Purification method of electronic special gas

Abstract

The embodiment of the present application provides a method for purifying electronic special gases, which belongs to the technical field of semiconductor manufacturing gas purification. The electronic special gas is an alkane gas, and the purification method includes an adsorption process: using porous carbon modified by alkali treatment and / or acid treatment to adsorb the electronic special gas in the electronic special gas raw gas, so that the electronic special gas and impurity gas in the electronic special gas raw gas are separated. The purification method adopts an adsorption purification treatment method, which can avoid the problems of high purification energy consumption and high material loss; the modified porous carbon used therein has good adsorption activity, adsorption selectivity and adsorption capacity for electronic special gases, and can effectively adsorb electronic special gases to achieve the separation of electronic special gases and impurity gases, thereby effectively removing various impurity gases in the electronic special gas raw gas.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor manufacturing gas purification, and in particular, to a method for purifying electronic special gases. Background Art

[0002] High-purity electronic special gases such as arsine (AsH3) and phosphine (PH3) are mainly used in semiconductor integrated circuit manufacturing processes, and their purity is required to be greater than 99.9999%; trace impurities include N2, O2, Ar2, H2O, CO, CO2, CH4, C2H6, etc., and their content is required to be less than 100ppb.

[0003] In the current process, in order to remove the above-mentioned trace impurities so that the electronic special gas meets the high purity requirements of the semiconductor integrated circuit manufacturing process, it is usually necessary to use a combination of measures such as distillation, low-temperature adsorption, etc.

[0004] When using distillation to remove impurities from arsine and phosphine, the energy consumption is high and the material loss is high. In addition, some impurities are difficult to remove by distillation because their boiling points are close to those of the process gas (for example, the boiling point of PH3 is -87.8℃, and the boiling point of C2H6 is -88.6℃).

[0005] When using the low-temperature adsorption method, most of the adsorption materials used are zeolite molecular sieves (models such as 3A, 4A, 5A, 13X), activated carbon, etc., which can usually only effectively adsorb and remove impurities such as H2O and CO2, but have poor removal effects on impurity gases such as N2, O2, Ar2, and H2. Summary of the invention

[0006] The purpose of this application is to provide a method for purifying electronic special gases, which can improve the problems of high purification energy consumption and high material loss, and can effectively remove various impurity gases in the electronic special gas raw gas.

[0007] The embodiment of the present application is implemented as follows:

[0008] An embodiment of the present application provides a method for purifying electronic special gas, which is an alkane gas, including an adsorption process: using porous carbon modified by alkali treatment or acid treatment to adsorb the electronic special gas in the electronic special gas raw gas, so that the electronic special gas and impurity gas in the electronic special gas raw gas are separated.

[0009] The method for purifying electronic special gases provided in the embodiment of the present application has the following beneficial effects:

[0010] Adsorption purification treatment is performed on porous carbon modified by alkali treatment or acid treatment. This treatment method can avoid the problems of high purification energy consumption and high material loss. Among them, the modified porous carbon has good adsorption activity, adsorption selectivity and adsorption capacity for alkane electronic special gases such as arsine and phosphine, and can effectively adsorb alkane electronic special gases such as arsine and phosphine to achieve separation of electronic special gases and impurity gases, thereby effectively removing various impurity gases in the raw gas of electronic special gases. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0012] Figure 1 This is a process diagram of the purification equipment used in some exemplary embodiments of the present application.

[0013] Icons: 100-A group adsorption device; 200-B group adsorption device; 300-temperature controller; 400-vacuum pressure gauge; 500-raw gas supply unit; 600-high purity helium supply unit; 700-product gas collection unit; 800-vacuum system; 900-gas chromatograph; 1000-flow meter. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0015] It should be noted that, in the description of the present application, unless otherwise specified, the meaning of "multiple" in "one or more" refers to more than two types; the meaning of "above" and "below" include the number itself; the range of "value a ~ value b" includes the two end values ​​"a" and "b", and the "unit of measurement" in "value a ~ value b + unit of measurement" represents the "unit of measurement" of both "value a" and "value b".

[0016] The applicant noted that in the current low-temperature adsorption process, adsorbents are usually used to adsorb and remove impurity gases. Taking alkane gases arsine and phosphine as an example, since the adsorption competitiveness of impurity gases such as N2, O2, Ar2, and H2 is weaker than that of arsine and phosphine, the adsorbent cannot adsorb impurity gases such as N2, O2, Ar2, and H2 well, resulting in poor removal effect for impurity gases such as N2, O2, Ar2, and H2.

[0017] The applicant also noted that when using the low-temperature adsorption process, the porous carbon is modified by alkali treatment and / or acid treatment, which changes the functional groups on the surface of the porous carbon and the ions and compounds loaded on the surface, thereby changing the chemical properties of its surface, so that the porous carbon modified by alkali treatment and / or acid treatment has good adsorption activity, adsorption selectivity and adsorption capacity for alkane electronic special gases such as arsine and phosphine, and can separate electronic special gases from impurity gases by adsorbing alkane electronic special gases such as arsine and phosphine, wherein the impurity gases with weaker adsorption can be effectively removed by vacuuming after enrichment; moreover, after removing the impurity gases, alkane electronic special gases such as arsine and phosphine can be efficiently resolved from the modified porous carbon, which is convenient for further collection and purification of the high-purity electronic special gases.

[0018] Based on this, the present application proposes a method for purifying electronic special gases, which will be described in detail below in conjunction with a specific implementation method.

[0019] The present application provides a method for purifying electronic special gas, wherein the electronic special gas is an alkane gas, and the process includes an adsorption process, which includes: using porous carbon modified by alkali treatment and / or acid treatment to adsorb the electronic special gas in the electronic special gas raw gas, so that the electronic special gas and impurity gas in the electronic special gas raw gas are separated.

[0020] It is understandable that the adsorption process is mainly used to reflect how to effectively separate the electronic special gas and impurity gas in the electronic special gas raw gas, so as to ensure that various impurity gases in the electronic special gas raw gas can be effectively removed. Before the adsorption process, the adsorbent can be loaded, analyzed, dried, etc. as needed; after the adsorption process, the impurity gas can be removed and the electronic special gas can be analyzed as needed.

[0021] In the present application, alkane electronic special gases can be understood according to conventional definitions, including but not limited to silane, borane, arsine and phosphine.

[0022] Studies have found that, especially when adsorbing arsine raw gas and phosphine raw gas, porous carbon modified by alkali treatment and / or acid treatment can usually show extremely good adsorption activity, adsorption selectivity and adsorption capacity.

[0023] Based on this, as an example, the electronic special gas is selected from arsine and phosphine. That is, the purification method of the electronic special gas can be used for the purification of arsine, and the purification method of the electronic special gas can also be used for the purification of phosphine.

[0024] In the present application, the porous carbon may be a porous material prepared using coal, biomass, high molecular polymer, etc. as raw materials.

[0025] In order to ensure that the modified porous carbon has better adsorption activity, adsorption selectivity and adsorption capacity for electronic special gases such as arsine and phosphine, the specific surface area and pore volume of the porous carbon can be specifically selected, and the largest possible specific surface area and pore volume can be selected under certain standards to ensure better adsorption performance. Among them, since the modification of this application mainly changes the surface activity of the porous carbon, and the specific surface area and pore volume are not affected too much, therefore, the specific surface area and pore volume defined in the exemplary scheme of this application can refer to the indicators before the porous carbon is modified, and can also refer to the indicators after the porous carbon is modified.

[0026] Optionally, the specific surface area of ​​the porous carbon is ≥ 900 m 2 / g.

[0027] Optionally, the pore volume of the porous carbon (also known as pore volume, which refers to the total volume of pores per unit mass of a porous solid) is ≥ 0.4 cm 3 / g.

[0028] It should be noted that the porous carbon modified by alkali treatment and / or acid treatment may be porous carbon modified by alkali treatment only, porous carbon modified by acid treatment only, porous carbon first modified by alkali treatment and then by acid treatment, or porous carbon first modified by acid treatment and then by alkali treatment.

[0029] The study found that porous carbons with different modification methods showed different degrees of improvement in the amount of electronic special gases compared to unmodified porous carbon. Among them, when adsorbing arsine raw gas, compared with the absorption of arsine by unmodified porous carbon, the absorption of arsine by porous carbon modified by acid after alkali treatment can be increased by 50% or more, the absorption of arsine by porous carbon modified by alkali treatment alone can be increased by about 5%, the absorption of arsine by porous carbon modified by acid treatment alone can be increased by about 25%, and the absorption of arsine by porous carbon modified by alkali treatment after acid treatment can be increased by about 40%. When adsorbing the raw gas of phosphine, compared with the absorption of phosphine by the unmodified porous carbon, the absorption of phosphine by the porous carbon modified by alkali treatment and then acid treatment can be increased by 60% or more, the absorption of phosphine by the porous carbon modified by alkali treatment alone can be increased by about 5%, the absorption of phosphine by the porous carbon modified by acid treatment alone can be increased by about 25%, and the absorption of phosphine by the porous carbon modified by alkali treatment and then acid treatment can be increased by about 40%. It can be seen that compared with the unmodified porous carbon, the porous carbon modified by alkali treatment and then acid treatment has significantly improved adsorption activity, adsorption selectivity and adsorption capacity for arsine and phosphine, and the porous carbon modified by alkali treatment and acid treatment can effectively achieve the separation of electronic special gas and impurity gas when adsorbing the raw gas of arsine and phosphine.

[0030] Based on this, as an example, in the adsorption process, porous carbon modified by alkali treatment and acid treatment in sequence is used to adsorb the electronic special gas in the electronic special gas raw gas.

[0031] In some possible embodiments, during the alkali treatment modification process, the alkali used is selected from NaOH, KOH and NH3·H2O. In order to ensure a better alkali treatment modification effect, the alkali is, for example, a strong alkali such as NaOH and KOH; further, in order to control costs, the alkali is, for example, NaOH.

[0032] Optionally, during the alkali treatment modification process, the concentration of alkali in the alkali solution is 8 to 12M (i.e. mol / L), for example but not limited to any one of 8M, 9M, 10M, 11M and 12M or a range between any two of them; the mass ratio of the raw porous carbon (i.e. the raw material used to prepare the modified porous carbon during the modification treatment, that is, the unmodified porous carbon) to the alkali solution is 1:(1.5 to 2.2), for example but not limited to any one of 1:1.5, 1:1.6, 1:1.7, 1:1.7, 1:1.9, 1:2.0, 1:2.1 and 1:2.2 or a range between any two of them.

[0033] In the above-mentioned implementation scheme, the concentration of alkali in the alkali solution, and the mass ratio of the porous carbon to the alkali solution are controlled according to specific standards to ensure better alkali modification and activation effect on the porous carbon, so that the porous carbon modified by alkali treatment has better adsorption activity, adsorption selectivity and adsorption capacity for electronic special gases such as arsine and phosphine.

[0034] In some possible embodiments, during the acid treatment modification process, the acid used is selected from HNO3, H2SO4 and H3PO4. In order to ensure a better alkaline treatment modification effect, the acid is, for example, a strong acid such as HNO3, H2SO4; further, in order to avoid the introduction of impurities after the acid treatment, the acid is, for example, HNO3. In the embodiment where the electronic special gas is phosphine, in order to avoid the introduction of impurities after the acid treatment, the acid is, for example, HNO3 or H3PO4.

[0035] Optionally, during the acid treatment modification process, the acid concentration in the acid solution is 3 to 5M, for example but not limited to any one of 3M, 4M and 5M or a range between any two of them; the mass ratio of the alkali-modified porous carbon (referring to the porous carbon obtained by the above-mentioned alkali treatment modification) to the acid solution is 1:(1.5 to 2.2), for example but not limited to any one of 1:1.5, 1:1.6, 1:1.7, 1:1.7, 1:1.9, 1:2.0, 1:2.1 and 1:2.2 or a range between any two of them.

[0036] It should be noted that in the present application, during the alkali treatment modification and acid treatment modification processes, after the acid-base treatment solution and the porous carbon are mixed, a mixing operation such as stirring or shaking can be performed all the time or at intervals to ensure that the acid-base modification component can always maintain good contact and reaction with the porous carbon. After the alkali treatment modification and acid treatment modification processes, in order to ensure that the modified porous carbon has a good cleanliness, it can be further washed and dried.

[0037] In some exemplary embodiments, the purification method includes the following steps performed in sequence:

[0038] Providing an adsorption device process: providing an adsorption device filled with porous carbon and having an internal negative pressure state;

[0039] Cooling process: Refrigerate the adsorption device;

[0040] Purge process: fill the adsorption device with helium to normal pressure or positive pressure, balance for a first preset time, and then evacuate to negative pressure;

[0041] Adsorption process: The electronic special gas raw gas is filled into the adsorption device, and the porous carbon adsorbs the electronic special gas while the impurity gas is in a free state;

[0042] Exhaust process: Exhaust impurity gases from the adsorption device;

[0043] Temperature recovery process: heating the adsorption device to desorb the electronic special gas from the porous carbon;

[0044] Gas production process: output the desorbed electronic special gas from the adsorption device.

[0045] Regarding the process of providing an adsorption device, as an example, the process of providing an adsorption device includes: filling porous carbon into an adsorption device (for example, a steel cylinder with a cylinder valve), then evacuating to a pressure of less than 0.1 mbar, filling with helium to a pressure of 1 to 3 bar, balancing for 3 to 5 minutes, and then evacuating to a pressure of less than 0.1 mbar; wherein the operation of filling with helium, balancing and then evacuating is repeated 3 to 5 times. In this exemplary process flow, after the porous carbon is filled into the adsorption device, it is ensured that the gas adsorbed on the porous carbon particles is effectively removed.

[0046] Furthermore, after repeating the operation of filling with helium, balancing and then evacuating 3 to 5 times, a vacuum drying operation can be performed. Exemplarily, the vacuum drying operation includes: heating the environment where the adsorption device is located at a set temperature of more than 90°C, and opening the vacuum system until the pressure in the adsorption device is stabilized below 0.05mbar, at which time the drying is qualified.

[0047] Regarding the cooling process, as an example, the cooling process includes: cooling the environment where the adsorption device is located according to the standard of setting the temperature below -20°C and lasting for 3 to 5 (for example, 4) hours.

[0048] Regarding the purging process, as an example, in the purging process, helium is filled into the adsorption device until the air pressure reaches 1 to 3 bar, the first preset time is 3 to 5 minutes, and then the air is evacuated to a pressure below 0.1 mbar; wherein, the purging process is repeated 3 to 5 times between the cooling process and the adsorption process.

[0049] Regarding the adsorption process, as an example, in the adsorption process, the filling rate of the electronic special gas raw material is 15 to 20 lpm (liters / minute), and the gas pressure in the adsorption device is below 1 bar; the adsorption balance is 3 to 5 (for example, 4) hours until the pressure gauge reading stabilizes and the adsorption process is ended.

[0050] Regarding the exhaust process, as an example, the exhaust process: the adsorption device is exhausted to the outside until the pressure drop value reaches more than 0.1 bar.

[0051] Regarding the temperature recovery process, as an example, in the temperature recovery process, the environment where the adsorption device is located is heated according to the standard of setting a temperature of 50 to 60° C. and lasting for 3 to 5 hours.

[0052] Regarding the gas production process, as an example, in the gas production process, the time for gas analysis and output is 10 to 14 (for example, 12) hours. After the electronic special gas is output from the adsorption device, it is analyzed by a gas chromatograph and the product is collected after it passes the analysis.

[0053] Since in the exemplary embodiment, the time taken for the gas production process is equivalent to the total time taken for the cooling process to the temperature return process, both are about 12 hours, in order to improve the purification efficiency, two groups of adsorption devices (each group of adsorption devices may include one or more adsorption devices) may be configured to work alternately. When one group of adsorption devices (referred to as group A) starts the gas production process, the other group of adsorption devices (referred to as group B) may carry out other processes before gas production; when group A completes the gas production process and group B completes other processes before gas production, group A ends the gas production process and carries out other processes before gas production, and group B starts the gas production process. The adsorption devices of group A and group B work alternately according to the above example.

[0054] Based on this, as an example, two groups of adsorption devices are used in the purification method to work alternately. When one group of adsorption devices starts the gas production process, the other group of adsorption devices starts the operation from the cooling process to the heating process.

[0055] Reference Figure 1 The following will provide an exemplary description of the purification method for electronic special gases provided in this application in combination with specific purification equipment.

[0056] like Figure 1 As shown, the adsorption device is a steel cylinder with a cylinder valve, and the adsorption device is divided into two groups, namely, group A adsorption device 100 and group B adsorption device 200. The two groups of adsorption devices AB are respectively placed in an environment with a temperature controller 300, corresponding to the two groups of temperature controllers 300; the two groups of adsorption devices AB are also respectively provided with two groups of vacuum pressure gauges 400. In addition, the inlet and outlet lines of the two groups of adsorption devices AB are also respectively provided with two groups of valves AB, which are respectively connected with the raw gas supply unit 500, the high-purity helium supply unit 600, the product gas collection unit 700 and the vacuum system 800, and the pipeline between the raw gas supply unit 500 and the two groups of adsorption devices AB is also provided with a flow meter 1000.

[0057] See also Figure 1 , the purification methods of electronic special gases include:

[0058] An adsorption device is provided, including an A-group adsorption device 100 and a B-group adsorption device 200 .

[0059] Make sure all valves are closed.

[0060] Cooling: Adjust the thermostat to 300 to the cooling state, set the temperature below -20℃, and continue for 4 hours.

[0061] Purging: Open the bottle valve on the A side, open valve V3A, and fill high-purity helium through the high-purity helium supply unit 600 to a pressure of 1 to 3 bar; close V3A, balance for 3 to 5 minutes, then open valve V4A, and draw the vacuum to below 0.05 mbar through the vacuum system 800, and then close V4A. Repeat the purging process 3 to 5 times.

[0062] Adsorption: Open V1A, and charge the raw gas (phosphine or arsine) through the raw gas supply unit 500, control the speed at 15-20 lpm, and the pressure below 1 bar. The adsorption balance is 4 hours until the reading of the vacuum pressure gauge 400 is stable, and then close V1A. The bottle valve is not closed for balance to ensure greater adsorption of the raw gas. At this time, the electronic special gas has been adsorbed on the porous carbon, and the impurity gas (N2, O2, Ar2, H2, etc.) is in a free state.

[0063] Exhaust: Slowly open V4A to reduce the pressure in the cylinder by 0.1 bar to remove free impurity gases, and then close V4A.

[0064] Reheating: Adjust the thermostat 300 to a set temperature of 50-60°C and heat the cylinder for 4 hours. At this time, the raw gas begins to desorb and the pressure rises.

[0065] Gas production: Open V2A, the desorption process lasts for 12 hours, and the desorbed product gas is sent to the gas chromatograph 900 for analysis. After passing the analysis, the product gas is collected by the product gas collection unit 700.

[0066] When the adsorption device 100 of group A starts to collect the produced gas, the adsorption device 200 of group B starts to perform the operation from the cooling process to the heating process in sequence.

[0067] The following is an illustrative description of the method for purifying the electronic special gas provided in this application in combination with specific experiments.

[0068] 1. Preparation of porous carbon modified by alkali treatment and then acid treatment

[0069] (1) Alkali treatment modification

[0070] A. Prepare approximately 10M NaOH solution:

[0071] Dissolve 600 g of NaOH in 1.5 L of deionized water.

[0072] B. 1000g of raw porous carbon particles (porous carbon with a specific surface area of ​​1100m 2 / g, the pore volume of porous carbon is 0.45cm 3 / g) was soaked in the above solution. During this period, the beaker with the porous carbon soaked was placed on a shaker and shaken at room temperature for 24 hours.

[0073] C. Filter out the porous carbon particles and rinse with deionized water until the pH value of the filtered water is close to 7.

[0074] D. Dry the porous carbon particles in an oven at 105°C for 24 hr.

[0075] (2) Acid treatment modification

[0076] A. Prepare approximately 4M HNO3 solution:

[0077] Prepare by diluting 370 ml of 65 wt% HNO3 in 1150 ml of deionized water.

[0078] B. Soak 1000 g of the porous carbon particles modified by the alkali treatment in the solution. During this time, place the beaker containing the porous carbon particles on a shaker and shake at room temperature for 24 hours.

[0079] C. Filter out the porous carbon particles and rinse with deionized water until the pH value of the filtered water is close to 7.

[0080] D. Dry the porous carbon particles in an oven at 105°C for 24 hr.

[0081] 2. Testing the adsorption performance of different porous carbons for electronic special gases

[0082] The unmodified raw porous carbon particles used in the above preparation process and the prepared porous carbon modified by alkali treatment and then acid treatment are respectively used as porous carbon adsorbents, and the adsorption performance is tested as follows:

[0083] A. Take 1000g of dry porous carbon respectively, put them into 2.2L steel cylinders, install the cylinder valves, and check for leaks.

[0084] B. Place the cylinder in an oven above 200℃, purge and replace with helium, dry and evacuate to below 0.05mbar, cool to room temperature after stabilization, and close the cylinder valve. Remove the cylinder and weigh it on a high-precision electronic scale.

[0085] C. Fill the steel cylinders with phosphine gas source (purity>99.99%) until the gas pressure is stably maintained at normal pressure (1013 mbar A) and balance for 12 hours.

[0086] D. Close the bottle valve and remove it for weighing.

[0087] E. Extract the gas in the bottle and discharge it to the exhaust gas processor. Then repeat steps B, C, and D twice.

[0088] F. Change the gas source to arsine (purity>99.99%) and repeat steps B, C, and D three times.

[0089] G. Data collation, the results are shown in the following Table 1.

[0090] Table 1. Adsorption performance data summary

[0091]

[0092] Among them: the raw carbon in the raw carbon bottle weight refers to the unmodified raw porous carbon particles used in the above preparation process; the modified carbon in the modified carbon bottle weight refers to the porous carbon modified by alkali treatment and then acid treatment obtained in the above preparation process. The adsorption increase refers to the increase in the adsorption amount of the modified carbon relative to the adsorption amount of the raw carbon.

[0093] According to the results in Table 1, the raw porous carbon particles (before modification) have an average adsorption capacity of 0.1035 g PH3 / g carbon for phosphine and 0.3025 g AsH3 / g carbon for arsine. After the modification, the adsorption capacity of phosphine is 0.158 g PH3 / g carbon, which is increased by about 53%; the adsorption capacity of arsine is 0.4975 g AsH3 / g carbon, which is increased by about 64%.

[0094] 4. Purification of electronic special gases

[0095] (1) Provide adsorption device

[0096] A. Filling and bottling: Fill the steel cylinder with the treated modified porous carbon (porous carbon modified by the above-mentioned alkali treatment and then acid treatment), install the cylinder valve, and check for leaks.

[0097] B. Gas replacement: First use a vacuum pump to evacuate the air in the cylinder to below 0.1 mbar, then fill it with high-purity helium (purity>6N) to a pressure of 1-3 bar; balance for 3-5 minutes, then evacuate to below 0.1 mbar. Repeat the helium filling / vacuuming steps 3-5 times to remove the gas adsorbed on the porous carbon particles.

[0098] C. Vacuum drying: Raise the temperature of the thermostat to above 90℃, open the vacuum system, and wait until the pressure stabilizes below 0.05mbar, and the drying is qualified.

[0099] (2) Implement the adsorption process (combined with Figure 1 )

[0100] A. Make sure all valves are closed.

[0101] B. Cooling: Adjust the thermostat to 300 to the cooling state, set the temperature below -20℃, and continue for 4 hours.

[0102] C. Purge: Open the bottle valve on the A side, open valve V3A, and fill high-purity helium through the high-purity helium supply unit 600 to a pressure of 1 to 3 bar; close V3A, balance for 3 to 5 minutes, then open valve V4A, and draw the vacuum to below 0.05 mbar through the vacuum system 800, and then close V4A. Repeat the purge process 3 to 5 times.

[0103] D. Adsorption: Open V1A, and charge the raw gas (phosphine or arsine) through the raw gas supply unit 500, control the speed at 15-20 lpm, and the pressure below 1 bar. The adsorption balance is 4 hours until the reading of the vacuum pressure gauge 400 is stable, and then close V1A. At this time, the electronic special gas has been adsorbed on the porous carbon, and the impurity gas (N2, O2, Ar2, H2, etc.) is in a free state.

[0104] E. Exhaust: Slowly open V4A to reduce the pressure in the cylinder by 0.1 bar to eliminate free impurity gases, and then close V4A.

[0105] F. Temperature recovery: Adjust the temperature controller 300 to set the temperature of 50-60℃, heat the cylinder for 4 hours, at this time the raw gas begins to desorb and the pressure rises.

[0106] G. Gas production: Open V2A, and the desorption process lasts for 12 hours. At the same time, the desorbed product gas is sent to the gas chromatograph 900 for analysis. After passing the analysis, the product gas is collected by the product gas collection unit 700.

[0107] When the adsorption device 100 of group A starts to collect the produced gas, the adsorption device 200 of group B starts to perform the operation from the cooling process to the heating process in sequence.

[0108] The raw gas and product gas were analyzed and compared using a gas chromatograph. After testing, the concentration of impurity gases (N2, O2, Ar2, H2) in the raw gas was reduced from the ppm level to the ppb level. The specific purification results of several sets of parallel experiments are shown below.

[0109] Table 2. Experiment 1 (phosphine feed gas)

[0110]

[0111] Table 3. Experiment 2 (phosphine feed gas)

[0112]

[0113] Table 4. Experiment 3 (Arsine Raw Gas)

[0114]

[0115] Table 5. Experiment 4 (Arsine Raw Gas)

[0116]

[0117] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

Claims

1. A method for purifying electronic special gas, characterized in that: The electronic special gas is an alkane gas, and the purification method includes the following processes performed in sequence: Providing an adsorption device process: providing an adsorption device filled with porous carbon and in a negative pressure state, wherein the porous carbon is modified by alkali treatment and acid treatment in sequence; the alkali treatment modification comprises: immersing the porous carbon particles in an alkali solution; filtering out the porous carbon particles, and rinsing with deionized water until the pH value of the filtered water is close to 7; the acid treatment modification comprises: immersing the porous carbon particles in an acid solution; filtering out the porous carbon particles, and rinsing with deionized water until the pH value of the filtered water is close to 7; Cooling process: refrigerating the adsorption device; Purge process: filling the adsorption device with helium to a normal pressure state or a positive pressure state, balancing for a first preset time, and then evacuating to a negative pressure state; Adsorption process: the electronic special gas raw gas is charged into the adsorption device, and the porous carbon is used to adsorb the electronic special gas in the electronic special gas raw gas while the impurity gas is in a free state, so that the electronic special gas and the impurity gas in the electronic special gas raw gas are separated; Exhaust process: exhaust the impurity gas out of the adsorption device; Temperature recovery process: heating the adsorption device so that the electronic special gas is desorbed from the porous carbon; Gas production process: outputting the desorbed electronic special gas from the adsorption device.

2. The purification method according to claim 1, characterized in that The electronic special gas is selected from arsine and phosphine.

3. The purification method according to claim 1, characterized in that The porous carbon satisfies at least one of the following conditions (1) and (2): (1) Specific surface area ≥ 900m 2 / g; (2) Pore volume ≥ 0.4 cm 3 / g.

4. The purification method according to claim 1, characterized in that Satisfy at least one of the following conditions (1) and (2): (1) In the alkali treatment modification process, the alkali used is selected from NaOH, KOH and NH3·H2O; (2) During the acid treatment modification process, the acid used is selected from HNO3, H2SO4 and H3PO4.

5. The purification method according to claim 4, characterized in that During the alkali treatment modification process, the concentration of the alkali in the alkali solution is 8 to 12 M, and the mass ratio of the raw porous carbon to the alkali solution is 1:(1.5 to 2.2).

6. The purification method according to claim 4, characterized in that: During the acid treatment modification process, the concentration of the acid in the acid solution is 3-5 M, and the mass ratio of the alkali-modified porous carbon to the acid solution is 1:(1.5-2.2).

7. The purification method according to claim 1, characterized in that: Satisfy at least one of the following conditions (1) to (7); (1) The process of providing an adsorption device comprises: filling the porous carbon into the adsorption device, then evacuating the device to a pressure of less than 0.1 mbar, filling the device with helium to a pressure of 1 to 3 bar, balancing for 3 to 5 minutes, and then evacuating the device to a pressure of less than 0.1 mbar; wherein the operation of filling the device with helium, balancing, and then evacuating the device is repeated 3 to 5 times; (2) The cooling process includes: cooling the environment where the adsorption device is located according to the standard of setting the temperature below -20°C and lasting for 3 to 5 hours; (3) In the purge process, helium is filled into the adsorption device until the pressure reaches 1 to 3 bar, the first preset time is 3 to 5 minutes, and then the device is evacuated to a pressure below 0.1 mbar; wherein the purge process is repeated 3 to 5 times between the cooling process and the adsorption process; (4) In the adsorption process, the charging rate of the electronic special gas raw material gas is 15 to 20 lpm, and the gas pressure in the adsorption device is below 1 bar; the adsorption equilibrium is 3 to 5 hours until the pressure gauge reading is stable, and the adsorption process is terminated; (5) The exhaust process: the adsorption device is exhausted to the outside until the pressure drop value reaches more than 0.1 bar; (6) In the temperature recovery process, the environment where the adsorption device is located is heated according to the standard of setting the temperature to 50 to 60° C. and lasting for 3 to 5 hours; (7) In the gas production process, the gas analysis and output time is 10 to 14 hours. After the electronic special gas is output from the adsorption device, it is analyzed by a gas chromatograph and then the product is collected.

8. The purification method according to claim 1, characterized in that: Two groups of the adsorption devices are used to work alternately. When one group of the adsorption devices starts the gas production process, the other group of the adsorption devices starts the operation from the cooling process to the heating process.

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