JP4962074B2 - Silicon carbide single crystal manufacturing apparatus and manufacturing method - Google Patents

Description

  The present invention relates to an apparatus and a method for manufacturing a silicon carbide single crystal.

  Since silicon carbide single crystal has characteristics of high breakdown voltage and high electron mobility, it is expected as a semiconductor substrate for power devices. For the growth of a silicon carbide single crystal, a single crystal growth method generally called a sublimation method (improved Rayleigh method) is used. As disclosed in Patent Document 1, in order to continuously produce high-quality crystals, a technique of epitaxially growing a silicon carbide single crystal by a CVD method is used in a temperature range used in a sublimation method.

  However, in this growth method, since a raw material gas in which a gas containing Si and a gas containing C is mixed in advance is introduced into the susceptor that has been heated to a high temperature, the susceptor inlet or the like is in the vicinity of the susceptor. Also in the gas passage for introducing the raw material gas, the mixed raw material gas reacts to generate SiC crystals, which are deposited on the inner wall of the gas passage. For this reason, there is a problem that the gas passage is blocked, the raw material gas cannot be introduced into the susceptor, and the silicon carbide single crystal cannot be continuously grown.

  Therefore, as a technique for solving this problem, a technique described in Patent Document 2 and a technique described in Non-Patent Document 1 have been proposed.

  In the technique described in Patent Document 2, a double-structure gas introduction pipe having coaxially arranged introduction pipes is installed, and a raw material gas (silane, chlorosilane, propane, methane) for growing SiC from the inner introduction pipe is used. , Ethylene, etc.) and a carrier gas (helium, argon, etc.) is introduced from the outer introduction pipe, and the source gas is surrounded by the carrier gas and the chamber in which the seed crystal is installed By introducing into the gas passage, the contact between the source gas and the gas passage is suppressed, and the deposition of the product on the inner wall of the gas passage is suppressed.

On the other hand, in the technique described in Non-Patent Document 1, a double structure gas introduction pipe in which introduction pipes are coaxially arranged is installed, and propane (C ₃ H ₈ as a gas containing C is introduced from the inner introduction pipe. ) And hydrogen gas (H ₂ ) are introduced, and chlorosilane (SiCl ₄ ) and argon gas (Ar) as gas containing Si are introduced from the outer introduction pipe. This is because the gas containing C and the gas containing Si are separately introduced to prevent the reaction between the gas containing C and the gas containing Si in the gas passage, and the generation of deposits. I try to prevent.
Japanese National Patent Publication No. 11-508531 JP-T-2001-501161 S. Nigam (Carnegie Mellon Univ.), Journal of Crystal Growth 284 (2005) 112-122

  However, the techniques described in Patent Document 2 and Non-Patent Document 1 have a problem that the crystal growth rate of the silicon carbide single crystal is low as described below.

  That is, in the technique described in Patent Document 2, a large amount of carrier gas is introduced in order to sufficiently suppress contact of the raw material gas with the gas passage by setting the raw material gas surrounded by the carrier gas. There is a need. For this reason, the carrier gas is excessively supplied with respect to the raw material gas, and the partial pressure of the raw material gas in the entire gas that reaches the seed crystal is lowered, so that the growth rate of the silicon carbide single crystal is low. Occurs.

In the technique described in Non-Patent Document 1, only chlorosilane (SiCl ₄ ) is used as a gas containing Si, and chlorosilane is stable in a state of SiCl ₂ or the like even at a high temperature of 2100 ° C. or higher. Since there is little generation of gases such as SiC ₂ , Si ₂ C, and Si that are considered to contribute directly to SiC growth, it is difficult to contribute to SiC growth, so the Si concentration in the source gas that reaches the seed crystal Becomes substantially low. For this reason, the problem that the growth rate of a silicon carbide single crystal is low arises.

  Thus, conventionally, it has been difficult to produce a silicon carbide single crystal by a method that does not cause clogging in the gas passage and can be continuously grown at a high speed.

  In view of the above points, the present invention is capable of producing a high-quality silicon carbide single crystal by a method capable of continuous high-speed growth while preventing clogging of gas passages that occur during continuous growth of the silicon carbide single crystal. An object of the present invention is to provide an apparatus and a method for producing a silicon carbide single crystal that can be produced.

  In order to achieve the above object, the present invention provides a silicon carbide single crystal manufacturing apparatus including a gas introduction pipe (30) for introducing a raw material gas into a reaction vessel, and the gas introduction pipe is arranged on the inner side. An introduction pipe (31) and an outer introduction pipe (32) arranged coaxially outside the inner introduction pipe, and a gas containing silane and C as a gas containing Si from the inner introduction pipe or The first feature is that these dilution gases are introduced into the reaction vessel, and chlorosilane as a gas containing Si or its dilution gas is introduced into the reaction vessel from the outer introduction pipe.

  In the first feature of the present invention, silane and chlorosilane are employed as the gas containing Si. Here, silane decomposes at a relatively low temperature to generate hydrogen, which accelerates the decomposition of chlorosilane. Therefore, when silane and chlorosilane are mixed and introduced into the reaction vessel together with the gas containing C, chlorosilane is decomposed in the gas passage to the reaction vessel, so that a large amount of Si is generated, and this generates C. SiC reacts with the contained gas and is deposited on the inner wall of the gas passage. If this is continued, the gas passage is blocked, and steady crystal growth cannot be sustained.

  In contrast, in the first feature of the present invention, silane is introduced from the inner introduction pipe (31) of the gas introduction pipe (30) so as to separate silane and chlorosilane as much as possible, and the outer introduction pipe (32). Therefore, the decomposition of chlorosilane in the gas passage to the reaction vessel can be suppressed. Thereby, the production | generation of SiC by decomposition | disassembly of chlorosilane can be suppressed.

  In the first feature of the present invention, since chlorosilane is allowed to flow on the outer peripheral side of the silane, the chlorosilane prevents the gas introduced from the inner introduction pipe from contacting the inner wall of the gas passage, and the chlorosilane is etched by SiC. By acting as a gas, it can be expected to suppress the deposition of SiC on the inner wall of the gas passage.

  From these facts, according to the first feature of the present invention, it is possible to prevent clogging of the gas passage that occurs during the continuous growth of the silicon carbide single crystal.

  Further, in the first feature of the present invention, the chlorosilane as the gas containing Si is caused to flow outside the mixed gas of the gas containing silane and the gas containing C as the gas containing Si. As described above, the concentration (partial pressure) of the source gas in the entire gas reaching the seed crystal can be increased as compared with the technique described in Patent Document 2 in which an excessive carrier gas needs to flow on the outer periphery of the source gas.

  In the first feature of the present invention, chlorosilane is introduced into the reaction vessel from the outer introduction pipe, a gas having C is introduced from the inner introduction pipe, and silane as a Si-containing gas is further introduced from the inner introduction pipe. Therefore, as described above, as compared with the technique described in Non-Patent Document 1, which employs only chlorosilane that does not easily contribute to the growth of SiC as the gas containing Si, the Si concentration in the source gas Can be high.

  From these facts, according to the first feature of the present invention, compared to the techniques described in Patent Document 2 and Non-Patent Document 1, continuous high-speed growth of a silicon carbide single crystal is possible.

  Regarding the first feature of the present invention, as a result of investigation of the amount of product deposited on the inner wall of the gas passage by the present inventor, the distance from the tip of the gas introduction pipe to the reaction vessel is 0 mm or more and 500 mm or less. It was found that when the flow rate ratio of the gas flowing through the inner introduction pipe and the outer introduction pipe was 1/3 or more and 3 or less, the amount of accumulated product was very small.

  Therefore, the gas introduction pipe is arranged at a position where the distance from the tip to the reaction vessel is 0 mm or more and 500 mm or less, and the flow rate ratio of the gas flowing through the inner introduction pipe and the outer introduction pipe is 1/3 or more and 3 or less. It is preferable that

  In the present invention, the silicon carbide single crystal manufacturing apparatus further includes a gas introduction pipe (40) for introducing the raw material gas into the reaction vessel, and the gas introduction pipes are coaxial in order from the inside toward the outside. A first introduction pipe (41), a second introduction pipe (42), and a third introduction pipe (43), wherein a gas having C is introduced into the reaction vessel from the first introduction pipe; A gas containing Si is introduced into the reaction vessel from the introduction tube, and an inert gas is introduced into the reaction vessel from the second introduction tube located between the first introduction tube and the third introduction tube. Is the second feature.

  According to this, for the purpose of preventing generation of SiC that causes clogging in the gas passage, the gas containing Si is separated from the gas containing Si and the gas containing C as much as possible. Since the source gas can be introduced into the reaction vessel with an inert gas inserted between the gas containing C and the gas containing C, the gas containing Si and the gas containing C in the gas passage Reaction can be suppressed and the production | generation of SiC can be suppressed.

  In this case, in the technique described in Non-Patent Document 1 described above, the gas containing C may be mixed with the gas containing Si immediately after being blown out from the gas introduction pipe. Even after being blown out from the tube, since an inert gas is inserted between the gas containing C and the gas containing Si, the gas containing C and the gas containing Si are separated. It becomes possible.

  Further, in this case, the amount of inert gas required to suppress the generation of SiC in the gas passage is small compared with the technique described in Patent Document 2 described above, and thus the seed crystal is reached. The concentration (partial pressure) of the source gas in the entire gas can be increased.

  Therefore, according to the second feature of the present invention, it is possible to prevent the gas passage from being blocked during the continuous growth of the silicon carbide single crystal, and compared with the technique described in Patent Document 2, Continuous high-speed growth is possible.

  Regarding the second feature of the present invention, it is preferable to employ He as the inert gas. He is an inert gas that has a high rectification property and is less likely to be turbulent, and separates a gas containing Si and a gas containing C while being blown out of the gas introduction pipe and reaching the reaction vessel. It is because the effect to do is high.

  In addition, regarding the second feature of the present invention, as a result of the investigation of the amount of product deposited on the inner wall of the gas passage by the present inventor, the distance from the tip of the gas introduction pipe to the reaction vessel is 0 mm or more and 500 mm or less. Thus, it was found that when the ratio of the largest flow rate to the smallest flow rate among the flow rates of the gas flowing through the first to third introduction pipes is 1 or more and 3 or less, the amount of product deposited is very small.

  Therefore, the gas introduction pipe is arranged at a position where the distance from the tip to the reaction vessel is 0 mm or more and 500 mm or less, and has the largest flow velocity and the smallest flow velocity among the flow velocity of the gas flowing through each of the first to third introduction tubes. The ratio is preferably set to 1 or more and 3 or less.

  Moreover, regarding the first and second features of the present invention, for example, it is preferable to dispose the gas introduction tube at a position where the distance from the tip to the reaction vessel is 20 mm or more. If this distance is less than 20 mm, the temperature of the gas introduction pipe becomes too high because it is too close to the reaction vessel heated at a high temperature, and carbon is generated in the gas introduction pipe and the gas introduction pipe is blocked. Because.

  Further, in the present invention, in the method for producing a silicon carbide single crystal, as the gas introduction pipe (30) for introducing the raw material gas into the reaction vessel, the inner introduction pipe (31) disposed on the inner side, and the inner introduction pipe A gas introduction pipe (30) having an outer introduction pipe (32) arranged coaxially on the outside is used, and silane and C-containing gas as Si-containing gas or their dilution gas is reacted from the inner introduction pipe. The third feature is that, while being introduced into the vessel, chlorosilane or a diluted gas thereof as a gas containing Si is introduced into the reaction vessel from the outer introduction pipe. According to this, there exists an effect similar to the 1st characteristic of this invention.

  Also in the third feature of the present invention, as in the first feature, the gas introduction tube is arranged such that the distance from the tip to the reaction vessel is 0 mm or more and 500 mm or less, and flows through the inner introduction tube and the outer introduction tube, respectively. The gas flow rate ratio is preferably 1/3 or more and 3 or less.

  Moreover, in this invention, in the manufacturing method of a silicon carbide single crystal, it is the 1st introduction | transduction arrange | positioned in order coaxially from the inner side to the outer side as the gas introduction pipe | tube (40) for introduce | transducing source gas into a reaction container. Using the gas introduction pipe (40) having the pipe (41), the second introduction pipe (42) and the third introduction pipe (43), the gas having C is introduced into the reaction vessel from the first introduction pipe, and the third introduction A fourth feature is that a gas containing Si is introduced into the reaction vessel from the tube, and an inert gas is introduced into the reaction vessel from the second introduction tube located between the first introduction tube and the third introduction tube. Yes. According to this, the same effect as the second feature of the present invention can be obtained.

  In the fourth feature of the present invention, as in the second feature, it is preferable to use He as the inert gas, and the gas introduction pipe is arranged so that the distance from the tip to the reaction vessel is 0 mm or more and 500 mm or less. Of the gas flow rates flowing through the first to third introduction pipes, the ratio of the largest flow rate to the smallest flow rate is preferably 1 or more and 3 or less.

  Further, regarding the third and fourth features of the present invention, for example, it is preferable to dispose the gas introduction tube at a position where the distance from the tip to the reaction vessel is 20 mm or more.

  In addition, the code | symbol in the bracket | parenthesis of each means described in the claim and this column is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

(First embodiment)
In FIG. 1, the schematic sectional drawing of the manufacturing apparatus of the silicon carbide single crystal in 1st Embodiment of this invention is shown.

  As shown in FIG. 1, the silicon carbide single crystal manufacturing apparatus includes a vacuum vessel 10 that is cylindrical and arranged in an upright state. The vacuum container 10 is made of, for example, quartz. A cylindrical first heat insulating material 11 covering the inner wall of the vacuum vessel 10 is disposed inside the vacuum vessel 10, and a cylindrical reaction vessel 12 is further erected inside the first heat insulating material 11. Is arranged in.

  The reaction vessel 12 constitutes a space in which the supplied source gas reacts to grow a single crystal. For example, the reaction vessel 12 includes a cylindrical portion 13 forming a side wall portion and a circular plate material 14 forming a bottom portion. The cylindrical part 13 is installed on the plate material 14. Note that the side wall portion and the bottom portion may be integrally formed. The reaction vessel 12 is made of, for example, graphite, tantalum carbide, or a graphite member coated with tantalum carbide.

  A graphite pedestal 15 is installed above the reaction vessel 12, and a silicon carbide single crystal substrate 16 serving as a seed crystal is attached to the lower surface thereof. The silicon carbide single crystal substrate 16 becomes a seed crystal, and the silicon carbide single crystal 17 grows inside the reaction vessel 12.

  The pedestal 15 is connected and supported by the pipe material 18. The pipe material 18 extends in the vertical direction. A rotating / vertical moving mechanism (not shown) is installed at the upper end portion of the pipe material 18, and the pipe material 18 can be rotated and vertically moved (lifted / lowered) by this mechanism.

  Inside the first heat insulating material 11, for example, a cylindrical second heat insulating material 19 is disposed below the reaction vessel 12. Inside the second heat insulating material 19, a raw material gas supply passage 19 a is formed as a gas passage leading to the opening 14 a provided in the plate material 14, and the raw material gas flows from here toward the upper reaction vessel 12. Supplied (introduced). The diameter of the source gas supply passage 19a is, for example, 10 mm to 100 mm.

  Further, a baffle plate 20 for the purpose of stirring and heating the supplied raw material gas is disposed below the inside of the reaction vessel 12 so as to extend in the horizontal direction. The center of silicon carbide single crystal substrate (seed crystal) 13, the center of source gas supply passage 19 a of second heat insulating material 19, and the center of baffle plate 20 coincide. When the source gas supplied from the source gas supply passage 19a hits the baffle plate 20, the source gas is agitated and heat-exchanged with the baffle plate 20, thereby promoting the mixing of the source gas and the transfer of heat to the source gas. The The baffle plate 20 is made of, for example, tantalum carbide or a graphite member coated with tantalum carbide.

  In addition, high frequency induction coils (RF coils) 21 and 22 are wound around the outer periphery of the vacuum vessel 10. Of the high-frequency induction coils, upper coil 21 located on the upper side is roughly arranged to face a range in which silicon carbide single crystal substrate (seed crystal) 13 moves in the height direction when silicon carbide single crystal 17 is grown. In addition, by energizing the upper coil 21, the silicon carbide single crystal substrate (seed crystal) 16 can be heated during growth.

  Further, among the high frequency induction coils, the lower coil 22 positioned on the lower side is roughly arranged to face the lower half side of the reaction vessel 12, and by energizing the lower coil 22, the reaction vessel 12 and The baffle plate 20 is heated so that the raw material gas passing therethrough can be heated. The upper and lower coils 21 and 22 are controlled to be independently energized.

  Further, the manufacturing apparatus of the present embodiment includes an exhaust system for discharging the raw material gas that has not contributed to the growth, and adjusts the opening degree of a discharge valve to a pump (not shown) provided in the exhaust system. Thus, the atmospheric pressure in the manufacturing apparatus can be adjusted to be constant.

  In addition, the manufacturing apparatus according to the present embodiment includes a gas introduction pipe 30 disposed inside the source gas supply passage 19 a of the second heat insulating material 19. Source gas is introduced into the reaction vessel 12 from the gas introduction pipe 30 through the source gas supply passage 19a.

  FIG. 2 is a sectional view taken along line AA in FIG. As shown in FIG. 2, the gas introduction pipe 30 has an inner introduction pipe 31 arranged on the inner side and an outer introduction pipe 32 arranged coaxially on the outer side of the inner introduction pipe. It has a structure consisting of two layers. An inner gas passage is constituted by the inner wall of the inner introduction pipe 31, and an outer gas passage is constituted by the outer wall of the inner introduction pipe 31 and the inner wall of the outer introduction pipe 32. In the present embodiment, the inner introduction tube 31 has a cylindrical shape, and the outer introduction tube 32 has a cylindrical shape that concentrically surrounds the inner introduction tube 31.

  The opening diameters of the inner introduction pipe 31 and the outer introduction pipe 32 can be adjusted by the diameter and thickness of the pipe. The optimum value of the opening diameter of the pipe varies depending on the gas flow rate. For example, the opening diameter of the inner introduction pipe 31 = Φ1 to 20 mm, and the opening diameter of the outer introduction pipe 32 = (outer diameter of the inner introduction pipe 31) +1. ~ 20 mm.

  Further, as shown in FIG. 1, in the gas introduction pipe 30, the distal end of the inner introduction pipe 31 and the distal end of the outer introduction pipe 32 are at the same position on the distal end side (upper end portion in FIG. 1) serving as a gas outlet. And the distance L from the front end of the gas introduction pipe 30 to the lower end of the plate material 14 of the reaction vessel 12 is L = 20 to 500 mm. The inner introduction pipe 31 and the outer introduction pipe 32 are preferably made of a heat resistant material such as a refractory metal.

  Next, a method for manufacturing a silicon carbide single crystal using the manufacturing apparatus having the above-described configuration will be described.

  In the manufacturing apparatus having the configuration shown in FIG. 1, the pressure in the vacuum vessel 10 is controlled to be constant within a range of 1 to 100 Kpa, and the upper and lower coils 21 and 22 are set to a temperature at which the silicon carbide single crystal 17 is generated. Thus, the seed crystal 16 is heated, and the reaction vessel 12 and the baffle plate 20 are heated to a temperature at which silicon carbide is not deposited. These temperatures vary depending on conditions such as the partial pressure of the source gas to be supplied, and are set in the range of 2000 to 2700 ° C., for example. In the present embodiment, as shown in FIG. 1, the temperature of the reaction vessel 12 gradually increases from the upper side of the reaction vessel 12 to the lower side, that is, as it moves away from the seed crystal 16. Heat to have a temperature gradient.

Then, a gas containing Si and a gas containing C as a raw material gas are introduced into the reaction vessel 12 in the heated state from the gas introduction pipe 30 through the raw material gas supply passage 19a. In this embodiment, a mixed gas of silane (for example, SiH ₄ ) as a gas containing Si, propane (C ₃ H ₈ ) as a gas having C, and hydrogen (H ₂ ) as a carrier gas is used. It introduces from the inner introduction pipe 31. In addition, chlorosilane (for example, SiCl ₄ ) as a gas containing Si and He as a carrier gas are introduced from the outer introduction pipe 32 surrounding it. The flow rate of each gas is, for example, as follows.

SiH ₄ = 0.1-3 slm (introduced from the inner introduction pipe 31)
C ₃ H ₈ = 0.1 to 2 slm (introduced from the inner introduction pipe 31)
H ₂ = 0.1-20 slm (introduced from the inner introduction pipe 31)
SiCl ₄ = 0.1-3 slm (introduced from the outer introduction pipe 32)
He = 0.1-20 slm (introduced from the outer introduction pipe 32)
It is.

Here, silane is represented by Si _n H _{2n + 2} (n is an arbitrary number), and chlorosilane is obtained by substituting H of silane with Cl. Therefore, Si ₂ H ₆ can be used as the silane in addition to SiH ₄ , and SiHCl ₃ or SiH ₂ Cl ₂ can be used as the chlorosilane in addition to SiCl ₄ .

  Further, since it is desirable that these gases form a laminar flow in the raw material gas supply passage 19a, in this embodiment, the ratio of the flow rate of the inner introduction pipe 31 and the flow rate of the outer introduction pipe 32 is 1/3 or more. The diameter and thickness of the pipe are adjusted in advance and the gas flow rate is adjusted so as to be 3 or less.

  Thereby, the mixed gas blown out from the inner introduction pipe 31 and the chlorosilane blown out from the outer introduction pipe 32 each flow in the raw material gas supply passage 19a as a laminar flow, and then the inside of the reaction vessel 12 Then, by contacting the baffle plate 20, the reaction proceeds by mixing and heating, and the silicon carbide single crystal 17 grows on the silicon carbide single crystal substrate 16 at a growth rate of, for example, 0.1 to 10 mm / h. .

  When silicon carbide single crystal 17 is grown, silicon carbide single crystal substrate 16 as a seed crystal is formed by pipe material 18 in a direction opposite to the growth direction of silicon carbide single crystal 17. Move at the same rate as the growth rate. Further, the source gas that has not contributed to the growth is exhausted to the exhaust system. In this way, the silicon carbide single crystal 17 having excellent quality is continuously grown.

  Next, main features of the present embodiment will be described.

In the present embodiment, a gas introduction tube 30 having a coaxial two-layer structure is used, and a mixed gas of silane (for example, SiH ₄ ), propane (C ₃ H ₈ ), and hydrogen (H ₂ ) is disposed on the inner side. While introducing into the reaction vessel 12 from the introduction tube 31, a mixed gas of chlorosilane (for example, SiCl ₄ ) and He is introduced into the reaction vessel 12 from the outer introduction tube 32 surrounding the introduction vessel 31. .

  Here, silane decomposes at a relatively low temperature to generate hydrogen, which accelerates the decomposition of chlorosilane. Therefore, when silane and chlorosilane are mixed and introduced into the reaction vessel 12 together with propane, chlorosilane is decomposed in the gas passage to the reaction vessel 12, that is, in the gas introduction pipe 30 and the gas supply passage 19a. As a result, a large amount of Si is generated, and SiC reacts with propane to generate SiC, and SiC is deposited on the inner walls of the gas introduction pipe 30 and the gas supply passage 19a. If this is continued, the gas introduction pipe 30 and the gas supply passage 19a are closed, and steady crystal growth cannot be maintained.

As a countermeasure, a method using only chlorosilane as a raw material gas without introducing silane as a hydrogen generation source is also conceivable, but in this case, SiC ₂ , Si required for the desired SiC crystal growth There is a drawback that it is difficult to generate gas species such as ₂ C and Si, and the growth rate cannot be increased.

  On the other hand, according to this embodiment, when passing through the gas introduction pipe 30 and the raw material gas supply passage 19a, it can be introduced into the reaction vessel 12 so that silane and chlorosilane are not mixed. By decomposing chlorosilane and reacting with propane, it is possible to suppress the deposition of SiC on the inner walls of the gas introduction pipe 30 and the gas supply passage 19a. However, even in the present embodiment, it is difficult to completely separate silane and chlorosilane in the source gas supply passage 19a when the source gas is introduced, and there is a possibility that some confusion will occur.

  Further, according to the present embodiment, the raw material gas is allowed to flow in a state where chlorosilane is arranged on the outer peripheral side of the mixed gas containing silane and propane until reaching the reaction vessel 12 from the gas introduction pipe 30. Therefore, even if SiC is generated by the reaction between silane and propane, chlorosilane prevents contact with the inner wall of the gas passage and acts as an etching gas for SiC. The effect of suppressing deposition can be expected.

Moreover, in this embodiment, since chlorosilane is made to flow to the outer peripheral side of the mixed gas containing silane and propane, in the technique described in Patent Document 2, in order to prevent blockage of the gas passage, By causing the carrier gas to flow excessively on the outer periphery of the gas, the partial pressure of the raw material gas in the entire gas reaching the seed crystal is not lowered. Rather, in the present embodiment, since chlorosilane is caused to flow instead of the carrier gas flowing outside the mixed gas of the gas containing Si and the gas containing C in the technique described in Patent Document 2, gas introduction is performed. When the flow rate of the mixed gas flowing inside the tube is the same, the concentrations of SiC ₂ , Si ₂ C, and Si that contribute to the growth of SiC in the source gas are compared with the technique described in Patent Document 2. Can be high. In addition, according to the present embodiment, the Si concentration in the source gas is increased as compared with the technique described in Non-Patent Document 1 in which only chlorosilane that does not easily contribute to the growth of SiC is used as the Si-containing gas. be able to. Therefore, according to the present embodiment, the growth rate of the silicon carbide single crystal can be increased as compared with the techniques described in Patent Document 2 and Non-Patent Document 1.

  Moreover, in this embodiment, since the distance L from the tip of the gas introduction pipe 30 to the lower end of the reaction vessel 12 is 20 to 500 mm, in the source gas supply passage 19a, a mixed gas containing silane and propane, and chlorosilane are mixed. A laminar flow with the contained gas can be formed, and mixing of these gases can be suppressed.

Here, FIG. 3 shows the results of investigating the speed of SiC adhering to the source gas supply passage 19a and the state of the gas introduction pipe when the distance L from the tip of the gas introduction pipe 30 to the reaction vessel 12 is variously changed. Show. In FIG. 3, the gas flow rates are as follows: SiH ₄ = 1 slm, C ₃ H ₈ = 1 slm, H ₂ = 10 slm (hereinafter introduced from the inner introduction pipe 31), SiCl ₄ = 1 slm, He = 0.1 to 20 slm ( As described above, the results are obtained when the ratio of the flow rate of the inner introduction tube 31 to the flow rate of the outer introduction tube 32 is 1, the atmospheric pressure is 50 kPa, and the reaction vessel temperature is 2500 ° C.

  As shown in FIG. 3, when the distance L is 20 mm or more and 500 mm or less, the deposition rate of SiC is small, that is, the amount of SiC attached to the source gas supply passage 19a is small, and the source gas supply passage 19a is satisfactorily supplied to the source gas. Was found to pass. On the other hand, when the distance L is greater than 500 mm, it is difficult to maintain the laminar flow of the source gas, and much SiC adheres to the source gas supply passage 19a. It was found that the temperature of the gas introduction pipe 30 was high so that the maximum pipe temperature ≧ 1500 ° C., so that SiC was generated in the pipe and the gas introduction pipe 30 was blocked.

  Further, FIG. 4 shows the speed and gas of SiC adhering to the source gas supply passage 19a when the ratio of the flow rate of the gas flowing through the inner introduction pipe 31 and the flow rate of the gas flowing through the outer introduction pipe 32 is variously changed. The result of investigating the state of the introduction pipe is shown.

  As can be seen from FIG. 4, by setting the flow rate ratio of the gas flowing through the inner introduction pipe 31 and the outer introduction pipe 32 to 1/3 or more and 3 or less, the amount of accumulated product can be reduced very much. The result of FIG. 4 was the same when the distance L was in the range of 20 mm to 500 mm.

  As described above, according to the present embodiment, a high-quality silicon carbide single crystal can be continuously grown at a high speed while preventing the gas passage from being blocked during the continuous growth of the silicon carbide single crystal.

(Second Embodiment)
In FIG. 5, the schematic sectional drawing of the manufacturing apparatus of the silicon carbide single crystal in 2nd Embodiment of this invention is shown. In FIG. 5, the same components as those in FIG. FIG. 6 is a cross-sectional view taken along line BB in FIG. Hereinafter, a description will be given focusing on differences from the first embodiment.

  In the present embodiment, as shown in FIGS. 5 and 6, a gas introduction pipe 40 is arranged in a coaxial manner in order from the inside to the outside, a first introduction pipe 41, a second introduction pipe 42, and a third introduction pipe. 43, and has a structure composed of three coaxial layers. An inner gas passage is constituted by the inner wall of the first introduction pipe 41, an outer gas passage is constituted by the outer wall of the first introduction pipe 41 and the inner wall of the second introduction pipe 42, and the outer wall of the second introduction pipe 42 is further formed. The third introduction pipe 43 and the inner wall constitute an outermost gas passage. In the present embodiment, the first introduction tube 41 has a cylindrical shape, the second introduction tube 42 has a cylindrical shape that concentrically surrounds the first introduction tube 41, and the third introduction tube 43 concentrics the second introduction tube 42. It has a cylindrical shape surrounding the shape.

  The optimum values of the opening diameters of the first to third introduction pipes 41 to 43 differ depending on the gas flow rate. For example, the opening diameter of the first introduction pipe 41 = Φ1 to 20 mm, the opening diameter of the second introduction pipe 42 = ( The outer diameter of the first introduction pipe 41 + 1 to 20 mm), the opening diameter of the third introduction pipe 43 = (the outer diameter of the second introduction pipe 42 + 1 to 20 mm).

  Further, as shown in FIG. 5, the tip of the first to third inlet pipes 41 to 43 is the same position on the tip side (the upper end portion in FIG. 5) of the gas inlet pipe 40 as a gas outlet, It arrange | positions so that the distance L from the front-end | tip of the gas inlet tube 40 to the plate material 14 lower end of the reaction container 12 may be set to L = 20-500 mm.

In the present embodiment, propane (C ₃ H ₈ ) / H ₂ is introduced from the first introduction pipe 41 as the gas containing C and the carrier gas, and helium as the inert gas from the second introduction pipe 42 outside the first introduction pipe 41. (He) is introduced. Furthermore, Si—chlorosilane (SiH ₄ / SiCl ₄ ) / He is introduced as a gas containing Si and a carrier gas from the third introduction pipe 43 on the outer side. The flow rate of each gas is, for example, as follows.

C ₃ H ₈ = 0.1 to 2 slm (introduced from the first introduction pipe 41)
H ₂ = 0.1-20 slm (introduced from the first introduction pipe 41)
He = 0.1-20 slm (introduced from the second introduction pipe 42)
SiH ₄ = 0.1 to 3 slm (introduced from the third introduction pipe 43)
SiCl ₄ = 0.1-3 slm (introduced from the third introduction pipe 43)
He = 0.1-20 slm (introduced from the third introduction pipe 43)
It is.

  Since it is desirable that these gases form a laminar flow in the raw material gas supply passage 19a, in the present embodiment, the largest flow velocity / the smallest flow velocity among the flow velocity of the first to third introduction pipes 41, 42, and 43. The flow rate is 1 or more and 3 or less.

  As described above, in the present embodiment, the gas introduction pipe 40 having a coaxial three-layer structure is used, and propane is introduced into the reaction vessel 12 from the first introduction pipe 41 located at the center, and the first is located on the outermost circumference. 3 A mixed gas of silane and chlorosilane is introduced into the reaction vessel 12 from the introduction tube 43, and helium is introduced into the reaction vessel 12 from the second introduction tube 42 located between the first introduction tube 41 and the third introduction tube 43. It has become.

  As a result, in the gas supply passage 19a, helium can be separated between the propane and the silane / chlorosilane with helium inserted. As a result, it is possible to suppress the generation of SiC that causes the gas passage to be blocked.

  Further, in the technique described in Non-Patent Document 1, there is a high possibility that a gas containing C and a gas containing Si are mixed immediately after being blown out from the gas introduction pipe. Even after being blown out from the gas introduction pipe, helium is inserted in layers between the gas containing C (propane) and the gas containing Si (silane / chlorosilane). Therefore, according to the present embodiment, the effect of separating the gas containing C and the gas containing Si is higher in the source gas supply passage 19a than the technique described in Non-Patent Document 1. However, even in this embodiment, it is difficult to completely separate silane / chlorosilane and propane, and there is a possibility that some confusion may occur between them.

  Further, in this embodiment, since propane is flowed inward and silane / chlorosilane is flowed outward, even if Si is generated in the raw material gas supply passage 19a, the raw material gas supply passage 19a is provided in the reaction vessel 12. Since it is located in the vicinity, the temperature is relatively high. Usually, Si is in a molten state at such a temperature. Therefore, Si is deposited on the inner wall of the source gas supply passage 19a, so that the source gas supply passage 19a is blocked. Never do.

  In addition, when the inside and the outside are switched and propane is flowed to the outside, carbon is generated in the source gas supply passage 19a and is deposited on the inner wall of the source gas supply passage 19a, and the source gas supply passage 19a is blocked. There is a fear. This is because carbon exists as a solid at the heating temperature of the reaction vessel 12 for growing a SiC single crystal. On the other hand, in this embodiment, since silane and chlorosilane are flowed outside, this can be avoided.

  Further, according to the present embodiment, the amount of inert gas required to suppress the generation of SiC in the source gas supply passage 19a can be reduced as compared with the technique described in Patent Document 2 described above. Therefore, the concentration (partial pressure) of the source gas in the entire gas reaching the seed crystal 16 can be increased.

  Therefore, according to the present embodiment, the clogging of the source gas supply passage 19a that occurs during the continuous growth of the silicon carbide single crystal 17 can be prevented, and compared with the technique described in Patent Document 2, Continuous high-speed growth is possible.

  Further, in this embodiment, as in the first embodiment, the gas introduction tube 40 is set such that the distance L from the tip of the gas introduction tube 40 to the lower end of the plate material 14 of the reaction vessel 12 is L = 20 to 500 mm. Therefore, in the source gas supply passage 19a, a three-layer flow of a gas containing propane, helium, and a gas containing silane / chlorosilane can be formed, and mixing of these gases can be suppressed.

Here, FIG. 7 shows the results of investigating the speed of SiC adhering to the source gas supply passage 19a and the state of the gas introduction pipe when the distance L from the tip of the gas introduction pipe 40 to the reaction vessel 12 is variously changed. Show. In FIG. 7, the gas flow rates are C ₃ H ₈ = 1 slm, H ₂ = 10 slm (hereinafter introduced from the first introduction pipe 41), He = 5 slm (introduction from the second introduction pipe 42), SiH ₄ = 1 slm. , SiCl ₄ = 1 slm, He = 5 slm (hereinafter introduced from the third introduction pipe 43), the ratio of the flow velocities of the gas flowing through the first to third introduction pipes 41 to 43 is 1, the atmospheric pressure is 50 kPa, the reaction This is the result when the container temperature is 2500 ° C.

  As can be seen from FIG. 7, when the distance L is 20 mm or more and 500 mm or less, the deposition rate of SiC is low, that is, the amount of SiC attached to the source gas supply passage 19a is small, and the source gas supply passage 19a is satisfactorily supplied to the source gas. Can be passed. On the other hand, when the distance L is greater than 500 mm, the laminar flow of the source gas cannot be maintained, so that more SiC adheres to the source gas supply passage 19a. Since the temperature of the gas-introducing gas introduction pipe 40 becomes a high temperature such that the maximum pipe temperature ≧ 1500 ° C., carbon is generated in the pipe and the gas introduction pipe 40 (particularly the introduction pipe 41) is blocked.

  Further, in FIG. 8, the raw material gas supply passage when the ratio of the largest gas flow rate to the smallest gas flow rate among the flow rates of the gases flowing through the first to third introduction pipes 41 to 43 is variously changed. The result of investigating the speed of SiC adhering to 19a and the state of the gas introduction pipe is shown. In addition, the result of FIG. 8 was the same when the distance L was 20 mm or more and 500 mm or less. As can be seen from FIG. 8, by setting the ratio of the largest gas flow rate to the smallest gas flow rate to be 1 or more and 3 or less, the amount of accumulated product can be very small. When the ratio of the largest gas flow rate to the smallest gas flow rate is 1, it means that the flow rates of the gases flowing through the first to third introduction pipes 41 to 43 are all the same.

  In this embodiment, helium (He) is employed as the inert gas, but other inert gases may be employed. However, He is highly inert in an inert gas, hardly turbulent, and is blown out from the gas introduction pipe 40 and reaches the reaction vessel 12, and gas containing propane, silane / chlorosilane, Therefore, it is preferable to use He as an inert gas.

(Other embodiments)
(1) In the first embodiment, the mixed gas is introduced from the inner introduction pipe 31 and the chlorosilane is introduced from the outer introduction pipe 32. However, the mixed gas and the chlorosilane are inert, represented by helium, argon, etc., respectively. You may introduce | transduce as dilution gas diluted with gas.

  (2) In the first and second embodiments, the baffle plate 20 is used. However, the baffle plate 20 may be omitted if the mixing and heating of the source gas can be sufficiently ensured.

  (3) In the first embodiment, the mixed gas of silane and propane is introduced from the inner introduction pipe 31, but the inner introduction pipe 31 is divided into concentric circles from the inner side and the outer side in the inner introduction pipe 31. In each case, silane and propane may be introduced separately. That is, it is good also as a structure which has arrange | positioned the introduction pipe concentrically inside the inner introduction pipe 31 with respect to the gas introduction pipe 30 shown by FIG.

  (4) In the second embodiment, the mixed gas of silane and chlorosilane is introduced from the third introduction pipe 43. However, the third introduction pipe 43 is further divided into concentric circles so that silane and You may make it introduce | transduce chlorosilane separately.

  (5) In the first and second embodiments, propane is employed as the gas containing C. However, other gases may be employed as long as they can be a raw material gas for the SiC single crystal. For example, a hydrocarbon gas such as methane or ethylene can be used as the gas containing C.

  (6) In the second embodiment, a mixed gas of silane and chlorosilane is adopted as the gas containing Si. However, only silane may be adopted. Further, other gas containing Si may be adopted as long as it can be a raw material gas for the SiC single crystal.

  In addition, each above-mentioned embodiment is arbitrarily combinable in the range which can be implemented.

It is a schematic sectional drawing of the manufacturing apparatus of the silicon carbide single crystal in 1st Embodiment of this invention. It is the sectional view on the AA line in FIG. In the manufacturing apparatus shown in FIG. 1, it is a figure which shows the relationship between the distance L from the front-end | tip of the gas introduction pipe | tube 30 to the reaction container 12, and the deposition rate of SiC deposited on the raw material gas supply channel 19a. In the manufacturing apparatus shown in FIG. 1, the relationship between the ratio of the flow rate of the gas flowing through the inner introduction pipe 31 and the flow rate of the gas flowing through the outer introduction pipe 32 and the deposition rate of SiC deposited in the source gas supply passage 19a is shown. FIG. It is a schematic sectional drawing of the manufacturing apparatus of the silicon carbide single crystal in 2nd Embodiment of this invention. FIG. 6 is a sectional view taken along line BB in FIG. 5. In the manufacturing apparatus shown in FIG. 5, it is a figure which shows the relationship between the distance L from the front-end | tip of the gas introduction pipe | tube 40 to the reaction container 12, and the deposition rate of SiC deposited in the raw material gas supply channel 19a. In the manufacturing apparatus shown in FIG. 5, the ratio of the largest gas flow rate to the smallest gas flow rate among the flow rates of the gases flowing through the first to third introduction pipes 41 to 43 and the source gas supply passage 19a are deposited. It is a figure which shows the relationship with the deposition rate of SiC.

Explanation of symbols

12 ... Reaction vessel, 16 ... Silicon carbide single crystal substrate, 17 ... Silicon carbide single crystal,
20 ... baffle plate, 21, 22 ... high frequency induction coil,
30, 40 ... gas introduction pipe, 31 ... inner introduction pipe, 32 ... outer introduction pipe,
41 ... 1st introduction pipe, 42 ... 2nd introduction pipe, 43 ... 3rd introduction pipe.

Claims (12)

A silicon carbide single crystal substrate (16) serving as a seed crystal is disposed in the reaction vessel (12), and at least the gas containing Si (silicon) and C (carbon) are contained in the heated reaction vessel. In a silicon carbide single crystal manufacturing apparatus for growing a silicon carbide single crystal from the silicon carbide single crystal substrate by introducing a source gas containing a gas to be produced from outside the reaction vessel,
A gas introduction pipe (30) for introducing the source gas into the reaction vessel;
The gas introduction pipe has an inner introduction pipe (31) arranged inside, and an outer introduction pipe (32) arranged coaxially outside the inner introduction pipe,
The silane and the gas containing C or the diluted gas as the gas containing Si from the inner introduction pipe are introduced into the reaction vessel, and the chlorosilane as the gas containing Si from the outer introduction pipe or An apparatus for producing a silicon carbide single crystal, wherein the dilution gas is introduced into the reaction vessel. The gas introduction pipe is arranged at a position where the distance from the tip to the reaction vessel is 0 mm or more and 500 mm or less,
2. The apparatus for producing a silicon carbide single crystal according to claim 1, wherein a flow rate ratio of a gas flowing through each of the inner introduction pipe and the outer introduction pipe is set to 1/3 or more and 3 or less. A silicon carbide single crystal substrate (16) serving as a seed crystal is disposed in the reaction vessel (12), and at least the gas containing Si (silicon) and C (carbon) are contained in the heated reaction vessel. In a silicon carbide single crystal manufacturing apparatus for growing a silicon carbide single crystal from the silicon carbide single crystal substrate by introducing a source gas containing a gas to be produced from outside the reaction vessel,
A gas introduction pipe (40) for introducing the source gas into the reaction vessel;
The gas introduction pipe has a first introduction pipe (41), a second introduction pipe (42) and a third introduction pipe (43) arranged coaxially in order from the inside to the outside,
A gas having C is introduced into the reaction vessel from the first introduction tube, a gas containing Si is introduced into the reaction vessel from the third introduction tube, and the first introduction tube and the third introduction tube An apparatus for producing a silicon carbide single crystal, wherein an inert gas is introduced into the reaction vessel from the second introduction pipe positioned therebetween. The apparatus for producing a silicon carbide single crystal according to claim 3, wherein He as an inert gas is introduced into the reaction vessel from the second introduction pipe. The gas introduction pipe is arranged at a position where the distance from the tip to the reaction vessel is 0 mm or more and 500 mm or less,
5. The ratio of the largest flow rate to the smallest flow rate among the flow rates of the gas flowing through each of the first to third introduction pipes is set to 1 or more and 3 or less. An apparatus for producing a silicon carbide single crystal. 6. The apparatus for producing a silicon carbide single crystal according to claim 2, wherein the gas introduction pipe is disposed at a position where a distance from a tip of the gas introduction pipe to the reaction vessel is 20 mm or more. A silicon carbide single crystal substrate (16) serving as a seed crystal is disposed in the reaction vessel (12), and at least the gas containing Si (silicon) and C (carbon) are contained in the heated reaction vessel. In the method for producing a silicon carbide single crystal, a silicon carbide single crystal is grown from the silicon carbide single crystal substrate by introducing a source gas containing a gas to be produced from outside the reaction vessel,
As a gas introduction pipe (30) for introducing the source gas into the reaction vessel, an inner introduction pipe (31) arranged inside, and an outer introduction pipe (coaxially arranged outside the inner introduction pipe) ( 32) using the gas inlet pipe (30)
The silane and the gas containing C or the diluted gas as the gas containing Si from the inner introduction pipe are introduced into the reaction vessel, and the chlorosilane as the gas containing Si from the outer introduction pipe or A method for producing a silicon carbide single crystal, wherein the dilution gas is introduced into the reaction vessel. The gas introduction pipe is arranged such that the distance from the tip to the reaction vessel is 0 mm or more and 500 mm or less,
8. The method for producing a silicon carbide single crystal according to claim 7, wherein a flow rate ratio of a gas flowing through each of the inner introduction pipe and the outer introduction pipe is set to 1/3 or more and 3 or less. A silicon carbide single crystal substrate (16) serving as a seed crystal is disposed in the reaction vessel (12), and at least the gas containing Si (silicon) and C (carbon) are contained in the heated reaction vessel. In the method for producing a silicon carbide single crystal, a silicon carbide single crystal is grown from the silicon carbide single crystal substrate by introducing a source gas containing a gas to be produced from outside the reaction vessel,
As a gas introduction pipe (40) for introducing the source gas into the reaction vessel, a first introduction pipe (41), a second introduction pipe (42), and a second introduction pipe (42), which are coaxially arranged in order from the inside to the outside. Using a gas introduction pipe (40) having a third introduction pipe (43),
A gas having C is introduced into the reaction vessel from the first introduction tube, a gas containing Si is introduced into the reaction vessel from the third introduction tube, and the first introduction tube and the third introduction tube A method for producing a silicon carbide single crystal, wherein an inert gas is introduced into the reaction vessel from the second introduction pipe positioned therebetween. The method for producing a silicon carbide single crystal according to claim 9, wherein He is used as the inert gas. The gas introduction pipe is arranged such that the distance from the tip to the reaction vessel is 0 mm or more and 500 mm or less,
11. The silicon carbide single crystal according to claim 9, wherein a ratio of the largest flow rate to the smallest flow rate among the flow rates of the gas flowing through the first to third introduction pipes is 1 or more and 3 or less. Manufacturing method. 12. The method for producing a silicon carbide single crystal according to claim 8, wherein the gas introduction pipe is disposed so that a distance from a tip of the gas introduction pipe to the reaction vessel is 20 mm or more.

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