An apparatus system and method for recovering helium from semiconductor process tail gas

Abstract

The present invention belongs to the technical field of tail gas treatment, and relates to a device system and method for recovering helium from semiconductor process tail gas. By adopting a composite device system of an adsorption device, a membrane separation module, and a gas purification tower, it can complete the recovery and purification operations of low-concentration helium under the conditions of containing toxins, corrosion, and a mixture of multiple rare gases. The recovered helium can be purified to more than 99.999%. It has a high recovery rate, high purity, makes full use of heat exchange of the front and rear gases, has low energy consumption, and further broadens the helium supply source. The device system has no gas venting throughout the process, and all are refluxed, collected, and discharged back into the tail gas pipeline, and is applicable to various semiconductor processes.

Description

Technical Field

[0001] The present invention belongs to the technical field of tail gas treatment, and particularly relates to a device system and method for recovering helium from the tail gas of semiconductor manufacturing processes. Background Art

[0002] Helium is a monatomic noble gas with excellent properties such as stable chemical properties, radioactivity inertness, good thermal conductivity, good permeability, and high potential. It is widely used in national defense, aerospace, high-end manufacturing, medical treatment, scientific research and other fields.

[0003] Helium extraction mainly comes from natural gas in addition to air separation. The helium content in natural gas in China is 0.01 - 0.10%. Therefore, it is urgent to develop new helium extraction and recovery methods. At present, the consumption of high-purity helium in the semiconductor industry accounts for a relatively high proportion, and the helium-containing tail gas concentration in semiconductor manufacturing processes is only 1 - 2%. Factories directly burn it and discharge it into the atmosphere without recycling. Developing a helium recovery device for semiconductor manufacturing process tail gas can effectively relieve the demand pressure of helium in the industry and improve the supply safety of helium.

[0004] CN111573643A discloses a helium recovery and purification device and method. The helium recovery and purification device includes a recovery gas tank, a recovery compression pump, a gas membrane separator, a gas purification tower, and a vacuum pump. This invention controls the flow through a mass flowmeter, and after purification by the gas membrane separator, it enters two groups of parallel gas purification towers for pressure swing adsorption to purify helium, and is suitable for the recovery and purification of low-concentration helium, hydrogen, and neon. This invention adopts a composite method of membrane and pressure swing adsorption, but this invention cannot cope with the working conditions of toxic and corrosive gases in semiconductor manufacturing processes, and cannot purify the helium-containing tail gas mixed with multiple rare gases to a higher concentration. In addition, there is also the problem of large occupied area caused by the use of multiple towers in series.

[0005] CN206156757U discloses a helium recovery and purification device, including a flowmeter, a primary filter, a vacuum pump, a compressor, a precision filter, a first buffer tank, an adsorption system, a second buffer tank, and a cryogenic tower connected in sequence; the adsorption system includes at least 2 groups of adsorption columns connected in series, and at least three groups of heat exchangers connected in series are arranged in the cryogenic tower, so that the purity of the purified helium is greater than or equal to 99.999%. This prior art only removes moisture and carbon dioxide, and cannot be applied to the tail gas helium recovery in the complex working conditions of semiconductor manufacturing processes and the recovery and purification of low-concentration helium, with high energy consumption.

[0006] Therefore, developing a device suitable for recovering low-concentration helium from semiconductor manufacturing process tail gas, which can improve the purity of helium, reduce energy consumption, and broaden the source channels of helium, has high practical significance and economic value. Summary of the Invention

[0007] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a device system and method for recovering helium from semiconductor process tail gas, which can complete the recovery and purification operations of low-concentration helium in the working conditions of poisonous, corrosive gases, and mixed rare gases, with high recovery efficiency and low energy consumption.

[0008] To achieve the purpose of this invention, the following technical solutions are adopted:

[0009] In the first aspect, the present invention provides a device system for recovering helium from semiconductor process tail gas. The device system includes a main tail gas pipeline, and a first compressor, a first-stage parallel adsorption column, a second-stage series adsorption column, a membrane separation module, a gas purification tower, a second compressor, and a helium storage device are sequentially connected along the tail gas flow direction on the branch of the main tail gas pipeline; the exhaust gases discharged from the first-stage parallel adsorption column and the gas purification tower independently flow into the main tail gas pipeline after the branch; the membrane separation module includes at least 2 groups of series-connected separation membrane groups, wherein, the first group of separation membrane groups includes at least 2 parallel separation membrane modules, and starting from the second group of separation membrane groups, the permeate-side gas of the separation membrane group is refluxed to the main tail gas pipeline before the branch; the retentate-side gas of the separation membrane group flows into the main tail gas pipeline after the branch.

[0010] The device system for recovering helium from semiconductor process tail gas provided by the present invention adopts a composite device system of an adsorption device, a membrane separation module, and a gas purification tower, which can complete the recovery and purification operations of low-concentration helium in the working conditions of poisonous, corrosive gases, and mixed rare gases, and there is no gas evacuation throughout the process, and all are refluxed, collected, and discharged back to the tail gas pipeline, which is applicable to various semiconductor processes, with high recovery efficiency and low energy consumption.

[0011] The first-stage parallel adsorption column can remove poisonous gases such as halogen-containing gases, phosphine, arsine, etc. in the semiconductor process tail gas, and can also remove corrosive gases such as hydrogen fluoride, hydrogen chloride, sulfur dioxide, etc. The second-stage series adsorption column can remove impurities such as nitrogen oxides, carbon dioxide, moisture, etc. in the semiconductor process tail gas.

[0012] The series-connected separation membrane groups are at least 2 groups, for example, they can be 2 groups, 3 groups, or 4 groups, but are not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0013] The first group of separation membrane groups includes at least 2 parallel separation membrane modules, for example, they can be 2, 3, or 4, but are not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0014] By adopting series-connected separation membrane groups, the recovered low-concentration helium can be concentrated to more than 60%.

[0015] Preferably, a gas check valve is provided on the main tail gas pipeline after the branch.

[0016] Preferably, the membrane separation module includes a first separation membrane group and a second separation membrane group connected in series. The gas on the permeate side of the first separation membrane group flows through a first buffer device and then enters the gas purification tower. The gas on the permeate side of the second separation membrane group flows through a second buffer device and then returns to the main tail gas pipeline before the branch.

[0017] A needle valve is provided on the pipeline between the permeate side of the second separation membrane group and the second buffer device.

[0018] Setting the second buffer device and the needle valve on the pipeline can ensure that while purifying helium, the recovery rate of helium is further improved.

[0019] Preferably, a helium concentration detection three-way valve controlled by a PLC, an electric heater, and a pneumatic valve are sequentially provided on the pipeline between the second-stage series adsorption column and the first separation membrane group. The helium concentration detection three-way valve is connected to the main tail gas pipeline after the branch.

[0020] Aiming at the problem of the fluctuation of the helium concentration in the tail gas of the semiconductor process, the present invention has set a helium concentration detection three-way valve controlled by a PLC before entering the separation membrane group, which can directly discharge the raw material gas with a lower helium concentration back to the main tail gas pipeline, further improving the recovered helium concentration.

[0021] The present invention has set an electric heater before entering the separation membrane group, which can maintain the temperature of the raw material gas within a reasonable range, stabilize the working condition, and make the subsequent helium membrane separation and concentration reach the best effect.

[0022] The present invention has set a pneumatic valve before entering the separation membrane group. A needle valve is installed on the instrument air pipeline of the valve. The air intake is slow at a small opening, which can prevent the gas pressure at the inlet end of the separation membrane group from being too large, causing impact and damage to the membrane.

[0023] Preferably, the gas discharged from the first buffer device flows through a first heat exchanger, exchanges heat with the helium gas from the gas purification tower, and then enters the gas purification tower; the waste gas discharged from the gas purification tower flows through a second heat exchanger, exchanges heat with the gas from the first compressor, and then enters the main tail gas pipeline after the branch; the retentate side gas of the second separation membrane group flows through a third heat exchanger, exchanges heat with the gas from the second-stage series adsorption column, and then enters the main tail gas pipeline after the branch.

[0024] In the present invention, the gas at the outlet of the first compressor is heat-exchanged with the gas at the lower outlet of the gas purification tower to cool down, enhancing the low-temperature adsorption capacity of the first parallel adsorption column for impurity gases; the gas at the outlet of the second series adsorption column is heat-exchanged with the retentate-side gas of the second separation membrane module to increase the gas temperature, reducing the energy consumption of the electric heater; the gas at the outlet of the first buffer device is heat-exchanged with the gas at the upper part of the gas purification tower to cool down, reducing the consumption of the cold source.

[0025] Preferably, the gas purification tower includes a cryogenic tower with 10 - 15 trays per meter and a draw rate θ of 0.6 - 0.8; the cryogenic tower is connected to a condenser.

[0026] The cryogenic tower has 10 - 15 trays per meter, which can be, for example, 10 trays per meter, 11 trays per meter, 12 trays per meter, 13 trays per meter, 14 trays per meter, or 15 trays per meter, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0027] The draw rate θ of the cryogenic tower is 0.6 - 0.8, which can be, for example, 0.6, 0.7, or 0.8, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0028] The draw rate θ of the cryogenic tower refers to the quantity of the substance extracted from the cryogenic tower within a specific time.

[0029] The first compressor and the second compressor each independently include an oil-free piston compressor, and the inlet pressure of the oil-free piston compressor ≥ 200 mbarg and the outlet pressure ≤ 10 barg.

[0030] The inlet pressure of the oil-free piston compressor ≥ 200 mbarg, which can be, for example, 200 mbarg, 220 mbarg, 250 mbarg, 280 mbarg, or 300 mbarg, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0031] The outlet pressure of the oil-free piston compressor ≤ 10 barg, which can be, for example, 10 barg, 8 barg, 5 barg, 3 barg, or 1 barg, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0032] Preferably, the helium storage device includes a helium storage tank.

[0033] Preferably, the first buffer device includes a first buffer tank.

[0034] Preferably, the second buffer device includes a second buffer tank.

[0035] Preferably, the material of the pipeline used in the device system includes 316 stainless steel.

[0036] In a second aspect, the present invention provides a method for recovering helium from semiconductor process tail gas. The method is carried out by the device system for recovering helium from semiconductor process tail gas described in the first aspect, and the method includes the following steps:

[0037] (1) The semiconductor process tail gas in the main tail gas pipeline enters the branch, and successively undergoes a first compression treatment and a first adsorption and impurity removal to obtain a first adsorbed and impurity-removed gas and a first waste gas; the obtained first waste gas flows into the main tail gas pipeline after the branch for post-treatment;

[0038] (2) The first adsorbed and impurity-removed gas obtained in step (1) undergoes a second adsorption and impurity removal, and the obtained second adsorbed and impurity-removed gas undergoes a first membrane separation treatment to obtain a permeate-side gas and a retentate-side gas; the obtained permeate-side gas is subjected to gas purification to obtain helium and a second waste gas; the obtained second waste gas flows into the main tail gas pipeline after the branch for post-treatment, and the obtained helium is stored after a second compression treatment;

[0039] (3) The retentate-side gas obtained in step (2) undergoes a second membrane separation treatment, the obtained permeate-side gas is recycled and mixed with the semiconductor process tail gas in the main tail gas pipeline, and the obtained retentate-side gas flows into the main tail gas pipeline after the branch for post-treatment.

[0040] The method for recovering helium from semiconductor process tail gas provided by the present invention adopts a composite method of adsorption, membrane separation and gas purification, and can complete the low-concentration helium recovery and purification operations for the complex working conditions of semiconductor process containing toxic, corrosive and rare gases. The recovered helium can be purified to more than 99.999%, with high recovery rate, high purity, and full utilization of heat exchange between front and back gases, and low energy consumption, further broadening the helium supply source.

[0041] Preferably, before the gas purification of the permeate-side gas in step (2), it further includes a step of performing a first heat exchange with the helium obtained by gas purification.

[0042] The cold source used for gas purification in step (2) includes any one of dry ice, liquid nitrogen, R403 or R507.

[0043] For helium mixed with different rare gases, different cold sources such as dry ice, liquid nitrogen, R403, R507, etc. can be used.

[0044] Preferably, before the first adsorption and impurity removal after the first compression treatment in step (1), it further includes a step of performing a second heat exchange with the second waste gas obtained by gas purification.

[0045] The impurity remover used in the first adsorption and impurity removal in step (1) includes any one or a combination of at least two of an alkaline adsorbent, silica gel, activated alumina or molecular sieve. Typical but non-limiting combinations include the combination of an alkaline adsorbent and silica gel, the combination of silica gel, activated alumina and molecular sieve, or the combination of an alkaline adsorbent, silica gel, activated alumina and molecular sieve.

[0046] Preferably, the impurity remover used in the second adsorption and impurity removal in step (2) includes activated carbon and activated alumina with a mass ratio of (1-5):1. For example, it can be 1:1, 2:1, 3:1, 4:1 or 5:1, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0047] Before the first membrane separation treatment of the second adsorption and impurity removal gas in step (2), it also includes the steps of sequentially performing the third heat exchange with the retentate gas obtained from the second membrane separation treatment, helium concentration detection, and heating.

[0048] In the helium concentration detection, when the helium concentration of the second adsorption and impurity removal gas after the third heat exchange is lower than the target required concentration, the tail gas main pipeline after flowing into the branch is post-treated.

[0049] The temperature of the heating is 40-50 °C. For example, it can be 40 °C, 42 °C, 45 °C, 48 °C or 50 °C, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0050] The types of membranes used in the first membrane separation treatment and the second membrane separation treatment in step (2) include any one of polyimide, polysulfone, polydimethylsiloxane, cellulose acetate or metal-organic framework.

[0051] The applicable pressure of the membranes used in the first membrane separation treatment and the second membrane separation treatment is 5-15 barg. For example, it can be 5 barg, 8 barg, 10 barg, 12 barg or 15 barg, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] The device system for recovering helium from semiconductor process tail gas provided by the present invention adopts a composite device system of an adsorption device, a membrane separation module and a gas purification tower, which can complete the recovery and purification operations of low-concentration helium in the working conditions of containing toxins, corrosion and a mixture of various rare gases. The recovered helium can be purified to more than 99.999%. It has a high recovery rate, high purity and makes full use of the heat exchange of the front and rear gases, with low energy consumption, further broadening the helium supply source; the device system has no gas evacuation throughout the process, and all are refluxed, collected and discharged back into the tail gas pipeline, and is applicable to various semiconductor processes. Brief Description of the Drawings

[0054] Figure 1 It is a schematic structural diagram of the device system for recovering helium from the tail gas of the semiconductor manufacturing process provided in Embodiment 1 of the present invention.

[0055] Wherein: 1, main tail gas pipeline; 2, first oil-free piston compressor; 3, first-stage parallel adsorption column; 4, second-stage series adsorption column; 5, cryogenic tower; 6, second oil-free piston compressor; 7, helium storage tank; 8, condenser; 9, first separation membrane module; 10, second separation membrane module; 11, first buffer tank; 12, needle valve; 13, second buffer tank; 14, gas check valve; 15, helium concentration detection three-way valve; 16, electric heater; 17, pneumatic valve; 18, first heat exchanger; 19, second heat exchanger; 20, third heat exchanger. Detailed Embodiments

[0056] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0057] Embodiment 1

[0058] This embodiment provides a device system for recovering helium from the tail gas of the semiconductor manufacturing process, as Figure 1 shown. The material of the pipeline used in the device system is 316 stainless steel. The device system includes a main tail gas pipeline 1. Along the tail gas flow direction on the branch of the main tail gas pipeline 1, a first oil-free piston compressor 2, a first-stage parallel adsorption column 3, a second-stage series adsorption column 4, a membrane separation module, a cryogenic tower 5, a second oil-free piston compressor 6, and a helium storage tank 7 are sequentially connected; the waste gases discharged from the first-stage parallel adsorption column 3 and the cryogenic tower 5 independently flow into the main tail gas pipeline 1 after the branch; the number of trays of the cryogenic tower 5 is 13 pieces / meter, and the take-off quantity θ is 0.7. The cryogenic tower 5 is connected to a condenser 8; the inlet pressures of the first oil-free piston compressor 2 and the second oil-free piston compressor 6 are both 200 mbarg, and the outlet pressures are both 10 barg.

[0059] The membrane separation module includes a first separation membrane module 9 and a second separation membrane module 10 connected in series. The first separation membrane module 9 includes 2 parallel separation membrane modules. The gas on the permeate side of the first separation membrane module 9 flows into the cryogenic tower 5 after passing through the first buffer tank 11. The gas on the permeate side of the second separation membrane module 10 flows through a needle valve 12 and a second buffer tank 13 in sequence and then returns to the main tail gas pipeline 1 before the branch. The gas on the retentate side of the second separation membrane module 10 flows into the main tail gas pipeline 1 after the branch; a gas check valve 14 is provided on the main tail gas pipeline 1 after the branch.

[0060] On the pipeline between the secondary series adsorption column 4 and the first separation membrane module 9, a PLC-controlled helium concentration detection three-way valve 15, an electric heater 16, and a pneumatic valve 17 are sequentially arranged. The helium concentration detection three-way valve 15 is connected to the main tail gas pipeline 1 after the branch.

[0061] The gas discharged from the first buffer tank 11 flows through the first heat exchanger 18, exchanges heat with the helium gas from the cryogenic tower 5, and then enters the cryogenic tower 5; the waste gas discharged from the cryogenic tower 5 flows through the second heat exchanger 19, exchanges heat with the gas from the first oil-free piston compressor 2, and then enters the main tail gas pipeline 1 after the branch; the retentate-side gas of the second separation membrane module 10 flows through the third heat exchanger 20, exchanges heat with the gas from the secondary series adsorption column 4, and then enters the main tail gas pipeline 1 after the branch. Figure 1 In A→B, C→D, and E→F, all represent the material flow directions.

[0062] The method for recovering helium from the semiconductor process tail gas using the said device system includes the following steps:

[0063] (1) The semiconductor process tail gas in the main tail gas pipeline enters the branch, and successively undergoes the first compression treatment and the first adsorption and impurity removal by silica gel, to obtain the first adsorption and impurity removal gas and the first waste gas; the obtained first waste gas flows into the main tail gas pipeline after the branch for post-treatment;

[0064] (2) The first adsorption and impurity removal gas obtained in step (1) undergoes the second adsorption and impurity removal, and the used impurity remover is activated carbon and activated alumina with a mass ratio of 2:1. The obtained second adsorption and impurity removal gas undergoes the first membrane separation treatment to obtain the permeate-side gas and the retentate-side gas; the obtained permeate-side gas is purified, and the used cold source is liquid nitrogen, to obtain helium gas and the second waste gas; the obtained second waste gas flows into the main tail gas pipeline after the branch for post-treatment, and the obtained helium gas undergoes the second compression treatment and then is stored;

[0065] (3) The retentate-side gas obtained in step (2) undergoes the second membrane separation treatment. The obtained permeate-side gas is recycled and mixed with the semiconductor process tail gas in the main tail gas pipeline, and the obtained retentate-side gas flows into the main tail gas pipeline after the branch for post-treatment.

[0066] Before the gas purification of the permeate side gas described in step (2), there is also a step of performing the first heat exchange with the helium gas obtained from the gas purification; before the first adsorption impurity removal after the first compression treatment described in step (1), there is also a step of performing the second heat exchange with the second waste gas obtained from the gas purification; before the first membrane separation treatment of the second adsorption impurity removal gas described in step (2), there are also steps of performing the third heat exchange with the retentate side gas obtained from the second membrane separation treatment, helium concentration detection, and heating at 45°C in sequence; in the helium concentration detection, when the helium concentration of the second adsorption impurity removal gas after the third heat exchange is lower than the target required concentration, the tail gas main pipeline after flowing into the branch is post-treated.

[0067] The types of membranes used in the first membrane separation treatment and the second membrane separation treatment described in step (2) are polyimide, and the inlet pressure of the first membrane separation treatment is adjusted to 8 barg.

[0068] The helium gas volume purity of the permeate side of the first separation membrane group can reach 68% when tested by a portable gas chromatograph analyzer. The helium recovery rate is calculated to be 93%. Among them, R A is the helium recovery rate, %; F is the molar flow rate, mol·S -1 ; A is the helium gas volume fraction, %; the subscript i represents the raw gas composition; the subscript r represents the product gas composition. The helium gas volume purity is tested to be ≥99.999% at the upper end outlet of the cryogenic tower, and the recovery rate can reach 85%. This shows that using the device system provided in this embodiment to recover helium from the semiconductor process tail gas can obtain helium with high purity and recovery rate, and there is no gas venting throughout the process, and all are refluxed, collected, and discharged back to the tail gas main pipeline.

[0069] Example 2

[0070] The device system provided in this embodiment for recovering helium from the semiconductor process tail gas is different from that in Example 1 in that a pneumatic valve is not provided on the pipeline between the secondary series adsorption column 4 and the first separation membrane group 9, and the rest are the same as in Example 1.

[0071] When tested by a portable gas chromatograph analyzer, the helium gas volume purity of the permeate side of the first separation membrane group reaches 60%, and the helium recovery rate can reach 85%. Since a pneumatic valve is not provided on the pipeline between the secondary series adsorption column and the first separation membrane group, the gas pressure at the inlet end of the separation membrane group is too high, which impacts the membrane. Prolonged time will cause damage, resulting in a decline in the membrane separation effect, a reduction in helium purity, and a decrease in the recovery rate.

[0072] Example 3

[0073] This embodiment provides a device system for recovering helium from semiconductor process tail gas. The difference from Embodiment 1 is that a helium concentration detection three-way valve 15 controlled by a PLC is not provided on the pipeline between the secondary series adsorption column 4 and the first separation membrane module 9, and the helium concentration detection step in step (3) is adaptively removed, and the rest is the same as in Embodiment 1.

[0074] Using a portable gas chromatograph analyzer, it is tested that the volume purity of helium on the permeate side of the first separation membrane module reaches 30%, and the recovery rate of helium can reach 94%. Since a helium concentration detection three-way valve is not provided on the pipeline between the secondary series adsorption column and the first separation membrane module, the raw gas with a lower helium concentration cannot be directly discharged back to the main tail gas pipeline, thereby reducing the helium concentration.

[0075] Embodiment 4

[0076] This embodiment provides a device system for recovering helium from semiconductor process tail gas. The difference from Embodiment 1 is that an electric heater 16 is not provided on the pipeline between the secondary series adsorption column 4 and the first separation membrane module 9, and the heating step in step (3) is adaptively removed, and the rest is the same as in Embodiment 1.

[0077] Using a portable gas chromatograph analyzer, it is tested that the volume purity of helium on the permeate side of the first separation membrane module reaches 50%, and the recovery rate of helium can reach 92%. Since an electric heater is not provided on the pipeline between the secondary series adsorption column and the first separation membrane module, the gas temperature is too low and fluctuates, resulting in a decrease in the subsequent helium membrane separation and enrichment efficiency.

[0078] Embodiment 5

[0079] This embodiment provides a device system for recovering helium from semiconductor process tail gas. The difference from Embodiment 1 is that except that the number of trays of the cryogenic tower 5 is adjusted to 5 trays / meter, the rest is the same as in Embodiment 1.

[0080] Using a portable gas chromatograph analyzer, it is tested that the volume purity of helium at the top outlet of the cryogenic tower can reach 86%, and the recovery rate of helium can reach 85%. Since the number of trays of the gas purification cryogenic tower is insufficient, the gas separation efficiency is reduced, resulting in a decrease in the helium purity finally.

[0081] Embodiment 6

[0082] This embodiment provides a device system for recovering helium from semiconductor process tail gas. The difference from Embodiment 1 is that except that the feed rate θ of the cryogenic tower 5 is adjusted to 0.95, the rest is the same as in Embodiment 1.

[0083] Using a portable gas chromatograph analyzer, the volume purity of helium at the top outlet of the cryogenic tower can reach 90%, and the recovery rate can reach 90%. Due to the excessive amount of gas taken for purification, the purity of helium decreases while the recovery rate increases.

[0084] Example 7

[0085] This example provides a device system for recovering helium from semiconductor process exhaust gas. The method for recovering helium from semiconductor process exhaust gas using the device system is different from that of Example 1 in that, except that the inlet pressure of the first membrane separation treatment in step (2) is adjusted to 1 barg, the rest are the same as those in Example 1.

[0086] Using a portable gas chromatograph analyzer, the volume purity of helium on the permeate side of the first separation membrane module reaches 20%, and the recovery rate of helium can reach 95%. Due to the too low inlet pressure of the first separation membrane module, helium cannot diffuse and permeate for purification, resulting in a decrease in the purity of helium.

[0087] Comparative Example 1

[0088] This comparative example provides a device system for recovering helium from semiconductor process exhaust gas. The difference from Example 1 is that the cryogenic tower 5 is not set, and the gas purification step in step (2) is adaptively removed. The obtained permeate side gas is directly stored after the second compression treatment, and the rest are the same as those in Example 1.

[0089] Using a portable gas chromatograph analyzer, the volume purity of helium on the permeate side of the first separation membrane module reaches 68%, and the recovery rate of helium can reach 93%. Due to the absence of the cryogenic tower, the purity of helium decreases significantly.

[0090] Comparative Example 2

[0091] This comparative example provides a device system for recovering helium from semiconductor process exhaust gas. The difference from Example 1 is that the membrane separation module only includes the first separation membrane module 9, and the retentate side gas of the first separation membrane module 9 directly flows into the main exhaust gas pipeline 1 after the branch. The second membrane separation treatment step in step (3) is adaptively removed, and the rest are the same as those in Example 1.

[0092] Using a portable gas chromatograph analyzer, the volume purity of helium on the permeate side of the first separation membrane module reaches 58%, and the recovery rate of helium can reach 60%. Due to the fact that the membrane separation module only includes one separation membrane module, the purity of helium decreases, and the recovery rate of helium decreases significantly.

[0093] Comparative Example 3

[0094] This comparative example provides a device system for recovering helium from semiconductor process tail gas. The difference from Example 1 is that except for adjusting the 2 parallel separation membrane modules of the first separation membrane group 9 to a single separation membrane module, the rest are the same as in Example 1.

[0095] Using a portable gas chromatograph analyzer, the volume purity of helium on the permeate side of the first separation membrane group was tested to reach 35%, and the recovery rate of helium could reach 92%. Since the number of separation membrane modules in the first separation membrane group decreased, the gas purification treatment volume and efficiency decreased, and the concentration enhancement effect of membrane separation decreased.

[0096] In summary, the device system for recovering helium from semiconductor process tail gas provided by the present invention adopts a composite device system of an adsorption device, a membrane separation component, and a gas purification tower, which can complete the recovery and purification operations of low-concentration helium under the conditions of containing toxins, corrosion, and a mixture of various rare gases. The recovered helium can be purified to more than 99.999%. It has a high recovery rate, high purity, and makes full use of heat exchange between the front and rear gases, with low energy consumption, further broadening the helium supply source; the device system has no gas evacuation throughout the process, and all are refluxed, collected, and discharged back into the tail gas pipeline, and is applicable to various semiconductor processes.

[0097] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A method for recovering helium from the tail gas of a semiconductor manufacturing process, characterized in that, The described method for recovering helium from semiconductor process tail gas is carried out by using a device system for recovering helium from semiconductor processes; The device system includes a main tail gas pipeline, and a first compressor, a first parallel adsorption column, a second series adsorption column, a membrane separation module, a gas purification tower, a second compressor, and a helium storage device are sequentially connected along the tail gas flow direction on the branch of the main tail gas pipeline; The waste gases discharged from the first parallel adsorption column and the gas purification tower independently flow into the main tail gas pipeline after the branch; The membrane separation module includes a first separation membrane group and a second separation membrane group connected in series in sequence; A helium concentration detection three-way valve controlled by a PLC, an electric heater, and a pneumatic valve are sequentially arranged on the pipeline between the second series adsorption column and the first separation membrane group, and the helium concentration detection three-way valve is communicated with the main tail gas pipeline after the branch; The permeate side gas of the first separation membrane group enters the gas purification tower after flowing through the first buffer device, and the permeate side gas of the second separation membrane group flows back to the main tail gas pipeline before the branch after flowing through the second buffer device; The gas purification tower includes a cryogenic tower; The described method for recovering helium from semiconductor process tail gas includes the following steps: (1) The semiconductor process tail gas in the main tail gas pipeline enters the branch, and undergoes first compression treatment and first adsorption for impurity removal in sequence to obtain a first adsorption impurity removal gas and a first waste gas; The obtained first waste gas flows into the main tail gas pipeline after the branch for post-treatment; (2) The first adsorption impurity removal gas obtained in step (1) is subjected to second adsorption for impurity removal, and the obtained second adsorption impurity removal gas undergoes first membrane separation treatment to obtain a permeate side gas and a retentate side gas; The obtained permeate side gas is subjected to gas purification to obtain helium and a second waste gas; The obtained second waste gas flows into the main tail gas pipeline after the branch for post-treatment, and the obtained helium is stored after second compression treatment; (3) The retentate side gas obtained in step (2) is subjected to second membrane separation treatment, the obtained permeate side gas flows back and mixes with the semiconductor process tail gas in the main tail gas pipeline, and the obtained retentate side gas flows into the main tail gas pipeline after the branch for post-treatment; Before the first membrane separation treatment of the second adsorption impurity removal gas described in step (2), steps of third heat exchange, helium concentration detection, and heating are also included in sequence with the retentate side gas obtained in the second membrane separation treatment; In the helium concentration detection, when the helium concentration of the second adsorption impurity removal gas after the third heat exchange is lower than the target required concentration, it flows into the main tail gas pipeline after the branch for post-treatment.

2. The method for recovering helium from the tail gas of a semiconductor manufacturing process according to claim 1, wherein A gas check valve is provided on the main tail gas pipeline after the branch.

3. The method for recovering helium from the tail gas of a semiconductor manufacturing process according to claim 1, wherein, A needle valve is provided on the pipeline between the permeate side of the second separation membrane group and the second buffer device.

4. The method for recovering helium from semiconductor process exhaust gas according to claim 3, characterized in that, The gas discharged from the first buffer device flows through a first heat exchanger, exchanges heat with the helium from the gas purification tower, and then enters the gas purification tower; The waste gas discharged from the gas purification tower flows through a second heat exchanger, exchanges heat with the gas from the first compressor, and then enters the main tail gas pipeline after the branch; The retentate side gas of the second separation membrane group flows through a third heat exchanger, exchanges heat with the gas from the second series adsorption column, and then enters the main tail gas pipeline after the branch.

5. The method for recovering helium from the tail gas of a semiconductor manufacturing process according to claim 1, wherein, The number of trays in the cryogenic column is 10 - 15 trays / m, and the withdrawal rate θ is 0.6 - 0.8; the cryogenic column is connected to a condenser; The first compressor and the second compressor each independently include an oil-free piston compressor, and the inlet pressure of the oil-free piston compressor is ≥ 200 mbarg and the outlet pressure is ≤ 10 barg.

6. The method for recovering helium from the tail gas of a semiconductor manufacturing process according to claim 1, wherein Before the permeate-side gas undergoes gas purification in step (2), it further includes a step of performing a first heat exchange with the helium gas obtained from the gas purification. The cold source used for the gas purification in step (2) includes any one of dry ice, liquid nitrogen, R403, or R507.

7. The method for recovering helium from the tail gas of a semiconductor manufacturing process according to claim 1, characterized in that, Before the first adsorption for impurity removal after the first compression treatment in step (1), it further includes a step of performing a second heat exchange with the second waste gas obtained from the gas purification. The impurity removal agent used for the first adsorption for impurity removal in step (1) includes any one or a combination of at least two of an alkaline adsorbent, silica gel, activated alumina, or molecular sieve.

8. The method for recovering helium from the tail gas of a semiconductor manufacturing process according to claim 1, wherein The impurity removal agent used for the second adsorption for impurity removal in step (2) includes activated carbon and activated alumina with a mass ratio of (1 - 5):

1. The temperature of the heating is 40 - 50 °C; The types of membranes used for the first membrane separation treatment in step (2) and the second membrane separation treatment in step (3) include any one of polyimide, polysulfone, polydimethylsiloxane, cellulose acetate, or metal-organic framework; the applicable pressure of the membranes used for the first membrane separation treatment and the second membrane separation treatment is 5 - 15 barg.

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