JP6553739B2 - Gas recovery apparatus, gas recovery method, and semiconductor cleaning system - Google Patents

Description

  The present invention separates carbon dioxide and an inert gas separately from a mixed gas containing carbon dioxide and an inert gas as a main component to obtain gas recovery capable of obtaining carbon dioxide of high purity and inert gas of high purity. The present invention relates to an apparatus and a gas recovery method.

  In the semiconductor manufacturing process, cleaning gas is sprayed onto the substrate to remove dirt and particles. As the cleaning gas, an inert gas such as nitrogen, argon or helium is mainly used.

  For example, in Patent Documents 1 and 2, a mixed gas of helium and carbon dioxide is used for cleaning. A high pressure carbon dioxide gas is discharged into a vacuum, and the adiabatic expansion lowers the gas temperature to near its boiling point to generate carbon dioxide nanoclusters. The nanoclusters of carbon dioxide generated at the time of spraying scatter and remove particles present on the substrate, and the energy of the nanoclusters is adjusted by changing the proportion of helium gas to be mixed.

JP2015-41646A JP 2014-72383 A

  The above inert gas such as helium and carbon dioxide gas are both gases used in various industrial applications, not limited to the above-mentioned semiconductor manufacturing field. In semiconductor manufacturing, the gas used in the cleaning process is preferably recovered and reused.

  In recent years, the inert gas has become more expensive year by year, and the rise in helium gas is particularly remarkable. Carbon dioxide gas is also rising as well as helium gas, and is a cause of global warming, and there is a demand for recovery and reuse.

  Therefore, in addition to the recovery and reuse of the cleaning gas, it is important to improve the recovery rate of the gas to be reused.

  In addition to the cleaning process of semiconductor manufacturing, in the case of assuming the reuse of helium gas for industrial use, a purity of 99% or more is required.

  However, when helium gas is generated from the used cleaning gas, the conventional method using compression / cooling requires a large facility and requires a large amount of power. The higher the purity of the gas and the higher the recovery rate, the larger the equipment, the greater the energy required, and the higher the cost.

  Therefore, an object of the present invention is to provide a gas recovery apparatus and a gas recovery method capable of achieving a high recovery rate of inert gas, high purification, and energy saving.

  The present invention also provides a semiconductor cleaning system that can reuse the recovered inert gas as a cleaning gas in the cleaning process of a semiconductor device using the gas recovery apparatus or gas recovery method of the present invention. Objective.

In order to achieve the above object, a gas recovery apparatus according to the present invention comprises:
An inert gas after being used as a cleaning gas in the cleaning step of the semiconductor device, and a first separation unit separating at least the inert gas from a first gas to be processed containing carbon dioxide gas;
The first separation unit includes:
A first processing chamber to which the first gas to be processed is supplied;
A second processing chamber;
And a first separation membrane separating the first processing chamber and the second processing chamber and having a permeability of the carbon dioxide higher than that of the inert gas.
The first gas to be processed has a first separation gas in the first processing chamber in which the purity of the inert gas is higher than that of the first gas to be processed and the purity of the carbon dioxide gas is lower, and a first gas in the second processing chamber. It is characterized by being separated into two separated gases.

The gas recovery apparatus according to the present invention having the above characteristics further includes:
It is preferable that the first separation membrane is a facilitated transport membrane to which a carrier that selectively reacts with carbon dioxide is added.

The gas recovery apparatus according to the present invention having the above characteristics further includes:
It is preferable to further include a water vapor addition unit that mixes water vapor gas with the first gas to be treated.

  In the gas recovery apparatus according to the present invention having the above characteristics, it is preferable that a sweep gas is flowed into the second processing chamber.

  In the gas recovery apparatus according to the present invention having the above characteristics, it is preferable that the sweep gas further includes a water vapor gas.

The gas recovery apparatus according to the present invention having the above characteristics further includes:
A second separation unit separating at least the inert gas from the second separation gas, further comprising:
The second separator is
A third processing chamber to which the second separation gas is supplied;
The fourth processing room,
And a second separation membrane separating the third processing chamber from the fourth processing chamber and having a permeability of the carbon dioxide higher than a permeability of the inert gas.
The second separation gas includes a third separation gas in the third processing chamber in which the purity of the inert gas is higher than that of the second separation gas and the purity of the carbon dioxide gas is lower, and a fourth separation in the fourth processing chamber. It is preferable to separate into gas.

The gas recovery apparatus according to the present invention having the above characteristics further includes:
At least a portion of the fourth separated gas is mixed with the first process gas and supplied to the first processing chamber, or at least a portion of the fourth separated gas is mixed with the second separated gas. And is preferably supplied to the third processing chamber.

The gas recovery apparatus according to the present invention having the above characteristics further includes:
It further comprises a third separation part for separating at least the inert gas from the first separation gas,
The third separation unit includes
A fifth processing chamber to which the first separation gas is supplied;
The sixth processing room,
And a third separation membrane separating the fifth processing chamber from the sixth processing chamber and having a permeability of the carbon dioxide higher than that of the inert gas.
The first separation gas includes a fifth separation gas in the fifth processing chamber in which the purity of the inert gas is higher than that in the first separation gas and the purity of the carbon dioxide gas is lower, and a sixth separation in the sixth processing chamber. Preferably it is separated into gases.

  In the gas recovery apparatus according to the present invention having the above characteristics, preferably, the inert gas is helium gas.

The gas recovery apparatus according to the present invention having the above characteristics further includes:
The inert gas is helium gas,
A fourth separation unit separating at least the carbon dioxide gas from the second separation gas, further comprising:
The fourth separator is
A seventh processing chamber to which the second separation gas is supplied;
The eighth processing room,
And a fourth separation membrane separating the seventh processing chamber from the eighth processing chamber and having a permeability of the helium gas higher than that of the carbon dioxide gas.
A seventh separated gas in the seventh processing chamber and a seventh separated gas in the seventh processing chamber, wherein the second separated gas has a purity of the carbon dioxide gas higher than that of the second separated gas and a purity of the helium gas, and an eighth separated gas in the eighth processing chamber It is preferable to be separated.

The gas recovery apparatus according to the present invention having the above characteristics further includes:
The inert gas is helium gas;
And a fifth separation unit configured to separate at least the carbon dioxide gas from a second process gas containing the helium gas and the carbon dioxide gas after being used as the cleaning gas.
The fifth separator is
A ninth processing chamber to which the second processing gas is supplied;
A tenth processing chamber;
And a fifth separation membrane separating the ninth processing chamber from the tenth processing chamber and having a permeability of the helium gas higher than that of the carbon dioxide gas.
A ninth separated gas in the ninth processing chamber and a tenth separated gas in the ninth processing chamber, wherein the second gas to be treated has a purity of the carbon dioxide gas higher than that of the second gas to be treated and a purity of the helium gas is lower than that of the tenth treatment chamber. Separated into separation gas,
It is preferable that the tenth separation gas be supplied to the first processing chamber as the first process gas.

In order to achieve the above object, a gas recovery method according to the present invention comprises:
An inert gas after being used as a cleaning gas in the cleaning step of the semiconductor device, and a first step of separating at least the inert gas from a first gas to be treated containing carbon dioxide gas;
In the first step, the first gas to be treated is allowed to pass through the first separation membrane, in which the permeability of the carbon dioxide gas is higher than the permeability of the inert gas, so that the first gas to be treated can be subjected to the first treatment gas. Separating the first separation membrane having a high purity of inert gas and a low purity of the carbon dioxide gas into a non-permeated first separation gas and a second separation gas containing a gas permeated through the first separation membrane; It features.

The gas recovery method according to the present invention having the above characteristics further includes:
It is preferable that the first separation membrane is a facilitated transport membrane to which a carrier that selectively reacts with carbon dioxide is added.

The gas recovery method according to the present invention having the above characteristics further includes:
It is preferable to mix water vapor gas with the said 1st to-be-processed gas at a said 1st process.

The gas recovery method according to the present invention having the above characteristics further includes:
The purity of the inert gas is higher than that of the second separated gas by causing the second separated gas to pass through the second separation membrane in which the permeability of the carbon dioxide gas is higher than the permeability of the inert gas. It is preferable to further include a second step of separating the second separation membrane having low purity of carbon dioxide gas into a third separation gas which is not transmitted and a fourth separation gas containing a gas which has been transmitted through the second separation membrane. .

The gas recovery method according to the present invention having the above characteristics further includes:
In the first step, at least part of the fourth separation gas is mixed with the first gas to be processed that is allowed to pass through the first separation membrane, or is allowed to pass through the second separation membrane in the second step. Preferably, at least a portion of the fourth separated gas is mixed with the second separated gas.

  In the gas recovery method according to the present invention having the above characteristics, it is preferable that the inert gas is helium gas.

In order to achieve the above object, a semiconductor cleaning system according to the present invention includes:
A gas recovery apparatus according to the present invention of the above-mentioned feature for separating and recovering at least the inert gas from the exhaust gas containing the inert gas and carbon dioxide gas after being used as the cleaning gas in the cleaning step of the semiconductor device; A mixing unit that mixes carbon dioxide gas at a predetermined mixing ratio with the inert gas recovered by the gas recovery device,
The gas mixed in the mixing unit may be supplied to the semiconductor cleaning apparatus as the cleaning gas.

The semiconductor cleaning system according to the present invention having the above characteristics further includes:
The gas recovery apparatus separates and recovers the carbon dioxide gas from the exhaust gas,
The carbon dioxide gas mixed with the inert gas recovered by the gas recovery apparatus may include at least a part of the carbon dioxide gas recovered by the gas recovery apparatus.

  According to the gas recovery apparatus and the gas recovery method of the present invention, when the mixed gas of carbon dioxide and inert gas discharged in the cleaning process of the semiconductor device is reused, the first separation membrane is used to By removing carbon dioxide, an inert gas with high purity can be obtained. The first separation membrane is preferably a facilitated transport membrane to which a carrier that selectively reacts with carbon dioxide is added.

  Although the above-mentioned gas recovery device by membrane permeation requires a large membrane area so as to obtain a high-purity separation gas, it is still energy saving as compared with a conventional recovery device by compression / cooling.

  On the other hand, when using a facilitated transport film, the presence of water is essential to obtain a high permeation rate, so that the gas obtained by mixing the water vapor gas with the exhaust gas is allowed to pass through the facilitated transport film, even in a high temperature environment. Carbon dioxide gas can be permeated with high selective performance. As a result, the separation gas is mixed with the steam gas, but the steam gas is easily removed by cooling or using another selective permeation membrane.

The schematic diagram which shows the principal part structure of the gas recovery apparatus which concerns on 1st Embodiment of this invention. The schematic diagram which shows the principal part structure of the gas recovery apparatus which concerns on 2nd Embodiment of this invention. The schematic diagram which shows the principal part structure of the gas recovery apparatus which concerns on 3rd Embodiment of this invention. The schematic diagram which shows the principal part structure of the gas recovery apparatus which concerns on 4th Embodiment of this invention. The schematic diagram which shows the principal part structure of the gas recovery apparatus which concerns on 5th Embodiment of this invention. The schematic diagram which shows the principal part structure of the gas recovery apparatus which concerns on 6th Embodiment of this invention. The schematic diagram which shows the principal part structure of the gas recovery apparatus which concerns on 7th Embodiment of this invention. Table showing the results of evaluating the CO ₂ selective performance of the facilitated transport film for helium gas Table showing the results of evaluating the CO ₂ selective performance of the facilitated transport film for helium gas A table showing the results of evaluating the area of the facilitated transport film required for recovery of high purity helium gas The block diagram which shows typically the principal part of the semiconductor cleaning system which concerns on one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail.

  The principal part structure of the gas recovery apparatus 1 which concerns on FIG. 1 at 1st Embodiment of this invention is shown typically. The arrows in FIG. 1 simply show the flow path and direction in which the gas flows, and the chemical formulas shown in FIG. 1 conceptually indicate the main components included in the gas flowing in the direction of the arrows in the drawing. Represents ingredients. Also, the description of the three-way valve and the mixing valve that are necessary in the gas flow path is omitted. The same applies to the configuration of the relevant parts of the gas recovery system described below. Moreover, in each principal part block diagram, the same code | symbol shall be attached | subjected about the same component and the description may be abbreviate | omitted.

  The gas recovery apparatus 1 includes a first separation unit 13 provided with a first processing chamber 11 and a second processing chamber 12. The first processing chamber 11 and the second processing chamber 12 of the first separation unit 13 are separated by a first separation film 14. A flow of a first process gas containing at least an inert gas and carbon dioxide is supplied to the first processing chamber 11 via the gas flow path 15. The first separation film 14 has a function of selectively permeating carbon dioxide gas contained in the first process gas to the second processing chamber 12 with a permeability higher than that of the inert gas. ing. Thereby, the purity of the carbon dioxide of the gas in the 1st processing chamber 11 falls, and the purity of an inert gas rises. On the other hand, the purity of carbon dioxide in the gas in the second processing chamber 12 increases.

  Here, the purity of a gas refers to the ratio of the molar concentration of the gas component to the total gas (that is, the ratio of the partial pressure of the gas component to the total pressure). This is the same in the following description.

  The first separation membrane 14 is preferably composed of a facilitated transport membrane. The facilitated transport film is a film formed by, for example, adding a carrier that selectively reacts with a specific gas molecule (here, carbon dioxide) in a gel film. The specific configuration of the facilitated transport film will be described later.

In the above CO ₂ facilitated transport membrane, CO ₂ permeates as a reaction product with the carrier in addition to physical permeation by the dissolution / diffusion mechanism, so that the permeation rate is promoted. On the other hand, gases such as N ₂ and H ₂ that do not react with the carrier permeate mainly by physical permeation, and therefore the separation coefficient of CO ₂ for these gases is extremely large. The same applies to an inert gas such as Ar or He, and since it does not react with the carrier, the permeability compared with CO ₂ is extremely small. Furthermore, since the energy generated when the CO ₂ reacts with the carrier is used for the energy for the carrier to release CO ₂ , there is no need to supply energy from the outside, which is an energy saving process in nature.

  Here, the “carrier” is a substance having an effect of increasing the permeation rate of a specific gas by containing the substance in the membrane.

The CO ₂ -promoting transport film is not only highly energy-saving, but also very compact, and if mass production is possible, CO ₂ separation and recovery will be much cheaper than current chemical absorption methods and more expensive PSA methods. since the process can be constructed, other decarboxylation process described above, the power generation gas, steel gas, CO ₂ recovered from a cement exhaust gas or the like, further, CTL: the next generation such as the field (coal-to liquids liquid fuel production from coal) Can be applied to small-scale energy plants and small-scale chemical plants and equipments to which existing decarbonation fields can not be applied, and it is possible to easily separate and recover CO _2, thereby contributing significantly to a low carbon society Expected.

  Due to the first separation film 14, the first gas to be treated containing the inert gas and the carbon dioxide gas has a higher purity of the inert gas than the first gas to be treated, and a low purity of the carbon dioxide gas in the first treatment chamber 11. The first separated gas is separated into the second separated gas in the second processing chamber 12 in which the purity of carbon dioxide gas is higher than that of the first process gas and the purity of inert gas is lower. The first separation gas can be reused as an inert gas, and the second separation gas as a carbon dioxide gas. The first separation gas is recovered via the gas flow path 17 and the second separation gas is recovered via the gas flow path 18.

  By the way, since the permeation rate of carbon dioxide is generally very small when there is no moisture in the first separation membrane 14, the moisture in the membrane is indispensable to obtain a high permeation rate. One way to maintain the water content in the first separation membrane 14 is to make the gel layer of a highly water-retaining hydrogel. As a result, even under high temperature where water content in the separation function layer decreases, it is possible to retain water in the film as much as possible, and high selective permeation performance can be realized at high temperature of 100 ° C. or higher, for example.

  As another method, a gas obtained by mixing a steam gas (steam) with the first gas to be treated may be used as the gas to be treated and introduced into the first processing chamber 11. The water vapor gas supplied from the water vapor addition unit 19 is mixed with the first process gas, and the mixed gas is supplied to the first processing chamber 11 of the first separation unit 13 via the gas flow path 15. The water vapor separation unit 20a removes the water vapor gas from the second separated gas that has permeated into the second processing chamber 12 via the first separation membrane 14, and the carbon dioxide gas is separated. On the other hand, the water vapor separation unit 20b removes the water vapor gas from the first separation gas to obtain a high purity inert gas. It is also possible to recover the removed steam gas, mix it with the first treated gas, and reuse it.

  The water vapor separation units 20a and 20b may be those using a condenser or a known configuration using a water vapor permeable membrane. When the water vapor permeable membrane is used, the water vapor gas is not collected in the cooled liquid state, but is collected in the gas state (in the state of having latent heat), so the removed water vapor gas is supplied to the water vapor addition portion 19 as it is. The water vapor gas can be introduced into the first gas to be processed through the water vapor addition unit 19.

  The relative humidity of the first process gas mixed with the steam gas is preferably 30% to 100%, more preferably 40% to 100%.

  The first gas to be treated mixed with the water vapor gas may be increased in pressure or increased in temperature. By increasing the pressure, the partial pressure difference of carbon dioxide gas, which is the driving force of permeation, can be increased, and the permeation amount of carbon dioxide can be increased. In addition, the steam partial pressure increases due to the pressure increase, which also has the effect of increasing the relative humidity that decreases as the temperature rises. In the case of boosting, in consideration of the energy required for boosting, it is preferably 200 kPa (A) to 1000 kPa (A), more preferably 400 kPa (A) to 1000 kPa (A). The temperature may be around room temperature, but the permeability of carbon dioxide tends to increase with temperature, so 60 ° C. to 160 ° C. is preferable, and 80 ° C. to 120 ° C. is more preferable.

In the second processing chamber 12, it is preferable to flow a sweep gas in order to lower the partial pressure of carbon dioxide on the permeation side and obtain a partial pressure difference which is a driving force for selective permeation. The sweep gas is supplied from the gas flow path 16. The sweep gas preferably contains water vapor gas. The water vapor gas is supplied from the water vapor addition unit 19. By supplying water vapor gas as the sweep gas, the partial pressure difference of the water vapor gas between the supply side (first processing chamber 11) and the permeation side (second processing chamber 12) is reduced, By reducing the permeation amount of the water vapor gas, it is possible to suppress the decrease in the relative humidity of the first process gas. In addition, the higher the CO ₂ recovery rate, the lower the relative humidity of the gas in the second processing chamber 12 (second separation gas) because the ratio of the water vapor gas on the permeate side becomes lower, but the water vapor contained in the sweep gas. A decrease in relative humidity can be suppressed by increasing the flow rate of the gas. However, when water vapor gas is used as the sweep gas, it is necessary to control the pressure on the permeate side to be equal to or lower than the saturated water vapor pressure at the temperature to be used. That is, when only water vapor gas is used as a sweep gas under a temperature condition of less than 100 ° C., the permeation side needs to be depressurized.

When the gas recovery apparatus 1 is used for reusing exhaust gas that is exhausted after being used as cleaning gas in a semiconductor device manufacturing process, the exhaust gas includes a mixed gas mainly composed of helium gas and carbon dioxide gas. Become. Oil and moisture such as particles generated by washing are removed in advance. In general, the exhaust gas contains at most several ppm of N ₂ , O ₂ and CH ₄ gases, the rest being helium and carbon dioxide gases.

  A first gas to be treated containing exhaust gas is supplied to the first treatment chamber 11, and carbon dioxide gas in the first gas to be treated is permeated through the first separation membrane 14 at a higher permeability than helium gas. As a result, in the first processing chamber 11, an unpermeated gas (first separation gas) remains through the first separation membrane 14 in which the purity of the inert gas is higher than that of the first gas to be processed and the purity of the carbon dioxide is lower. A gas (second separation gas) that passes through the first separation membrane 14 containing carbon dioxide gas but hardly containing helium gas is obtained in the processing chamber 12. The first separation gas can be used as high purity helium gas, and the second separation gas can be used as high purity carbon dioxide gas by removing the sweep gas component.

  Depending on the performance of the first separation membrane 14 and the membrane area, the purity of the helium gas which is the first separation gas may not necessarily be high enough to be reutilizable for industrial use, but it is possible to use other than helium gas in the first separation gas. The remaining gas is almost carbon dioxide gas, and its concentration can be predicted. Therefore, by appropriately mixing the carbon dioxide gas with the first separated gas, the concentration ratio of the inert gas and the carbon dioxide gas is made to be a predetermined ratio suitable for use as the cleaning gas, thereby manufacturing the semiconductor device. It is also easy to generate a mixed gas of inert gas and carbon dioxide for use in the process.

  Note that an inert gas of higher purity can be obtained in the first processing chamber 11 by mixing at least a part of the first separation gas with the first process gas.

  In FIG. 2, the principal part structure of the gas recovery system 2 which concerns on 2nd Embodiment of this invention is shown typically. The gas recovery apparatus 2 having the configuration shown in FIG. 2 is a first processing target in which the water vapor gas supplied from the water vapor addition unit 19 and at least a part of the second separation gas are mixed in the gas recovery apparatus 1 shown in FIG. Gas is supplied to the first processing chamber 11. Thus, the inert gas recovery rate of the inert gas in the second separated gas that has been unintentionally permeated through the first separation membrane 14 can be returned to the first gas to be treated, thereby improving the inert gas recovery rate.

  The principal part structure of the gas recovery system 3 which concerns on FIG. 3 concerning 3rd Embodiment of this invention is shown typically. The gas recovery apparatus 3 configured as shown in FIG. 3 has a third processing chamber 21 and a fourth processing chamber 22 in addition to the first separation unit 13 including the first processing chamber 11 and the second processing chamber 12. A second separation unit 23 is provided, and the second separation gas obtained by the first separation unit 13 is configured to be further supplied to the third processing chamber 21 via the gas flow path 18. The third processing chamber 21 and the fourth processing chamber 22 of the second separation unit 23 are separated by a second separation film 24.

  The second separation membrane 24 has the same function as that of the first separation membrane 14, and the carbon dioxide gas contained in the second separation gas supplied to the third processing chamber 21 has a permeability of inert gas Also, the light is selectively transmitted to the fourth processing chamber 22 side with high transmittance. Thereby, the purity of the carbon dioxide of the gas in the 3rd processing chamber 21 falls, and the purity of an inert gas rises. On the other hand, the purity of carbon dioxide in the gas in the fourth processing chamber 22 increases. The second separation membrane 24 is preferably composed of a facilitated transport membrane. In this case, the second separation film 24 may or may not be made of the same material or film structure as the first separation film 14.

  The second separation gas is supplied to the third processing chamber 21 of the second separation unit 23. Thereby, the second separation gas has a higher purity of inert gas than the second separation gas and a lower purity of carbon dioxide gas (third separation gas) in the third processing chamber 21 and in the fourth processing chamber 22. Is separated into the fourth gas (the fourth separated gas). The third separation gas can be reused as an inert gas, and the recovery rate of the inert gas can be improved together with the first separation gas. The third separated gas is sent to the water vapor separation unit 20c via the gas flow path 26, and the water vapor gas is removed from the third separated gas to obtain an inert gas of high purity. On the other hand, the fourth separated gas is a gas which contains a large amount of carbon dioxide gas but hardly contains a helium gas, and can be used as a high purity carbon dioxide gas by removing the sweep gas component. The fourth separated gas is sent to the water vapor separation unit 20a via the gas flow path 27, and the water vapor gas is removed from the fourth separated gas to obtain high purity carbon dioxide gas. It is also possible to collect the water vapor gas removed by the water vapor separation units 20a, 20b, and 20c, mix it with the first gas to be processed, and reuse it.

  Similar to the gas recovery apparatus 1, the sweep gas is supplied to the second processing chamber 12 via the gas flow path 16. Further, the sweep gas can be flowed to the fourth processing chamber 22 through the gas flow channel 25. As the sweep gas, water vapor gas is preferable.

  The second separation gas is a gas containing carbon dioxide that has permeated through the first separation membrane 14 as a main component and an inert gas that has permeated through the first separation membrane 14. By passing the second separation gas through the second separation membrane 24 of the third processing chamber 21, most of the carbon dioxide in the second separation gas permeates through the second separation membrane 24, while the inert gas does not permeate. Remain. Therefore, the third separated gas is a gas mainly composed of the inert gas that could not be separated in the first separation unit 13 and slightly containing carbon dioxide. By appropriately mixing the carbon dioxide gas with the third separation gas, the concentration ratio of the inert gas and the carbon dioxide gas is made to be a predetermined ratio suitable for use as the cleaning gas, and the manufacturing process of the semiconductor device is performed. It is also easy to generate a mixed gas of an inert gas and carbon dioxide for use. Note that an inert gas with higher purity can be obtained in the first processing chamber 11 by mixing at least a part of the third separation gas with the first process gas.

  In FIG. 4, the principal part structure of the gas collection | recovery apparatus 4 which concerns on 4th Embodiment of this invention is shown typically. The gas recovery apparatus 4 having the configuration shown in FIG. 4 has a configuration in which the first process gas in which at least a part of the fourth separated gas is mixed is supplied to the first processing chamber 11 in the gas recovery apparatus 3 shown in FIG. It is a thing. As a result, the inert gas in the fourth separation gas that has permeated through the first separation membrane 14 and the second separation membrane 24 can be returned to the first gas to be processed, and the recovery rate of the inert gas can be improved. The sweep gas flowing to the second processing chamber 12 and the fourth processing chamber 22 is preferably a steam gas.

  Note that, instead of mixing at least a part of the fourth separated gas with the first process gas, at least a part of the fourth separated gas is mixed with the second separated gas to form the third processing chamber 21 of the second separation unit 23. It is good also as a structure supplied to.

  The principal part structure of the gas recovery apparatus 5 which concerns on FIG. 5 at 5th Embodiment of this invention is shown typically. The gas recovery apparatus 5 having the configuration shown in FIG. 5 has a fifth processing chamber 61 and a sixth processing chamber 62 in addition to the first separation unit 13 having the first processing chamber 11 and the second processing chamber 12. The third separation unit 63 is provided, and the first separation gas obtained by the first separation unit 13 is configured to be further supplied to the fifth processing chamber 61 via the gas flow path 17. The fifth processing chamber 61 and the sixth processing chamber 62 of the third separation unit 63 are separated by a third separation film 64.

  The third separation film 64 has the same function as that of the first separation film 14, and the carbon dioxide gas contained in the first separation gas supplied to the fifth processing chamber 61 is determined by the permeability of the inert gas. Also, the light is selectively transmitted to the sixth processing chamber 62 side with high transmittance. As a result, the purity of carbon dioxide in the gas in the fifth processing chamber 61 is reduced, and the purity of the inert gas is increased. On the other hand, the purity of carbon dioxide in the gas in the sixth processing chamber 62 increases. The third separation membrane 64 is preferably composed of a facilitated transport membrane. In this case, the third separation membrane 64 may or may not be made of the same material or membrane structure as the first separation membrane 14.

  The first separation gas is supplied to the fifth processing chamber 61 of the third separation unit 63. As a result, the first separation gas has a higher inert gas purity than the first separation gas and a low carbon dioxide gas purity in the fifth processing chamber 61 and the sixth processing chamber 62. Is separated into the first gas (sixth separated gas). The fifth separated gas is sent to the water vapor separation unit 20b via the gas flow path 66, and the water vapor gas is removed from the fifth separated gas to obtain an inert gas of extremely high purity. On the other hand, each of the second separation gas and the sixth separation gas can be used as a carbon dioxide gas by removing the sweep gas component. The second separation gas is sent to the water vapor separation unit 20a via the gas flow path 18, and the water vapor gas is removed from the second separation gas to obtain carbon dioxide gas. The sixth separation gas is sent to the water vapor separation unit 20d through the gas flow channel 67, and the water vapor gas is removed from the sixth separation gas to obtain carbon dioxide gas. It is also possible to collect the water vapor gas removed by the water vapor separators 20a, 20b, and 20d, mix it with the first gas to be processed, and reuse it.

  Similar to the gas recovery apparatus 1, the sweep gas is supplied to the second processing chamber 12 via the gas flow path 16. Furthermore, the sweep gas can be flowed to the sixth processing chamber 62 through the gas flow channel 65. As the sweep gas, water vapor gas is preferable.

  In the gas recovery apparatus 5 shown in FIG. 5, at least a part of the second separated gas may be supplied to the sixth processing chamber 62. However, when the second separated gas is sent to the water vapor separation unit 20a to obtain carbon dioxide gas as in the gas recovery apparatus 5 shown in FIG. 5, carbon dioxide gas in the fifth processing chamber 61 and the sixth processing chamber 62 is obtained. It is preferable to increase the purity of the inert gas in the fifth separation gas by increasing the carbon dioxide gas permeability in the third separation film 64 by increasing the partial pressure difference in the above.

  In FIG. 6, the principal part structure of the gas collection | recovery apparatus 6 which concerns on 6th Embodiment of this invention is shown typically. A gas recovery apparatus 6 having a configuration shown in FIG. 6 includes a seventh processing chamber 71 and an eighth processing chamber 72 in addition to the first separation unit 13 including the first processing chamber 11 and the second processing chamber 12. A fourth separation unit 73 is provided, and the second separation gas obtained by the first separation unit 13 is configured to be further supplied to the seventh processing chamber 71 via the gas flow path 18. The seventh processing chamber 71 and the eighth processing chamber 72 of the fourth separation unit 73 are separated by a fourth separation film 74.

  The fourth separation membrane 74 has a function different from that of the first separation membrane 14, and the inert gas contained in the second separation gas supplied to the seventh processing chamber 71 is determined by the permeability of carbon dioxide gas. Also, it is selectively transmitted to the eighth processing chamber 72 side with high transmittance. Thereby, the purity of the inert gas of the gas in the 7th processing chamber 71 falls, and the purity of carbon dioxide gas rises. On the other hand, the purity of the inert gas in the eighth processing chamber 72 is increased.

  In the gas recovery device 6, the fourth separation part 73 needs the fourth separation film 74 which is easily permeable to the inert gas which is difficult to cause chemical permeation and which is not easily permeable to the carbon dioxide gas. For example, the fourth separation membrane 74 is required to perform gas separation based on the difference in the solubility in the membrane and the diffusivity in the membrane. Therefore, from the viewpoint of enhancing the selectivity of the inert gas and the carbon dioxide gas as much as possible, it is preferable to use an inert gas having a molecular diameter sufficiently smaller than the molecular diameter of the carbon dioxide gas. Specifically, it is preferable to use helium gas as the inert gas. In this case, for example, as proposed in WO 2014/007140, it is disposed on the base made of an α-alumina porous body, the γ-alumina porous portion containing Ni element, and the inner wall of the communicating hole. The fourth separation membrane 74 may be configured using a helium separation material having a silica membrane portion and a gas separation portion joined to the base portion. This is merely an example, and the fourth separation membrane 74 can be configured using a known helium gas separation material such as a separation material made of a polymer.

  The second separation gas is supplied to the seventh processing chamber 71 of the fourth separation unit 73. Thereby, the second separation gas has a higher carbon dioxide gas purity than the second separation gas and a lower inert gas purity (the seventh separation gas) in the seventh processing chamber 71 and the eighth processing chamber 72. (The eighth separated gas) is separated. The seventh separated gas can be reused as carbon dioxide gas. The seventh separated gas is sent to the water vapor separation unit 20e through the gas flow path 76, and the water vapor gas is removed from the seventh separated gas to obtain carbon dioxide gas of high purity. On the other hand, the eighth separation gas is a gas containing a large amount of inert gas, and can be used as an inert gas by removing the sweep gas component, and improves the recovery rate of the inert gas together with the first separation gas. it can. The eighth separated gas is sent to the water vapor separation unit 20f via the gas flow path 77, and the water vapor gas is removed from the eighth separated gas to obtain an inert gas. It is also possible to collect the water vapor gas removed by the water vapor separators 20b, 20e, and 20f, mix it with the first gas to be processed, and reuse it.

  Similar to the gas recovery apparatus 1, the sweep gas is supplied to the second processing chamber 12 via the gas flow path 16. Further, the sweep gas can be flowed to the eighth processing chamber 72 through the gas flow path 75. As the sweep gas, water vapor gas is preferable.

  Incidentally, by appropriately mixing carbon dioxide gas with the eighth separated gas, the concentration ratio of the inert gas and the carbon dioxide gas is made to be a predetermined ratio suitable for use as the cleaning gas, thereby manufacturing a semiconductor device. It is also easy to generate a mixed gas of inert gas and carbon dioxide for use in the process. Note that an inert gas with higher purity can be obtained in the first processing chamber 11 by mixing the eighth separation gas with the first process gas.

  The principal part structure of the gas recovery system 7 which concerns on FIG. 7 at 7th Embodiment of this invention is shown typically. The gas recovery apparatus 7 having the configuration shown in FIG. 7 has a ninth processing chamber 81 and a tenth processing chamber 82 in addition to the first separation unit 13 having the first processing chamber 11 and the second processing chamber 12. 5 separation part 83 is provided. The ninth processing chamber 81 and the tenth processing chamber 82 of the fifth separation unit 83 are separated by a fifth separation film 84. However, in the gas recovery device 7, unlike the above-described gas recovery devices 1 to 6, the second process gas including the exhaust gas is supplied to the ninth processing chamber 81 via the gas flow path 85. In addition, the gas in the tenth processing chamber 82 is supplied to the first processing chamber 11 via the gas path 88 as the first gas to be processed.

  The fifth separation film 84 has the same function as the fourth separation film 74 (see FIG. 6), and oxidizes the inert gas contained in the second process gas supplied to the ninth processing chamber 81 by The gas is selectively permeated to the tenth processing chamber 82 side with a permeability higher than the permeability of carbon gas. Thereby, the purity of the inert gas of the gas in the ninth processing chamber 81 is decreased, and the purity of the carbon dioxide gas is increased. On the other hand, the purity of carbon dioxide in the gas in the tenth processing chamber 82 increases. For the fifth separation membrane 84, a known inert gas separation material (for example, the helium gas separation material exemplified in the description of the fourth separation membrane 74 described above) can be used.

  The second processing gas is supplied to the ninth processing chamber 81 of the fifth separation unit 83. As a result, the second gas to be processed is a gas in the ninth processing chamber 81 (the ninth separation gas) in which the purity of the carbon dioxide gas is higher and the purity of the inert gas is lower than that of the second gas to be processed, and the tenth processing chamber. It is separated into the gas in 82 (the tenth separated gas). The ninth separated gas can be reused as carbon dioxide gas. The ninth separated gas is sent to the water vapor separation unit 20 g through the gas flow path 87, and the water vapor gas is removed from the ninth separated gas to obtain high purity carbon dioxide gas. On the other hand, the tenth separated gas is supplied to the first processing chamber 11. It is also possible to collect the water vapor gas removed by the water vapor separation units 20a, 20b, and 20g, mix it with the second gas to be processed, and reuse it.

  Similar to the gas recovery apparatus 1, the sweep gas is supplied to the second processing chamber 12 via the gas flow path 16. Further, a sweep gas can be flowed into the tenth processing chamber 82 via the gas flow path 86. Steam gas is preferable as the sweep gas.

  A higher purity inert gas can be obtained in the ninth processing chamber 81 by mixing the first separation gas with the second process gas.

  By using the above gas recovery devices 1 to 7, it is possible to realize high recovery rate of inert gas, high purification, and energy saving.

  Moreover, said gas collection | recovery apparatuses 1-7 can be implemented combining partially as long as there is no contradiction. For example, the above gas recovery devices 3 and 5 may be combined to constitute a gas recovery device including the first separation unit 13, the second separation unit 23, and the third separation unit 63. In this case, the second separation unit 23 and the third separation unit 63 are arranged in parallel, and the first separation gas of the first separation unit 13 is supplied to the fifth processing chamber 61 of the third separation unit 63. The second separation gas of the separation unit 13 is supplied to the third processing chamber 21 of the second separation unit 23. Further, for example, the above gas recovery devices 3 and 6 may be combined to constitute a gas recovery device including the first separation unit 13, the second separation unit 23, and the fourth separation unit 73. In this case, the second separation unit 23 and the fourth separation unit 73 are arranged in parallel, and the second separation gas of the first separation unit 13 is transferred to the third processing chamber 21 of the second separation unit 23 and the fourth separation unit 73 of the fourth separation unit 73. It is supplied to each of the seven separation chambers 71. Further, for example, the above gas recovery devices 3 and 7 may be combined to constitute a gas recovery device including the first separation unit 13, the second separation unit 23, and the fifth separation unit 83. In this case, the fifth separation unit 83, the first separation unit 13, and the second separation unit 23 are arranged in series, and the tenth separation gas of the fifth separation unit 83 is supplied to the first processing chamber 11 of the first separation unit 13. At the same time, the second separation gas of the first separation unit 13 is supplied to the third processing chamber 21 of the second separation unit 23. Note that these are merely examples, and the first to fifth separation units 13, 23, 63, 73, 83 may be arbitrarily combined in parallel or in series and arranged according to the above example.

  Below, the structure of the 1st-3rd separation film 14, 24, 64 and a manufacturing method are demonstrated concretely.

<Film structure>
First to third separation membrane 14,24,64 is CO ₂ -facilitated transport membrane, as described above, has a structure which contains a carrier which selectively reacts with CO ₂ in the gel film. Examples of the CO ₂ carrier include cesium carbonate or cesium hydrogen carbonate, or carbonates or bicarbonates of alkali metals such as rubidium carbonate or rubidium hydrogen carbonate. Similarly, hydroxides of alkali metals such as cesium hydroxide or rubidium hydroxide can be said to be equivalent because they react with carbon dioxide to form carbonates and bicarbonates. In addition, amino acids such as 2,3-diaminopropionate (DAPA) and glycine are known to exhibit high CO ₂ permeation performance.

More specifically, CO ₂ facilitated transport membrane, the above carrier gel layer that is configured to include in the gel film, it can be made by supporting the hydrophilic or hydrophobic porous membrane. Examples of the film material constituting the gel film include a polyvinyl alcohol (PVA) film, a polyacrylic acid (PAA) film, and a polyvinyl alcohol-polyacrylic acid (PVA / PAA) salt copolymer film. Here, in those skilled in the art, the polyvinyl alcohol-polyacrylate copolymer may be referred to as a polyvinyl alcohol-polyacrylic acid copolymer.

It is known that the CO ₂ -facilitated transport membrane of the above configuration exhibits high CO ₂ selective permeation performance.

However, such a CO ₂ -facilitated transport membrane, the permeation rate of carbon dioxide if the water is not in the film is generally very small, moisture in the film is essential to obtain a high permeation rate. For this reason, the gel membrane is preferably a hydrogel membrane. By constituting the gel film with a hydrogel film having high water retention, it is possible to retain moisture in the film as much as possible even in an environment where the moisture in the gel film is reduced (for example, at a high temperature of 100 ° C. or higher). It becomes possible, and high CO ₂ permeance can be realized. In the above-described example, the polyvinyl alcohol-polyacrylic acid (PVA / PAA) salt copolymer film is a hydrogel film.

  The hydrogel is a three-dimensional network structure formed by crosslinking a hydrophilic polymer by chemical crosslinking or physical crosslinking, and has a property of swelling by absorbing water.

Furthermore, a catalyst that accelerates the reaction between the CO ₂ carrier and the CO ₂ may be contained in the membrane. Such a catalyst preferably contains a carbonic anhydrase or an oxo acid compound, and in particular, an oxo acid of at least one element selected from the group 14 element, group 15 element, and group 16 element It is preferable that the composition includes a compound. Alternatively, it is preferable that the catalyst comprises at least any one of a telluric acid compound, a selenite compound, an arsenous acid compound, and an orthosilicic acid compound.

In this embodiment, the facilitated transport film uses polyvinyl alcohol-polyacrylic acid (PVA / PAA) salt copolymer as an example of a film material, and cesium carbonate (Cs ₂ CO ₃ ) as a carbon dioxide carrier. . The CO ₂ -facilitated transport film is composed of a PVA / PAA gel film containing a carbon dioxide carrier and a porous film supporting the same. The film structure of the CO ₂ -facilitated transport film is not limited to this specific example. For example, a gel film including a carrier is formed on the outer peripheral side surface or the inner peripheral side surface of a cylindrical porous support. It does not matter.

<Method of producing membrane>
Hereinafter, a method for manufacturing the CO ₂ facilitated transport membrane.

First, a membrane-forming solution is prepared, which is composed of an aqueous solution containing a PVA / PAA salt copolymer and a carrier (here, Cs ₂ CO ₃ ) (Step 1). More specifically, 2 g of PVA / PAA salt copolymer (for example, SS gel manufactured by Sumitomo Seika Chemicals Co., Ltd.) and 4.67 g of Cs ₂ CO ₃ are weighed into a sample bottle, and 80 g of water is added thereto to obtain a room temperature And stirring for 4 days to dissolve to obtain a cast solution. Next, the membrane-forming solution obtained in step 1 is cast on the surface of a porous PTFE membrane (for example, HP-010-60 made by Sumitomo Electric Co., Ltd.) with an applicator (step 2). Then, it is dried at room temperature for about half a day to gelate the membrane forming solution to form a gel layer (Step 3).

<Performance evaluation result>
Hereinafter, the evaluation results of the selectivity for helium gas which film has been CO ₂ -facilitated transport membrane by the above manufacturing method. Hereinafter, an evaluation result in the case where a CO ₂ facilitated transport membrane is applied to the first separation membrane 14 in the gas recovery apparatus 1 shown in FIG. 1 will be exemplified.

As a CO ₂ carrier constituting the CO ₂ facilitated transport film, a film using glycine instead of the above Cs ₂ CO ₃ (hereinafter referred to as “film A”), and a film using Cs ₂ CO ₃ (hereinafter referred to as “film”). (Referred to as “film B”). Further, both membrane A and membrane B were hydrogel membranes obtained by adding a CO ₂ carrier to a PVA / PAA salt copolymer. However, when using amino acids such as glycine or DAPA as CO ₂ carrier, CO ₂ does not react with _NH ^{3 +,} by reacting the free NH ₂ of, it is known that CO ₂ is facilitated transport There is. For this reason, in the case of membrane A using glycine as a CO ₂ carrier, a deprotonating agent for converting NH ₃ ^{+ in} which the amino group of glycine (NH ₂ —CH ₂ —COOH) is protonated into NH ₂ is used as an amino acid. It is necessary to add to the said film-forming solution preferably the same mole number or more with respect to the group. The deprotonating agent may be any one as long as it removes a proton from protonated NH ₃ ⁺ and has a strong basicity enough to convert it to NH _2, and a hydroxide or carbonate of an alkali metal element can be suitably used. . Here, CsOH of the same mole as glycine is added to the membrane-forming solution as a deprotonating agent to prepare a membrane A, which is used as the first separation membrane 14 of the gas recovery device 1. Further, in the membrane B, potassium tellurite was added to the membrane-forming solution as a catalyst for accelerating the reaction between the CO ₂ carrier and the CO ₂ to produce the membrane B, which was used as the first separation membrane 14 of the gas recovery device 1.

<Performance evaluation condition-1>
First, evaluation results of the film A under three conditions where the temperature and the pressure on the supply side (the first processing chamber 11 side) (total pressure) were constant and the partial pressure ratio of CO ₂ to He of the gas to be processed were changed Show. Under the following three conditions, the processing temperature is set to 50 ° C., the total pressure of the processing target gas is set to atmospheric pressure, and the partial pressure of the water vapor gas supplied to the first processing chamber 11 is kept constant. The partial pressure of CO ₂ and He was changed. Further, a mixed gas of argon gas and water vapor gas was used as a composition of the sweep gas supplied to the permeation side (second processing chamber 12 side). The sweep gas has a total pressure of atmospheric pressure, as in the case of the first treated gas.

The composition ratios (partial pressure ratios) of the first gas to be treated and the sweep gas under the three conditions are shown below. The composition ratio of the sweep gas is the same under the three conditions. The relative humidity of the first gas to be treated and the sweep gas at this time is 58%.
・ First gas composition:
Condition 1-1: CO ₂ : He: H ₂ O = 43.6: 49.0: 7.4
(CO ₂ : He = 47.1: 52.9)
Condition 1-2: CO ₂ : He: H ₂ O = 23.1: 69.5: 7.4
(CO ₂ : He = 25.0: 75.0)
Condition 1-3: CO ₂ : He: H ₂ O = 9.3: 83.3: 7.4
(CO ₂ : He = 10.0: 90.0)
・ Sweep gas composition:
Ar: H ₂ O = 92.6: 7.4 for all of the conditions 1-1 to 1-3

Figure 8 shows the results of evaluation of the CO ₂ selective performance for He of facilitated transport membranes under the above conditions. Under the condition 1-1, since the He permeance is very small, the concentration of He in the second separation gas having permeated through the first separation membrane 14 is too low to detect He by gas chromatography, and the permeance It could not be calculated.

CO ₂ / He selectivity can be expressed as the ratio of CO ₂ permeance to He permeance. From FIG. 8, it can be seen that the membrane A has a CO ₂ / He selectivity exceeding 400 at a relatively low temperature of 50 ° C.

It should be noted that the CO ₂ partial pressure of the gas to be treated is varied under the conditions 1-1 to 1-3, but the lower the CO ₂ partial pressure, the higher the CO ₂ permeance. Here, the CO ₂ permeance is a value obtained by dividing CO ₂ Flux (value of CO ₂ gas flow rate permeating the membrane divided by the membrane area) by the partial pressure difference between the permeation side and the supply side. Therefore, the fact that the CO ₂ permeance increases with a decrease in the CO ₂ partial pressure means that even if the partial pressure difference, which is the driving force of the membrane permeation, is reduced by a predetermined percentage A%, the transmitted CO ₂ flux The amount of decrease means staying below A%. In FIG. 8, the partial pressure difference decreases to almost half under condition 1-2 compared to condition 1-1, and the partial pressure difference decreases to near 1/5 under condition 1-3 compared to condition 1-1. However, the decrease in CO ₂ Flux is kept small.

Such partial pressure dependence on the selectively permeated gas is a phenomenon unique to facilitated transport membranes. In the gas recovery apparatus, the to-be-treated gas supplied from the gas flow path 15 into the first processing chamber 11 is removed from CO ₂ by coming into contact with the first separation membrane 14 and becomes a first separated gas. It flows into the road 17. At this time, the CO ₂ partial pressure of the gas in the first processing chamber 11 is high on the inlet side (near the gas flow path 15) and low on the outlet side (near the gas flow path 17). Distribution occurs in the CO ₂ partial pressure according to the upper position. As the recovery rate of inert gas such as He is higher, that is, as the removal rate of CO ₂ is higher, the partial pressure of CO ₂ at the position on the outlet side (in the vicinity of the gas flow path 17) is lowered. In particular, the permeation performance under low partial pressure of CO ₂ is excellent.

<Performance evaluation condition-2>
Next, the pressure (total pressure) on the supply side (the first processing chamber 11 side), the relative humidity, the ratio of CO ₂ to He in the gas to be treated are made constant, and the permeation of the membrane A and the membrane B while changing the processing temperature The results of evaluating the performance are shown. Here, assuming that the cleaning gas discharged from the semiconductor cleaning apparatus is heated and increased in pressure and supplied as the processing gas, the total pressure of the processing gas is set to 900 kPa (A). Moreover, three conditions of 100 degreeC, 110 degreeC, and 120 degreeC were considered as process temperature. The treatment temperature is set to 100 ° C. or higher because the facilitated transport film generally has excellent permeation performance in a temperature range of about 100 ° C. to 160 ° C. The reason why the pressure is set to 900 kPa (A) is to obtain a partial pressure difference which is a driving force for permeation of the membrane. A mixed gas of argon gas and water vapor gas was used as the sweep gas supplied to the permeation side (second processing chamber 12 side). The sweep gas has a total pressure of atmospheric pressure, and the partial pressure of the water vapor gas is changed according to the temperature so that the relative humidity is constant.

Below, the composition ratio (partial pressure ratio) of the process temperature, the 1st to-be-processed gas, and sweep gas in three conditions is shown. In the following, the relative humidity of the first gas to be processed and the sweep gas is 58% and 50%, respectively, regardless of the temperature.
・ First gas composition:
Condition 2-1: CO ₂ : He: H ₂ O = 23.3: 70.1: 6.6
(CO ₂ : He = 25.0: 75.0)
Condition 2-2: CO ₂ : He: H ₂ O = 22.7: 68.0: 9.3
(CO ₂ : He = 25.0: 75.0)
Condition 2-3: CO ₂ : He: H ₂ O = 21.8: 65.4: 12.8
(CO ₂ : He = 25.0: 75.0)
・ Sweep gas composition:
Condition 2-1: Ar: H ₂ O = 49.3: 50.7
Condition 2-2: Ar: H ₂ O = 28.4: 71.6
Condition 2-3: Ar: H ₂ O = 0: 100
Processing temperature:
100 ° C., 110 ° C., 120 ° C. in the order of conditions 2-1, 2-2, 2-3

Figure 9 shows the results of evaluation of the CO ₂ selective performance for He membrane A and membrane B under the above conditions. Although CO ₂ partial pressure of the first gas to be treated under the conditions 2-1 to 2-3 are different, a difference of a few percent. Accordingly, in FIG. 9, the CO ₂ permeance increases as the temperature rises, but the effect due to the difference in CO ₂ partial pressure is slight, and it can be said that the increase in CO ₂ permeance is mainly due to the effect of temperature.

Required membrane area
FIG. 10 shows the result of calculating the film area required to obtain a gas with a He purity of 99% or more, based on the film performance evaluation results of conditions 1-2 and conditions 2-1 to 2-3 described above. . In FIG. 10, the target gas composition, the sweep gas composition, and the permeation performance under each of the above conditions are substituted in the simulator, and the He purity of the first separated gas excluding the water vapor gas is changed while changing the membrane area and the flow rate of the sweep gas. The minimum film area that was 99% or more and the relative humidity of the gas to be processed and the sweep gas could be maintained at 40% or more in any region of the film was determined. The flow rate of the processing gas supplied to the first processing chamber 11 was set such that the flow rate of the mixed gas (supply dry gas) of CO ₂ gas and He gas excluding the water vapor gas was 30 l / min.

Further, the CO ₂ permeance was set to a constant value (the value shown in FIG. 8 or FIG. 9) regardless of the membrane region. However, as described above, the facilitated transport film is characterized in that the CO ₂ permeance increases as the difference in partial pressure of CO ₂ on the supply side (the first processing chamber 11 side) and the permeation side (the second processing chamber 12 side) decreases. For this reason, in fact, due to the distribution on the membrane of the partial pressure of CO ₂ in the first processing chamber 11, the closer to the outlet side of the membrane (near the gas channel 17) from the inlet side of the film (near the gas channel 15) CO ₂ permeance is higher. Therefore, when the facilitated transport film is used, it is considered that the actually required film area is smaller than the film area shown in FIG.

From FIG. 10, the required membrane area in the case of condition 1-2 is 120 m ² , and a relatively large area is required because the CO ₂ permeance is smaller compared to conditions 2-1 to 2-3. However, the gas recovery device 1 can be sufficiently realized by combining a plurality of membrane modules.

On the other hand, in the case of conditions 2-1 to 2-3, the required film area is a small area of at most about 4 to 8 m ² regardless of whether the film A or the film B is used. The gas recovery device 1 can be easily realized using only one typical membrane module, and the recovery device can be miniaturized. In general, the gas recovery method using a separation membrane has an advantage of being more compact than other methods such as a chemical absorption method, but in particular, recovery using a facilitated transport membrane under conditions 2-1 to 2-3 The device is suitable for use in places where installation space is limited, such as semiconductor manufacturing plants.

  As described above, according to the above gas recovery apparatus and gas recovery method, high recovery rate and high purification of inert gas can be achieved, and energy saving can be realized.

<Semiconductor cleaning system>
Hereinafter, an example in which the gas recovery apparatus and the gas recovery method described above are used for reuse of the cleaning gas used in the manufacture of the semiconductor device will be described. As shown in the block diagram of FIG. 11, the semiconductor cleaning system 100 according to an embodiment of the present invention includes any one of the gas recovery devices 1 to 7 described above (here, the gas recovery device 1) and a gas recovery device. And a mixing unit 52 for mixing carbon dioxide gas with the inert gas separated and collected by

  The exhaust gas after being used as the cleaning gas in each of the plurality of semiconductor manufacturing apparatuses 50 a to 50 c is mixed, and the mixed exhaust gas is used as a first process gas of the gas recovery apparatus 1. Although a mixed gas of an inert gas and a carbon dioxide gas is used as the cleaning gas, the concentration ratio of the inert gas to the carbon dioxide gas is determined according to the specific cleaning process being performed in each semiconductor manufacturing apparatus. Can be different. The mixed exhaust gas is a gas mainly composed of carbon dioxide gas and an inert gas.

  As described above by the gas recovery apparatus 1, the mixed exhaust gas is a gas mainly composed of an inert gas having a higher purity of the inert gas and a lower purity of the carbon dioxide gas (first separated gas), The carbon dioxide gas is separated and recovered into a gas (second separation gas) mainly composed of carbon dioxide gas having a higher purity of the carbon dioxide gas and a lower purity of the inert gas. After removing the steam gas, the first separated gas can be reused as an inert gas and the second separated gas can be reused as a carbon dioxide gas.

  The mixing unit 52 mixes carbon dioxide gas at a predetermined mixing ratio with a gas mainly composed of an inert gas obtained from the first separation gas, thereby generating a mixed gas of carbon dioxide gas and inert gas.

  The gas obtained from the first separation gas is a high-purity inert gas, and the remaining gas is substantially carbon dioxide gas. Therefore, by adjusting the mixing ratio of the mixing unit 52, it is possible to obtain a mixed gas of carbon dioxide gas and an inert gas with a desired concentration ratio.

  Furthermore, as the carbon dioxide gas mixed in the mixing unit 52, a gas containing carbon dioxide gas obtained from the second separated gas as the main component can be used. Since the gas obtained from the second separated gas is a carbon dioxide gas of high purity and the remaining gas is an inert gas, carbon dioxide of a desired concentration ratio can be adjusted by adjusting the mixing ratio of the mixing unit 52. A mixed gas of gas and inert gas can be obtained.

  The mixed gas of the inert gas and the carbon dioxide gas is adjusted by the mixing unit 52 to have a desired concentration ratio corresponding to each cleaning process of the semiconductor manufacturing devices 50a to 50c, and the cleaning gas is supplied to the semiconductor manufacturing devices 50a to 50c. Supplied as

Another Embodiment
Another embodiment will be described below.

<1> In the gas recovery devices 1 to 7 and the gas recovery method according to the above embodiment, it is assumed that the CO ₂ facilitated transport film is a flat film, but the present invention is not necessarily limited thereto. It may be a curved shape in which a gel layer containing a carrier is supported on the inner side surface or the outer side surface of the membrane, or a hollow fiber membrane. Similarly, the present invention does not depend on the arrangement of the processing chambers in each separation unit, but a configuration in which a plurality of cylindrical processing chambers having a common axial center are separated by a CO ₂ promoting transport film or a permeable film, A configuration can be considered in which the processing chambers are arranged in series in the extension direction of the axial center.

<2> In the above embodiment, the polyvinyl alcohol as the material of the CO ₂ facilitated transport membrane - but using a gel film constituted by polyacrylic acid salt copolymers, this is an example, CO ₂ selective separation ability It is possible to employ similar hydrophilic polymers that exert Further, the CO ₂ carrier is not limited to the materials mentioned in the embodiments, and other material membranes may be adopted as long as it has desired CO ₂ selective permeation performance.

  <3> In the gas recovery apparatus 1 shown in FIG. 1, water vapor gas is used as the sweep gas, but sweep gas flowing into the second processing chamber 12 of the first separation unit 13 is limited to water vapor gas Absent. For example, the sweep gas may be nitrogen gas or argon gas. However, since the gas is contained in the second separation gas, a step of separating the gas is required to reuse the second separation gas as carbon dioxide gas. Further, in the configuration in which at least a part of the second separated gas is circulated into the first processing chamber 11 as in the gas recovery apparatus 2 shown in FIG. 2, the sweep gas is included in the first separated gas. In order to reuse one separated gas as an inert gas, a step of separating the gas is required.

  In this respect, it is preferable that the sweep gas flowed into the second processing chamber 12 can be easily separated from the inert gas in the first separated gas and the carbon dioxide gas in the second separated gas, and the steam gas Is preferred. Steam gas may be mixed with a part of the second separation gas, and the mixed gas may be reused as a sweep gas.

  Similarly, in the gas recovery apparatus 3 shown in FIG. 3, the sweep gas flowing into the fourth processing chamber 22 may be another gas other than the steam gas, but it is easy from the carbon dioxide gas in the fourth separated gas Those that can be separated are preferred. Further, in the gas recovery apparatus 4 shown in FIG. 4, the sweep gas flowing into the second processing chamber 12 and the fourth processing chamber 22 is not only carbon dioxide gas in the fourth separation gas but also the first and third separation gases. Those that can be easily separated from the inert gas are preferred. Steam gas is preferred in this respect. As a sweep gas for supplying a mixed gas obtained by mixing at least a part of the second separation gas and water vapor gas to the second processing chamber 12, or a mixed gas obtained by mixing at least a part of the fourth separation gas and water vapor gas in the second process. It may be reused as a sweep gas supplied to the chamber 12 or the fourth processing chamber 22. Furthermore, the same applies to the gas recovery devices 5 to 7 shown in FIGS. 5 to 7, and it is preferable to use a steam gas as the sweep gas, and at least a part of the second, sixth, and seventh separation gases are mixed with the steam gas. The mixed gas may be reused as a sweep gas supplied to the second processing chamber 12 or the sixth processing chamber 62.

  <4> Further, in the above embodiment, the gas recovery apparatus and the gas recovery method according to the present invention are used to reuse the cleaning gas used in the semiconductor manufacturing, but they are separated according to the present invention Carbon dioxide gas and helium gas can be reused for other industrial applications depending on their purity.

<5> The gas recovery unit 6 shown in FIG. 6 and the gas recovery unit 7 shown in FIG. 7 are provided with a separation unit (fourth separation unit 43, fifth separation) including a separation membrane that selectively transmits inert gas. It is common in that both of the part 53) and the separation part (first separation part 13) provided with the separation membrane that selectively transmits the carbon dioxide gas are common, but the positions of both are different. Specifically, in the gas recovery device 6 shown in FIG. 6, the fourth separation unit 43 is provided on the downstream side of the first separation unit 13, but in the gas recovery device 7 shown in FIG. 7, the first separation is performed. A fifth separation unit 53 is provided on the upstream side of the unit 13. Here, in general, it is possible to reduce the film area by selectively removing the gas having a smaller concentration, or when using a CO ₂ -facilitated transport film, the amount of carbon dioxide gas on the supply side. In view of the fact that sufficient permeation performance can be exhibited even when the pressure is low (see FIG. 8), when the purity of the inert gas in the gas to be separated is larger, the gas recovery apparatus 6 shown in FIG. It is preferable to adopt (the first separation unit 13 is on the upstream side).

  <6> In the case of adopting a configuration in which the obtained gas is fed back in the gas recovery devices 1 to 7 shown in FIGS. 1 to 7 (for example, in the gas recovery device 2 shown in FIG. In the case of supplying to the chamber 11, or in the case of supplying the fourth separated gas to the first processing chamber 11 in the gas recovery apparatus 4 shown in FIG. 4, etc.), feedback is performed based on at least one of concentration and flow rate of gas to be fed back. The gas flow rate may be controlled. Thereby, it becomes possible to suppress the fluctuation of the concentration or flow rate of the gas in each part of the gas recovery devices 1 to 7. In this case, a sensor for measuring at least one of the concentration and flow rate of the gas to be fed back, and a controller for controlling the flow rate of the feedback gas are required.

  The present invention separates carbon dioxide and an inert gas separately from a mixed gas containing carbon dioxide and an inert gas as a main component, and obtains a gas recovery apparatus and gas that obtain carbon dioxide of high purity and inert gas of high purity. It can be used for recovery methods. Specifically, it can be used as a semiconductor cleaning system for reusing a cleaning gas used in semiconductor manufacturing.

1 to 7: Gas recovery apparatus 13: First separation unit 11: First treatment chamber 12: Second treatment chamber 14: First separation film 15 to 18: Gas flow passage 19: Water vapor addition unit 20a to 20 g: Water vapor separation unit 23: second separation unit 21: third processing chamber 22: fourth processing chamber 24: second separation film 25 to 27: gas flow path 50a to 50c: semiconductor manufacturing apparatus 52: mixing unit 63: third separation unit 61: 5th processing chamber 62: 6th processing chamber 64: 3rd separation membrane 65-67: Gas flow path 73: 4th separation part 71: 7th processing chamber 72: 8th processing chamber 74: 4th separation membrane 75-77 Gas flow path 83: fifth separation unit 81: ninth processing chamber 82: tenth processing chamber 84: fifth separation membrane 85 to 88: gas flow path 100: semiconductor cleaning system

Claims (20)

A gas recovery unit that separates and recovers the inert gas and the carbon dioxide gas separately from the first gas to be processed that contains the inert gas and carbon dioxide gas after being used as cleaning gas in the cleaning process of the semiconductor device Equipped with
The gas recovery unit includes a first separation unit that separates at least the inert gas from the first gas to be processed, and a water vapor addition unit that mixes a water vapor gas with the first gas to be processed .
The first separation unit includes:
A first processing chamber to which the first gas to be processed is supplied;
The second processing room,
Facilitated transport added with a carrier selectively reacting with carbon dioxide , which separates the first processing chamber and the second processing chamber and has a higher carbon dioxide permeability than the inert gas permeability. A first separation membrane that is a membrane ,
The first gas to be processed has a first separation gas in the first processing chamber in which the purity of the inert gas is higher than that of the first gas to be processed and the purity of the carbon dioxide gas is lower, and a first gas in the second processing chamber. Separated into two separated gases ,
A first water vapor separation unit that separates and removes water vapor from a first mixed gas containing the inert gas and the water vapor gas recovered by the gas recovery unit;
The inert gas after the water vapor is removed from the first mixed gas in the first water vapor separation unit, and a mixing unit that mixes carbon dioxide gas at a predetermined mixing ratio for use as a cleaning gas. It includes optionally gas recovery apparatus according to claim Rukoto.   It further comprises a second water vapor separation unit for separating and removing water vapor from a second mixed gas containing the carbon dioxide and the water vapor gas recovered by the gas recovery unit,
  The carbon dioxide gas supplied to the mixing unit includes at least a part of the carbon dioxide gas after the water vapor is removed from the second mixed gas in the second water vapor separation unit. The gas recovery device described in 1. Gas recovery apparatus according to claim 1 or 2, characterized in that it comprises a gas flow path for supplying a sweep gas into the second processing chamber. The gas recovery apparatus according to claim 3 , wherein the sweep gas contains a water vapor gas. The gas recovery unit further includes a second separation unit that separates at least the inert gas from the second separated gas,
The second separator is
A third processing chamber to which the second separation gas is supplied;
A fourth processing chamber;
Accelerated transport added with a carrier selectively reacting with carbon dioxide , which separates the third processing chamber and the fourth processing chamber and has a higher carbon dioxide permeability than the inert gas permeability. A second separation membrane that is a membrane ,
The second separation gas includes a third separation gas in the third processing chamber in which the purity of the inert gas is higher than that of the second separation gas and the purity of the carbon dioxide gas is lower, and a fourth separation in the fourth processing chamber. The gas recovery apparatus according to any one of claims 1 to 4 , which is separated into gas. At least a portion of the fourth separated gas is mixed with the first process gas and supplied to the first processing chamber, or at least a portion of the fourth separated gas is mixed with the second separated gas. The gas recovery apparatus according to claim 5 , wherein the gas is supplied to the third processing chamber. The gas recovery system according to any one of claims 1 to 6 , wherein at least a part of the second separated gas is mixed with the first gas to be treated and supplied to the first processing chamber. . The gas recovery unit further includes a third separation unit that separates at least the inert gas from the first separation gas,
The third separation unit includes
A fifth processing chamber to which the first separation gas is supplied;
A sixth processing chamber;
With separating said sixth processing chamber and the fifth processing chamber, said higher than the transmittance of the transmittance the inert gas carbon dioxide, facilitated transport carrier of selectively reacting with carbon dioxide is added A third separation membrane that is a membrane ,
The first separation gas includes a fifth separation gas in the fifth processing chamber in which the purity of the inert gas is higher than that in the first separation gas and the purity of the carbon dioxide gas is lower, and a sixth separation in the sixth processing chamber. The gas recovery apparatus according to any one of claims 1 to 7 , which is separated into gas. The gas recovery device according to any one of claims 1 to 8 , wherein the inert gas is helium gas. The inert gas is helium gas,
The gas recovery unit further includes a fourth separation unit that separates at least the carbon dioxide gas from the second separated gas,
The fourth separator is
A seventh processing chamber to which the second separation gas is supplied;
An eighth processing chamber;
And a fourth separation membrane separating the seventh processing chamber from the eighth processing chamber and having a permeability of the helium gas higher than that of the carbon dioxide gas.
The second separation gas is a seventh separation gas in the seventh processing chamber in which the purity of the carbon dioxide gas is higher than that of the second separation gas and the purity of the helium gas is lower, and an eighth separation gas in the eighth processing chamber. The gas recovery apparatus according to any one of claims 1 to 9 , wherein the gas recovery apparatus is separated. The inert gas is helium gas;
The gas recovery unit further includes a fifth separation unit that separates at least the carbon dioxide gas from the second treated gas containing the helium gas and the carbon dioxide gas after being used as the cleaning gas;
The fifth separator is
A ninth processing chamber to which the second processing gas is supplied;
The tenth processing room,
And a fifth separation membrane separating the ninth processing chamber from the tenth processing chamber and having a permeability of the helium gas higher than that of the carbon dioxide gas.
A ninth separated gas in the ninth processing chamber and a tenth separated gas in the ninth processing chamber, wherein the second gas to be treated has a purity of the carbon dioxide gas higher than that of the second gas to be treated and a purity of the helium gas is lower than that of the tenth treatment chamber. Separated into separation gas,
Gas recovery apparatus according to any one of claims 1 to 1 0, characterized in that said tenth separation gas is supplied to the first processing chamber as said first gas to be treated.   The mixing unit according to any one of claims 1 to 11, wherein the mixing unit mixes the inert gas and the carbon dioxide gas at a plurality of different predetermined mixing ratios for use as a cleaning gas. Gas recovery equipment. A gas recovery step of separating and recovering the inert gas and the carbon dioxide gas separately from the first gas to be treated containing the inert gas and the carbon dioxide gas after being used as the cleaning gas in the semiconductor device cleaning step. Equipped with
The gas recovery step includes a first step of separating at least an inert gas from the first process gas,
In the first step, water vapor gas is mixed with the first gas to be treated , and the first gas to be treated is selected as carbon dioxide having a permeability of the carbon dioxide gas higher than that of the inert gas. The first separation membrane, which is a facilitated transport membrane to which a reactive carrier is added , permeates the first separation gas so that the purity of the inert gas is higher than that of the first gas to be processed and the purity of the carbon dioxide gas is lower. Separating the separation membrane into a first separation gas which has not been permeated and a second separation gas which contains the gas which has permeated the first separation membrane ,
A first water vapor separation step of separating and removing water vapor from a first mixed gas containing the inert gas and the water vapor gas recovered in the gas recovery step;
A mixing step of mixing the inert gas after removing water vapor from the first mixed gas in the first water vapor separation step and carbon dioxide gas at a predetermined mixing ratio for use as a cleaning gas; gas recovery method according to features characterized Rukoto.   The method further comprises a second water vapor separation step of separating and removing water vapor from a second mixed gas containing the carbon dioxide and the water vapor gas recovered in the gas recovery step;
  The carbon dioxide gas used in the mixing step includes at least a part of the carbon dioxide gas after removing the water vapor from the second mixed gas in the second water vapor separation step. The gas recovery method according to claim 13. The gas recovery step is a facilitated transport film to which a carrier selectively reacting with carbon dioxide is added , wherein the second separated gas has a permeability of the carbon dioxide gas higher than that of the inert gas. A second separation membrane which is impermeable to the second separation membrane by passing through the second separation membrane, the purity of the inert gas being higher than that of the second separation gas, and the purity of the carbon dioxide gas being lower, and the second separation membrane The gas recovery method according to claim 13 or 14 , further comprising a second step of separating into a fourth separated gas containing the gas that has permeated the separation membrane. In the first step, at least part of the fourth separation gas is mixed with the first gas to be processed that is allowed to pass through the first separation membrane, or is allowed to pass through the second separation membrane in the second step. gas recovery method of claim 1 5, characterized by mixing at least a portion of said fourth separation gas to the second separation gas. In the first step, in any one of claims 13 to 1 6, which comprises mixing at least a portion of the second separation gas to the first gas to be treated is transmitted into the first separation membrane The gas recovery method as described. The gas recovery method according to any one of claims 13 to 17 , wherein the inert gas is helium gas.   19. The mixing step according to any one of claims 13 to 18, wherein the inert gas and the carbon dioxide gas are mixed at a plurality of different predetermined mixing ratios for use as a cleaning gas. Gas recovery method. Bei give a gas recovery apparatus according to any one of 請 Motomeko 1-12,
Semiconductor cleaning system the mixed gas in the mixing section, as the cleaning gas, characterized in that it is supplied to the apparatus for performing the cleaning process of the semiconductor device.

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