JP2010189271A - Apparatus for producing silicon carbide single crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for producing a silicon carbide single crystal enabling to inhibit abrupt pressure rise in the apparatus even when a cooling liquid in the apparatus leaks out by breakage of a cooling section. <P>SOLUTION: The apparatus comprises a crucible 30 in a vacuum container, wherein a seed crystal is arranged, a gas introducing pipe 50 to supply a mixed gas from a lower side to an inner space 31 of the crucible 30, and the cooling section 70 placed at a position free of interrupting a supply route of the mixed gas, being apart from the crucible 30. The crucible 30 has a through-hole 30a at the bottom, and the mixed gas is supplied via the through-hole 30a. The gas introducing pipe 50 is placed apart from the reactor 30. The cooling section 70 is placed on the side face of the gas introducing pipe 50 at the end toward the reactor 30, where at least a part of the section is arranged at a lower position than the reactor 30. The mechanical strength of the wall of the cooling section 70 in a portion other than opposing to an inner region of the reactor 30, is lower than that of an opposing portion. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an apparatus for producing a silicon carbide single crystal provided with a cooling portion in the vicinity of an end portion on a reaction vessel side in a gas introduction pipe.

  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. As a method for obtaining such a silicon carbide single crystal, for example, a single crystal growth method (so-called high temperature CVD method) in which silicon carbide single crystal is grown by epitaxially growing silicon carbide by CVD at high temperature is known. (See Patent Document 1).

  In the silicon carbide single crystal manufacturing apparatus disclosed in Patent Document 1, the mixed gas supplied from the supply means (gas introduction pipe) moves into the susceptor (reaction vessel) through the passage formed by the heat insulating material. It has become. Therefore, when the gas is moved from the insulated passage into the susceptor, the mixed gas is rapidly heated, so that generally a high-quality silicon carbide single crystal cannot be obtained.

  As a countermeasure, it is conceivable to raise the temperature of the mixed gas even in the passage and supply the mixed gas having a certain high temperature into the susceptor. However, when the temperature of the mixed gas reaches about 500 ° C. or more, Si deposits on the wall surface of the passage, and when the mixed gas reaches the reaction temperature of Si and C, Si and C react to deposit SiC on the wall surface of the passage. Resulting in. These passages clog the passage.

  Therefore, in the silicon carbide single crystal manufacturing apparatus disclosed in Patent Document 2, a cooling mechanism (cooling) such as cooling with water to an introduction pipe (gas introduction pipe) for introducing a mixed gas into a crucible (reaction vessel). Etc.), and thereby, a temperature gradient is provided so that the temperature of the crucible side becomes high.

Japanese National Patent Publication No. 11-508531 JP 2002-154899 A

  As shown in Patent Document 2, when the cooling unit is provided, the gas introduction pipe can be efficiently cooled. However, in the case of a configuration having a cooling part, when cooling water leaks out due to breakage of the cooling part and enters the reaction vessel, the pressure in the apparatus rapidly rises with vaporization of the cooling water, and the manufacturing apparatus is damaged. There is a fear.

  In view of the above problems, the present invention provides a silicon carbide single crystal manufacturing apparatus capable of suppressing a rapid pressure increase in the apparatus even when the cooling section is damaged and the cooling liquid leaks out. Objective.

In order to achieve the above object, the invention described in claim 1
A vacuum vessel;
A reaction vessel disposed in a vacuum vessel and having a silicon carbide single crystal substrate serving as a seed crystal disposed therein;
A gas introduction pipe for communicating a gas containing Si and a gas containing C from below from the outside of the vacuum vessel to the silicon carbide single crystal substrate in the reaction vessel. When,
A cooling unit that is disposed away from the reaction vessel at a position that does not interfere with the supply path of the mixed gas from the gas introduction pipe to the silicon carbide single crystal substrate located above, and that lowers the ambient temperature by the liquid flowing inside the reaction vessel; An apparatus for producing a silicon carbide single crystal comprising:
The reaction vessel is provided with a through hole at the bottom thereof for communicating the inner region of the reaction vessel with a portion below the reaction vessel in the inner region of the vacuum vessel, and the mixed gas is passed through the through hole. Supplied to the inner region of the reaction vessel,
The gas introduction pipe is arranged away from the reaction vessel,
The cooling unit is disposed at the end of the reaction vessel side on the side surface of the gas introduction pipe,
The mechanical strength of the wall portion in the cooling portion is characterized in that the portion excluding the facing portion is lower than the portion facing the internal region of the reaction vessel.

  As described above, according to the present invention, the mechanical strength of the wall portion of the cooling section is differentiated, and the strength of the portion excluding the portion facing the internal region of the reaction vessel is lowered. Therefore, even if the cooling unit is damaged, it is difficult for the liquid to enter the internal region of the reaction vessel, so that a rapid pressure increase in the apparatus can be suppressed.

  For example, as described in claim 2, the wall portion of the cooling portion may be configured such that the portion excluding the facing portion is thinner than the portion facing the internal region of the reaction vessel. According to this, the intensity | strength of the site | parts excluding the site | part facing a reaction container is low, and it has the structure which a liquid cannot enter easily into the internal area | region of a reaction container.

  In the first or second aspect of the invention, as described in the third aspect of the present invention, a supply pipe that communicates the inside and outside of the vacuum vessel and supplies the liquid to the cooling unit, and the liquid from the cooling unit to the vacuum vessel are provided. A discharge pipe for discharging to the outside, a liquid amount adjusting means for adjusting a supply amount of the liquid to the cooling unit, and a vacuum vessel provided below the reaction vessel and from the cooling unit. As a configuration comprising: a leak detecting means for detecting a liquid leak; and a first control means for controlling the liquid amount adjusting means to stop the supply of the liquid when the leak detecting means detects a liquid leak. Also good.

  According to this, even if the cooling unit is damaged, the leakage detection unit detects the leakage of the liquid from the cooling unit, and the first control unit controls the liquid amount adjustment unit to supply the liquid to the cooling unit. Can be stopped. Thereby, the liquid quantity which leaks from a cooling part can be reduced. Accordingly, it is possible to suppress a rapid pressure increase in the apparatus.

  After the supply of liquid to the cooling unit is stopped and the liquid is discharged from the cooling unit through the discharge pipe, when air is sucked into the vacuum vessel through the discharge pipe, the air reacts with the mixed gas at a high temperature. However, it is conceivable that the apparatus is damaged due to heat generation or volume expansion. On the other hand, if it is set as the structure by which the non-return valve was provided in the discharge pipe as described in Claim 4, it can prevent inhalation of the air from a discharge pipe.

  In the invention according to claim 3 or claim 4, as described in claim 5, heating is performed when a leakage of liquid is detected by the heating means for heating the inner region of the reaction vessel and the leak detection means. It is good also as a structure provided with the 2nd control means which controls a heating means so that the output of a means may fall or stop.

  According to this, even if the cooling unit is damaged, the leakage detection unit can detect the leakage of the liquid from the cooling unit, and the second control unit can reduce or stop the output of the heating unit. Thereby, vaporization of the leaked liquid can be suppressed, and as a result, a rapid pressure increase in the apparatus can be suppressed.

  In the invention according to claim 3 or claim 4, as described in claim 6, the exhaust pipe is provided above the reaction vessel and communicates with the inside and outside of the vacuum vessel, and the exhaust pipe is provided. A pressure adjusting means for adjusting the pressure in the vacuum vessel by the opening degree; and a pressure adjusting means for controlling the pressure adjusting means so that the opening degree of the pressure adjusting means is fully opened when a liquid leak is detected by the leak detecting means. It is good also as a structure provided with 3 control means.

  According to this, even if the cooling unit is damaged, the leakage detection unit can detect the liquid leakage from the cooling unit, and the third control unit can fully open the opening of the pressure adjustment unit. Thereby, the pressure in a vacuum vessel can be reduced and by extension, the rapid pressure rise in an apparatus can be suppressed.

It is a schematic diagram which shows schematic structure of the manufacturing apparatus of the silicon carbide single crystal which concerns on a 1st reference example. It is an expanded sectional view which shows the periphery of a shielding part and a cooling part among the manufacturing apparatuses shown in FIG. It is sectional drawing which follows the III-III line of FIG. It is a figure which shows an example of the control flow for suppressing the damage at the time of the leak of cooling water generating. It is sectional drawing which shows a modification. It is an expanded sectional view which shows the periphery of the shielding part and cooling part which are the characteristic parts among the manufacturing apparatuses of the silicon carbide single crystal which concerns on a 2nd reference example. It is an expanded sectional view which shows the periphery of the shielding part and cooling part which are the characteristic parts among the manufacturing apparatuses of the silicon carbide single crystal which concerns on embodiment of this invention.

Hereinafter, reference examples will be described before embodiments of the present invention are described with reference to the drawings.
(First Reference Example)
FIG. 1 is a schematic diagram showing a schematic configuration of a silicon carbide single crystal manufacturing apparatus according to a first reference example. FIG. 2 is an enlarged cross-sectional view showing the periphery of the shielding part and the cooling part in the manufacturing apparatus shown in FIG. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2, and the shielding portion is indicated by a broken line for comparison. In the following, the penetration direction of the through-hole formed in the crucible 30 is the vertical direction, and the direction perpendicular to the vertical direction is the horizontal direction.

  As shown in FIG. 1, the silicon carbide single crystal manufacturing apparatus 1 according to the first reference example includes, as main parts, a vacuum vessel 10, a crucible 30 as a reaction vessel disposed in the vacuum vessel 10, and a raw material in the crucible 30. A gas introduction pipe 50 for supplying gas, a cooling section 70 for cooling the gas introduction pipe 50 to provide a temperature gradient, and a shielding plate 90 for blocking cooling water leaking from the cooling section 70 are provided.

  The cylindrical vacuum container 10 (chamber) includes a lower container 11 that is a part into which the crucible 30 is put and an upper container 12 that is a part from which the completed silicon carbide (SiC) is taken out, and the upper container 12 and the lower container 11. And are assembled.

  The upper container 12 is made of, for example, SUS (stainless steel), and a sample take-out port 12a for taking out the crystal-grown SiC single crystal is provided on the side surface. An opening at the upper end of the upper container 12 is closed by an upper lid member (flange) 13 made of, for example, SUS. An exhaust pipe 14 is connected to a portion of the upper container 12 excluding the sample outlet 12a. The exhaust pipe 14 is connected to a vacuum pump (including an actuator) via a pressure adjusting valve 15 (including an actuator) as pressure adjusting means. (Not shown) is connected. The inside of the vacuum vessel 10 is pressure controlled (evacuated) by the vacuum pump and the pressure adjusting valve 15.

  The lower container 11 is made of, for example, quartz, and the opening at the lower end is closed by a lower lid member (flange) 16 made of, for example, SUS. A crucible 30 is disposed in the lower container 11, and the periphery of the crucible 30 is surrounded by a heat insulating member 17.

  The crucible 30 has a bottomed cylindrical shape with an upper opening, and a pedestal 32 is installed in the inner space 31 away from the inner wall of the crucible 30, and a silicon carbide single unit is formed on the lower surface of the pedestal 32. A crystal substrate 33 is attached. Then, the internal space 31 of the crucible 30 is a growth region (reaction region) for growing the SiC single crystal by using the silicon carbide single crystal substrate 33 as a seed crystal. The internal space 31 corresponds to the internal region described in the claims, and is specifically surrounded by the upper end (including the opening), the side outer surface, and the bottom outer surface (including the through hole 30a) of the crucible 30. The space within the specified range is shown. Therefore, the internal space 31 is also an internal space of the vacuum vessel 10.

  As a material of the crucible 30 configured in this manner, high-purity graphite that can withstand high temperatures (for example, about 2400 ° C.) can be used. By using such high purity graphite, it is possible to reduce the generation of impurities from the heated crucible 30 and the incorporation of impurities into the crystal during crystal growth.

  The pedestal 32 described above is fixed to the lower end of the shaft 18 extending in the vertical direction. The shaft 18 is connected to a rotation / vertical movement mechanism (not shown) so that the shaft 18 can be rotated and moved up and down by this mechanism. That is, the grown SiC can be moved to the sample take-out chamber by the upward movement of the shaft 18 from the state shown in FIG. 1, and the silicon carbide single crystal substrate 33 is moved downward from the upward movement state, and the crucible 30. It is possible to move to the internal space 31. Furthermore, the silicon carbide single crystal substrate 33 can be rotated by rotating the shaft 18 during growth in a state where the silicon carbide single crystal substrate 33 is disposed in the internal space 31 of the crucible 30. The shaft 18 is tubular, and the side close to the crucible 30 is made of quartz, and the far side is made of SUS.

  In addition, a through hole 30 a is provided in the center portion surrounded by the peripheral edge portion at the bottom of the crucible 30. The internal space 31 of the crucible 30 is an internal space of the vacuum vessel 10 and communicates with a low temperature region (for example, a lower storage portion 21 described later) below the crucible 30 through the through hole 30a. . Further, a raw material gas (mixed gas) is supplied to the internal space 31 of the crucible 30 from the crucible side end 51 of the gas introduction pipe 50 disposed below the crucible 30. Specifically, as the source gas, a mixture of monosilane (a gas containing Si), propane (a gas containing C), and at least one of hydrogen, helium, and argon at a predetermined ratio is used. The

  The gas introduction pipe 50 is disposed away from the crucible 30 because a cooling unit 70 described later is disposed in the vicinity thereof. As the arrangement of the crucible 30, the raw material gas can be supplied to the internal space 31 (the silicon carbide single crystal substrate 33 disposed in the internal space 31) of the crucible 30, and the cooling water leaked from the cooling unit 70 described later There is no particular limitation as long as it can be dropped below the space 31. In the first reference example, as shown in FIGS. 1 and 2, the gas introduction pipe 50 made of SUS is arranged so that the crucible side end portion 51 is located below the bottom portion of the crucible 30. That is, the gas introduction pipe 50 (the crucible side end 51 thereof) is disposed outside the internal space 31 of the crucible 30.

  In the vacuum vessel 10 and in the vicinity of the gas introduction pipe 50, the gas introduction pipe 50 and the crucible 30 suppress the rapid temperature change of the source gas, and the gas introduction pipe 50 is clogged due to deposition of Si and SiC. In order to suppress this, for the purpose of providing a predetermined temperature gradient in the gas introduction pipe 50, a cooling unit 70 is disposed that lowers the ambient temperature by circulation of cooling water as a liquid. The portion closer to the crucible 30 of the gas introduction pipe 50 becomes higher in temperature, and there is a possibility that the clogging occurs. Further, in order to keep the temperature of the internal space 31 at a high temperature and prevent the crucible 30 from being damaged due to a temperature difference, it is preferable that the cooling unit 70 is arranged away from the crucible 30. Therefore, in the first reference example, as shown in FIG. 2, one end of the member 71 made of SUS having a substantially U-shaped cross section (pan bottom shape) is a side surface of the gas introduction pipe 50 positioned below the crucible 30. And a cooling space provided with a storage space 72 in which cooling water is circulated by the member 71 and the side surface of the gas introduction pipe 50. Part 70 is configured. That is, the member 71 and the gas introduction pipe 50 correspond to the wall portion described in the claims. As shown in FIG. 3, the cooling unit 70 (reservation space 72) is provided in an annular shape so as to surround the gas introduction pipe 50, and as shown in FIG. 2, the thickness of the member 71 is the crucible 30 ( The upper part 71a facing the internal space 31), the lower part 71b facing the flange 16, and the side part 71c connecting the upper part 71a and the lower part 71b are substantially uniform, and the horizontal direction (radial direction) of the gas introduction pipe 50 The wall thickness is thicker. And the supply piping 73 for supplying cooling water to the cooling unit 70 (storage space 72) from the outside of the vacuum vessel 10 through the lower part 71b of the cooling unit 70 (member 71), and the cooling unit 70 (storage space) 72) A discharge pipe 74 for discharging the cooling water from the vacuum vessel 10 to the outside of the vacuum vessel 10 is connected to the cooling unit 70 (storage space 72) so that the cooling water can flow. As shown in FIG. 3, the supply pipe 73 and the discharge pipe 74 are opposed to each other with the gas introduction pipe 50 interposed therebetween. As shown in FIG. 1, the supply piping 73 has a supply adjustment valve 75 as a liquid amount adjusting means for adjusting the supply amount of cooling water to the cooling unit 70 (storage space 72) outside the vacuum vessel 10. (Including actuators) are provided. In addition, the discharge pipe 74 is provided with a check valve 76 for preventing the suction of the direction opposite to the cooling water discharge direction outside the vacuum vessel 10.

  Further, the gas introduction pipe 50 is a heat insulating material having a high-purity graphite layer 34 on the surface around a predetermined range from the crucible side end 51 to a portion below the lower end of the cooling unit 70 as shown in FIG. It is surrounded by the member 35. That is, in the above range, the heat insulating member 17 and the heat insulating member 35 having the graphite layer 34 on the surface are disposed between the gas introduction pipe 50 and the lower container 11 in which the cooling unit 70 is integrated. One end of the heat insulating member 35 including the graphite layer 34 is connected to the bottom (peripheral portion) of the crucible 30, and the internal space 31 of the crucible 30 and the internal space below the heat insulating member 35 in the vacuum vessel 10 ( A narrow region (gap) is formed between the low-temperature region and the low-temperature region. As a result, the heat on the crucible 30 side is less likely to escape below the heat insulating member 35. Further, when the cooling unit 70 (member 71) is damaged and the cooling water leaks out, the cooling water falls into the internal space below the heat insulating member 35 in the vacuum vessel 10 through the narrow region. It has become.

  Further, between the cooling unit 70 and the internal space 31 of the crucible 30, cooling is performed when the cooling unit 70 (member 71) is damaged and cooling water leaks out so as not to disturb the source gas supply path. A shielding plate 90 that blocks water from scattering in the internal space 31 of the crucible 30 is disposed. The shielding plate 90 corresponds to the shielding portion described in the claims. As the constituent material of the shielding plate 90, any material having excellent thermal conductivity and heat resistance (for example, carbon-based material, SiC, molybdenum, etc.) can be employed. Preferably, the cooling water in contact with the crucible 30 is less likely to evaporate (evaporate) (for example, formed using a material having a specific heat smaller than that of the crucible 30, or the bulk density of the carbon material is 1.0 g / cm 3 or less. The porous body is preferable. In the first reference example, as described above, the cooling unit 70 is disposed below the crucible 30 together with the gas introduction pipe 50, and the carbon-based material is formed on the wall surface of the through hole 30 a provided at the bottom of the crucible 30. An annular shielding plate 90 is fixed. Specifically, the thickness of the shielding plate 90 in the vertical direction is thinner than the bottom of the crucible 30 and is fixed to the through-hole wall surface in a non-horizontal direction by fastening means such as screws (not shown). Further, in the horizontal direction, the center of the annular shielding plate 90 substantially coincides with the center of the gas introduction pipe 50 and the center of the silicon carbide single crystal substrate 33, and the annular inner periphery of the shielding plate 90 is shown in FIG. As shown, it is outside in the horizontal direction from the gas introduction pipe 50. The supply path of the source gas is a range connecting the opening in the crucible side end 51 of the gas introduction pipe 50 and both ends in the horizontal direction of the silicon carbide single crystal substrate 33 (range between broken lines shown in FIG. 2). It is.

  Further, below the crucible 30 in the vacuum vessel 10, a function as a leak detection means for detecting the leakage of the cooling water when the cooling unit 70 (member 71) is broken and the cooling water leaks, A temperature sensor 19 that is used together with a controller 26 to be described later is disposed. In the first reference example, the temperature sensor 19 made of a thermocouple is provided directly below a narrow region between the cooling unit 70 and the heat insulating member 35 having the graphite layer 34, and stands on the flange 16. For example, it is arrange | positioned in the flange vicinity of the lower storage part 21 comprised by the annular wall part 20 which consists of SUS.

  In addition, the generated steam is cooled above the crucible 30 in the vacuum vessel 10 in order to suppress rapid pressure fluctuation due to vaporization of cooling water leaking from the cooling unit 70 (member 71) due to breakage. A cooling trap 22 for trapping and an upper storage part 23 for storing water trapped by the water-cooled trap 22 are provided. In the first reference example, an upper storage part 23 having a predetermined depth is provided at the end of the upper container 12 on the lower container 11 side, and a water-cooled cooling trap 22 is provided immediately above the upper storage part 23.

  In addition, an RF coil 24 (high-frequency induction coil) as a heating means is wound around the outer peripheral portion of the vacuum vessel 10 at a position substantially the same as the arrangement height of the silicon carbide single crystal substrate 33. By energizing, silicon carbide single crystal substrate 33 can be heated during growth. Further, an RF coil 25 (high frequency induction coil) as a heating means is wound below the RF coil 24, and the coil 25 is energized so that a lower region of the crucible 30 and an upper region of the gas introduction pipe 50 are formed. It can be heated.

  Furthermore, in the first reference example, the manufacturing apparatus 1 determines, based on the detection signal of the temperature sensor 19 described above, a determination unit that determines whether or not the cooling water leaks from the cooling unit 70, and a determination result of the determination unit. And a controller 26 having a function of a control unit for controlling various actuators. That is, the temperature sensor 19 and the determination unit of the controller 26 constitute a leak detection means. The controller 26 also includes an actuator such as an electromagnetic valve that adjusts the opening of the pressure adjustment valve 15, an actuator such as an electromagnetic valve that adjusts the outputs of the RF coils 24 and 25, and an electromagnetic that adjusts the opening of the supply adjustment valve 75. Each actuator is electrically connected to an actuator such as a valve, and each actuator is controlled based on the presence or absence of water leakage. That is, the controller of the controller 26 also serves as the first control means, the second control means, and the third control means described in the claims. Moreover, the manufacturing apparatus 1 has the alerting | reporting part 27, can receive the leak detection signal from the controller 26, and can alert | report a leak with an audio | voice etc. now.

  Next, the manufacturing method of a SiC single crystal is demonstrated. First, a silicon carbide single crystal substrate 33 serving as a seed crystal is attached to one surface of the pedestal 32, and the shaft 18 is adjusted to place the silicon carbide single crystal substrate 33 at a predetermined position in the internal space 31 (growth chamber) of the crucible 30. Next, the inside of the vacuum vessel 10 is evacuated through the exhaust pipe 14, and power is supplied to the RF coils 24 and 25 to inductively heat the crucible 30 and the like. Thereby, the temperature of the crucible 30 is stabilized at a high temperature (1420 ° C. or higher, which is the melting temperature of Si, preferably around 2400 ° C. at which SiC can be sublimated). Ar gas or the like is introduced to set the pressure in the vacuum vessel 10 to a predetermined pressure. In this state, when the source gas is introduced from the gas introduction pipe 50 into the upper space 31 of the crucible 30 positioned above, a silicon carbide single crystal grows from the silicon carbide single crystal substrate 33. Thereby, a silicon carbide single crystal can be obtained.

  Next, as an example of control by the controller 26, control of the supply adjustment valve 75 will be described with reference to FIG. FIG. 4 is a diagram illustrating an example of a control flow for minimizing damage when leakage of cooling water occurs.

  As described above, when the production of the SiC single crystal is started (the raw material gas is introduced into the internal space 31 of the crucible 30 from the gas introduction pipe 50), sensing of the temperature sensor 19 is started as shown in FIG. 10) The detection signal is input to the controller 26 having a determination unit.

  In the controller 26, it is determined from the change in the detection signal of the temperature sensor 19 (for example, by comparison with a threshold value) whether or not the cooling water is leaking in the cooling unit 70 (presence of leakage of cooling water) (step 20). . If it is determined in step 20 that there is no leakage, steps 10 and 20 are repeatedly executed, and the production of the SiC single crystal is continued.

  If it is determined in step 20 that there is a leak, the controller 26 having a control unit outputs a fully closed signal to an actuator that adjusts the opening degree of the supply adjustment valve 75 provided in the cooling water supply pipe 73. . As a result, the supply adjustment valve 75 is closed (the supply pipe 73 is closed), and the cooling water supply to the cooling unit 70 (the storage space 72) is stopped (step 30).

  In addition, the controller 26 outputs a signal indicating that a coolant leak has occurred to a notification unit 27 such as a buzzer or a patrol light. Upon receiving the signal, the notification unit 27 reports that a coolant leak has occurred. (Step 40). Then, the production of the SiC single crystal is stopped on the assumption that a sudden abnormality (breakage of the cooling unit 70) has occurred in the production apparatus 1.

  In addition, in FIG. 4, the example which adjusts the opening degree of the supply adjustment valve 75 by the presence or absence of the leakage of cooling water was shown as an example. However, not only the supply adjustment valve 75 but also the opening of the pressure adjustment valve 15 and the outputs of the RF coils 24 and 25 are adjusted in the same manner as the opening of the supply adjustment valve 75. Specifically, when it is determined in step 20 that there is a leak, the controller 26 provided with the control unit causes the opening of the pressure adjustment valve 15 provided in the exhaust pipe 14 to be fully opened (vacuum). A signal is output to the actuator (so that the gas in the container 10 is discharged to the outside). Further, a signal is output to the actuator so that the outputs of the RF coils 24 and 25 are reduced or the output is stopped (heating stop).

  Next, the effect of the characteristic part of the above-described silicon carbide single crystal manufacturing apparatus 1 will be described. First, in the manufacturing apparatus 1, a water-cooled cooling unit 70 is disposed in the vicinity of the crucible side end portion 51 of the gas introduction pipe 50 disposed below the crucible 30. A shielding plate 90 extending in the horizontal direction is provided on the wall surface of the through hole 30 a provided at the bottom of the crucible 30 so as not to prevent the supply of the source gas to the silicon carbide single crystal substrate 33. Therefore, even if the cooling part 70 (member 71) for cooling the gas introduction pipe 50 is broken and the leaked cooling water is scattered above the cooling part 70, it is scattered as shown by broken line arrows in FIG. The cooling water is reflected by the shielding plate 90 having a temperature lower than that of the crucible 30. And it falls in the lower storage part 21 which is the low temperature area | region inside the vacuum vessel 10 and below the crucible 30 through the narrow area | region between the cooling part 70 and the heat insulation member 35 containing the graphite layer 34. FIG. Thus, according to the first reference example, scattering of the cooling water from the cooling unit 70 to the internal space 31 of the crucible 30 that is a high-temperature region located above the cooling unit 70 can be suppressed. Therefore, it is possible to suppress the cooling water from being scattered in the internal space 31 of the crucible 30 and to suppress a rapid pressure increase in the vacuum vessel 10 due to vaporization (evaporation) of the cooling water.

  The annular shielding plate 90 has an inner peripheral opening larger than the crucible side end 51 of the gas introduction pipe 50 so as not to hinder the supply of the source gas while being disposed above the cooling unit 70. ing. Therefore, the source gas can be supplied from the gas introduction pipe 50 to the silicon carbide single crystal substrate 33 located in the internal space 31 of the crucible 30.

  Further, in the first reference example, the gas introduction pipe 50 and the cooling unit 70 are disposed below the crucible 30, whereby the opposing area (gas supply path) between the cooling unit 70 and the internal space 31 of the crucible 30. Is small). Therefore, even if the shielding plate 90 is provided only above the cooling unit 70, the scattering of the cooling water into the internal space 31 can be suppressed. That is, the installation range of the shielding plate 90 (shielding portion) can be reduced, and the configuration of the shielding plate 90 can be simplified.

  In the first reference example, even if the cooling unit 70 is damaged, the temperature sensor 19 and the controller 26 can detect the leakage of the cooling water. When the leakage of the cooling water is detected, the controller 26 controls the operation of the actuator of the supply adjustment valve 75 provided in the supply pipe 73 to stop the supply of the cooling water to the cooling unit 70. Can do. Thereby, the liquid quantity (namely, the amount of cooling water vaporized) which leaks from the cooling unit 70 can be reduced. And the further pressure rise in the vacuum vessel 10 can be suppressed.

  In addition, when the leakage of the cooling water is detected, the controller 26 controls the operation of the actuator that adjusts the output of the RF coils 24 and 25 to reduce the output of the RF coils 24 and 25 or stop the output (stop heating). ). Also by this, vaporization (evaporation) of the leaked cooling water can be suppressed, and a sudden pressure increase in the vacuum vessel 10 can be suppressed.

  Further, when the leakage of the cooling water is detected, the controller 26 controls the operation of the actuator of the pressure adjustment valve 15 provided in the exhaust pipe 14 to discharge the gas in the vacuum vessel 10 to the outside. it can. Thereby, the pressure in the vacuum vessel 10 can be reduced, and as a result, a sudden pressure increase can be suppressed.

  In the first reference example, a check valve 76 is provided at a portion outside the vacuum vessel 10 in the discharge pipe 74 connected to the cooling unit 70. Therefore, the discharge pipe 74 can discharge the cooling water from the storage space 72 of the cooling unit 70 to the outside of the vacuum vessel 10 and can suppress the suction of fluid from the discharge pipe 74 side. That is, as described above, even if the supply adjustment valve 75 is fully closed, the supply of the cooling water to the cooling unit 70 is stopped and the storage space 72 of the cooling unit 70 is empty. The fluid (for example, air) is not sucked into the storage space 72 of the cooling unit 70 via the air. Thereby, the sucked air leaks from the cooling unit 70 and reacts with the raw material gas in the internal space 31 of the crucible 30, thereby preventing the production apparatus 1 from being damaged due to heat generation or volume expansion.

  In the first reference example, the cooling trap 22 and the upper storage part 23 are provided above the crucible 30 and up to the exhaust pipe 14. Therefore, even if the cooling unit 70 is damaged, the vapor evaporated in the internal space 31 of the crucible 30 can be returned to water by the cooling trap 22 and stored in the upper storage unit 23. Also by this, it is possible to suppress sudden pressure fluctuation due to vaporization of the cooling water.

  In the first reference example, the shielding plate 90 is fixed to the bottom of the crucible 30 in the configuration in which the gas introduction pipe 50 and the cooling unit 70 are disposed below the crucible 30. However, the arrangement of the shielding plate 90 is not limited to the above example. For example, the shielding plate 90 may be fixed to the gas introduction pipe 50 or the cooling unit 70. For example, in the example shown in FIG. 5, the shielding plate 90 having an inverted L-shaped cross section is formed using a porous body such as graphite, and the L-shaped short portion 90 a facing the upper portion 71 a is the crucible of the gas introduction pipe 50. The side end 51 and a part of the upper part 71a are contacted, and the longitudinal part 90b is fixed to the part of the side part 71c by screw fastening or the like. Moreover, the opening part of the short part 90a is substantially coincident with the opening of the gas introduction pipe 50, and the lower end of the long part 90b is located below the lower part 71b. With such a configuration, the cooling water leaked from the cooling unit 70 soaks into the shielding plate 90 made of a porous body and then falls downward. Therefore, scattering of the cooling water caused by hitting and reflecting the shielding plate 90 can be suppressed. Since the cooling water soaks into the shielding plate 90, the cooling water can escape downward without providing a gap between the cooling unit 70 and the shielding plate 90. Moreover, since only the downward side (lower part 71b) side of the cooling unit 70 is in the escape direction of the leaked cooling water, it is possible to effectively suppress the scattering of the cooling water to the internal space 31 of the crucible 30. it can. Furthermore, since the shielding plate 90 made of a porous material has a heat insulating property, thermal damage to the cooling unit 70 (member 71) can be reduced. FIG. 5 is a cross-sectional view showing a modification, and corresponds to FIG.

  In the example shown in FIG. 5, an example in which the shielding plate 90 made of a porous body is fixed in contact with the cooling unit 70 is shown. However, a material that does not soak cooling water into the shielding plate 90 (a material that reflects cooling water) is used. In the case where it is used, the side portion 71c and the longitudinal portion 90b are not brought into contact with each other, but have a gap for allowing cooling water leaked on the upper portion 71a side to escape downward (see FIG. 6 described later). It is preferable that

  In the example shown in FIG. 5, the example in which the shielding plate 90 made of a porous body has an inverted L-shaped cross section is shown. However, the shape of the shielding plate 90 made of a porous body is limited to the example shown in FIG. 5. Is not to be done. For example, a porous body may be used for the flat shielding plate 90 shown in FIG.

  In the first reference example, the temperature sensor 19 and the controller 26 detect the leakage of the cooling water from the cooling unit 70, and supply the cooling water to the cooling unit 70 when the leakage of the cooling water is detected. An example is shown in which the gas in the vacuum vessel 10 is stopped, the output of the RF coils 24 and 25 is stopped. However, the manufacturing apparatus 1 should just have a shielding part (shielding plate 90) at least. Further, only one of the above three controls may be performed, or only two may be performed.

  In the first reference example, the cooling unit 70 is provided integrally with the gas introduction pipe 50. With such a configuration, the gas introduction pipe 50 can be efficiently cooled and a predetermined temperature gradient can be provided.

(Second reference example)
Next, a second reference example will be described based on FIG. FIG. 6 is an enlarged cross-sectional view showing the periphery of the shielding part and the cooling part, which are characteristic parts, in the silicon carbide single crystal manufacturing apparatus according to the second reference example. FIG. 6 corresponds to FIG. 2 shown in the first reference example.

  Since the silicon carbide single crystal manufacturing apparatus according to the second reference example is often in common with that according to the first reference example, detailed description of the common parts will be omitted, and different parts will be described mainly. In addition, the same code | symbol shall be provided to the element same as the element shown in the 1st reference example.

  In the first reference example, an example in which the cooling unit 70 is disposed below the crucible 30 is shown. In contrast, the second reference example is characterized in that a part of the cooling unit 70 is disposed in the internal space 31 of the crucible 30 (positioned above the outer surface of the bottom of the crucible 30). In the example shown below (see FIG. 6), the configuration other than the shape of the shielding plate 90, the arrangement of the gas introduction pipe 50, the cooling unit 70, and the shielding plate 90 is the configuration shown in the first reference example (FIGS. 1 to 1). (See FIG. 3).

  In the example shown in FIG. 6, a predetermined range from the crucible side end portion 51 of the gas introduction pipe 50 is disposed in the internal space 31 of the crucible 30 through the through hole 30a. Similarly to the first reference example, the cooling unit 70 integrated with the gas introduction pipe 50 is also arranged in the internal space 31 of the crucible 30 up to a part of the side part 71c through the through hole 30a. A gap is provided between the crucible 30, the gas introduction pipe 50, and the cooling unit 70 for communicating the internal space 31 with a low-temperature portion below the crucible 30 in the internal space of the vacuum vessel 10. .

  Further, the shielding plate 90 has an inverted L-shaped cross section similar to the configuration shown in FIG. 5, and the gas introduction is performed in the horizontal direction so that the L-shaped short portion 90a faces the entire upper portion 71a. The tube 50 extends from the crucible side end 51 to the outside of the cooling unit 70. In addition, the longitudinal portion 90b extends from above to below the cooling unit 70 in the vertical direction so as to face the entire side portion 71c. Therefore, the entire short part 90 a and a part of the long part 90 b in the shielding plate 90 are arranged in the internal space 31 of the crucible 30. And the L-shaped short part 90a is being fixed by screw fastening etc. in the state which contacted the crucible side edge part 51 of the gas introduction pipe | tube 50, and a part of upper part 71a. The shielding plate 90 is formed using a material that reflects cooling water, and there is a gap between a part of the upper portion 71a and the short portion 90a and between the side portion 71c and the long portion 90b. The gap is provided as a passage for allowing the cooling water to escape downward.

  As described above, according to the silicon carbide single crystal manufacturing apparatus 1 according to the second reference example, a part of the cooling unit 70 is arranged in the internal space 31 of the crucible 30 and is cooled by the shielding plate 90. It is possible to block water from scattering in the internal space 31 of the crucible 30. And the leaked cooling water can be dropped to the low temperature area | region (lower storage part 21) below the crucible 30 (internal space 31) in the internal space of the vacuum vessel 10. FIG. Therefore, a rapid pressure increase in the vacuum vessel 10 due to vaporization (evaporation) of the cooling water can be suppressed.

  In the second reference example, it is only necessary that the shielding plate 90 is disposed at least at a portion facing the internal space 31 in the cooling unit 70. This way of thinking is the same as the first reference example. Therefore, the lower end of the longitudinal portion 90b facing the side portion 71c only needs to be positioned at a position that coincides with the lower outer surface of the crucible 30 in the vertical direction or below it. For the other points, the configuration (including the modification) shown in the first reference example can be applied.

(This embodiment)
Next, an embodiment of the present invention will be described with reference to FIG. FIG. 7 is an enlarged cross-sectional view showing the periphery of the shielding part and the cooling part, which are characteristic parts, in the silicon carbide single crystal manufacturing apparatus according to the embodiment of the present invention. FIG. 7 corresponds to FIG. 2 shown in the first reference example.

  Since the silicon carbide single crystal manufacturing apparatus according to the embodiment of the present invention is often in common with each of the reference examples described above, a detailed description of the common parts will be omitted below, and different parts will be mainly described. In addition, the same code | symbol shall be provided to the element same as the element shown to the reference example mentioned above.

  In the reference example described above, an example is shown in which the shielding plate 90 is provided so that the cooling water leaked from the cooling unit 70 is blocked by the shielding plate 90 and the cooling water is prevented from scattering in the internal space 31 of the crucible 30. It was. On the other hand, in this embodiment, even if the cooling unit 70 is damaged, the wall constituting the cooling unit 70 is configured such that the direction in which the cooling water leaks is different from the direction of the internal space 31 of the crucible 30. It is characterized in that a partial mechanical strength difference is provided in the member 71 as a part. In the example shown below (see FIG. 7), the first reference example (FIG. 1) is provided except that the shielding plate 90 is not provided and the thickness of the member 71 constituting the cooling unit 70 is partially different. (See FIG. 3).

  In the example illustrated in FIG. 7, the gas introduction pipe 50 and the cooling unit 70 are disposed below the crucible 30. Similarly to the first reference example, one end of the member 71 made of SUS having a substantially U-shaped cross section is joined to the side surface of the gas introduction pipe 50 near the upper end, and the other end is a part below the joined portion. The cooling unit 70 is provided with a storage space 72 through which cooling water is circulated by the member 71 and the side surface of the gas introduction pipe 50. The cooling unit 70 (reservation space 72) is provided in an annular shape so as to surround the gas introduction pipe 50. And the supply piping 73 for supplying cooling water to the cooling unit 70 (storage space 72) from the outside of the vacuum vessel 10 through the lower part 71b of the cooling unit 70 (member 71), and the cooling unit 70 (storage space) 72) A discharge pipe 74 for discharging the cooling water from the vacuum vessel 10 to the outside of the vacuum vessel 10 is connected to the cooling unit 70 (storage space 72) so that the cooling water can flow.

  In the example shown in FIG. 7, the thickness of the upper portion 71a of the member 71 facing the crucible 30 (internal space 31) is T1, the thickness of the lower portion 71b facing the flange 16 is T2, and the upper portion 71a and the lower portion 71b are When the thickness of the side portion 71c that is connected and faces the heat insulating member 35 is T3, the relationship between the thicknesses T1 to T3 is T1> T3> T2. That is, the thickness T1 of the upper portion 71a is the thickest, and the thickness T2 of the lower portion 71b is the thinnest. In other words, in the member 71, the mechanical strength of the upper part 71a is the highest, and the mechanical strength of the lower part 71b is the lowest. The horizontal thickness (radial direction) of the gas introduction pipe 50 is equal to or greater than the thickness T1 of the upper portion 71a.

  As described above, according to the silicon carbide single crystal manufacturing apparatus 1 according to the present embodiment, among the members 71 constituting the cooling unit 70, damage is likely to occur on the lower portion 71b side having the lowest mechanical strength. Damage is hardly caused on the upper portion 71 a side facing the space 31. Therefore, even if the cooling unit 70 is broken, the cooling water is difficult to scatter toward the internal space 31 of the crucible 30, so that the cooling water is prevented from being scattered in the internal space 31, and the vacuum is generated by vaporizing the cooling water. A sudden pressure increase in the container 10 can be suppressed.

  In particular, in the present embodiment, the thickness of the lower portion 71 b is made thinner than other portions of the member 71. Even if the lower portion 71b is damaged, the cooling water does not scatter upward, so that a rapid pressure increase in the vacuum vessel 10 due to vaporization of the cooling water can be effectively suppressed. However, the relationship between the wall thicknesses T1 to T3 is not limited to the above-described T1> T3> T2. For example, the relationship of T1 ≧ T3> T2 may be satisfied, or the relationship of T1> T3 ≧ T2 may be satisfied. However, it is preferable to make the thickness of the lower portion 71 b thinner than other portions of the member 71.

  In the present embodiment, the cooling unit 70 is disposed below the crucible 30. However, a configuration in which a part of the cooling unit 70 is disposed in the internal space 31 of the crucible 30 may be employed. In this case, in the member 71, the portion excluding the facing portion (the portion not facing the internal space 31) is more than the portion facing the internal space 31 of the crucible 30 (the portion above the outer surface of the bottom of the crucible 30). What is necessary is just to set it as the structure by which mechanical strength was made low. For example, when a part of the upper part 71 a and the side part 71 c are arranged in the inner space 31, the thickness of the part (at least the lower part 71 b) below the outer surface of the bottom part of the crucible 30 is set to the thickness of the part opposite to the member 71. What is necessary is just to make it thinner than thickness.

  Moreover, in this embodiment, the example which provides the partial mechanical strength difference in the member 71 as a wall part by adjusting the thickness of the member which comprises the cooling part 70 was shown. However, a mechanical strength difference can be provided in addition to the adjustment of the thickness. For example, by providing a welded part at a part excluding the part facing the internal space 31 of the crucible 30, in the unlikely event that damage occurs, the structure may be such that the welded part is easily damaged.

  The configuration shown in the present embodiment may be combined with the configuration shown in the first reference example and the configuration shown in the second reference example.

  The reference examples and preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described reference examples and embodiments, and various modifications can be made without departing from the spirit of the present invention. It is possible.

  In the reference example and the preferred embodiment of the present invention, the example of water (cooling water) is shown as the cooling liquid flowing through the storage space 72 of the cooling unit 70. However, the cooling liquid is not limited to cooling water.

  In the reference example and the preferred embodiment of the present invention, an example of the temperature sensor 19 is shown as a sensor constituting the leak detection means. However, the sensor for detecting leakage of cooling water from the cooling unit 70 is not limited to the above example. For example, a liquid level detection sensor that detects the liquid level height of the cooling water stored in the lower storage unit 21 may be applied.

  In the reference example and the preferred embodiment of the present invention, the example in which the leak detection means is configured by the temperature sensor 19 and the determination unit of the controller 26 has been described. That is, the example in which the determination unit is included in the controller 26 is shown. However, the temperature sensor 19 may include a determination unit, and the controller may include only the control unit.

  In the reference example and the preferred embodiment of the present invention, the controller 26 is a first control unit that controls the operation of the actuator of the supply adjustment valve 75 provided in the supply pipe 73, and an actuator that adjusts the outputs of the RF coils 24 and 25. The second control means for controlling the operation of the second control means The third control means for controlling the operation of the actuator of the pressure regulating valve 15 provided in the exhaust pipe 14 is shown as an example. However, a configuration in which each control unit is provided independently may be employed.

DESCRIPTION OF SYMBOLS 1 ... Manufacturing apparatus 10 ... Vacuum container 19 ... Temperature sensor (leak detection means)
26 ... Controller (leakage detection means, first to third control means)
30 ... Crucible (reaction vessel)
31 ... Internal space (internal area)
33 ... Silicon carbide single crystal substrate 50 ... Gas introduction pipe 50a ... Crucible side end 70 ... Cooling part 75 ... Supply regulating valve 90 ... Shielding plate (shielding part)

Claims (6)

A vacuum vessel;
A reaction vessel disposed in the vacuum vessel and having a silicon carbide single crystal substrate serving as a seed crystal disposed therein;
In order to supply a mixed gas containing a gas containing Si and a gas containing C from below to the silicon carbide single crystal substrate in the reaction vessel from the outside of the vacuum vessel in communication with the inside and outside of the vacuum vessel. Gas inlet pipes,
It is arranged away from the reaction vessel at a position that does not hinder the supply path of the mixed gas from the gas introduction pipe to the silicon carbide single crystal substrate located above it, and the surrounding temperature is lowered by the liquid flowing inside the reaction vessel. A silicon carbide single crystal manufacturing apparatus comprising:
The reaction vessel is provided with a through-hole communicating with an inner region of the reaction vessel and a portion below the reaction vessel in the inner region of the vacuum vessel at the bottom, and through the through-hole, The mixed gas is supplied to an internal region of the reaction vessel;
The gas introduction pipe is disposed away from the reaction vessel;
The cooling unit is disposed at an end of the reaction vessel side on the side surface of the gas introduction pipe,
The mechanical strength of the wall part in the said cooling part is lower than the site | part which opposes the internal region of the said reaction container, and the site | part except the said opposing part is made low, The manufacturing apparatus of the silicon carbide single crystal characterized by the above-mentioned.   2. The silicon carbide single crystal according to claim 1, wherein the wall portion of the cooling portion is thinner in a portion excluding the facing portion than in a portion facing the internal region of the reaction vessel. Manufacturing equipment. A supply pipe that communicates the inside and outside of the vacuum vessel and supplies the liquid to the cooling unit;
A discharge pipe for discharging the liquid from the cooling unit to the outside of the vacuum vessel;
A liquid amount adjusting means provided in the supply pipe for adjusting the supply amount of the liquid to the cooling unit;
Leak detection means provided in the vacuum vessel and below the reaction vessel, and detecting leakage of the liquid from the cooling unit;
The first control means for controlling the liquid amount adjusting means so as to stop the supply of the liquid when the leakage of the liquid is detected by the leak detection means. The apparatus for producing a silicon carbide single crystal according to claim 2.   The apparatus for producing a silicon carbide single crystal according to claim 7, wherein a check valve is provided in the discharge pipe. Heating means for heating the internal region of the reaction vessel;
4. A second control unit configured to control the heating unit so that an output of the heating unit is lowered or stopped when the leakage of the liquid is detected by the leak detection unit. Or the manufacturing apparatus of the silicon carbide single crystal of Claim 4. An exhaust pipe provided above the reaction vessel and communicating between the inside and outside of the vacuum vessel;
A pressure adjusting means that is provided in the exhaust pipe and adjusts the pressure in the vacuum vessel according to its opening;
And third control means for controlling the pressure adjusting means so that the opening degree of the pressure adjusting means is fully opened when the leakage of the liquid is detected by the leak detecting means. The manufacturing apparatus of the silicon carbide single crystal of Claim 3 or Claim 4.

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