JP2021098168A - Exhaust gas introduction pipe of scrubber and scrubber - Google Patents

Abstract

To provide an exhaust gas introduction pipe of a scrubber which can inhibit generation of by-products.SOLUTION: An exhaust gas introduction pipe of a scrubber can remove a first gas which flows from a reactor, which enables vapor growth of an SiC thin film therein, through an exhaust pipe to be exhausted. The exhaust gas introduction pipe of the scrubber has: a first pipe flowing the first gas to a gas storage part of the scrubber; and a second pipe disposed at the radial outer side of the first pipe and forming a double pipe structure with the first pipe. The second pipe is a pipe for flowing a second gas having a temperature higher than that of the first gas to the gas storage part.SELECTED DRAWING: Figure 1

Description

The present invention relates to an exhaust gas introduction pipe for a scrubber and a scrubber.

Chemical Vapor Deposition (CVD) equipment is widely used as a means of film formation of various layers. For example, a chemical vapor deposition apparatus is also used for growing an epitaxial film of silicon carbide (SiC).

In film formation using a CVD apparatus, a raw material gas is supplied into the reaction furnace to grow crystals on the surface of the substrate. Of the gases supplied into the reactor, the process gas that did not react in the reactor is exhausted from the exhaust pipe. The process gas flowing through the exhaust pipe may include, for example, a silane-based gas such as silane, dichlorosilane, trichlorosilane, and tetrachlorosilane as a hydride-based gas. When these silane-based gases are released into the air, they may spontaneously ignite. In addition, dichlorosilane, trichlorosilane, and tetrachlorosilane may generate hydrogen chloride when they react with the atmosphere. Therefore, the process gas containing these silane-based gases needs to be detoxified before being released into the air.

Patent Document 1 discloses a gas inlet portion of a scrubber that is detoxified by bringing a process gas into contact with an alkaline aqueous solution. The invention described in Patent Document 1 has been made in view of the fact that a precipitate is formed when a hydride-based gas and a high-concentration alkaline aqueous solution come into rapid contact with each other. Patent Document 1 describes that the generation of precipitates is suppressed because the hydride-based gas is not in direct contact with the alkaline aqueous solution but in contact with the mixed solution having a reduced concentration.

The process gas detoxification process is performed on a scrubber. Patent Document 2 discloses a scrubber including a combustion chamber. The scrubber of Patent Document 2 discloses that a process gas, an atmosphere, and a fuel gas are introduced into a combustion chamber and burned to detoxify the process gas.

Japanese Unexamined Patent Publication No. 2013-91026 Japanese Unexamined Patent Publication No. 2012-77924

However, even when the hydride-based gas and the alkaline aqueous solution do not come into direct contact with each other as described in Patent Document 1, by-products may be generated. For example, in the method of Patent Document 2, by-products due to the process gas are accumulated at the tip of the tubular nozzle that introduces the process gas into the combustion chamber, and the nozzle is further blocked. In order to remove the by-products accumulated on the nozzle, it is necessary to stop the operation of the scrubber, which reduces the throughput.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an exhaust gas introduction pipe for a scrubber capable of suppressing the generation of by-products.

The present invention provides the following means for solving the above problems.

(1) The exhaust gas introduction pipe of the scrubber according to the first aspect of the present invention removes the first gas discharged by flowing through the exhaust pipe from the reaction furnace capable of performing gas phase growth of the SiC thin film inside. A scrubber exhaust gas introduction pipe that can be harmed, the first pipe for flowing the first gas into the gas accommodating portion of the scrubber, and the first pipe arranged on the radial outer side of the first pipe. It has a second pipe forming a double pipe structure, and the second pipe is a pipe through which a second gas having a temperature higher than that of the first gas flows through the gas accommodating portion.

(2) In the exhaust gas introduction pipe of the scrubber according to the above aspect, the second pipe may be a pipe for flowing a second gas of 60 ° C. or higher and 400 ° C. or lower to the gas accommodating portion.

(3) In the exhaust gas introduction pipe of the scrubber according to the above aspect, the inner diameter of the second tip on the downstream side of the second pipe in the flow direction of the first gas is the flow of the first gas of the first pipe. It may be larger than the outer diameter of the first tip on the downstream side in the direction, and the difference between the inner diameter of the second tip and the outer diameter of the first tip may be 2 mm or more and 10 mm or less.

(4) In the exhaust gas introduction pipe of the scrubber according to the above aspect, the second pipe may have a tapered portion having a shape in which the inner diameter becomes smaller as it approaches the second tip.

(5) In the scrubber exhaust gas introduction pipe according to the above aspect, the second tip of the second pipe is located downstream of the first tip of the first pipe in the flow direction of the first gas. May be.

(6) In the exhaust gas introduction pipe of the scrubber according to the above aspect, the second pipe may be a pipe through which at least one or more gases selected from nitrogen and argon flow.

(7) The scrubber according to the second aspect of the present invention can detoxify the first gas discharged by flowing through the exhaust pipe from the reaction furnace capable of performing gas phase growth of the SiC thin film inside. A possible scrubber, the first pipe through which the first gas flows in a gas accommodating portion where a plurality of gases are collected, and the first pipe and a double pipe structure arranged on the radial outer side of the first pipe. The second pipe has a second pipe forming the above and a third pipe arranged on the side wall of the scrubber, and the second pipe is a pipe for flowing a second gas having a temperature higher than that of the first gas to the gas accommodating portion. The third pipe is arranged in a direction intersecting the flow direction of the first gas, and the third pipe is a pipe for flowing air into the gas accommodating portion.

According to the exhaust gas introduction pipe of the scrubber according to the above aspect, it is possible to suppress the generation of by-products.

It is a schematic diagram of the chemical vapor deposition apparatus which concerns on one aspect of this invention. It is sectional drawing which shows a part of the scrubber which concerns on one aspect of this invention. It is sectional drawing which shows a part of the scrubber which concerns on the comparative example for demonstrating the effect of this invention. It is sectional drawing which shows a part of the scrubber which concerns on one aspect of this invention. It is sectional drawing which shows a part of the scrubber which concerns on one aspect of this invention. It is sectional drawing which shows a part of the scrubber which concerns on one aspect of this invention. It is sectional drawing which shows a part of the scrubber which concerns on one aspect of this invention. It is sectional drawing which shows a part of the scrubber which concerns on one aspect of this invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as appropriate. The drawings used in the following description may be enlarged for convenience in order to make the features of the present invention easy to understand, and the dimensional ratios of the respective components may differ from the actual ones. is there. The materials, numbers, arrangements, dimensions, etc. exemplified in the following description are examples, and the present invention is not limited thereto, and can be appropriately modified and carried out within the range in which the effects of the present invention are exhibited. Is.

[Chemical vapor deposition equipment]
FIG. 1 is a schematic view schematically showing the configuration of the chemical vapor deposition apparatus 100 according to the first embodiment. The chemical vapor deposition apparatus 100 includes a reaction furnace 10, an exhaust pipe 20, a filter 30, an exhaust pump 40, and a scrubber 50. As the reaction furnace 10, the exhaust pipe 20, the filter 30, and the exhaust pump 40, known ones can be used.

FIG. 1 shows the flow direction of the process gas Gp supplied to the reactor 10 for convenience. As shown in FIG. 1, the process gas Gp flows through the exhaust pipe 20, the filter 30, the exhaust pump 40, and the scrubber 50. The process gas Gp refers to the gas supplied to the reactor 10.

In the chemical vapor deposition apparatus 100, when the process gas Gp flows into the reaction furnace 10, the vapor phase growth of the SiC thin film is performed inside the reaction furnace 10. The SiC thin film is, for example, a SiC epitaxial wafer. Hereinafter, the present embodiment will be described by taking the case of growing a SiC epitaxial wafer as an example. The process gas Gp is consumed in the reaction furnace 10, the exhaust pipe 20, the filter 30, and the like. The unconsumed process gas Gp flows into the scrubber 50 through the exhaust gas introduction pipe 1 of the scrubber 50, is detoxified by the scrubber 50, and is released to the atmosphere.

First, the direction is defined. In the exhaust gas introduction pipe 1 of the scrubber, the direction in which the process gas (first gas) Gp flows is defined as the z direction. Hereinafter, in the present specification, the process gas introduced into the scrubber 50 is referred to as a first gas G1 for convenience of explanation. The z direction is an example of the first direction. Further, the direction perpendicular to the z direction and extending from the center of the scrubber 50 is defined as the radial direction. FIG. 2 is a cross-sectional view cut along an arbitrary cross section along the central axis of the scrubber 50.

<First Embodiment>
FIG. 2 is a schematic cross-sectional view showing a part of a cross section of the scrubber 50 according to the present embodiment. In FIG. 2, for convenience of explanation, the center line of the exhaust gas introduction pipe 1 and the first gas G1 and the second gas G2 introduced into the scrubber 50 from the exhaust gas introduction pipe 1 are shown together. In the example shown in FIG. 2, the central axis of the scrubber 50 and the central axis of the exhaust gas introduction pipe 1 coincide with each other. Hereinafter, for convenience of explanation, the process gas introduced into the scrubber 50 is referred to as a first gas Gp.

The scrubber 50 is a device for detoxifying the first gas G1. The scrubber 50 has an exhaust gas introduction pipe 1. The first gas G1 flows through the exhaust gas introduction pipe 1 and is introduced into the scrubber 50. Further, in the flow direction of the process gas of the scrubber 50, the end close to the reactor 10 has an upper end 51 and a side wall 52 in contact with the upper end 51.

The exhaust gas introduction pipe 1 has a double pipe structure formed by a first pipe 1A and a second pipe 1B from the inside in the radial direction. Any material used as the pipe can be used for the first pipe 1A and the second pipe 1B. The first pipe 1A and the second pipe 1B are stainless steel pipes such as SUS304 and SUS316. When the flammable gas is not contained in the process gas Gp, vinyl chloride or the like may be used for the first pipe 1A and the second pipe 1B in addition to the above-mentioned example. Basically, there is no problem with SUS304 for the first pipe 1A and the second pipe 1B, but when the process gas Gp contains a corrosive gas, a material having excellent corrosion resistance such as SUS316 may be used. preferable. As the second pipe 1B, a pipe having a higher thermal conductivity than the first pipe 1A may be used.

A heat insulating material may be further provided on the radial outer side of the second pipe 1B. The heat insulating material may be arranged on the outer side in the radial direction of the second pipe 1B over the entire area in the first direction, or may be partially arranged. For example, in the flow direction of the first gas G1, it may be arranged only on the downstream side of the upper end 51.

The first pipe 1A is connected to the reaction furnace 10 via the exhaust pipe 20. The first pipe 1A is a pipe through which the first gas G1 flows. The tip on the upstream side in the flow direction of the first gas G1 of the first pipe 1A is referred to as the first root 11A, and the tip on the downstream side is referred to as the first tip 12A. The second pipe 1B is not connected to the reactor 10. Therefore, the process gas does not flow between the second pipe 1B and the first pipe 1A. The second pipe 1B is a pipe through which a second gas G2 having a temperature higher than that of the first gas G1 flows. The tip on the upstream side in the flow direction of the second gas G2 of the second pipe 1B is referred to as the second root 11B, and the tip on the downstream side is referred to as the second tip 12B.

In the present specification, for convenience of explanation, the first root 11A and the second root 11B may be collectively referred to as the root 11. Further, the first tip 12A and the second tip 12B may be collectively referred to as the tip 12.

_{The inner diameter RA} of the first pipe 1A is, for example, 30 mm or more and 60 mm or less, and preferably 40 mm or more and 50 mm or less. The inner diameter _{R B} of the second pipe 1B is, for example, 40m or less than 75mm, and a 45mm or 65mm or less, is preferably at least 50mm 60mm or less. The inner diameter RA of the first pipe 1A and the inner diameter RB of the second pipe 1B referred to here are the inner diameters of the tips on the downstream side in the flow direction of the first gas G1 of the first pipe 1A and the second pipe 1B, respectively. Say that. That the inner diameter _{R A} of the first pipe 1A, refers to the inner diameter of the first tip 12A, the inner diameter _{R B} of the second pipe 1B refers to the inner diameter of the second tip 12B.

The outer diameter of the first pipe 1A _{(R A} + _W A) is, for example, 40mm or 65mm or less, is preferably 45mm or more 55mm or less. The outer diameter of the second pipe 1B _{(R B} + _W B) is, for example, 45mm or 80mm or less, is preferably 55mm or more 65mm or less. The outer diameter of the first pipe 1A and the outer diameter of the second pipe 1B referred to here are the outer diameters of the tips on the downstream side in the flow direction of the first gas G1 of the first pipe 1A and the second pipe 1B, respectively. It means that. That is, the outer diameter (RA + WA) of the first pipe 1A means the outer diameter of the first tip 12A, and the outer diameter (RB + WB) of the second pipe 1B means the outer diameter of the second tip 12B. ..

The difference between the outer diameter _{(R A} + _W A) of an inside diameter _{R B} and the first pipe 1A of the second pipe 1B is, for example, 2mm or more 10mm or less, preferably 3mm or more 7mm or less, 3mm or more It is more preferably 5 mm or less.

The thickness (thickness) WA of the first pipe 1A and the thickness (thickness) WB of the second pipe 1B can be, for example, 2 mm or more and 3 mm or less. The thickness WA is preferably thin from the viewpoint of warming the first gas G1 with the second gas G2. On the other hand, if the thickness WA is too thin, the first gas G1 and the second gas G2 may be mixed or the strength may become brittle, so that the thickness WA is preferably moderately thick. The thickness WB should not be too thin so that the strength does not become brittle.

The thickness (thickness) of the second pipe 1B may be thicker or thinner than that of the first pipe 1A. However, the thickness (thickness) WB of the second pipe 1B is preferably thicker than that of the first pipe 1A from the viewpoint of heat insulating the second gas G2.

The gas that can be flowed as the second gas G2 is a gas having a higher temperature than the first gas G1. The second gas G2 is preferably a gas having low reactivity with the first gas G1. The second gas G2 is preferably one or more gases selected from, for example, nitrogen and a rare gas. As the noble gas, argon is preferably used from the viewpoint of cost.

The first gas G1 is heated by the second gas G2. The first gas G1 and the second gas G2 flow into the gas accommodating portion R inside the scrubber 50. The gas accommodating portion R refers to a region on the downstream side of the first tip 12A and the second tip 12B. The gas flowing from the first pipe 1A and the gas flowing through the second pipe 1B are collected in the gas accommodating portion R.

The exhaust gas introduction pipe 1 of the scrubber according to the present embodiment can raise the temperature of the first gas G1 even around the first tip 12A. Further, by flowing the second gas G2 to the outside of the first gas G1, it is possible to suppress the reaction between the silane gas and the water in the scrubber atmosphere around the tip 11. Therefore, the deposition of by-products by the first gas G1 can be suppressed around the tip 12. For example, it is possible to suppress the accumulation of by-products inside the first pipe 1A or between the first pipe 1A and the second pipe 1B. That is, it is possible to suppress the blockage of the first pipe 1A and the blockage of the region between the first pipe 1A and the second pipe 1B. Hereinafter, the reason will be described with reference to a comparative example.

<Comparison example>
FIG. 3 is a schematic cross-sectional view showing a part of the scrubber 50H according to the comparative example. The scrubber 50H is not included in the present invention. The upper end of the scrubber 50H is called the upper end 51H. The scrubber 50H has an exhaust gas introduction pipe 1H. The exhaust gas introduction pipe 1H is connected to the reactor via an exhaust pipe. The scrubber 50H according to Comparative Example 1 is different from the scrubber 50 in that the exhaust gas introduction pipe 1H has a single structure.

The exhaust gas introduction pipe 1H introduces the process gas (first gas) G1 into the scrubber 50H. Of both ends of the exhaust gas introduction pipe 1H, the upstream end in the flow direction of the first gas is referred to as the root 11H, and the downstream end is referred to as the tip 12H.

The temperature of the first gas G1 decreases as it approaches the tip 12H from the root 11H. As the temperature decreases, by-products are more likely to be produced. When the scrubber 50H is used, the temperature is lowered, and by-products are accumulated around the tip 12H, resulting in blockage. This by-product is produced, for example, by causing a Si-based gas in the process gas to undergo a hydrolysis reaction or the like due to the moisture in the atmosphere inside the scrubber 1.

As a method of heating the first gas G1, there is a means of heating the portion of the exhaust gas introduction pipe 1H on the upstream side of the upper end 51H of the scrubber 50H with a heater in the flow direction of the first gas G1. As the heater, for example, a ribbon heater or the like is used. However, although it depends on the type of heater used and the set temperature, this method cannot suppress the accumulation of by-products due to the first gas G1 around the tip 12H, and the exhaust gas introduction pipe 1H is blocked. There was also.

Further, as a method of heating the first gas G1, there is also a means of mixing the first gas G1 with high-temperature nitrogen and flowing it from the same pipe. Nitrogen can be heated and flowed by using a known fluid heating device or the like as described in Japanese Patent Application Laid-Open No. 2013-235945. The size of the diameter of the exhaust gas introduction pipe 1H is limited. The flow rate of the process gas discharged from the reactor is optimized for the growth of the SiC epitaxial wafer. The total flow rate of gas that can flow from the exhaust gas introduction pipe 1H is limited by the pipe. When the flow rate of the process gas is high, the amount of hot nitrogen that can flow is small. That is, the ratio of the process gas to the total flow rate of the gas flowing through the exhaust gas introduction pipe 1H increases. In the exhaust gas introduction pipe 1H, a large amount of process gas and high-temperature nitrogen are mixed. Hot nitrogen is cooled when mixed with process gas. This phenomenon is remarkable when a large amount of process gas is flowed, and high-temperature nitrogen is rapidly cooled. Therefore, this method could not suppress the deposition of by-products around the tip 12H. As a method of warming the first gas G1 to a higher temperature, there is a method of increasing the diameter of the exhaust gas introduction pipe 1H to increase the flow rate of high-temperature nitrogen and increasing the ratio of high-temperature nitrogen, but the efficiency is low and the cost is high. It ends up.

On the other hand, in the exhaust gas introduction pipe 1 of the scrubber 50 according to the first embodiment, the exhaust gas introduction pipe 1 has a double piping structure. Therefore, the flow path of the first gas G1 and the flow path of the second gas G2 can be separated. The first gas G1 flows inside the first pipe 1A, and the second gas G2 flows outside the first pipe 1A and outside the second pipe 1B. The length of the second pipe 1B from the upper end 51 is the same as the length of the first pipe 1A from the upper end 51, and the first gas G1 can be heated even around the tip 12. The first gas G1 is warmed to the second gas G2 via the first pipe 1A. Since the second gas G2 does not come into direct contact with the first gas G1, the second gas G2 is difficult to be cooled. Therefore, the first gas G1 can be efficiently warmed up. Further, since the second gas G2 flows outside in the radial direction of the first gas G1, it is possible to suppress the reaction between the first gas and the moisture in the scrubber atmosphere. Therefore, it is possible to suppress the generation of by-products around the tip 12 and the blockage of the exhaust gas introduction pipe 1H.

Although FIG. 2 shows a case where the exhaust gas introduction pipe 1 is one, the scrubber 50 according to the present embodiment is not limited to this example. The number of exhaust gas introduction pipes 1 can be appropriately selected according to the application. For example, in the scrubber 50, for example, two or more exhaust gas introduction pipes 1 may be provided, or four or more exhaust gas introduction pipes 1 may be provided. When a plurality of exhaust gas introduction pipes 1 are provided, for example, exhaust gas exhausted from a plurality of chambers can be introduced into the scrubber.

Note that FIG. 2 shows a case where the positions of the first tip 12A and the second tip 12B in the flow direction of the first gas G1 are the same. However, the exhaust gas introduction pipe 1 of the scrubber according to the present embodiment is not limited to this example. Specifically, the second tip 12B may be located downstream of the first tip 12A in the flow direction of the first gas G1.

That is, if the length from the upper end 51 to the first tip 12A and the length from the second tip 12B are the length LA and the length LB, respectively, the length LB may be longer than the length LA.

The exhaust gas introduction pipe 1 is a part of the scrubber 50. In the present embodiment, it is described that the gas flows through the exhaust gas introduction pipe 1 and is introduced into the scrubber 50. However, the term “inside the scrubber 50” as used herein means that the gas flows in the flow direction of the first gas G1. The region of the scrubber 50 on the downstream side of the tip 12. The same applies to the same expression for the second gas G2.

<Modification example 1>
FIG. 4 is a schematic cross-sectional view showing a part of the scrubber 50X according to the first modification. The scrubber 50X is different from the scrubber 50 in that the second pipe 1BX of the exhaust gas introduction pipe 1X has a tapered portion 13. The tapered portion 13 has a shape in which the inner diameter becomes smaller as it approaches the second tip 12BX. That is, the tapered portion 13 is narrowed toward the downstream side in the flow direction of the second gas G2. The same configuration as the scrubber 50 is designated by the same reference numerals, and the description thereof will be omitted.

The arrangement of the tapered portion 13 in the second pipe 1BX can be arbitrarily selected. That is, the angle θ of the tapered portion 13 and the length of the tapered portion 13 can be arbitrarily selected. The inner diameter RB of the second pipe 1BX means the inner diameter of the second tip 12B also in this modification. The difference between the inner diameter of the second pipe 1BX and the outer diameter of the first pipe 1A is the distance between the second tip 1BX and the first pipe 1A in the radial direction.

Even when the scrubber 50X according to the first modification is used, the same effect as when the scrubber 50 according to the first embodiment can be obtained can be obtained. Further, when the scrubber 50X according to the first modification is used, the second gas G2 can be focused in the vicinity of the first tip 12A. Therefore, it is possible to effectively suppress the temperature of the first gas G1 from becoming low in the vicinity of the first tip 12A. Therefore, the deposition of by-products in the vicinity of the first tip 12A can be effectively suppressed.

<Modification example 3>
FIG. 5 is a schematic cross-sectional view showing a part of the scrubber 50 ′ according to the modified example 3. The scrubber 50'is different from the scrubber 50 in the arrangement of the first pipe 1A'and the second pipe 1B' of the exhaust gas introduction pipe 1'. The first tip 12A'of the first pipe 1A and the second tip 12B'of the second pipe 1B are located at the upper ends 51. That is, the length _{L A} and _{L B} are 0. The same configuration as the scrubber 50 is designated by the same reference numerals, and the description thereof will be omitted.

Even when the scrubber 50'according to the third modification is used, the same effect as when the scrubber 50 according to the first embodiment can be obtained can be obtained. When the tip 12 is arranged at the same height as the upper end 51 and the heat insulating material is wrapped around the outer side of the second pipe 1B', the heat retaining effect around the tip 12 is further enhanced, as in the third gas described in detail below. It is possible to reduce the influence of cooling by safety exhaust.

<Second Embodiment>
FIG. 6 is a schematic cross-sectional view showing a part of the scrubber 50Y according to the second embodiment. The scrubber 50Y is different from the scrubber 50 according to the first embodiment in that it has the third pipe 6. The same configuration as the scrubber 50 is designated by the same reference numerals, and the description thereof will be omitted.

The third pipe 6 is arranged on the side wall 52 of the scrubber 50Y in a direction intersecting the flow direction of the first gas G1. The term "arranged in a direction intersecting the flow direction of the first gas G1" as used herein means that the scrubber 50Y is connected to the scrubber 50Y at an angle α. It means that the third pipe 6 and the scrubber 50Y are arranged at an angle α. The angle α is, for example, 30 ° or more and 90 ° or less, preferably 45 ° or more and 90 ° or less, and more preferably 60 ° or more and 90 ° or less.

The third pipe 6 is a pipe for flowing the third gas G3 through the gas accommodating portion R of the scrubber 50Y. The third gas G3 is introduced into the scrubber 50Y from the third exhaust port 60. The third exhaust port 60 is provided on the side wall 52 of the scrubber 50Y. The third exhaust port 60 has a first end 60T near the upper end 51 and a second end 60B away from the upper end 51. The third exhaust port 60 can be provided at an arbitrary position in the z direction. Further, it is preferable that the third exhaust port 60 and the second tip 12B are arranged at the same position in the flow direction of the first gas G1. That is, in the flow direction of the first gas G1, the length from the upper end 51 to the second tip 12B is preferably larger than the length from the upper end 51 to the first end 60T, and smaller than the length from the upper end 51 to the second end 60B. Is preferable. It is more preferable that the midpoints of the first end 60T and the second end 60B and the tip 12 are arranged so that the distances from the upper end 51 are equal.

The third gas G3 is a safety exhaust gas. The third gas G3 is, for example, at least one gas selected from the atmosphere, nitrogen and other inert gases. In the present embodiment, the gas accommodating portion R means a region downstream of the first tip 12A and the second tip 12B in the flow direction of the first gas G1. The gas that has flowed through the exhaust gas introduction pipe 1 collects in the gas accommodating portion R. That is, the first gas G1, the second gas G2, and the third gas G3 are aggregated.

The scrubber 50Y according to the present embodiment can obtain the same effect as when the scrubber 50 according to the first embodiment is used. In the scrubber 50Y, even when the atmosphere is used as the third gas G3, for example, the second gas G2 flows outward in the radial direction of the first gas G1, so that the moisture in the atmosphere reacts with the first gas G1. The effect of being able to suppress this is great. Further, when the scrubber 50Y according to the second embodiment is used, the flow path of the first gas G1 can be controlled by the third gas G3 introduced from the third pipe, and turbulence can be suppressed.

<Modification example 3>
FIG. 7 is a schematic cross-sectional view showing a part of the scrubber 50Z according to the modified example 3. The scrubber 50Z has a structure of the exhaust gas introduction pipe 1Z different from that of the scrubber 50Y. The same configuration as the scrubber 50Y is designated by the same reference numerals, and the description thereof will be omitted.

The first tip 12AZ of the first pipe 1AZ of the exhaust gas introduction pipe 1Z and the second tip 12BZ of the second pipe 1BZ are inclined with respect to the radial direction. Specifically, the length from the upper end 51 in the flow direction of the first gas G1 is inclined so that the second tip 12BZ is longer than the first tip 12AZ. In FIG. 7, the exhaust gas introduction pipe 1Z is arranged so that the tip 12Z is in a straight line. However, the scrubber 50Z according to the modified example 3 is not limited to this example, and for example, the straight line formed by the first tip 12AZ is located on the upper end 51 side of the straight line formed by the second tip 12BZ. May be good.

The angle β between the radial direction and the tip 12Z of the exhaust gas introduction pipe 1Z can be arbitrarily selected. The angle β can be arbitrarily selected, and is, for example, 0 ° or more and 60 ° or less, 0 ° or more and 45 ° or less, and the like.

The same effect as that of the scrubber 50Y can be obtained with the scrubber 50Z. Further, the exhaust gas introduction pipe 1Z has a tip 12Z inclined in the radial direction, and the flow velocity of the first gas G1 is effectively increased by introducing the third gas G3 from the third exhaust port 60. be able to.

The shape of the scrubber 50Z may be controlled so that the third exhaust port 60 is parallel to the cross section 53 of the scrubber 1Z. That is, the third gas G3 may be arranged so as to flow linearly inside the scrubber 50Z from the third exhaust port 60.

<Manufacturing method of SiC epitaxial wafer>
In the method for manufacturing a SiC epitaxial wafer according to the present embodiment, the SiC epitaxial wafer is manufactured by using the chemical vapor deposition apparatus 100 according to the above embodiment. The method for manufacturing a SiC epitaxial wafer according to the present embodiment includes a step of introducing the first gas G1 and the second gas G2 into the scrubber 50 via the exhaust gas introduction pipe 1, and a detoxification treatment of the first gas G1 by the scrubber 50. Has a process of

The method for manufacturing the SiC epitaxial wafer according to the present embodiment is a known method except that the scrubber according to the above embodiment is used and the second gas G2 is passed through the second pipe 1B of the exhaust gas introduction pipe 1 of the scrubber 50. Epitaxial wafers can be manufactured.

The first gas G1 is introduced into the scrubber 50 through the first pipe 1A of the exhaust gas introduction pipe 1. Further, the second gas G2 is introduced into the scrubber 50 through the second pipe 1B of the exhaust gas introduction pipe 1. The flow path of the second gas G2 is a gap between the first pipe 1A and the second pipe 1B.

The first gas G1 may react, for example, inside the exhaust gas introduction pipe 1 or at the tip 12 or the like to form a by-product. As the first gas, for example, five types of gases classified into "Si-based gas", "C-based gas", "Cl-based gas", "dopant gas", and "other gas" are used.

The "Si-based gas" is a gas containing Si as a constituent element of a molecule constituting the gas. For example, silane (SiH ₄ ), dichlorosilane (SiH ₂ Cl ₂ ), trichlorosilane (SiHCl ₃ ), tetrachlorosilane (SiCl ₄ ) and the like are applicable. In the present embodiment, the gas containing both Si and Cl is referred to as a silane-based gas. The Si-based gas is used as one of the raw material gases.

The "C-based gas" is a gas containing C as a constituent element of a molecule constituting the gas. For example, propane (C ₃ H ₈ ) and the like are applicable. The C-based gas is used as one of the raw material gases.

The "Cl-based gas" is a gas containing Cl as a constituent element of a molecule constituting the gas. For example, hydrogen chloride (HCl), dichlorosilane (SiH ₂ Cl ₂ ), trichlorosilane (SiHCl ₃ ), tetrachlorosilane (SiCl ₄ ) and the like are applicable. Here, dichlorosilane (SiH ₂ Cl ₂ ), trichlorosilane (SiHCl ₃ ), and tetrachlorosilane (SiCl ₄ ) are also the above-mentioned Si-based gases. Like these gases, it is a "Cl-based gas" and may be a "Si-based gas". The Cl-based gas is used as a raw material gas or an etching gas.

A "dopant gas" is a gas containing an element that serves as a donor or acceptor (carrier). Nitrogen for growing N-type, trimethylaluminum (TMA) and triethylaluminum (TEA) for growing P-type are used as dopant gases.

“Other gases” are gases that do not fall under the above four categories of gases. For example, Ar, He, H _{2 and the} like are applicable. These gases are gases that support the manufacture of SiC epitaxial wafers. For example, these gases support the gas flow for the source gas to efficiently supply to the SiC wafer.

Si gas may produce by-products when hydrolyzed. This by-product becomes a deposit. The viscosity of this by-product becomes high when the Si gas is a silane-based gas.

The flow rate of the first gas G1 can be arbitrarily selected. For example, it is preferably 30 (L / min) or more and 300 (L / min) or less, and 100 (L / min) or more and 200 (L / min) or less. The flow velocity of the first gas G1 is determined according to the flow rate of the first gas G1 and the size of the first pipe 1A.

As the second gas G2, a gas having a temperature higher than that of the first gas G1 is used. Therefore, the first gas G1 can be heated by the second gas G2. As the second gas G2, for example, nitrogen, a rare gas or the like is preferably used. The second gas G2 preferably heats the first gas G1 so that the temperature around the tip 12 of the first gas G1 becomes the same as the set temperature of the exhaust pipe 20.

The flow rate of the second gas G2 can be arbitrarily selected. For example, it is preferably 10 (L / min) or more and 150 (L / min) or less, and 20 (L / min) or more and 50 (L / min) or less. The flow velocity of the second gas G2 is determined according to the flow rate of the second gas G2 and the size of the gap between the second pipe 1B and the first pipe 1A. The flow velocity of the second gas G2 is, for example, 0.5 (M / S) or more and 3 (M / S) or less, and preferably 1 (M / S) or more and 2 (M / S) or less. By setting the flow velocity of the second gas G2 in this range, the formation of by-products can be suppressed more effectively.

The second gas G2 is heated by a known method. For example, it is heated using a heat beam cylinder (not shown) or the like. The temperature of the second gas G2 is set so that, for example, the temperature of the first gas G1 around the tip 12 becomes the same as the set temperature of the exhaust pipe 20. The temperature of the second gas G2 is higher than that of the first gas G1, for example, it is preferably 60 (° C.) or more and 400 (° C.) or less, and more preferably 100 (° C.) or more and 350 (° C.) or less. It is preferably 200 (° C.) or more, and more preferably 300 (° C.) or less. Within this range, the process gas can be heated to the extent that it does not liquefy, and deposition can be effectively suppressed. If the temperature is too high, the sealing member used to install the piping may deteriorate.

The first gas G1 introduced into the scrubber 50 is detoxified by a known method. Although not limited to this example, for example, it is detoxified by gas-liquid contact with water. Further, after gas-liquid contact, further combustion aggravation or the like may be performed. Although the specific configuration of gas-liquid contact is not shown, a known method can be used.

As described above, according to the chemical vapor deposition apparatus 100 according to the present embodiment, the first gas G1 can be heated and the accumulation of by-products can be suppressed. In addition, it is possible to prevent the exhaust gas introduction pipe 1 from being blocked. As a result, the operating time of the chemical vapor deposition apparatus 100 becomes longer, and the throughput of the chemical vapor deposition apparatus 100 increases.

<Example 1>
A simulation was performed using a scrubber 50J equipped with four exhaust gas introduction pipes 1Z. For convenience of explanation, the four exhaust gas introduction pipes 1Z are referred to as 1Z1, 1Z2, 1Z3, and 1Z4, respectively. The four exhaust gas introduction pipes 1Z are arranged point-symmetrically with respect to the central axis of the scrubber 50J. Further, the exhaust gas introduction pipe 1Z1 and the exhaust gas introduction pipe 1Z4, and the exhaust gas introduction pipe 1Z2 and the exhaust gas introduction pipe 1Z3 are arranged symmetrically with respect to the exhaust gas introduction pipe 6, respectively. For the four exhaust gas introduction pipes 1Z1, 1Z2, 1Z3 and 1Z4, the first pipe and the second pipe of the same standard were used. FIG. 8 is a schematic cross-sectional view showing a main part of the simulated scrubber 50J.

This simulation was performed using the fluid analysis software "FLUENT" manufactured by ANSYS. It has been confirmed that the simulation has a high correlation with the actual experimental results. The simulation was performed under the following conditions. The reference numerals under the following conditions are described for convenience in order to make it easier to understand the correspondence with the illustrated configuration, and the above-described embodiment is not limited to the following numerical values. It is assumed that the first gas G1 and the second gas G2 are flowing from the exhaust gas introduction pipes 1Z1, 1Z2, 1Z3 and 1Z4 under the same conditions. _{N 2} is assumed as the second gas G2. From the viewpoint of symmetry, the same results can be obtained for the exhaust gas introduction pipe 1Z1 and the exhaust gas introduction pipe 1Z4, the exhaust gas introduction pipe 1Z2 and the exhaust gas introduction pipe 1Z3, respectively. Therefore, in the following, the description of the results of the exhaust gas introduction pipe 1Z3 and the exhaust gas introduction pipe 1Z4 will be omitted.

Inner diameter of the first pipe of the exhaust gas introduction pipe 1Z: 43.0 (mm)
Outer diameter of the first pipe of the exhaust gas introduction pipe 1Z: 48.6 (mm)
Inner diameter of the second pipe of the exhaust gas introduction pipe 1Z: 54.9 (mm)
Outer diameter of the second pipe of the exhaust gas introduction pipe 1Z: 60.5 (mm)
Temperature of the first gas G1 in the vicinity of the first root 11AZ1 and the first root 11AZ2: 60 (° C.)
Breakdown of the first gas G1: H ₂ = 92200 (sccm), Ar = 31550 (sccm), SiHCl ₃ = 471 (sccm), C ₃ H ₈ = 180.6 (sccm),
HCl = 1884 (sccm), N ₂ = 34300 (sccm)
Temperature of the second gas G2 in the vicinity of the second root 11BZ1 and the second root 11BZ2: 60 (° C.)
Flow velocity of the second gas: 2.1 (m / s)
Flow rate of the third gas G3: 41.5 (m ³ / min)

When the above simulation was performed, the temperature T1 near the tip 12Z1 in the first pipe of the exhaust gas introduction pipe 1Z1 was 56.0 (° C.), and the temperature T2 near the tip 12Z2 in the first pipe of the exhaust gas introduction pipe 1Z2 was 57.0. It was (° C). In Example 1, the pipe of 40 (A) was used as the first pipe 1A, and the pipe of 50 (A) was used as the second pipe 1B.

<Examples 2 to 6>
In Examples 2 to 6, the flow rate of the second gas was changed from Example 1. Since the flow velocity of the second gas changed with the change of the flow rate of the second gas in each embodiment, it is also described. Other conditions were the same as in Example 1. Table 1 shows the results of the temperature T1 in the vicinity of the tip 12Z1 in the first pipe of the exhaust gas introduction pipe 1Z1 and the temperature T2 in the vicinity of the tip 12Z2 in the first pipe of the exhaust gas introduction pipe 1Z2. For convenience, Table 1 also lists the conditions and results of Example 1.

<Comparative Examples 1 to 9>
In Comparative Example 1, the exhaust gas introduction pipe was changed to a configuration consisting of only the first pipe. That is, the second pipes of the exhaust gas introduction pipes 1Z1 and 1Z2 of Example 1 were removed. As the first pipe, the same pipe as in Example 1 was used. Further, from the first pipe, in addition to the first gas G1 flowed in Example 1, a high temperature N ₂ was flowed. Comparative Examples 2 to 9 were also carried out in the same manner. Tables 2 and 3 show _{the high temperature and flow rate of N 2} in Comparative Examples 1 to 9 and the results. _{The temperature of N 2} shown in the table is a temperature in the vicinity of the root 11H.

In Examples 1 to 6, the temperature of the first gas G1 can be made higher than that of Comparative Examples 1 to 9, although the temperature of the gas introduced to heat the first gas G1 is lower. For example, the flow rate of the second gas in Example 4 and the flow rate of N _{2 in} Comparative Examples 2, 5 and 8 are the same, and Comparative Examples 2, 5 and 8 flowed _{N 2 at a higher temperature.} In Example 4, the first gas could be heated to a higher temperature. Further, the flow rate of the second gas of Example 5 and the flow rate of N _{2 of Comparative Examples 1, 4 and 7 were the same, and the higher temperature N 2} was flowed in Comparative Examples 1, 4 and 7, but this was carried out. Example 5 was able to heat the first gas to a higher temperature. Therefore, in Examples 1 to 6, it is possible to suppress the generation of by-products in the piping as compared with Comparative Examples 1 to 9.

Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various aspects of the present invention are described within the scope of the claims. It can be transformed and changed.

1: Exhaust gas introduction pipe 1A: First pipe 1B: Second pipe 10: Reaction furnace 11: Root 11A: First root 11B: Second root 12: Tip 12A: First tip 12B: Second tip 20: Exhaust pipe 30 : Filter 40: Exhaust pump 50: Scrubber 6: Third pipe 60: Third exhaust port 100: Chemical gas phase growth device R: Gas accommodating part Gp: Process gas G1: First gas G2: Second gas

Claims (7)

It is an exhaust gas introduction pipe of a scrubber that can flow through an exhaust pipe from a reactor capable of vapor phase growth of a SiC thin film inside and detoxify the discharged first gas.
A first pipe for flowing the first gas into the gas accommodating portion of the scrubber,
It has a second pipe arranged on the radial side of the first pipe and forming a double pipe structure with the first pipe.
The second pipe is an exhaust gas introduction pipe of a scrubber, which is a pipe for flowing a second gas having a temperature higher than that of the first gas into the gas accommodating portion. The exhaust gas introduction pipe for a scrubber according to claim 1, wherein the second pipe is a pipe for flowing a second gas having a temperature of 60 ° C. or higher and 400 ° C. or lower in the gas accommodating portion. The inner diameter of the second tip on the downstream side of the second pipe in the flow direction of the first gas is
It is larger than the outer diameter of the first tip on the downstream side in the flow direction of the first gas of the first pipe.
The exhaust gas introduction pipe for a scrubber according to claim 1 or 2, wherein the difference between the inner diameter of the second tip and the outer diameter of the first tip is 2 mm or more and 10 mm or less. The exhaust gas introduction pipe for a scrubber according to any one of claims 1 to 3, wherein the second pipe has a tapered portion having a shape in which the inner diameter becomes smaller as it approaches the second tip. The second tip of the second pipe is located downstream of the first tip of the first pipe in the flow direction of the first gas, according to any one of claims 1 to 4. Exhaust gas introduction pipe for scrubber. The exhaust gas introduction pipe for a scrubber according to any one of claims 1 to 5, wherein the second pipe is a pipe through which at least one gas selected from nitrogen and argon flows. A scrubber capable of detoxifying the first gas discharged through the exhaust pipe from a reactor capable of vapor phase growth of a SiC thin film inside.
A first pipe for flowing the first gas to a gas accommodating portion where a plurality of gases are collected, and
A second pipe arranged on the outer side in the radial direction of the first pipe and forming a double pipe structure with the first pipe,
It has a third pipe arranged on the side wall of the scrubber.
The second pipe is a pipe through which a second gas having a temperature higher than that of the first gas flows through the gas accommodating portion.
The third pipe is arranged so as to intersect the flow direction of the first gas.
The third pipe is a scrubber that allows air to flow through the gas accommodating portion.

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