Device system and method for recovering helium from semiconductor manufacturing process tail gas

Abstract

The invention belongs to the technical field of tail gas treatment, and relates to a device system and a method for recovering helium from semiconductor manufacturing process tail gas, by adopting a composite device system of an adsorption device, a membrane separation assembly and a gas purification tower, the recovery and purification operation of low-concentration helium containing toxic, corrosive and various rare gas mixed working conditions can be completed, and the helium recovery efficiency is improved. The recovered helium can be purified to 99.999% or above, the recovery rate is high, the purity is high, front and back gas heat exchange is fully utilized, the energy consumption is low, and the helium supply source is further widened; the device system is free of gas emptying in the whole process, reflows, collects and discharges back to a tail gas pipeline, and is suitable for various manufacturing processes of semiconductors.

Description

Technical Field

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

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

[0003] In addition to air separation, helium extraction mainly comes from natural gas, and the helium content of natural gas in my country is 0.01-0.10%. Therefore, it is urgent to develop new ways to extract and recover helium. At present, the consumption of high-purity helium in the semiconductor industry accounts for a high proportion, and the concentration of helium in the tail gas of the semiconductor process is only 1-2%. The factory directly discharges it into the atmosphere after burning it without recycling it. The development of a helium recovery device for semiconductor process tail gas can effectively alleviate the demand pressure for helium in the industry and improve the safety of helium supply.

[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. The invention controls the flow rate through a mass flow meter, and after purification through a gas membrane separator, it enters two sets of parallel gas purification towers for pressure swing adsorption to purify helium, which is suitable for the recovery and purification of low-concentration helium, hydrogen and neon. The invention adopts a composite method of membrane and pressure swing adsorption, but the invention cannot cope with the working conditions of semiconductor process technology containing toxic and corrosive gases, 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 due to the use of multiple towers.

[0005] CN206156757U discloses a helium recovery and purification device, including a flow meter, 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 two groups of adsorption columns connected in series, and the cryogenic tower is provided with at least three groups of heat exchangers connected in series, 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 is not applicable to the recovery of tail gas helium in complex working conditions of semiconductor processes and the recovery and purification of low-concentration helium, and has high energy consumption.

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

[0007] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a device system and method for recovering helium from semiconductor process exhaust gas, which can complete the low-concentration helium recovery and purification operations under conditions containing toxic, corrosive gases, and mixed conditions of multiple rare gases, with high recovery efficiency and low energy consumption.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a device system for recovering helium from semiconductor process exhaust gas, the device system comprising an exhaust gas main pipeline, a branch of the exhaust gas main pipeline having a first compressor, a primary parallel adsorption column, a secondary series adsorption column, a membrane separation assembly, a gas purification tower, a second compressor and a helium storage device connected in sequence along the exhaust gas flow direction; the waste gas discharged from the primary parallel adsorption column and the gas purification tower flows independently into the exhaust gas main pipeline after the branch; the membrane separation assembly comprises at least two groups of separation membrane groups connected in series, wherein the first group of separation membrane groups comprises at least two parallel separation membrane modules, and starting from the second group of separation membrane groups, the permeate side gas of the separation membrane group flows back to the exhaust gas main pipeline before the branch; the retentate side gas of the separation membrane group flows into the exhaust gas main 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 component and a gas purification tower, and can complete the low-concentration helium recovery and purification operation under working conditions containing toxic and corrosive gases and a mixture of multiple rare gases, and there is no gas exhaust in the whole process, and all gas is refluxed, collected and discharged back to the tail gas pipeline. It is suitable for various semiconductor processes, has high recovery efficiency and low energy consumption.

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

[0012] The number of separation membrane groups connected in series is at least 2, for example, 2, 3 or 4, but the numbers are not limited to the listed numbers, and other numbers not listed in the numerical range are also applicable.

[0013] The first separation membrane group includes at least two separation membrane modules connected in parallel, for example, 2, 3 or 4, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

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

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

[0016] Preferably, the membrane separation assembly comprises a first separation membrane group and a second separation membrane group connected in series in sequence, the permeate side gas of the first separation membrane group flows through a first buffer device and then enters the gas purification tower, and the permeate side gas of the second separation membrane group flows through a second buffer device and then flows back to the exhaust gas main 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] The second buffer device and the needle valve are arranged on the pipeline to ensure that the recovery rate of helium is further improved while the helium is purified.

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

[0020] In order to solve the problem of helium concentration fluctuation in semiconductor process tail gas, the present invention sets a PLC-controlled helium concentration detection three-way valve before entering the separation membrane group, which can directly discharge the raw gas with low helium concentration back to the tail gas main pipeline, further improving the helium recovery concentration.

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

[0022] The present invention sets a pneumatic valve before entering the separation membrane group, and a needle valve is installed on the instrument gas path 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 high, causing impact and damage to the membrane.

[0023] Preferably, the gas discharged from the first buffer device flows through the 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 the second heat exchanger, exchanges heat with the gas from the first compressor and then enters the exhaust gas main pipeline after the branch; the retentate side gas of the second separation membrane group flows through the third heat exchanger, exchanges heat with the gas from the secondary series adsorption column and then enters the exhaust gas main pipeline after the branch.

[0024] In the present invention, the outlet gas of the first compressor is heat-exchanged and cooled with the outlet gas at the lower end of the gas purification tower, thereby enhancing the low-temperature adsorption capacity of the first-stage parallel adsorption column for impurity gases; the outlet gas of the second-stage series adsorption column is heat-exchanged and heated with the retentate side gas of the second separation membrane group, thereby increasing the gas temperature and reducing the energy consumption of the electric heater; the outlet gas of the first buffer device is heat-exchanged and cooled with the gas at the upper end of the gas purification tower, thereby lowering the gas temperature and reducing the consumption of cold sources.

[0025] Preferably, the gas purification tower comprises a cryogenic tower, the number of plates of the cryogenic tower is 10-15 plates / m, and the material taking amount θ is 0.6-0.8; the cryogenic tower is connected to a condenser.

[0026] The number of plates of the cryogenic tower is 10-15 plates / m, for example, 10 plates / m, 11 plates / m, 12 plates / m, 13 plates / m, 14 plates / m or 15 plates / m, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0027] The material extraction amount θ of the cryogenic tower is 0.6-0.8, for example, it can be 0.6, 0.7 or 0.8, but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0028] The material extraction amount θ of the cryogenic tower refers to the amount of material extracted from the cryogenic tower within a specific time.

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

[0030] The inlet pressure of the oil-free piston compressor is ≥200 mbarg, for example, it can be 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 also applicable.

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

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

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

[0034] Preferably, the second buffer device comprises 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 being performed by the device system for recovering helium from semiconductor process tail gas according to the first aspect, the method comprising the following steps:

[0037] (1) The semiconductor process exhaust gas in the exhaust main pipeline enters the branch line, undergoes a first compression treatment and a first adsorption and impurity removal in sequence, and obtains a first adsorption and impurity removal gas and a first waste gas; the first waste gas flows into the exhaust main pipeline after the branch line for post-treatment;

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

[0039] (3) The retentate side gas obtained in step (2) is subjected to a second membrane separation treatment, the obtained permeate side gas is refluxed and mixed with the semiconductor process exhaust gas in the exhaust main pipeline, and the obtained retentate side gas flows into the exhaust main 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 semiconductor process with complex working conditions containing toxic, corrosive and rare gases. The recovered helium can be purified to more than 99.999%, with high recovery rate and high purity, and full use of front and rear gas heat exchange, low energy consumption, and further broadening the source of helium supply.

[0041] Preferably, before the permeate side gas is purified in step (2), a first heat exchange step with the helium obtained by gas purification is also included.

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

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

[0046] Preferably, the impurity remover used in the second adsorption impurity removal in step (2) comprises activated carbon and activated alumina in 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 values ​​not listed within the numerical range are also applicable.

[0047] Step (2) Before the second adsorbed impurity-removed gas is subjected to the first membrane separation treatment, the step further includes the steps of sequentially performing a third heat exchange with the retentate side 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 adsorbed impurity-removed gas after the third heat exchange is lower than the target required concentration, the exhaust gas main pipeline after the branch line flows into the branch line for post-treatment.

[0049] The heating temperature is 40-50°C, for example, 40°C, 42°C, 45°C, 48°C or 50°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0050] In step (2), the types of membranes used in the first membrane separation treatment and the second membrane separation treatment 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, 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 also 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 component and a gas purification tower, and can complete the recovery and purification operations of low-concentration helium in toxic, corrosive and mixed conditions of multiple rare gases, and can purify the recovered helium to more than 99.999%, with high recovery rate and high purity, and full use of front and rear gas heat exchange, low energy consumption, and further broadening the source of helium supply; the device system has no gas exhaust throughout the whole process, and all gas is refluxed, collected and discharged back to the tail gas pipeline, and is suitable for various semiconductor processes. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0055] Among them: 1, tail gas main 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 group; 10, second separation membrane group; 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 DESCRIPTION

[0056] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0057] Example 1

[0058] This embodiment provides a device system for recovering helium from semiconductor process tail gas, such as Figure 1 As shown, the material of the pipeline used in the device system is 316 stainless steel, and the device system includes an exhaust gas main pipeline 1, and the branch of the exhaust gas main pipeline 1 is connected in sequence along the exhaust gas flow direction with a first oil-free piston compressor 2, a primary parallel adsorption column 3, a secondary series adsorption column 4, a membrane separation component, a cryogenic tower 5, a second oil-free piston compressor 6 and a helium storage tank 7; the exhaust gas discharged from the primary parallel adsorption column 3 and the cryogenic tower 5 flows independently into the exhaust gas main pipeline 1 after the branch; the number of plates of the cryogenic tower 5 is 13 pieces / m, the material intake θ is 0.7, and the cryogenic tower 5 is connected to a condenser 8; the inlet pressure of the first oil-free piston compressor 2 and the second oil-free piston compressor 6 are both 200mbarg, and the outlet pressure is both 10barg.

[0059] The membrane separation component includes a first separation membrane group 9 and a second separation membrane group 10 which are connected in series in sequence. The first separation membrane group 9 includes two separation membrane modules connected in parallel. The permeate side gas of the first separation membrane group 9 flows through a first buffer tank 11 and then enters the deep cooling tower 5. The permeate side gas of the second separation membrane group 10 flows through a needle valve 12 and a second buffer tank 13 in sequence and then flows back to the exhaust gas main pipeline 1 before the branch. The retentate side gas of the second separation membrane group 10 flows into the exhaust gas main pipeline 1 after the branch. A gas check valve 14 is provided on the exhaust gas main pipeline 1 after the branch.

[0060] A PLC-controlled helium concentration detection three-way valve 15, an electric heater 16 and a pneumatic valve 17 are sequentially arranged on the pipeline between the secondary series adsorption column 4 and the first separation membrane group 9. The helium concentration detection three-way valve 15 is connected to the exhaust gas main 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 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 exhaust gas main pipeline 1 after the branch; the retentate side gas of the second separation membrane group 10 flows through the third heat exchanger 20, exchanges heat with the gas from the secondary series adsorption column 4, and then enters the exhaust gas main pipeline 1 after the branch. Figure 1 A→B, C→D, and E→F ​​all indicate the direction of material flow.

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

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

[0064] (2) performing a second adsorption and impurity removal on the first adsorbed and impurity-removed gas obtained in step (1), wherein the impurity-removing agent used is activated carbon and activated alumina in a mass ratio of 2:1, and the obtained second adsorption and impurity-removed gas is subjected to a first membrane separation treatment to obtain a permeate side gas and a retentate side gas; performing gas purification on the obtained permeate side gas, wherein the cold source used is liquid nitrogen, to obtain helium and a second waste gas; the obtained second waste gas flows into the tail gas main pipeline after the branch road for post-treatment, and the obtained helium is stored after a second compression treatment;

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

[0066] Before the permeate side gas is subjected to gas purification in step (2), the step also includes a step of performing a first heat exchange with the helium obtained by gas purification; after the first compression treatment and before the first adsorption and impurity removal in step (1), the step also includes a step of performing a second heat exchange with the second exhaust gas obtained by gas purification; before the second adsorption and impurity removal gas is subjected to the first membrane separation treatment in step (2), the step also includes the steps of performing a third heat exchange with the retentate side gas obtained by the second membrane separation treatment, detecting the helium concentration, and heating at 45° C. in sequence; during 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 exhaust gas main pipeline after the branch is subjected to post-treatment.

[0067] In step (2), the type of membrane used in the first membrane separation treatment and the second membrane separation treatment is polyimide, and the inlet pressure of the first membrane separation treatment is adjusted to 8 barg.

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

[0069] Example 2

[0070] This embodiment provides a device system for recovering helium from semiconductor process tail gas. The difference from Embodiment 1 is that no pneumatic valve is provided on the pipeline between the secondary series adsorption column 4 and the first separation membrane group 9. The rest is the same as Embodiment 1.

[0071] The volume purity of helium on the permeate side of the first separation membrane group tested by a portable gas chromatograph was 60%, and the recovery rate of helium could reach 85%. Since no pneumatic valve was installed 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 was too high, causing impact on the membrane, which would cause damage over time, leading to a decrease in membrane separation effect, reduced helium purity, and reduced 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 the pipeline between the secondary series adsorption column 4 and the first separation membrane group 9 is not provided with a PLC-controlled helium concentration detection three-way valve 15. The helium concentration detection step in step (3) is adaptively removed. The rest is the same as Embodiment 1.

[0074] The volume purity of helium on the permeate side of the first separation membrane group tested by a portable gas chromatograph was 30%, and the helium recovery rate could reach 94%. Since there was no helium concentration detection three-way valve on the pipeline between the secondary series adsorption column and the first separation membrane group, the raw gas with a low helium concentration could not be directly discharged back to the exhaust main pipeline, thereby reducing the helium concentration.

[0075] Example 4

[0076] This embodiment provides a device system for recovering helium from semiconductor process tail gas. The difference from Embodiment 1 is that no electric heater 16 is provided on the pipeline between the secondary series adsorption column 4 and the first separation membrane group 9. The heating step in step (3) is adaptively removed. The rest is the same as Embodiment 1.

[0077] The volume purity of helium on the permeate side of the first separation membrane group was tested using a portable gas chromatograph and found to be 50%, with a helium recovery rate of 92%. Since no electric heater was installed on the pipeline between the secondary series adsorption column and the first separation membrane group, the gas temperature was too low and fluctuated, resulting in a decrease in the subsequent helium membrane separation and concentration efficiency.

[0078] Example 5

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

[0080] The volume purity of helium at the top outlet of the cryogenic tower tested by a portable gas chromatograph can reach 86%, and the helium recovery rate can reach 85%. Due to the insufficient number of plates in the gas purification cryogenic tower, the gas separation efficiency is reduced, which ultimately leads to a decrease in the purity of helium.

[0081] Example 6

[0082] This embodiment provides a device system for recovering helium from semiconductor process tail gas, which is different from the embodiment 1 in that except for adjusting the material intake θ of the cryogenic tower 5 to 0.95, the rest is the same as the embodiment 1.

[0083] The volume purity of helium at the top outlet of the cryogenic tower tested by a portable gas chromatograph can reach 90%, and the recovery rate can reach 90%. Due to the excessive amount of material taken for gas purification, the purity of helium is reduced and the recovery rate is increased.

[0084] Example 7

[0085] This embodiment provides a device system for recovering helium from semiconductor process exhaust gas. The difference between the method for recovering helium from semiconductor process exhaust gas using the device system and that of Embodiment 1 is that, except for adjusting the inlet pressure of the first membrane separation treatment in step (2) to 1 barg, the rest is the same as that of Embodiment 1.

[0086] The portable gas chromatograph was used to test the helium volume purity on the permeate side of the first separation membrane group, which was 20%, and the helium recovery rate was 95%. Since the inlet pressure of the first separation membrane group was too low, the helium could not diffuse, permeate and be purified, thus reducing the purity of the helium.

[0087] Comparative Example 1

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

[0089] The volume purity of helium on the permeate side of the first separation membrane group tested by a portable gas chromatograph was 68%, and the helium recovery rate was 93%. Due to the lack of a cryogenic tower, the purity of the helium was significantly reduced.

[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 component only includes a first separation membrane group 9, and the retentate side gas of the first separation membrane group 9 directly flows into the exhaust gas main pipeline 1 after the branch. The second membrane separation treatment step in step (3) is adaptively removed, and the rest is the same as Example 1.

[0092] The portable gas chromatograph was used to test the helium volume purity on the permeate side of the first separation membrane group, which was 58%, and the helium recovery rate was 60%. Since the membrane separation component only included one separation membrane group, the purity of the helium was reduced and the helium recovery rate was significantly reduced.

[0093] Comparative Example 3

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

[0095] The portable gas chromatograph was used to test the helium volume purity on the permeate side of the first separation membrane group, which was found to be 35%, and the helium recovery rate was found to be 92%. Due to the reduction in separation membrane modules in the first separation membrane group, the gas purification processing capacity and efficiency were reduced, and the concentration effect of membrane separation was reduced.

[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 in toxic, corrosive and mixed conditions of multiple rare gases, and can purify the recovered helium to more than 99.999%, with high recovery rate and purity, and full use of front and rear gas heat exchange, low energy consumption, and further broadening the source of helium supply; the device system has no gas exhaust throughout the whole process, and all gas is refluxed, collected and discharged back to the tail gas pipeline, which is suitable for various semiconductor processes.

[0097] The applicant declares that the above is only a specific implementation mode 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 shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A device system for recovering helium from semiconductor process tail gas, characterized in that: The device system comprises an exhaust main pipeline, and a branch of the exhaust main pipeline is connected in sequence along the exhaust gas flow direction with a first compressor, a primary parallel adsorption column, a secondary series adsorption column, a membrane separation component, a gas purification tower, a second compressor and a helium storage device; the exhaust gas discharged from the primary parallel adsorption column and the gas purification tower flows independently into the exhaust main pipeline after the branch; The membrane separation component includes at least two separation membrane groups connected in series, wherein the first separation membrane group includes at least two separation membrane modules connected in parallel, and starting from the second separation membrane group, the permeate side gas of the separation membrane group flows back to the exhaust gas main pipeline before the branch; the retentate side gas of the separation membrane group flows into the exhaust gas main pipeline after the branch.

2. The device system for recovering helium from semiconductor process tail gas according to claim 1, characterized in that: A gas check valve is arranged on the tail gas main pipeline after the branch.

3. The device system for recovering helium from semiconductor process tail gas according to claim 1, characterized in that: The membrane separation assembly comprises a first separation membrane group and a second separation membrane group connected in series, the permeate side gas of the first separation membrane group flows through a first buffer device and then enters the gas purification tower, and the permeate side gas of the second separation membrane group flows through a second buffer device and then flows back to the tail gas main pipeline before the branch; 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 device system for recovering helium from semiconductor process tail gas according to claim 3, characterized in that: A PLC-controlled helium concentration detection three-way valve, an electric heater and a pneumatic valve are sequentially arranged on the pipeline between the secondary series adsorption column and the first separation membrane group. The helium concentration detection three-way valve is connected to the exhaust gas main pipeline after the branch.

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

6. The device system for recovering helium from semiconductor process tail gas according to claim 1, characterized in that: The gas purification tower comprises a cryogenic tower, the number of plates of the cryogenic tower is 10-15 pieces / m, and the material taking amount θ is 0.6-0.8; the cryogenic tower is connected to a condenser; The first compressor and the second compressor each independently comprise an oil-free piston compressor, wherein the inlet pressure of the oil-free piston compressor is ≥200 mbarg and the outlet pressure is ≤10 barg.

7. A method for recovering helium from semiconductor process tail gas, characterized in that: The method is carried out by the device system for recovering helium from semiconductor process tail gas according to any one of claims 1 to 6, and the method comprises the following steps: (1) The semiconductor process exhaust gas in the exhaust main pipeline enters the branch line, undergoes a first compression treatment and a first adsorption and impurity removal in sequence, and obtains a first adsorption and impurity removal gas and a first waste gas; the first waste gas flows into the exhaust main pipeline after the branch line for post-treatment; (2) performing a second adsorption and impurity removal on the first adsorbed and impurity-removed gas obtained in step (1); subjecting the obtained second adsorbed and impurity-removed gas to a first membrane separation treatment to obtain a permeate side gas and a retentate side gas; performing gas purification on the obtained permeate side gas to obtain helium and a second waste gas; the obtained second waste gas flows into the tail gas main pipeline after the branch line for post-treatment, and the obtained helium is stored after a second compression treatment; (3) The retentate side gas obtained in step (2) is subjected to a second membrane separation treatment, the obtained permeate side gas is refluxed and mixed with the semiconductor process exhaust gas in the exhaust main pipeline, and the obtained retentate side gas flows into the exhaust main pipeline after the branch for post-treatment.

8. The method for recovering helium from semiconductor process tail gas according to claim 7, characterized in that: Before the permeate side gas is purified in step (2), the step also includes a first heat exchange step with the helium obtained by gas purification; The cold source used for gas purification in step (2) includes any one of dry ice, liquid nitrogen, R403 or R507.

9. The method for recovering helium from semiconductor process tail gas according to claim 7, characterized in that: Step (1) includes, after the first compression treatment and before the first adsorption and impurity removal, a second heat exchange step with the second waste gas obtained by gas purification; The impurity remover used in step (1) of the first adsorption impurity removal comprises any one of alkaline adsorbent, silica gel, activated alumina or molecular sieve, or a combination of at least two of them.

10. The method for recovering helium from semiconductor process tail gas according to claim 7, characterized in that: Step (2) the impurity removal agent used in the second adsorption impurity removal comprises activated carbon and activated alumina in a mass ratio of (1-5):1; Step (2) before the second adsorbed impurity-removed gas is subjected to the first membrane separation treatment, the step further includes the steps of sequentially performing a third heat exchange with the retentate side gas obtained from the second membrane separation treatment, detecting the helium concentration, and heating; In the helium concentration detection, when the helium concentration of the second adsorbed impurity-removed gas after the third heat exchange is lower than the target required concentration, the exhaust gas main pipeline after the branch is flowed into for post-processing; The heating temperature is 40-50°C; Step (2) The type of membrane used in the first membrane separation treatment and the second membrane separation treatment includes any one of polyimide, polysulfone, polydimethylsiloxane, cellulose acetate or metal organic framework; the applicable pressure of the membrane used in the first membrane separation treatment and the second membrane separation treatment is 5-15 barg.

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