raman spectroscopic analysis with an excitation wavelength of 532 nm, is the feed substrate. The seed substrate 12 and the feed substrate 11 are configured such that the polycrystalline silicon carbide film 11c constituting the surface layer 11 is smaller than the polycrystalline silicon carbide film 12c constituting the surface layer of the seed substrate 12. ing.

  For this reason, the seed substrate 12 is relatively less likely to elute into the silicon melt layer 13, while the feed substrate 11 is relatively more likely to elute into the silicon melt layer 13. Therefore, by using the single crystal silicon carbide liquid phase epitaxial growth unit 14 of the present embodiment, the single crystal silicon carbide liquid phase epitaxial growth film 20 can be suitably formed. Moreover, both the seed substrate 12 and the feed substrate 11 have a surface layer containing polycrystalline silicon carbide whose crystal polymorph is 3C. Therefore, each of the seed substrate 12 and the feed substrate 11 can be easily and inexpensively manufactured by the CVD method. Therefore, compared with the case where the seed material has a surface layer made of 4H—SiC, 6H—SiC, or single crystal silicon carbide, the formation cost of the single crystal silicon carbide epitaxial growth film 20 can be reduced.

In addition, when the absolute value of the shift amount from the 972 cm ^{−1 of} the L0 peak is large, the elution to the silicon melt layer 13 is difficult to occur because the internal stress in the surface layer increases and the surface layer becomes dense. It is believed that there is. On the other hand, when the absolute value of the shift amount is small, elution into the silicon melt layer 13 is likely to occur because the internal stress in the surface layer is reduced and the denseness of the surface layer is reduced.

In addition, by using the single crystal silicon carbide liquid phase epitaxial growth unit 14 of the present embodiment, the hexagonal single crystal silicon carbide epitaxial growth film 20 having excellent characteristics can be formed. This is because, by using the seed substrate 12 having a high surface density, many of the crystal planes exposed on the surface of the surface layer have a shape similar to the hexagonal (0001) crystal plane, and a hexagonal single crystal This is considered to be because the epitaxial growth of silicon carbide proceeds suitably.

  A typical example of the hexagonal single crystal silicon carbide is single crystal silicon carbide whose crystal polymorph is 4H or 6H. Single crystal silicon carbide (4H-SiC, 6H-SiC) whose crystal polymorph is 4H or 6H has a wide band gap and excellent heat resistance compared to other crystal polymorphs of silicon carbide. There is an advantage that a semiconductor device can be realized.

From the viewpoint of enhancing the liquid-phase epitaxial growth rate of the single crystal silicon carbide, it is preferred that the absolute value of the shift amount from 972 cm ^-1 of the L0 peak in the feed substrate 11 is less than 4 cm ^-1. In this case, since elution from the feed substrate 11 to the silicon melt layer 13 is more likely to occur, it is considered that the liquid phase epitaxial growth rate can be further increased.

Further, it is preferable that the absolute value of the shift amount from 972 cm ^-1 of the L0 peak in the seed substrate 12 is ^{4 cm -1} or more. In this case, elution from the seed substrate 12 to the silicon melt layer 13 is less likely to occur, and it is considered that the liquid phase epitaxial growth rate can be further increased. The shift amount of from 972 cm ^-1 of the L0 peak in the seed substrate 12 is preferably ^{4 cm -1} or more.

In the feed substrate 11, the half width of the L0 peak is preferably 7 cm ⁻¹ or more. In this case, the epitaxial growth rate of single crystal silicon carbide can be further improved. This is presumably because the larger the half width of the L0 peak, the lower the crystallinity of the polycrystalline silicon carbide in the surface layer and the higher the impurity concentration, so that elution from the surface layer is more likely to occur.

On the other hand, in seed substrate 12, the half width of L0 peak is preferably 15 cm ⁻¹ or less. In this case, the epitaxial growth rate of single crystal silicon carbide can be further improved. This is because, as the half-value width of the L0 peak is smaller, the crystallinity of polycrystalline silicon carbide in the surface layer of the seed substrate 12 is higher or the impurity concentration is lower, so that elution from the surface layer of the seed substrate 12 is less likely to occur. This is probably because of this.

  Therefore, the half width of the L0 peak in the feed substrate 11 is preferably smaller than the half width of the L0 peak in the seed substrate 12.

  In the above-described embodiment, an example in which each of the feed substrate 11 and the seed substrate 12 is configured by the support materials 11b and 12b and the polycrystalline silicon carbide films 11c and 12c has been described. However, the present invention is not limited to this configuration. For example, as shown in FIGS. 4 and 5, each of the feed substrate 11 and the seed substrate 12 may be formed of a polycrystalline silicon substrate containing polycrystalline silicon carbide.

  The silicon carbide substrate can be produced, for example, by coating a graphite base material with polycrystalline silicon carbide by a CVD method and then mechanically or chemically removing the graphite. The silicon carbide substrate can also be produced by reacting a graphite material with a silicate gas to convert the graphite material into silicon carbide. The silicon carbide substrate can also be produced by adding a sintering aid to silicon carbide powder and sintering at a high temperature of 1600 ° C. or higher.

  Hereinafter, the present invention will be further described based on specific examples, but the present invention is not limited to the following specific examples.

(Production Example 1)
A graphite material (15 mm × 15 mm × 2 mm) made of high purity isotropic graphite material having a bulk density of 1.85 g / cm ³ and an ash content of 5 ppm or less was used as a base material. This base material was put in a CVD reactor, and a polycrystalline silicon carbide film having a thickness of 30 μm was formed on the base material by a CVD method to prepare Sample 1. Note that silicon tetrachloride and propane gas were used as the source gas. Film formation was performed at normal pressure and 1200 ° C. The deposition rate was 30 μm / h.

(Production Example 2)
A sample 2 was produced by forming a 50 μm polycrystalline silicon carbide film on the surface of the graphite material in the same manner as in Production Example 1 except that the reaction temperature was 1400 ° C. and the film formation rate was 60 μm / h. .

(Production Example 3)
Polycrystalline 50 μm on the surface of the graphite material in the same manner as in Preparation Example 1 except that the reaction temperature was 1250 ° C., the film formation rate was 10 μm / h, and CH ₃ SiCl ₃ was used instead of silicon tetrachloride. A silicon carbide coating was formed to prepare Sample 3.

(Production Example 4)
Graphite was prepared in the same manner as in Preparation Example 1 except that dichlorosilane (SiH ₂ Cl ₂ ) and acetylene were used instead of silicon tetrachloride and propane gas, the reaction temperature was 1300 ° C., and the film formation rate was 10 μm / h. A sample 4 was prepared by forming a 50 μm polycrystalline silicon carbide coating on the surface of the material. In Sample 4, the thickness of the polycrystalline silicon carbide film was about 1 mm.

(Raman spectroscopy analysis)
The Raman spectroscopic analysis of the surface layer of the samples 1 to 4 prepared above was performed. In the Raman spectroscopic analysis, an excitation wavelength of 532 nm was used. The measurement results are shown in FIG.

Next, from the measurement results shown in FIG. 6, the shift amount (Δω) of the L0 peak from 972 cm ⁻¹ and the full width at half maximum (FWHM) of the L0 peak in samples 1 to 4 were obtained. The results are shown in FIG.

As shown in FIG. 7, samples 3 and 4 had an absolute value of Δω of 4 cm ⁻¹ or more and FWHM of 7 cm ⁻¹ or more. On the other hand, Samples 1 and 2 were 7 cm ⁻¹ or more in the same way as Samples 3 and 4 with respect to FWHM, but the absolute value of Δω was less than 4 cm ⁻¹ .

(Growth rate evaluation of single crystal silicon carbide liquid phase epitaxial growth film)
Using the liquid phase epitaxial growth method described in the above embodiment, a single crystal silicon carbide epitaxial growth film 20 was produced under the following conditions using Samples 1 to 4 as a feed substrate. And the thickness of the silicon carbide epitaxial growth film | membrane 20 was measured by observing the cross section of the silicon carbide epitaxial growth film | membrane 20 using an optical microscope. The growth rate of the single crystal silicon carbide epitaxial growth film 20 was determined by dividing the measured thickness by the time during which the silicon carbide epitaxial growth was performed.

  The results are shown in FIGS. 8 and 9, the vertical axis represents the growth rate of the single crystal silicon carbide epitaxial growth film 20, and the horizontal axis represents the reciprocal (1 / L) of the thickness (L) of the silicon melt layer 13.

From the results shown in FIGS. 8 and 9, the smaller the absolute value of Δω, the higher the growth rate of the single crystal silicon carbide epitaxial growth film 20. From this result, it can be seen that the smaller the absolute value of Δω, the easier the elution into the silicon melt layer occurs.

(Measurement conditions of growth rate of single crystal silicon carbide epitaxial growth film 20)
Seed substrate: silicon carbide substrate with crystal polymorph 4H atmosphere pressure: 10 ⁻⁶ to 10 ⁻⁴ Pa
Atmospheric temperature: 1900 ° C

(Example)
Using the sample 1 prepared as the feed substrate 11 and the sample 3 prepared as the seed substrate 12, a liquid crystal epitaxial growth experiment of single crystal silicon carbide was performed under the same conditions as the growth rate evaluation experiment. Thereafter, a scanning electron microscope (SEM) photograph of the surface of the sample 3 as the seed substrate 12 was taken. An SEM photograph of the surface of Sample 3 is shown in FIG. From the photograph shown in FIG. 10, it can be seen that a hexagonal single crystal silicon carbide epitaxially grown film can be obtained by using the sample 3 having a large absolute value of Δω as the seed substrate 12.

DESCRIPTION OF SYMBOLS 10 ... Container 11 ... Feed substrate 11a ... Main surface 11b ... Support material 11c ... Polycrystalline silicon carbide film 12 ... Seed substrate 12a ... Main surface 12b ... Support material 12c ... Polycrystalline silicon carbide film 13 ... Silicon molten layer 14 ... Single crystal Silicon carbide liquid phase epitaxial growth unit 20 ... single crystal silicon carbide epitaxial growth film

Claims (11)

A unit of a seed material and a feed material used in a liquid phase epitaxial growth method of single crystal silicon carbide,
Each of the feed material and the seed material has a surface layer containing polycrystalline silicon carbide whose crystal polymorph is 3C,
By the Raman spectroscopic analysis of the surface layer with an excitation wavelength of 532 nm, an L0 peak derived from polycrystalline silicon carbide whose crystal polymorph is 3C is observed, and the absolute value of the shift amount of the L0 peak from 972 cm ⁻¹ is A unit for single-crystal silicon carbide liquid phase epitaxial growth in which the feed material is smaller than the seed material. The absolute value of the shift amount from 972 cm ^-1 of the L0 peaks in the feed material is less than 4 cm ^-1, monocrystalline silicon carbide liquid phase epitaxial growth unit as claimed in claim 1. The absolute value of the shift amount from the L0 peak of 972 cm ^-1 is 4 cm ^-1 or more, single crystal silicon carbide liquid phase epitaxial growth unit as claimed in claim 1 or 2 in the seed material. The single crystal silicon carbide liquid phase epitaxial growth unit according to any one of claims 1 to 3, wherein a half width of the L0 peak in the feed material is 7 cm ^-1 or more. The single crystal silicon carbide liquid phase epitaxial growth unit according to any one of claims 1 to 4, wherein a half width of the L0 peak in the seed material is 15 cm ^-1 or less.   6. The single-crystal silicon carbide according to claim 1, wherein in at least one of the feed material and the seed material, the surface layer includes polycrystalline silicon carbide having a crystal polymorphism of 3C as a main component. Unit for liquid phase epitaxial growth.   The unit for single-crystal silicon carbide liquid phase epitaxial growth according to claim 6, wherein the surface layer of at least one of the feed material and the seed material is substantially made of polycrystalline silicon carbide having a crystal polymorphism of 3C.   At least one of the feed material and the seed material includes a support material and a polycrystalline silicon carbide film that is formed on the support material and forms the surface layer. The single crystal silicon carbide liquid phase epitaxial growth unit according to claim 1.   The single crystal silicon carbide liquid phase epitaxial growth unit according to claim 8, wherein the polycrystalline silicon carbide film has a thickness in a range of 30 μm to 800 μm.   8. The single material according to claim 1, wherein at least one of the feed material and the seed material is made of a polycrystalline silicon carbide material including polycrystalline silicon carbide having a crystal polymorphism of 3C. Crystalline silicon carbide liquid phase epitaxial growth unit. A method for liquid phase epitaxial growth of single crystal silicon carbide using the unit for liquid crystal epitaxial growth of single crystal silicon carbide according to any one of claims 1 to 10,
A liquid crystal of single crystal silicon carbide that epitaxially grows single crystal silicon carbide on the surface layer of the seed material by heating the surface layer of the seed material and the surface layer of the feed material through a silicon melt layer. Phase epitaxial growth method.