JP2009071018A - Vapor deposition apparatus and exhaust method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a nasty smell produced when doing maintenance such as cleaning of a reactor of a vapor deposition apparatus, etc. <P>SOLUTION: A vapor deposition apparatus 100 supplies a wafer 150 heated up to a predetermined temperature with a process gas having a silicon constituent to form a film onto the wafer 150 through vapor deposition, wherein it has a reactor 101, a process gas feed portion 103, a primary exhaust portion 120, and a bypass pipe 130 prepared by branching it from the primary exhaust portion 120 to exhaust air from the reactor 101. This can inhibit occurrence of a nasty smell since the air exhausted from within the reactor 101 at the time of maintenance and by-products deposited on the primary exhaust portion 120 are not allowed to bring into contact. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vapor phase growth apparatus and an exhaust method for performing vapor phase growth and forming a vapor phase growth film on a semiconductor substrate, and in particular, depositing in an exhaust pipe connected to a reactor for performing vapor phase growth. The present invention relates to a vapor phase growth apparatus and an exhaust method that suppress the generation of off-flavors caused by by-products.

Epitaxial growth technology that can control the film thickness and impurity concentration is used in the manufacture of high-performance semiconductor elements such as ultra-high speed bipolar, ultra-high speed CMOS, and power MOS to improve the performance of the element. It is essential.
For epitaxial growth in which a single crystal film is formed on a semiconductor substrate such as a silicon wafer, atmospheric pressure chemical vapor deposition is generally used, and in some cases, low pressure chemical vapor deposition (LPCVD) is used.
In these vapor phase growth methods, the inside of a reaction furnace in which a semiconductor substrate such as a silicon wafer is disposed is maintained at normal pressure (0.1 MPa (760 Torr)) or reduced pressure, and the semiconductor substrate is heated and rotated. A process gas in which a source gas serving as a silicon source and a dopant gas are mixed is supplied into the vapor phase growth reactor. As the source gas, monosilane (SiH ₄ ), dichlorosilane (SiH ₂ Cl ₂ ), trichlorosilane (SiHCl ₃ ), or the like is used.

FIG. 5 is a conceptual diagram showing a conventional vapor phase growth apparatus 300.
A thermal decomposition reaction or hydrogen reduction reaction of a process gas is performed on a semiconductor substrate (hereinafter referred to as a wafer) housed in the reaction furnace 301, and a vapor deposition film is formed on the wafer. At this time, the gas in the reaction furnace 301 is exhausted from the exhaust unit 320, and harmful components are removed by an abatement apparatus (not shown) and exhausted to the outside.

The gas in the reaction furnace 301 after vapor phase growth includes unreacted components of the process gas not involved in vapor phase growth and unstable intermediate components generated by chemical reaction during film formation. Etc. exist. By cooling these components, by-products are gradually deposited on the inner surface of the reaction furnace 301 and the inner surface of the piping of the exhaust part 320. Therefore, in the reaction furnace 301 having a high temperature, by-products are likely to be deposited near the outlet of the exhaust gas having a relatively low temperature. In addition, in the piping of the exhaust part 320, by-products are likely to be deposited near the pressure adjustment valve 305 that is remote from the reaction furnace 301.
When the cross-sectional area of the space near the outlet of the exhaust gas in the reaction furnace 301 and in the piping of the exhaust part 320 becomes small due to the accumulation of by-products, the exhaust of the exhaust gas from the inside of the reaction furnace 301 is hindered, and the reaction furnace 301 The flow rate of the process gas in the inside fluctuates. If the flow rate of the process gas fluctuates, the pressure in the reaction furnace 301 or the degree of vacuum is irregularly affected, leading to destabilization of reaction conditions in which vapor phase growth is performed. As a result, the film thickness and impurity concentration of the vapor phase growth film formed on the wafer are made non-uniform, and the quality is deteriorated.
In order to prevent this, in the conventional vapor phase growth apparatus 300, for example, once a month or when necessary, the vapor phase growth apparatus is disassembled, and maintenance such as cleaning of the inside of the reaction furnace 301 is performed. ing. Further, in the exhaust unit 320, since the amount of by-product accumulated is smaller than that in the reaction furnace 301, maintenance such as cleaning is performed several times less frequently than the maintenance frequency of the reaction furnace 301.

In the maintenance of the reaction furnace 301, the inside is cleaned while the reaction furnace 301 is opened to the atmosphere. Therefore, when the reaction furnace 301 is sealed again, the inside is filled with the atmosphere. When this air is exhausted from the exhaust unit 320, a by-product accumulated in the vicinity of the pressure adjustment valve 305 of the exhaust unit 320 that has not been maintained yet comes into contact with the air, thereby generating a strange odor and returning to the environment. It will have an adverse effect. Therefore, when the atmosphere in the reaction furnace 301 is exhausted, the opening of the pressure adjustment valve 305 is adjusted and gradually exhausted little by little, or exhausted while gradually replacing with purge gas, etc. It was necessary to take measures to prevent the by-product from coming into contact. In addition, an attempt has been made to provide a thin exhaust pipe 322 having an opening / closing valve 321 in the reaction furnace 301 to discharge the atmosphere without bringing the atmosphere into contact with by-products.
However, in these aspects, the generation of off-flavor cannot be completely suppressed, and the air is not discharged quickly, so it takes a long time to readjust the operating environment of the vapor phase growth apparatus 300, Reduces mass productivity.
Further, in the conventional vapor phase growth apparatus and the like, various techniques have been disclosed and attempted to avoid chemical contamination in the reaction furnace at the time of opening to the atmosphere. No countermeasure has been taken against the off-flavor produced by the reaction between the atmosphere and by-products (see Patent Document 1).

However, in the apparatus for performing vapor phase growth using the process gas containing the silane compound as described above, deposition of by-products inside is inevitable. Therefore, it is desired to improve the mass productivity of the vapor phase growth apparatus while simultaneously achieving the suppression of the off-flavor generated by the by-product by contact with the atmosphere and stabilizing the reaction conditions of the vapor phase growth. .
JP-A-9-330859

As described above, in the conventional vapor phase growth apparatus 300, the atmosphere that flows out from the reaction furnace 301 in accordance with the maintenance of the reaction furnace 301 and the by-product accumulated in the exhaust part 320 come into contact with each other and react. There was a problem that a strange odor was generated. Therefore, the atmosphere is gradually exhausted from the reaction furnace 301 by means such as adjusting the opening of the pressure adjustment valve 305 provided in the exhaust unit 320 so as to suppress the generation of a strange odor.
However, even if the atmosphere is gradually exhausted from the reaction furnace 301 in this way, it is difficult to sufficiently suppress the off-flavor, and maintenance takes a long time, and the mass productivity of the vapor phase growth apparatus 300 is impaired.

  The present invention has been made to overcome such problems, and it is possible to suppress the generation of a strange odor when the atmosphere is discharged from the reactor in accordance with the maintenance, and the time required for the maintenance can be shortened. An object is to provide a vapor phase growth apparatus and an exhaust method.

The vapor phase growth apparatus of the present invention is
A vapor phase growth apparatus for supplying a process gas having a silicon component to a semiconductor substrate heated to a predetermined temperature and performing film formation on the semiconductor substrate by vapor phase growth,
A reactor for storing semiconductor substrates;
A process gas supply unit for supplying process gas into the reaction furnace;
A first exhaust unit provided in connection with the reactor and exhausting the exhaust gas of the reactor;
A branch pipe that is branched from the first exhaust section and discharges air from the reactor;
It is characterized by providing.

  It is preferable to provide switching means for switching the first exhaust part and the branch pipe to exhaust the exhaust gas or the air exhausted from the reaction furnace.

A load lock chamber disposed adjacent to the reactor described above;
A purge gas supply section for supplying purge gas to the load lock chamber;
A second exhaust for exhausting the exhaust gas from the load lock chamber;
Further comprising
It is preferable that the above-described branch pipe is configured by a pipe that communicates the first exhaust part and the second exhaust part.

  Furthermore, it is preferable that the above-described branch pipe is branched from the vicinity of the connection portion between the first exhaust portion and the reaction furnace.

The vapor phase growth method of the present invention comprises:
According to the exhaust gas discharged from the reaction furnace of the vapor phase growth apparatus or the atmosphere, the first exhaust part connected to the reaction furnace and the branch pipe branched from the first exhaust part are switched and discharged. It is characterized by.

  According to the present invention, even if the atmosphere is exhausted from the reactor during maintenance, no off-flavor is generated, and the time required for maintenance of the vapor phase growth apparatus can be shortened.

Embodiment 1
Hereinafter, the form of a vapor deposition apparatus for forming a film on a wafer by vapor deposition will be described in detail with reference to the drawings.
FIG. 1 is a conceptual diagram showing a vapor phase growth apparatus 100 according to the first embodiment. FIG. 2 is a structural cross-sectional view schematically showing the reaction furnace 101 and the load lock chamber 102.
As shown in FIG. 1, the reaction furnace 101 of the present embodiment includes a process gas supply unit 103 that supplies a process gas and a purge gas such as H _{2 to} the reaction furnace 101, and exhaust gas exhausted from the reaction furnace 101. One exhaust part 120 is provided. The first exhaust part 120 includes a first isolation valve 104 that shuts off a fluid discharged from the reaction furnace 101, a first pressure adjustment valve 105 that adjusts the pressure or flow rate of the process gas supplied into the reaction furnace 101, and A first vacuum pump 106 is connected and connected.

The vapor phase growth apparatus 100 according to the present embodiment includes a bypass pipe 130 that is a branch pipe that branches from the first exhaust part 120 and communicates with the second exhaust part 121 provided in the load lock chamber 102. .
The bypass pipe 130 is branched from the vicinity of the connection portion of the first exhaust part 120 with the reaction furnace 101, and a bypass valve 131 is provided downstream thereof.
Then, by using the bypass valve 131 and the first isolation valve 104 in the exhaust gas exhausted from the reactor 101 and the atmosphere, the first exhaust valve 120 and the bypass pipe 130 are switched according to the exhaust gas or the atmosphere. be able to.

  Further, the first isolation valve 104 is provided downstream of the first exhaust part 120 immediately adjacent to the portion where the bypass pipe 130 is branched. For this reason, the area | region of the 1st exhaust part 120 which always contacts with the exhaust gas discharged | emitted from the reaction furnace 101 is minimized. Further, since this portion is close to the reaction furnace 101, the temperature is high, and is a region in which the by-product is most difficult to deposit in the first exhaust part 120.

As shown in FIG. 2, the load lock chamber 102 stores a wafer 150 transferred from an I / O (Input / Output) chamber (not shown). The inside of the load lock chamber 102 is maintained in a purge gas atmosphere such as H ₂ supplied from the purge gas supply unit 107. For this reason, oxidation and particle contamination are suppressed on the surface of the stored wafer 150. Since the load lock chamber 102 is maintained in the purge gas atmosphere, the adjacent reactor 101 is shut off from the atmosphere. At this time, the purge gas supplied to the load lock chamber 102 is discharged to the outside of the vapor phase growth apparatus 100 by the second vacuum pump 110 via the second exhaust part 121.
Then, the wafer 150 in the load lock chamber 102 is carried into the reaction furnace 101 by a transfer module (not shown).

The reaction furnace 101 is supplied with process gas from the process gas supply unit 103 and is maintained at a predetermined degree of vacuum by the first pressure adjustment valve 105 and the first vacuum pump 106. At this time, the first isolation valve 104 is open.
The process gas supplied here is, for example, a raw material gas in which monosilane (SiH ₄ ), dichlorosilane (SiH ₂ Cl ₂ ), trichlorosilane (SiHCl ₃ ) serving as a silicon source, and H _{2 serving as} a carrier gas are mixed. , By adding a predetermined dopant gas. For example, diborane (B ₂ H ₆ ), phosphine (PH ₃ ), arsine (AsH ₃ ) and the like are known as dopant gases.

  As shown in FIG. 2, the wafer 150 accommodated in the reaction furnace 101 is placed on a support base 151 and heated by a heater 152 while being rotated at a predetermined rotational speed. Then, the thermal decomposition reaction or hydrogen reduction reaction of the process gas described above is performed on the wafer 150 to form a predetermined vapor deposition film. At this time, if diborane is added, a vapor phase growth film showing p-type conductivity, and if phosphine or arsine is added, n-type conductivity is formed. Then, the exhaust gas in the reaction furnace 101 including the unreacted gas after film formation is discharged from the first exhaust unit 120 to the outside of the vapor phase growth apparatus 100 by the first vacuum pump 106, and harmful components are removed by a decontamination apparatus (not shown). Is released in a state where it is removed.

Contrary to the case where the vapor deposition film is formed, the wafer 150 is pulled out to the load lock chamber 102 by the transfer module, and is carried outside. Further, new wafers 150 are carried into the reaction furnace 101 from the load lock chamber 102 by the transfer module, and the wafers 150 are successively manufactured in the same process.
In the normal operation of the vapor phase growth apparatus 100 for forming the vapor phase growth film on the wafer 150 as described above, the first exhaust unit 120 and the second exhaust unit 121 are provided in the bypass pipe 130 so as not to communicate with each other. The bypass valve 131 thus made is normally closed.
Therefore, the exhaust gas after the vapor phase growth that is discharged during the normal operation of the vapor phase growth apparatus 100 does not flow through the bypass pipe 130.

When the normal operation of the vapor phase growth apparatus 100 described above is repeated, by-products mainly composed of silicon hydride and the like are deposited in the reaction furnace 101 and the piping of the first exhaust unit 120. This by-product is caused by exhaust gas containing unreacted gas components not involved in vapor phase growth and unstable intermediate components generated by chemical changes during film formation coming into contact with the wall surface of the piping. When cooled, it condenses and accumulates. As a result, the cross-sectional area of the exhaust gas in the vicinity of the exhaust gas in the reaction furnace 101 and the space of the piping constituting the first exhaust part 120 is reduced, and smooth exhaust gas discharge from the reaction furnace 101 is hindered.
As a result, the desired flow rate and pressure of the process gas supplied into the reaction furnace 101 cannot be set, and the reaction conditions for vapor phase growth cannot be maintained.
Therefore, in order to continuously operate the vapor phase growth apparatus 100 and manufacture the wafer 150 on which a predetermined vapor phase growth film is formed, it is necessary to periodically perform maintenance such as internal cleaning.

The maintenance in the present embodiment is generally performed in the following procedure, for example.
First, in order to discharge the exhaust gas from the reaction furnace 101 after vapor phase growth, the reaction furnace 101 is evacuated using the first vacuum pump 106. At this time, harmful components are removed from the exhaust gas after vapor phase growth by an abatement apparatus (not shown) connected to the exhaust unit 120. At this time, both the first isolation valve 104 and the first pressure adjustment valve 105 are open, and the bypass valve 131 is closed.
Next, the first isolation valve 104 is closed and H ₂ or the like is supplied from the process gas supply unit 103 to return the reaction furnace 101 to normal pressure. Then, the reactor 101 is opened, and the inside is cleaned using a predetermined chemical or the like. At this time, it is desirable that the inside of the pipe to the first isolation valve 104 and the inside of the bypass pipe 130 to the bypass valve 131 are cleaned at the same time. Since these parts are provided in the vicinity of the first isolation valve 104 and the bypass valve 131, the by-product is not easily deposited in the pipe. However, it is desirable to clean the inside of the reaction furnace 101 at the same time so as to prevent any by-products from remaining.
At this time, the atmosphere flows into the reaction furnace 101 by opening the reaction furnace 101 to the atmosphere.

Next, the reactor 101 is sealed while the cleaning is completed and the atmosphere is filled. At this time, when the atmosphere is discharged through the first exhaust part 120 in the same manner as during normal operation, the atmosphere reacts with the by-product accumulated in the vicinity of the first pressure regulating valve 105, and a strange odor is produced. Will be generated.
Therefore, when the atmosphere is discharged from the reaction furnace 101, first, the first isolation valve 104 is closed so that the atmosphere does not flow to the first exhaust part 120. Next, the second isolation valve 108 is closed. As a result, the air flowing from the bypass pipe 130 to the second exhaust part 121 does not flow backward to the load lock chamber 102, and the suction force when the second vacuum pump 110 is operated is concentrated on the discharge of the atmosphere in the reaction furnace 101. be able to. Then, the second vacuum pump 110 is operated with the bypass valve 131 and the second pressure adjustment valve 109 opened. Thereby, the atmosphere in the reaction furnace 101 is quickly discharged to the outside via the bypass pipe 130 and the second exhaust part 121.

Since the inside of the second exhaust part 121 is a discharge path for the purge gas supplied to the load lock chamber 102 during normal operation of the vapor phase growth apparatus 100, no by-product is deposited. Further, in the bypass pipe 130, the by-product is not deposited because the bypass valve 131 is closed during normal operation of the vapor phase growth apparatus 100.
Therefore, when the atmosphere is discharged from the reaction furnace 101 to the outside during maintenance, the first pressure regulating valve in which the by-product of the first exhaust part 120 is accumulated most is switched to the discharge path as described above. It does not pass near 105.

After the atmosphere in the reaction furnace 101 is completely exhausted to the outside, the bypass valve 131 is closed and H _{2 and the} like are supplied to the reaction furnace 101 while the load lock chamber 102, the first exhaust part 120, the second exhaust are supplied. The unit 121 is returned to the same state as during normal operation. Thereby, the maintenance of the cleaning in the reaction furnace 101 is completed.
By such a procedure, the maintenance for cleaning the reaction furnace 101 of the vapor phase growth apparatus 100 can be quickly performed.

As described above, in the present embodiment, the first exhaust part 120 is switched by the first exhaust part 120 and the bypass pipe 130 in accordance with the exhaust gas exhausted from the reaction furnace 101 or the atmosphere. Contact between the by-product accumulated in the vicinity of the pressure control valve 105 and the atmosphere is prevented.
By this evacuation method, it is possible to suppress the generation of off-flavors due to the reaction between the atmosphere and by-products during maintenance of the vapor phase growth apparatus 100.

  Moreover, in this embodiment, since the atmosphere and a by-product do not contact, the 2nd vacuum pump 110 can be operated with the maximum output, and the time required for maintenance can also be shortened significantly.

Embodiment 2
FIG. 3 is a conceptual diagram showing a vapor phase growth apparatus 100 according to the second embodiment of the present invention.
In the present embodiment, the branch pipe 132 that exhausts the atmosphere directly from the first exhaust unit 120 connected to the reaction furnace 101 to the outside of the vapor phase growth apparatus 100 without passing through the second exhaust unit 121 includes: It branches off from the first exhaust part 120.

  The branch pipe 132 is branched from the first exhaust part 120 at a position substantially similar to the bypass pipe 130 of FIG. The branch pipe valve 133 that controls the flow of gas to the branch pipe 132 is provided downstream of the branch pipe 132 in the vicinity of the branch point from the first exhaust part 120.

In the vapor phase growth apparatus 100 of this mode, when maintenance such as cleaning of the reaction furnace 101 is performed, the air that has flowed into the reaction furnace 101 due to release to the atmosphere is discharged by the branch pipe vacuum pump 134 connected to the branch pipe 132. Then, it is discharged out of the vapor phase growth apparatus 100 through an abatement apparatus not shown.
Thereby, the atmosphere can be discharged to the outside of the vapor phase growth apparatus 100 without coming into contact with the by-product accumulated in the vicinity of the first pressure adjustment valve 105 of the first exhaust part 120.

  In the first embodiment described above, the atmosphere in the reaction furnace 101 is exhausted via the second exhaust part 121, but in this embodiment, the branch pipe 132 is not passed from the reaction furnace 101 via the second exhaust part 121. Since air is directly discharged from the outside to the outside, the operating environment of the load lock chamber 102 is not affected.

For example, when an unprocessed wafer is stored in the load lock chamber 102, the load lock chamber 102 is desirably maintained in an H ₂ atmosphere in order to prevent wafer oxidation and particle contamination. For this purpose, the second pressure adjustment valve 109 must be adjusted and the second vacuum pump 110 must be operating.
In the present embodiment, a purge gas such as H ₂ can be continuously supplied to the load lock chamber 102 regardless of the operating state of the reaction furnace 101.
Therefore, the unprocessed wafer 150 can be kept in the load lock chamber 102 even during the maintenance of the reaction furnace 101, and the wafer can be loaded quickly when the vapor phase growth apparatus 100 is restarted. Therefore, it can contribute to the further shortening of the time required for maintenance.

Embodiment 3
FIG. 4 is a conceptual diagram showing a vapor phase growth apparatus 200 according to Embodiment 3 of the present invention.
The present embodiment is a vapor phase growth apparatus 200 provided with an I / O (Input / Output) module 212 for carrying out and carrying in a wafer.

As with the load lock chamber 202, the I / O module 212 is provided with a purge gas supply unit 213, and the inside of the I / O module 212 is purged with H ₂ or the like. Further, the I / O module 212 includes a third exhaust part 222 provided with a third isolation valve 214, a third pressure adjustment valve 215, and a third vacuum pump 216 in cooperation with each other.

  The vapor phase growth apparatus 200 of this embodiment is provided with a bypass pipe 230 that is a branch pipe that branches from the first exhaust section 220 and communicates with a third exhaust section 222 provided in the I / O module 212. The bypass pipe 230 has a bypass valve 231 and can switch the discharge path according to the exhaust gas discharged from the reaction furnace 201 or the atmosphere.

The atmosphere flowing into the reaction furnace 201 when performing the maintenance of the reaction furnace 201 passes through the bypass pipe 230 and the third exhaust part 222, and thereby accumulates in the vicinity of the first pressure adjustment valve 205 of the first exhaust part 220. It can be discharged to the outside without being in contact with the product.
In this embodiment, the I / O module 212, the third exhaust part 222, the purge gas supply part 213, the third isolation valve 214, the third pressure adjustment valve 215, the third vacuum pump 216, the bypass pipe 230 and the bypass valve 231. Are the load lock chamber 102, the second exhaust part 121, the purge gas supply part 107, the second isolation valve 108, the second pressure adjustment valve 109, the second vacuum pump 110, the bypass pipe 130, and the first embodiment described above. This corresponds to each of the bypass valves 131.
Therefore, the detailed description of the maintenance procedure in the present embodiment is omitted by replacing the configuration of the present embodiment with the procedure of the first embodiment described above.

  In the present embodiment, as in the second embodiment, the exhaust gas is not discharged via the second exhaust part 121 of the load lock chamber 202, so that the operating environment of the load lock chamber 202 is not affected. For this reason, the wafer to be subsequently loaded into the reaction furnace 201 can be stored in the load lock chamber 202, and the time required for maintenance can be further shortened.

  Here, description of features of by-products, features of process gas supplied into the reaction furnace 201, and the like that are the same as those described in the other embodiments will be omitted.

The embodiment has been described above with reference to specific examples. The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.
Although the present invention has been described with respect to a single-wafer type vapor phase growth apparatus, a mechanism for performing vapor phase growth on a wafer using a process gas containing a predetermined silicon source and discharging exhaust gas after the vapor phase growth reaction is provided. As long as it has an apparatus, it may be a batch-type apparatus or another apparatus.

  In addition, although descriptions of parts that are not directly required for the present invention, such as apparatus configuration and control method, are omitted, the required apparatus configuration, control method, and the like can be appropriately selected and used.

  In addition, all the vapor phase growth apparatuses that include the elements of the present invention and can be appropriately modified by those skilled in the art, and the shapes of the respective members are included in the scope of the present invention.

It is a conceptual diagram which shows the vapor phase growth apparatus of Embodiment 1 of this invention. 2 is a configuration cross-sectional view schematically showing a reaction furnace and a load lock chamber in Embodiment 1. FIG. It is a conceptual diagram which shows the vapor phase growth apparatus of Embodiment 2 of this invention. It is a conceptual diagram which shows the vapor phase growth apparatus of Embodiment 3 of this invention. It is a conceptual diagram which shows the conventional vapor phase growth apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Vapor growth apparatus 101 ... Reaction furnace 102 ... Load lock chamber 103 ... Process gas supply part 104 ... First isolation valve 105 ... First pressure adjustment valve 106 ... First vacuum pump 107 ... Purge gas supply part 108 ... Second Isolation valve 109 ... second pressure regulating valve 110 ... second vacuum pump 120 ... first exhaust part 121 ... second exhaust part 130 ... bypass pipe 131 ... bypass valve 132 ... branch pipe 133 ... branch pipe valve 134 ... branch pipe vacuum Pump 150 ... wafer 151 ... support 152 ... heater

Claims (5)

A vapor phase growth apparatus for supplying a process gas having a silicon component to a semiconductor substrate heated to a predetermined temperature and performing film formation on the semiconductor substrate by vapor phase growth,
A reactor containing the semiconductor substrate;
A process gas supply unit for supplying a process gas into the reaction furnace;
A first exhaust part that is connected to the reaction furnace and exhausts exhaust gas from the reaction furnace;
A branch pipe that is branched from the first exhaust section and exhausts air from the reactor;
A vapor phase growth apparatus comprising:   2. The vapor phase growth apparatus according to claim 1, further comprising switching means for switching the first exhaust unit and the branch pipe to exhaust the exhaust gas or the air discharged from the reaction furnace. A load lock chamber disposed adjacent to the reactor;
A purge gas supply unit for supplying purge gas to the load lock chamber;
A second exhaust part for exhausting exhaust gas from the load lock chamber;
Further comprising
3. The vapor phase growth apparatus according to claim 1, wherein the branch pipe is configured by a pipe that communicates the first exhaust part and the second exhaust part. 4.   4. The vapor phase growth apparatus according to claim 1, wherein the branch pipe is branched from a vicinity of a connection portion between the first exhaust portion and the reaction furnace. 5.   According to the exhaust gas discharged from the reaction furnace of the vapor phase growth apparatus or the atmosphere, the first exhaust part connected to the reaction furnace and the branch pipe branched from the first exhaust part are switched and discharged. Exhaust method characterized by.

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