Cleaning method of cleaning object

Abstract

To provide a cleaning device and a cleaning method.SOLUTION: A cleaning device is a cleaning device including an outer wall body having an outer upper furnace wall body and an outer bottom furnace wall body, and an inner wall body having an inner upper furnace wall body and an inner bottom furnace wall body. The outer upper furnace wall body and the inner upper furnace wall body are provided so as to be movable up and down, a heating source is provided inside the outer upper furnace wall body and outside the inner upper furnace wall body. The cleaning device comprises: purge gas supply means of supplying a purge gas to a space inside the outer wall body and outside the inner wall body; and etching gas supply means for supplying an etching gas to a space inside the inner wall body. The outer upper furnace wall body is brought into contact with the outer bottom furnace wall body, the outer upper furnace wall body is integrated with the outer bottom furnace wall body, a sealed space can be formed inside the outer wall body constituted by the outer upper furnace wall body and the outer bottom furnace wall body, the inner upper furnace wall body is brought into contact with the inner bottom furnace wall body, the inner upper furnace wall body is integrated with the inner bottom furnace wall body, and a sealed space can be formed inside the inner wall body constituted by the inner upper furnace wall body and the inner bottom furnace wall body.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for cleaning an object to be cleaned. [Background technology]

[0002] In a vapor phase growth apparatus for forming a compound semiconductor thin film, a substrate is placed in a flow path for supplying raw material gases, and a compound semiconductor is grown on the substrate. In a vapor phase growth apparatus, reaction by-products called "depots" adhere to the components that form the flow channels. If a compound semiconductor is grown again with these reaction by-products adhering to the inside of the flow channel, the reaction by-products will detach from the inner walls of the flow channel and become incorporated into the compound semiconductor being grown, forming defects called pits. For example, if the vapor phase growth apparatus is an apparatus for depositing a semiconductor layer such as gallium nitride, reaction by-products such as gallium nitride may be generated inside the flow channel. Therefore, it is desirable to clean the members (hereinafter referred to as reactor members) that form the flow paths in the vapor phase growth apparatus after each compound semiconductor growth.

[0003] Conventionally, the techniques described in Patent Documents 1 and 2 below are known as devices for cleaning this type of reactor components. Patent Document 1 describes a cleaning device that contains an object to be cleaned in a dome, covers the dome with a heat insulating material, and heats the entire dome to a desired temperature using a heating means provided inside the heat insulating material. This cleaning device has a mechanism for introducing chlorine gas into the dome, and has the function of etching reaction by-products adhering to the object to be cleaned while heated, thereby cleaning the object. Patent Document 2 discloses a dry cleaning device that introduces a halogen-based gas into a vacuum container containing an object to be treated, heats the container, removes any deposits on the object, and also introduces a separate cleaning liquid into the vacuum container to clean the inside of the vacuum container. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6679413 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-186311 Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional technologies described in Patent Documents 1 and 2, when reaction by-products adhering to the object to be cleaned are removed by etching, a hot wall structure is adopted in which an electric heater is placed outside the dome part or outside the vacuum furnace to prevent chlorides from adhering to the inside of the cleaning equipment. By passing electricity through an electric heater, the entire dome portion or the entire vacuum vessel is heated to the desired temperature while etching the reaction product, thereby preventing unwanted deposition of chlorides inside the device. However, if a hot wall structure that heats the entire dome portion or the entire vacuum vessel is adopted, it takes time to heat and cool the entire apparatus, which increases the processing time required for cleaning.

[0006] To shorten the processing time, it is preferable to use a cold-wall structure in which the cleaning furnace is water-cooled. However, if the cleaning furnace is made with a cold-wall structure, chlorides (such as gallium chloride) generated as reaction products during cleaning may adhere and remain inside the cleaning furnace.

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a method for cleaning an object to be cleaned that enables the adoption of a cold wall structure to shorten the cleaning time, while also enabling cleaning to be performed without causing chlorides and the like to adhere to the inside of the cleaning furnace. [Means for solving the problem]

[0008] The present invention employs the following aspects. (1) A cleaning method for an object to be cleaned according to one embodiment of the present invention is a cleaning device having a double-structured wall including an outer wall having an outer upper furnace wall and an outer bottom furnace wall, and an inner wall having an inner upper furnace wall and an inner bottom furnace wall, wherein the outer upper furnace wall and the outer bottom furnace wall are arranged so as to be movable relative to each other up and down, the inner upper furnace wall and the inner bottom furnace wall are arranged so as to be movable relative to each other up and down, a heating means is provided inside the outer wall and outside the inner wall, and a space inside the outer wall is provided a first gas supply means for supplying a purge gas to the space outside the inner wall body and a first gas exhaust means for exhausting the purge gas from the space inside the outer wall body; a second gas supply means for supplying at least one of a purge gas and an etching gas to the space inside the inner wall body and a second gas exhaust means for exhausting gas from the space inside the inner wall body; a cleaning method for an object to be cleaned using a cleaning device capable of forming an enclosed space inside the outer wall body composed of a wall body and the outer bottom furnace wall body, and bringing the inner upper furnace wall body into contact with the inner bottom furnace wall body to integrate the inner upper furnace wall body with the inner bottom furnace wall body, and forming an enclosed space inside the inner wall body composed of the inner upper furnace wall body and the inner bottom furnace wall body, The method is characterized in that a purge gas is supplied to the inside of the outer wall body formed by integrating and sealing the outer upper furnace wall body and the outer bottom furnace wall body while they are separated from each other without being integrated, and the inner spaces inside the outer upper furnace wall body and the outer bottom furnace wall body and the inner spaces inside the inner upper furnace wall body and the inner bottom furnace wall body are filled with the purge gas, and then an etching gas is introduced into the inner space inside the inner wall body formed by integrating and sealing the inner upper furnace wall body and the inner bottom furnace wall body, and the object to be cleaned is cleaned by etching.

[0009] The outer wall body is formed by moving the outer upper furnace wall body and the outer bottom furnace wall body relative to each other and integrating them, and the inner space inside the outer wall body can be filled with purge gas by supplying purge gas into the inner space inside the outer wall body. The inner wall body is formed by moving the inner upper furnace wall body and the inner bottom furnace wall body relative to each other and integrating them, and the inner space inside the inner wall body can be filled with etching gas by supplying etching gas into the inner space inside the inner wall body. Therefore, by storing a cleaning target such as a reactor component inside the inner wall body, reaction by-products adhering to the cleaning target can be cleaned by etching.

[0010] If the inner upper furnace wall and the inner bottom furnace wall are not integrated and the space between them is left open, the space between the inner upper furnace wall and the inner bottom furnace wall can be quickly filled with purge gas. Thereafter, the inner upper furnace wall and the inner bottom furnace wall are integrated, and the space surrounded by the inner upper furnace wall and the inner bottom furnace wall is filled with etching gas, thereby cleaning the object to be cleaned. After the cleaning process is completed, the heated inner upper furnace wall and inner bottom furnace wall can be quickly cooled by opening the space between the inner upper furnace wall and the inner bottom furnace wall while leaving the outer upper furnace wall and the outer bottom furnace wall integrated. These time-saving effects can reduce the time required for each batch of cleaning processing.

[0011] Because the heating means is installed inside the outer wall body but outside the inner wall body, the object to be cleaned can be placed inside the inner wall body and cleaned by heating the inside of the inner wall body to a temperature appropriate for etching. The heating means only needs to heat the inner wall body and its internal space to the temperature required for etching, not the entire outer wall body and its internal space. Therefore, compared to conventional devices that required heating means to be installed outside the outer wall body to heat and clean the entire outer wall body, including its interior, and then cooling the entire body after cleaning, the time required per batch from the start of cleaning to the end of cleaning, and then switching to the next object to be cleaned and starting cleaning again can be shortened. By using the cleaning device of this embodiment, only the inner wall body can be made into a hot wall structure and the outer wall body can be made into a cold wall structure, making it possible to provide a cleaning method that can shorten the cleaning time while avoiding the problem of compound adhesion from the object to be cleaned.

[0012] (2) In one embodiment of the cleaning method according to the present invention, during the etching, the pressure in the inner space of the outer wall body outside the inner wall body is preferably made higher than the pressure in the inner space of the inner wall body.

[0013] During etching, if the pressure in the space inside the outer wall body outside the inner wall body is higher than that in the space inside the inner wall body, the risk of the etching gas present in the space inside the inner wall body leaking to the outside is reduced. The heating means heats the space inside the inner wall body to a temperature suitable for etching, but the temperature of the outer wall body and its space inside it may be lower than that of the space inside the inner wall body. If the etching gas leaks to the outside of the inner wall body, components contained in the etching gas may precipitate in any low-temperature region inside the outer wall body. Therefore, cleaning can be performed while preventing the precipitation of precipitates on the outside of the inner wall body.

[0014] (3) In one embodiment of the cleaning method according to the present invention, it is preferable to fill the inner spaces of the inner upper furnace wall body and the inner bottom furnace wall body, which are separated and not integrated, and the inner space of the outer wall body with purge gas, then reduce the pressure in these inner spaces as a whole, integrate the inner upper furnace wall body and the inner bottom furnace wall body after the reduction in pressure to seal the inner space of the inner wall body, and after this sealing, replace the purge gas in the inner space of the inner wall body with etching gas and perform etching.

[0015] After filling the inner space of the inner wall body and the inner space of the outer wall body with purge gas, the entire inner space is depressurized, and after depressurization, the inner upper furnace wall body and the inner bottom furnace wall body are integrated to form an enclosed space, and by supplying etching gas to this enclosed space, it is possible to adjust the atmosphere to a desired reduced pressure for etching.

[0016] (4) In one embodiment of the cleaning method according to the present invention, after the etching, it is preferable to adjust the pressure in the sealed space inside the inner wall body and the pressure in the space inside the outer wall body outside the inner wall body to be equal, then separate the inner upper furnace wall body from the inner bottom furnace wall body, stop heating by the heating means, and cool.

[0017] By cooling the upper and lower inner furnace walls while they are spaced apart, the space between them can be cooled quickly while remaining connected to the interior space of the outer wall. As the cooling time is shortened, the processing time per batch from the start of the cleaning process to the end of the cleaning process, changing the object to be cleaned, and starting cleaning the next object can be shortened. [Effects of the Invention]

[0018] According to the present invention, the outer wall body is formed by integrating the outer upper furnace wall body and the outer bottom furnace wall body, and the inner space of the outer wall body can be filled with purge gas by supplying purge gas into the inner space of the outer wall body. The inner wall body is formed by integrating the inner upper furnace wall body and the inner bottom furnace wall body, and the inner space of the inner wall body can be filled with etching gas by supplying etching gas into the inner space of the inner wall body. Therefore, by placing a cleaning object such as a reactor component inside the inner wall body, the cleaning object can be cleaned by etching.

[0019] Since the heating means is installed inside the outer wall body and outside the inner wall body, the object to be cleaned can be placed inside the inner wall body and cleaned by heating the inside of the inner wall body to a temperature appropriate for etching. The heating means only needs to heat the inner wall body and its internal space to the temperature required for etching, rather than the entire outer wall body and its internal space. Therefore, etching is possible with less input of thermal energy than in conventional devices that required heating the entire body, including the outer wall body. Furthermore, when cooling and replacing the object to be cleaned after etching, it is sufficient to cool the inner wall body and its internal space, so the heating time and cooling time can be shortened compared to conventional devices that heated and cooled the entire device including the outer wall body. The cleaning apparatus used in the cleaning method of this embodiment can have only the inner wall body of a hot wall structure and the outer wall body of a cold wall structure, so by using this cleaning apparatus, it is possible to provide a cleaning method that can shorten the processing time while avoiding problems such as adhesion of compounds from the object to be cleaned. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a cross-sectional view showing a cleaning device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing the cleaning device and a piping system connected to the cleaning device. [Figure 3] 10 is a cross-sectional view showing the cleaning apparatus in a state in which the outer upper furnace wall body and the inner upper furnace wall body are raised and separated from the outer bottom furnace wall body and the inner bottom furnace wall body. FIG. [Figure 4] FIG. 10 is a cross-sectional view showing the state in which the outer upper furnace wall and the inner upper furnace wall are separated from the outer bottom furnace wall and the inner bottom furnace wall in the cleaning device, and an object to be cleaned is inserted between the upper and lower furnace walls. [Figure 5] A cross-sectional view showing the state in which the outer upper furnace wall body is lowered and integrated with the outer bottom furnace wall body in the cleaning device, the inner upper furnace wall body is separated from the inner bottom furnace wall body, and the object to be cleaned is placed between the inner upper furnace wall body and the inner bottom furnace wall body. [Figure 6] A cross-sectional view showing the state in which the inner upper furnace wall and the inner bottom furnace wall are integrated in the cleaning device, and the object to be cleaned is placed in the space closed by the inner upper furnace wall and the inner bottom furnace wall and is being cleaned. [Figure 7] 7 is a schematic diagram showing the state of the cleaning device shown in FIG. 6 and the connection relationship between the cleaning device and a piping system connected to the cleaning device. [Figure 8] FIG. 2 is an explanatory diagram showing the pressure and temperature of each part of the cleaning device used and the timing of supplying necessary gases in the cleaning method according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0021] A cleaning device according to a first embodiment of the present invention will be described below. The embodiments described below are specifically described to provide a better understanding of the gist of the present invention, and do not limit the present invention unless otherwise specified. Furthermore, the scale of the drawings used to explain the embodiments below has been changed appropriately to make each part easier to see.

[0022] As shown in FIG. 1, the cleaning device 1 according to the first embodiment of the present invention is a cleaning device having a double-wall structure including an outer wall body 5 having an outer upper furnace wall body 2 and an outer bottom furnace wall body 3, and an inner wall body 8 having an inner upper furnace wall body 6 and an inner bottom furnace wall body 7. The outer upper furnace wall 2 has a ceiling portion 2A and a peripheral wall portion 2B. The outer bottom furnace wall 3 has a bottom wall portion 3A and a peripheral wall portion 3B. The outer upper furnace wall 2 and the outer bottom furnace wall 3 are, for example, chamber structures made of stainless steel plates. The inner upper furnace wall 6 and the inner bottom furnace wall 7 are, for example, made of a heat-resistant material such as graphite. For example, the ceiling portion 2A and the bottom wall portion 3A preferably have the same shape in a plan view, and the peripheral wall portion 2B and the peripheral wall portion 3B preferably have the same shape in a plan view. For example, if the ceiling portion 2A has a circular shape in a plan view, the bottom wall portion 3A is preferably also formed to have a circular shape in a plan view, and if the ceiling portion 2A has a rectangular shape in a plan view, the bottom wall portion 3A is preferably also formed to have a rectangular shape in a plan view. For example, when the ceiling portion 2A is circular in plan view, the peripheral wall portion 2B is preferably cylindrical, and when the bottom wall portion 3A is circular in plan view, the peripheral wall portion 3B is preferably cylindrical. For example, when the ceiling portion 2A is rectangular in plan view, the peripheral wall portion 2B is preferably rectangular tubular, and when the bottom wall portion 3A is rectangular in plan view, the peripheral wall portion 3B is preferably rectangular tubular.

[0023] 1, when the bottom surface of the peripheral wall portion 2B and the top surface of the peripheral wall portion 3B are aligned and brought into contact with each other and integrated, a sealed outer wall body 5 is formed from the outer upper furnace wall body 2 and the outer bottom furnace wall body 3. At the same time, a sealed space A is defined outside the inner bottom furnace wall body 7 and the inner upper furnace wall body 6 and inside the outer wall body 5. The outer upper furnace wall body 2 is configured so that the sealed space A can be formed by integrating it with the outer bottom furnace wall body 3.

[0024] Although not shown in FIG. 1 , sealing members and sealing mechanisms are provided on the bottom side of the peripheral wall portion 2B and the top side of the peripheral wall portion 3B, respectively, so that when the bottom surface of the peripheral wall portion 2B and the top surface of the peripheral wall portion 3B are butted together, the butted portion can be airtightly sealed. Also, although not shown in FIG. 1 , a vertical movement mechanism is provided around the outer upper furnace wall 2 to support the outer upper furnace wall 2 so that it can move up and down, and the outer upper furnace wall 2 is supported so that it can move up and down while maintaining the posture shown in FIG. 1 . Similarly, a vertical movement mechanism is provided around the outer bottom furnace wall 3 to support the outer bottom furnace wall 3 so that it can move up and down. In this embodiment, the outer bottom furnace wall 3 is supported so that it can move down synchronously with the lowering of the outer upper furnace wall 2. The outer upper furnace wall 2 and the outer bottom furnace wall 3 are provided so that they can move up and down relative to each other. Although not shown in the drawings, the entire cleaning device 1, including the outer upper furnace wall 2, the outer bottom furnace wall 3, and the base member 13 described below, is installed in an atmosphere control box (not shown), and the internal space of the atmosphere control box is configured so that an inert gas atmosphere such as nitrogen gas can be maintained. In addition, the outer upper furnace wall 2 and the outer bottom furnace wall 3 have a cold wall structure equipped with a water cooling mechanism (not shown).

[0025] A hanger member 10 for suspension support is provided on the underside of the ceiling of the outer upper furnace wall 2, and the inner upper furnace wall 6 is suspended and supported by this hanger member 10. The hanger member 10 is made of a heat-resistant material such as a quartz rod. The inner upper furnace wall 6 has a ceiling portion 6A and a peripheral wall portion 6B. The ceiling portion 6A is preferably formed in a circular or rectangular shape in plan view, similar to the ceiling portion 2A. As in the case of the ceiling portion 2A, when the ceiling portion 6A is circular in plan view, the peripheral wall portion 6B is preferably cylindrical, and when the ceiling portion 6A is rectangular in plan view, the peripheral wall portion 6B is preferably formed in a rectangular tubular shape. The outer diameter (or width) of the ceiling portion 6A of the inner upper furnace wall 6 is smaller than the outer diameter (or width) of the ceiling portion 2A of the outer upper furnace wall 2. The height of the peripheral wall portion 6B of the inner upper furnace wall 6 is smaller than the height of the peripheral wall portion 2B of the outer upper furnace wall 2.

[0026] In the example shown in FIG. 1, the ceiling portion 6A is suspended at a position about half the height of the peripheral wall portion 2B, and the lower end of the peripheral wall portion 6B is suspended so as to be positioned slightly lower than the lower end of the peripheral wall portion 2B. A first heating means 11 such as a heater is provided below the ceiling 2A of the outer upper furnace wall 2 and around the inner upper furnace wall 6. As an example, the first heating means 11 is composed of a heat source such as a heater installed in a position covering the upper surface side of the ceiling 6A and in a position covering the peripheral surface side of the peripheral wall 6B. An infrared lamp heater can be used as an example of the heat source.

[0027] In the example of Fig. 1, the peripheral wall 3B of the outer bottom furnace wall 3 is formed to have a height approximately equal to that of the peripheral wall 2B of the outer upper furnace wall 2. A base member 13 having a size approximately equal to that of the bottom wall 3A is disposed below the bottom wall 3A of the outer bottom furnace wall 3. In the outer bottom furnace wall 3, the height of the peripheral wall 3B is not limited to the example shown in Fig. 1, and the size of the base member 13 is not limited to the example shown in Fig. 1, but Fig. 1 shows them as an example. A through-hole 13a is formed in the center of the base member 13, and a gas nozzle 15 is installed through this through-hole 13a and extending in the vertical direction. This gas nozzle 15 extends into the interior of the outer bottom furnace wall 3 through a through-hole 3a formed in the center of the bottom wall 3A. A plurality of support members 16 are arranged on the upper surface of the base member 13 so as to surround the periphery of the position where the gas nozzle 15 passes through. The support members 16 are made of a heat-resistant material such as quartz. These support members 16 extend into the interior of the outer bottom furnace wall 3 through through-holes 3b formed in the bottom wall portion 3A.

[0028] A plate-shaped inner bottom furnace wall 7 is installed inside the outer bottom furnace wall 3 and is supported by a plurality of support members 16. The inner bottom furnace wall 7 preferably has the same shape in plan view as the ceiling portion 6A of the inner upper furnace wall 6 described above. The inner bottom furnace wall 7 is supported by the support members 16 and is horizontally supported inside the outer bottom furnace wall 3. Furthermore, the inner bottom furnace wall 7 is supported by the plurality of support members 16 and is horizontally supported at a position approximately half the height of the peripheral wall portion 3B in the state shown in FIG. 1 . An air cylinder (linear motion device) 17 for adjusting the support force of the support member 16 is provided on the underside of the position where the support member 16 is provided on the base member 13. The support member 16 is arranged to be inserted vertically through a through hole formed in the base member 13, and is supported by the air cylinder 17 so as to be freely movable in the vertical direction. The lower part of the support member 16 is supported by the base member 13 outside the outer bottom furnace wall body 3, and is also supported by the air cylinder 17 so as to be freely movable. The air cylinder 17 can move the inner bottom furnace wall 7 slightly up and down via the support members 16, allowing fine adjustment of the vertical position of the inner bottom furnace wall 7 relative to the inner upper furnace wall 6. This has the function of ensuring close contact between the inner upper furnace wall 6 and the inner bottom furnace wall 7, or separating the close-contacted inner upper furnace wall 6 and the inner bottom furnace wall 7. When the underside of the peripheral wall of the inner upper furnace wall 6 and the peripheral edge of the inner bottom furnace wall 7 are brought into close contact with each other, the space surrounded by the inner upper furnace wall 6 and the inner bottom furnace wall 7 can be made into an enclosed space B shown in Figure 6, which will be described later.

[0029] A cylindrical bellows member 18 made of a metal material such as stainless steel is disposed between the base member 13 and the bottom wall portion 3A at a position surrounding the bottom opening of the through-hole 3b. The upper end of this bellows member 18 surrounds the periphery of the bottom opening of the through-hole 3b, and the lower end is integrated with the upper surface of the base member 13. The provision of the bellows member 18 allows the bottom opening of the through-hole 3b to be closed airtight. The bellows member 18 is configured to be able to expand and contract a small distance in the vertical direction.

[0030] The gas nozzle 15 has a double-pipe structure comprising an inner pipe 15A and an outer pipe 15B. The inner pipe 15A penetrates the inner bottom furnace wall 7 and extends to a position above the inner bottom furnace wall 7. In the state shown in FIG. 1, the upper end of the inner pipe 15A extends to a position slightly above the opening on the upper surface of the outer bottom furnace wall 3. The outer pipe 15B surrounds the outer peripheral surface of the inner pipe 15A and extends to a position slightly lower than the upper end of the inner pipe 15A. A through-hole is formed in the center of the inner bottom furnace wall 7, and the outer pipe 15B and inner pipe 15A are inserted through this hole and extended to the aforementioned height position. At the portion where the outer pipe 15B of the gas nozzle 15 penetrates the inner bottom furnace wall 7, an outward flange portion 15a is formed on the underside of the inner bottom furnace wall 7. This flange portion 15a is in contact with the bottom of the inner bottom furnace wall 7. A plurality of injection ports 15b are formed around the periphery of the upper end of the inner pipe 15A, and a plurality of exhaust ports 15c are formed around the periphery of the upper end of the outer pipe 15B.

[0031] In the gas nozzle 15, the bottom side of the inner tube 15A is connected to a gas supply source 30 (see FIG. 2) that can supply a purge gas or an etching gas, which will be described later. When the purge gas or the etching gas is supplied from the gas supply source 30, the purge gas or the etching gas can be ejected from the ejection port 15b of the inner tube 15A. In the gas nozzle 15, the bottom side of the outer tube 15B is connected to a dry pump P (see FIG. 2) via a gas exhaust pipe 28, which will be described later, and the dry pump P is connected to an exhaust treatment facility 35, which will be described later. With this configuration, gas around the exhaust port 15c can be sucked through the exhaust port 15c of the outer tube 15B and sent to the exhaust treatment facility 35 via the gas exhaust pipe 28. The gas nozzle 15 supplies gas from the nozzle 15b and exhausts gas from the exhaust port 15c, and is therefore provided for supplying and exhausting gas.

[0032] Although not shown, a disk-shaped cleaning target support is provided at the upper end of the outer tube 15B of the gas nozzle 15. A first cleaning target 20 shown in FIG. 1 is placed while being supported by this cleaning target support. A second cleaning target 21 is placed on the inner bottom furnace wall 7. One example of the first cleaning target 20 is a ceiling plate (reactor component) that constitutes a flow path provided in a vapor phase growth apparatus for forming a compound semiconductor thin film. One example of the second cleaning target 21 is a susceptor cover (reactor component) that constitutes the same flow path. The placement positions of the first cleaning target 20 and the second cleaning target 21 may be upside down relative to the positions shown in FIG. 1. In this example, the first cleaning object 20 and the second cleaning object 21 are placed around the gas nozzle 15, but other reactor components may be placed as the cleaning objects.

[0033] A second heating means 22 is provided above the bottom wall 3A of the outer bottom furnace wall 3 and below the inner bottom furnace wall 7. The second heating means 22 is installed at a position where it can cover the bottom side of the inner bottom furnace wall 7.

[0034] 1, a purge gas supply pipe 25, a purge gas exhaust pipe 26, a gas supply pipe 27, and a gas exhaust pipe 28 are connected as shown in FIG. 1, one end of the purge gas supply pipe 25 is connected to a purge gas supply port 2a formed in the ceiling portion 2A of the outer upper furnace wall body 2, and the other end of the purge gas supply pipe 25 is connected to a purge gas supply source 29. With this configuration, purge gas can be supplied from the purge gas supply source 29 to the inner space of the outer upper furnace wall body 2 via the purge gas supply port 2a. The purge gas supply source 29 and the purge gas supply pipe 25 constitute a first gas supply means 24. As described above, one end of the gas supply pipe 27 is connected to the inner pipe 15A of the gas nozzle 15 shown in FIG. With this configuration, etching gas or purge gas can be supplied from the gas supply source 30 to the space between the inner upper furnace wall 6 and the inner bottom furnace wall 7 via the gas supply pipe 27 and the gas nozzle 15. The gas supply source 30, the gas supply pipe 27, and the inner pipe 15A of the gas nozzle 15 constitute a second gas supply means 34. The gas supply source 30 has both the function of supplying a purge gas such as an inert gas and the function of supplying an etching gas, and is configured to be able to supply either the purge gas or the etching gas, or a mixed gas containing both gases at a predetermined ratio, via the gas supply pipe 27 as needed.

[0035] One end of a purge gas exhaust pipe (first gas exhaust means) 26 penetrates the peripheral wall portion 2B of the outer upper furnace wall 2 and is connected to the inner space of the outer upper furnace wall 2, and the other end is connected to the input side of a dry pump P via a pressure adjustment valve 31. A pressure gauge 32 for measuring purge gas exhaust is incorporated into the purge gas exhaust pipe 26 in a portion between the outer upper furnace wall 2 and the pressure adjustment valve 31. The pressure gauge 32 and the pressure adjustment valve 31 are connected by control wiring so that the aperture of the pressure adjustment valve 31 can be adjusted according to the pressure value measured by the pressure gauge 32. The pressure gauge 32 and the pressure adjustment valve 31 may be connected by wireless communication means, and the pressure adjustment valve 31 may be configured to adjust its aperture according to the pressure value measured by the pressure gauge 32.

[0036] One end of the gas exhaust pipe 28 is connected to the outer pipe 15B of the gas nozzle 15, and the other end is connected to the input side of the dry pump P via a pressure adjustment valve 33. The exhaust side of the dry pump P is connected to exhaust processing equipment 35. The gas exhaust pipe 28 and the outer pipe 15B of the gas nozzle 15 form a second gas exhaust means 38. A pressure gauge 36 for exhausting etching gas or page gas is incorporated into the gas exhaust pipe 28 in a portion between the outer bottom furnace wall 3 and the pressure regulating valve 33. The pressure gauge 36 and the pressure regulating valve 33 are connected by control wiring, so that the aperture of the pressure regulating valve 33 can be adjusted according to the pressure value measured by the pressure gauge 36. The pressure gauge 36 and the pressure regulating valve 33 may also be connected by wireless communication means, and the pressure regulating valve 33 may be configured to adjust its aperture according to the pressure value measured by the pressure gauge 36.

[0037] (Processing of objects to be cleaned) "1" Initial state of the cleaning device FIG. 1 shows the initial state of a cleaning device 1 used in this embodiment. Before the initial state shown in FIG. 1 is reached, the outer upper furnace wall 2 is moved above the outer bottom furnace wall 3 so that a sufficient gap is created between the inner upper furnace wall 6 and the inner bottom furnace wall 7, as shown in FIG. 3. In this state, the object to be cleaned 20 is placed between the inner upper furnace wall 6 and the inner bottom furnace wall 7, as shown in FIG. 4. Note that in FIGS. 3 to 7, which are used to explain the operation from this paragraph onward, the gas nozzle 15 shown in FIG. 1 is omitted, and the outer upper furnace wall 2, outer bottom furnace wall 3, inner upper furnace wall 6, and inner bottom furnace wall 7 are shown, focusing on their relative positions. For simplicity of explanation, only the object to be cleaned 20 is shown, and the object to be cleaned 21 is omitted. Furthermore, the members supporting the object to be cleaned 20 are also omitted. 3 to 7, for the sake of convenience, the gas nozzle 15 is omitted, but it goes without saying that the gas nozzle 15 is used to supply and exhaust gas during cleaning.

[0038] 4, the outer upper furnace wall 2 is lowered as shown in FIG. 5, so that the peripheral wall portion 2B of the outer upper furnace wall 2 and the peripheral wall portion 3B of the outer bottom furnace wall 3 come into contact with each other and are integrated. By integrating the two, an outer wall body 5 with a sealed structure is formed. By tightly contacting the lower surface of the peripheral wall 2B with the upper surface of the peripheral wall 3B, the inner space surrounded by the outer upper furnace wall 2 and the outer bottom furnace wall 3 can be made into a sealed space A. A predetermined gap is provided between the peripheral wall 6B of the inner upper furnace wall 6 and the inner bottom furnace wall 7. The state shown in FIG. 5 is the same as the state shown in FIG. 1, but as mentioned above, the gas nozzle 15 is not shown in FIG. 5. 1 and 5, the object to be cleaned 20 is accommodated between the peripheral wall portions 6B of the inner upper furnace wall body 6, and the peripheral wall portions 6B of the inner upper furnace wall body 6 and the inner bottom furnace wall body 7 are not in contact with each other. In this state, the inner space between the inner upper furnace wall body 6 and the inner bottom furnace wall body 7 communicates with the sealed space A, and the two spaces communicate with each other.

[0039] "2" Purge gas supply 5, an inert gas such as N2 gas or argon gas is supplied as a purge gas from a purge gas supply source 29 and a gas supply source 30. In this state, the pressures of pressure gauge 32 and pressure gauge 36 are controlled using pressure regulating valves 31 and 33, respectively, so that the pressures indicated by pressure gauge 32 and pressure gauge 36 are the same. This state is illustrated in Figures 8(1) and 8(2), which show the supply and stop of etching gas, the supply and stop of purge gas, and the opening and closing (indicated as "Open and Close of Hot Cell") of the inner upper furnace wall 6 and the inner bottom furnace wall 7. Furthermore, Figure 8 shows the pressure of the outer upper furnace wall 2 and the outer bottom furnace wall 3 (indicated as "Inside Pressure of Hot Cell"), the pressure of the inner upper furnace wall 6 and the inner bottom furnace wall 7 (indicated as "Outside Pressure of Hot Cell"), the temperature of the outer upper furnace wall 2 and the outer bottom furnace wall 3 (indicated as "Temp. of Reactor"), and the etching temperature (indicated as "Temp. of Reactor").

[0040] "3" Closing operation of the inner upper furnace wall 6 and the inner bottom furnace wall 7 After the purge gas supply procedure, the pressure inside the furnace is reduced to a pressure suitable for etching. Pressure is controlled so that the pressure in the sealed space A (pressure inside the reactor) gradually decreases, and the pressure gauges 32 and 36 have the same set pressure. After the pressure is reduced, as shown in Figure 6, the outer upper furnace wall 2 and the outer bottom furnace wall 3 are lowered together, and the peripheral wall 6B of the inner upper furnace wall 6 is brought into contact with the inner bottom furnace wall 7 and integrated. The integration of the inner upper furnace wall 6 and the inner bottom furnace wall 7 forms the inner wall 8. Here, it is preferable to finely adjust the vertical position of the inner bottom furnace wall 7 by operating the multiple air cylinders 17, and to reliably integrate the lower end of the peripheral wall 6B with the peripheral edge of the inner bottom furnace wall 7 to close the gap between them. By tightly contacting the peripheral wall 6B of the inner upper furnace wall 6 with the peripheral edge of the inner bottom furnace wall 7, an airtight space B can be formed between them. After sealing, pressure control is continued using the pressure regulating valve 31 for purge gas exhaust and the pressure regulating valve 33 for etching gas exhaust so that the pressure gauge 32 for purge gas exhaust and the pressure gauge 36 for etching gas exhaust indicate the same pressure. In FIG. 8, (2) and (3) show the respective states.

[0041] "4" Pressure adjustment After the above-mentioned procedure, the pressure is adjusted by adjusting the opening of the pressure adjusting valve 31 so that the reading on the pressure gauge 32 is slightly higher than the reading on the pressure gauge 36 . The optimum value for the displayed value of the pressure gauge 32 at this time is determined based on the allowable pressure of a conventional device with a hot cell structure. For example, a value approximately half the allowable pressure of the hot cell is considered appropriate. In this embodiment, the inner upper furnace wall 6 and the inner bottom furnace wall 7 constitute the hot cell, so a pressure approximately half the allowable pressure of the hot cell constituted by the inner upper furnace wall 6 and the inner bottom furnace wall 7 is appropriate. As an example, if the allowable pressure of the hot cell constituted by the inner upper furnace wall 6 and the inner bottom furnace wall 7 is 10 to 20 kPa, it is preferable to set the value to approximately 5 to 10 kPa, with a safety factor of approximately 2. In Figure 8, (4) shows each state.

[0042] "5" Etching gas supply After the above steps, a portion of the purge gas supplied from the gas supply source 30 is replaced with etching gas. In other words, without changing the total gas flow rate supplied from the gas supply source 30 in steps "2" to "4," the proportion of etching gas is increased while keeping the gas flow rate constant, and the amount of purge gas is decreased. Chlorine-based gases such as HCl and Cl2 can be used as the etching gas. In Figure 8, each state is shown in (5).

[0043] The temperature of the sealed space B is adjusted to a temperature suitable for etching, about 1000° C., using the first heating means 11 and the second heating means 22. On the other hand, the outer upper furnace wall 2 and the outer bottom furnace wall 3 may be at a lower temperature, so that the outer upper furnace wall 2 and the outer bottom furnace wall 3 can have a cold wall structure in which a cooling mechanism (not shown) is provided. Here, since the etching gas has already been introduced into the sealed space B, reaction by-products such as gallium nitride adhering to the objects 20 and 21 to be cleaned can be removed by etching. By controlling the pressure so that the reading on pressure gauge 32 is higher than the reading on pressure gauge 36, the sealed space A can be maintained at a higher pressure than the sealed space B. For example, if the sealed space B is set at about 4 to 8 kPa, the sealed space A can be set at a higher pressure of about 9 to 18 kPa. This allows the etching cleaning process to be performed while maintaining a state in which the etching gas does not leak from the sealed space B into the sealed space A. Therefore, reaction by-products such as chlorides are not produced on the inner surfaces of the outer upper furnace wall 2 and the outer bottom furnace wall 3 that constitute the sealed space A due to leakage of the etching gas. Therefore, the cleaning process can be performed without causing unnecessary precipitation of compounds resulting from the constituent elements of the reaction by-products on the inner surfaces of the outer upper furnace wall 2 and the outer bottom furnace wall 3. If gallium nitride is attached to the object to be cleaned 20 as a reaction by-product, leakage of the etching gas containing gallium may result in precipitation of gallium chloride in low-temperature areas.

[0044] When the reaction by-product is gallium chloride, its boiling point is 201°C. Therefore, the inner space of the inner wall body 8 formed by the inner upper furnace wall body 6 and the inner bottom furnace wall body 7 must be heated to a temperature sufficiently high above this boiling point. As described above, it is preferable to perform the cleaning operation using etching gas while heating to a high temperature and controlling the pressure in the sealed space B so that it is lower than the pressure in the sealed space A, thereby preventing gas from leaking from the sealed space B.

[0045] "6" Etching gas exhaust After etching of the cleaning objects 20 and 21 is completed, the flow rate of the etching gas supplied from the gas supply source 30 is reduced without changing the total flow rate, and the flow rate of the purge gas is increased, in the reverse order of step "5." The purge state is then maintained until the etching gas remaining in the furnace is completely removed. In Figure 8, each state is shown in (6).

[0046] "7" Pressure adjustment Conversely to step "4", the pressure of the purge gas is controlled using the pressure regulating valves 31 and 33 so that the pressure gauges 32 and 36 have the same pressure readings. In Figure 8, (7) shows each state.

[0047] "8" Hot cell opening operation After the pressure adjustment procedure described in "7", the pressure setting value is gradually decreased and the opening of the pressure adjustment valve 31 is adjusted so that the reading on the pressure gauge 32 becomes the same as the reading on the pressure gauge 36. Thereafter, an operation is performed to increase the vertical distance between the inner upper furnace wall 6 and the inner bottom furnace wall 7 so that a gap is created between them. For example, an operation is performed to lower the inner bottom furnace wall 7 by operating the linear motion device 17 as shown in Figure 5. Furthermore, heating by the first heating means 11 and the second heating means 22 is stopped. In Figure 8, (7) to (8) show the respective states. As described above, when a gap is formed between the inner upper furnace wall 6 and the inner bottom furnace wall 7, the sealed space B is opened and communicates with the sealed space A, so that the inner upper furnace wall 6 and the inner bottom furnace wall 7 can be quickly cooled, thereby shortening the cooling time. In addition, by supplying purge gas from the gas supply sources 29 and 30 at the maximum possible supply pressure, the cooling time of the inner upper furnace wall 6 and the inner bottom furnace wall 7 can be further shortened. In Figure 8, (8) shows each state.

[0048] "9" Pressure adjustment In order to transport the object to be cleaned 20 located between the inner upper furnace wall body 6 and the inner bottom furnace wall body 7 out of the cleaning device 1, the internal pressure of the outer wall body 5 (internal pressure of the reactor) is set to atmospheric pressure. At this time, the pressure indication values ​​of the pressure gauges 32 and 36 are set to the same value, and the openings of the respective pressure regulating valves 31 and 33 are adjusted so that the pressure gradually increases from a reduced pressure state to atmospheric pressure. In FIG. 8, (9) to (10) show the respective states.

[0049] "10" Next cleaning work After adjusting to atmospheric pressure, the outer upper furnace wall 2 and the inner upper furnace wall 6 are raised as shown in Figure 4 to separate them from the outer bottom furnace wall 3 and the inner bottom furnace wall 7, and once their temperatures have dropped to a predetermined temperature, they return to the state shown in Figure 4, allowing the object to be cleaned 20 to be removed after cleaning. At this point, the next object to be cleaned is prepared, and the same procedure is repeated to sequentially clean the objects. When the temperatures of the inner upper furnace wall 6 and the inner bottom furnace wall 7 have dropped to about 200°C, it is preferable to use a transfer robot or the like to replace the object to be cleaned.

[0050] As described above, when cleaning the objects 20 and 21 to be cleaned, the first heating means 11 and the second heating means 22 are used to heat only the enclosed space B inside the inner upper furnace wall 6 and the inner bottom furnace wall 7 to a temperature suitable for etching, thereby enabling the cleaning process by etching to be carried out. In conventional apparatuses of this type, the entire apparatus had to be heated to a temperature desired for etching. However, in comparison with such conventional apparatuses, the present invention allows the next cleaning process to be performed within a cooling time corresponding to the time required for the inner upper furnace wall 6 and the inner bottom furnace wall 7 to be completely cooled. After etching is completed and the etching gas is removed from the sealed space B, the gap between the inner upper furnace wall 6 and the inner bottom furnace wall 7 is opened to allow for quick cooling as described above, thereby shortening the cooling time. As a result, the time required per batch from the start of cleaning of the object 20 to the end of cleaning and replacement with the next object can be significantly reduced.

[0051] For example, the applicant of the present application produces a cleaning device described in Patent Document 1. With this equipment, it takes 15 hours per batch to load the object to be cleaned, introduce various gases, heat the entire dome, perform the cleaning process, and then exhaust the various gases and cool the temperature after the cleaning process is complete, until the equipment is ready to load the next object to be cleaned. In contrast, when the cleaning process of the object to be cleaned is performed using the cleaning apparatus 1 described based on Figures 1 to 7 under the same processing conditions (same etching time, etching temperature, and etching gas type), the time required per batch can be reduced to 5.5 hours. Therefore, by using the cleaning apparatus 1 described based on Figures 1 to 7 and carrying out the cleaning method described above, the time required per batch of cleaning processing can be significantly reduced to less than half of that required for the cleaning apparatus described in Patent Document 1. [Explanation of symbols]

[0052] A, B... sealed space, 1... cleaning device, 2... outer upper furnace wall, 2a... purge gas supply port, 3...Outer bottom furnace wall, 5...Outer wall, 6...Inner upper furnace wall, 7...Inner bottom furnace wall, 8...inner wall body, 11...heating means, 13...base member, 15...gas nozzle, 15A...inner tube, 15B...outer tube, 16...support member, 17...linear motion device, 18...bellows member, 20...first cleaning object, 21... second cleaning object, 22... heating means, 24... first gas supply means, 25... purge gas supply pipe, 26... purge gas exhaust pipe (first gas exhaust means), 27...gas supply pipe, 28...gas exhaust pipe, 29...purge gas supply source, 30...gas supply source, 31... pressure regulating valve, 32... pressure gauge, 34... second gas supply means, P... dry pump, 36... pressure gauge, 38... second gas exhaust means.

Claims

1. A cleaning device having a double-wall structure including an outer wall having an outer upper furnace wall and an outer bottom furnace wall, and an inner wall having an inner upper furnace wall and an inner bottom furnace wall, The outer upper furnace wall body and the outer bottom furnace wall body are provided so as to be movable relative to each other up and down, The inner upper furnace wall body and the inner bottom furnace wall body are provided so as to be movable relative to each other up and down, a heating means provided inside the outer wall body and outside the inner wall body; a first gas supply means for supplying a purge gas to a space inside the outer wall body and outside the inner wall body, and a first gas exhaust means for exhausting the purge gas from the space inside the outer wall body; a second gas supply means for supplying at least one of a purge gas and an etching gas to the space inside the inner wall body, and a second gas exhaust means for exhausting gas from the space inside the inner wall body; the outer upper furnace wall body is brought into contact with the outer bottom furnace wall body to be integrated with the outer bottom furnace wall body, and a sealed space can be formed inside the outer wall body composed of the outer upper furnace wall body and the outer bottom furnace wall body, A cleaning method for an object to be cleaned using a cleaning device in which the inner upper furnace wall body is brought into contact with the inner bottom furnace wall body to integrate the inner upper furnace wall body with the inner bottom furnace wall body, and an enclosed space can be formed inside the inner wall body composed of the inner upper furnace wall body and the inner bottom furnace wall body, The object to be cleaned is accommodated between the inner upper furnace wall body and the inner bottom furnace wall body, a purge gas is supplied to the inside of an outer wall body in which the outer upper furnace wall and the outer bottom furnace wall are integrated and sealed while the inner upper furnace wall and the inner bottom furnace wall are separated from each other without being integrated, and the purge gas is filled into the inner spaces of the outer upper furnace wall and the outer bottom furnace wall and the inner spaces of the inner upper furnace wall and the inner bottom furnace wall; A method for cleaning an object to be cleaned, characterized in that an etching gas is introduced into the space inside the inner wall body, which is formed by integrating and sealing the inner upper furnace wall body and the inner bottom furnace wall body, and the object to be cleaned is cleaned by etching.

2. 2. The method for cleaning an object according to claim 1, wherein, during the etching, the pressure in the inner space of the outer wall body outside the inner wall body is made higher than the pressure in the inner space of the inner wall body.

3. 3. The method for cleaning an object to be cleaned according to claim 1, wherein the inner spaces of the inner upper furnace wall body and the inner bottom furnace wall body, which are not integrated but are separated from each other, and the inner space of the outer wall body, are filled with purge gas, and then these inner spaces are entirely depressurized, and after the depressurization, the inner upper furnace wall body and the inner bottom furnace wall body are integrated to seal the inner space of the inner wall body, and after this sealing, the purge gas in the inner space of the inner wall body is replaced with an etching gas to perform etching.

4. 3. The method for cleaning an object to be cleaned according to claim 1, wherein after the etching, the pressure in the sealed space inside the inner wall body and the pressure in the space inside the outer wall body outside the inner wall body are adjusted to be equal, and then the inner upper furnace wall body and the inner bottom furnace wall body are separated from each other, and heating by the heating means is stopped to cool them down.

Images