Method for increasing gas purity using vacuum swing adsorption

Abstract

The method includes pressurizing a gas column by supplying input gas from an input mass flow controller and discharging output gas from the gas column via an output mass flow controller. The input gas includes at least 99.9% Xe and 0.05% to 0.1% Ar. An input mass flow rate of the input mass flow controller is greater than an output mass flow rate of the output mass flow controller to adsorb Xe into an adsorbent in the gas column. In response to the gas column reaching a maximum pressure, the input gas supply is stopped and the output gas is purged from the gas column. The output gas includes less than 99.9% Xe and greater than 0.1% Ar. Purified gas is extracted from the gas column to desorb the Xe from the adsorbent. The purified gas includes at least 99.99% Xe.

Description

Cross-reference of related applications

[0001] This application claims priority to provisional patent application No. 63 / 560,781, filed on March 4, 2024, the entire disclosure of which is incorporated herein by reference. Technical Field

[0002] This disclosure relates to a gas purification process for use in semiconductor manufacturing. Background Technology

[0003] The development of the semiconductor manufacturing industry has placed higher demands on yield management, especially metrology and inspection systems. Critical dimensions continue to shrink, yet the industry still needs to reduce the time required to achieve high yield rates and high-value production. Minimizing the total time from detecting a yield problem to resolving it determines the return on investment for semiconductor manufacturers.

[0004] Fabricating semiconductor devices, such as logic and memory devices, typically involves processing semiconductor wafers using numerous fabrication processes to form the various features and multiple layers of the semiconductor device. For example, photolithography is a semiconductor fabrication process involving transferring a pattern from a photomask to a photoresist disposed on a semiconductor wafer. Additional examples of semiconductor fabrication processes include, but are not limited to, chemical mechanical polishing (CMP), etching, deposition, and ion implantation. The arrangement of multiple semiconductor devices fabricated on a single semiconductor wafer can be separated into individual semiconductor devices.

[0005] Inspection processes are used at various stages of semiconductor manufacturing to detect defects on wafers, thereby promoting higher yields and, consequently, higher profits in the manufacturing process. Inspection has always been a crucial part of manufacturing semiconductor devices such as integrated circuits (ICs). However, as the size of semiconductor devices shrinks, inspection becomes even more critical for successfully manufacturing acceptable semiconductor devices, as even small defects can cause device malfunctions. For example, as the size of semiconductor devices decreases, the detection of defects of reduced size becomes necessary, because even relatively small defects can cause unwanted aberrations in semiconductor devices.

[0006] Some testing and manufacturing processes rely on the supply of inert gases (e.g., xenon), where the accuracy and quality of these processes depend on the purity of the supplied gas. After use, inert gases may become mixed with various contaminants. Therefore, to reuse inert gases in future processes, the gas can be purified to at least partially remove contaminants from the gaseous mixture. However, existing pressure swing adsorption (PSA) methods cannot purify gases to sufficiently high concentrations. This results in either a reduction in purity (and consequently, a reduction in the accuracy and quality of the testing or manufacturing process) or the introduction of a new gas supply into the system, which increases costs. While other distillation techniques can be used to achieve higher purity levels, these systems are complex and have high implementation and operating costs, making them impractical for low-volume applications.

[0007] Therefore, an improved gas purification method is needed. Summary of the Invention

[0008] Embodiments of this disclosure provide a method. The method may include pressurizing a gas column by supplying an input gas from an input mass flow controller and discharging an output gas from the gas column via an output mass flow controller. The input gas may include at least 99.9% Xe and 0.05% to 0.1% Ar. The gas column may contain an adsorbent. The input mass flow rate of the input mass flow controller may be greater than the output mass flow rate of the output mass flow controller to adsorb Xe into the adsorbent.

[0009] In response to the gas column reaching its maximum pressure, the method may further include stopping the supply of the input gas to the gas column and purging the output gas from the gas column. The output gas may include less than 99.9% Xe and more than 0.1% Ar.

[0010] The method may further include extracting purified gas from the gas column to desorb the Xe from the adsorbent. The purified gas may contain at least 99.99% Xe.

[0011] In some embodiments, before extracting the purified gas from the gas column, the method may further include receiving a gas sample of the output gas purged from the gas column using a residual gas analyzer. The method may further include measuring the Ar concentration of the gas sample using the residual gas analyzer. In response to the Ar concentration of the gas sample being less than 0.01%, the method may further include re-feeding the output gas from the emission port to the outlet port.

[0012] In some embodiments, the emission port may be connected to a gas recovery system configured to increase the Xe concentration of the output gas to up to 99.9% Xe.

[0013] In some embodiments, the outlet port may be connected to a storage tank configured to store the purified gas.

[0014] In some embodiments, the outlet port may be connected to a semiconductor testing system configured to supply the purified gas.

[0015] In some embodiments, the input gas supplied to the gas column via the input mass flow controller may be connected to a gas recovery system configured to reduce the Ar concentration of the input gas to 0.05% to 0.1% Ar.

[0016] In some embodiments, the output gas can be purged from the gas column by vacuum pressure from a vacuum pump.

[0017] In some embodiments, the purified gas may include at least 99.999% Xe.

[0018] In some embodiments, the adsorbent may be configured to preferentially adsorb Xe compared to Ar.

[0019] In some embodiments, the step of extracting the purified gas from the gas column may be performed after the output gas has been purged from the gas column for a predetermined duration. Attached Figure Description

[0020] For a more complete understanding of the nature and purpose of this disclosure, reference should be made to the following detailed description taken in conjunction with the accompanying drawings, in which:

[0021] Figure 1 A diagram of a system according to an embodiment of the present disclosure;

[0022] Figure 2 This is a diagram of a system according to another embodiment of the present disclosure;

[0023] Figure 3 This is a flowchart of a method according to an embodiment of the present disclosure;

[0024] Figure 4 This is a graph showing the flow rate versus pressure measurement of an example disclosed herein; and

[0025] Figure 5 This is a graph of Ar concentration measurements for an example of this disclosure. Detailed Implementation

[0026] Although the claimed subject matter will be described with reference to certain embodiments, other embodiments, including those that do not provide all the benefits and features set forth herein, are also within the scope of the invention. Various structural, logical, process, and electronic changes may be made without departing from the scope of this disclosure. Therefore, the scope of this disclosure is defined only by reference to the appended claims.

[0027] Embodiments of this disclosure provide a system 100. System 100 can be configured to provide enhanced purification of a gas stream. For example, system 100 can receive gas from a gas recovery system and improve the purity of the gas. In one example, system 100 can receive gas from a xenon recovery system (XRS). The XRS can use pressure swing adsorption (PSA) technology to separate an incoming gaseous mixture of argon and xenon (e.g., about 85% Ar and about 15% Xe) into purified Xe and waste Ar. However, the purified Xe produced by the XRS may only be about 99.5% to about 99.95% Xe. System 100 can therefore be used as a post-process of the XRS to increase the Xe purity to 99.99% to 99.999% or higher. Although system 100 is described in connection with the removal of Ar from Xe gas, system 100 can process other gases, and system 100 is not limited herein.

[0028] like Figure 1 As shown, system 100 may include a gas column 120. The gas column 120 may contain an adsorbent. The adsorbent may be configured to preferentially adsorb Xe compared to Ar. The adsorbent may be a zeolite or activated carbon material. In one example, the adsorbent may be KostrolithNaMSXK, SorboNorit B3, or other adsorbent materials selected to preferentially adsorb a specific gas compared to other gases (Xe, Ar, or other gases).

[0029] System 100 may further include an input mass flow controller 110 and an output mass flow controller 130, respectively connected to the input and output terminals of the gas column 120. The input mass flow rate of the input mass flow controller 110 may be greater than the output mass flow rate of the output mass flow controller 130. For example, the input mass flow rate of the input mass flow controller 110 may be up to 3 slm. The input mass flow controller 110 may be configured to receive input gas via an inlet port 101 of system 100. The inlet port 101 may be connected to an upstream gas recovery system (e.g., XRS) that provides the input gas.

[0030] The system 100 may further include an input pressure indicator 115 configured to measure the pressure in the air column 120.

[0031] System 100 may further include pump 140. Pump 140 may be configured to generate a vacuum pressure to purge or extract gas from gas column 120 to outlet port 102 or discharge port 103 of system 100. For example, the inlet of pump 140 may be connected to output mass flow controller 130, and the outlet of pump 140 may be connected to outlet port 102 and discharge port 103. The vacuum pressure may be less than 1 bar absolute (e.g., 0.0 bar absolute to 0.02 bar absolute). In some embodiments, pump 140 may be a scroll pump or a different type of pump. System 100 may further include outlet valve 112 and discharge valve 113, outlet valve 112 being configured to control the flow rate at outlet port 102 and discharge valve 113 being configured to control the flow rate at discharge port 103. Therefore, pump 140 can be configured to draw gas from gas column 120 to outlet port 102 or outlet port 103 depending on which of outlet valve 112 or discharge valve 113 is open.

[0032] The outlet port 102 can be connected to a storage tank 160 configured to store gas. Alternatively, the outlet port 102 can be connected to a semiconductor testing system to directly supply the gas used in the testing process.

[0033] The discharge port 103 can be connected to a recirculation system 150. The recirculation system can be configured to direct the output gas from the gas column 120 back to a gas recovery system (e.g., XRS).

[0034] System 100 may further include a residual gas analyzer (RGA) 155. RGA 155 may be configured to receive a gas sample of the output gas from gas column 120. For example, RGA 155 may be connected to the outlet of pump 140. RGA 155 may be configured to measure one or more properties of the gas sample. For example, RGA 155 may be configured to measure Ar concentration, Xe concentration, or the concentration of another gas present in the gas sample. The properties of the gas sample can be used to determine when the output gas from gas column 120 has been sufficiently purified to produce purified gas.

[0035] System 100 may further include a processor 165. Processor 165 may include a microprocessor, microcontroller, or other device. Processor 165 may be coupled to components of system 100 in any suitable manner (e.g., via one or more transmission media, which may include wired and / or wireless transmission media) such that processor 165 can receive output. Processor 165 may be configured to use the output to perform several functions. Optionally, processor 165 may electronically communicate with inspection tools, metering tools, repair tools, or re-inspection tools (not illustrated) to receive additional information or send instructions. For example, processor 165 may electronically communicate with a gas recovery system (e.g., XRS).

[0036] Processor 165 may be part of a variety of systems, including personal computer systems, graphics computers, mainframe computer systems, workstations, network appliances, Internet appliances, or other devices. A subsystem or system may also include any suitable processor known in the art, such as a parallel processor. Additionally, a subsystem or system may include a platform with high-speed processing and software as a standalone tool or a networking tool.

[0037] Processor 165 may be located in or part of system 100 or another device. In one example, processor 165 may be part of a separate control unit or located in a centralized quality control unit. Multiple processors 165 may be used to define multiple subsystems of system 100.

[0038] In practice, processor 165 can be implemented through any combination of hardware, software, and firmware. Furthermore, the functions described herein can be performed by a single unit or distributed among different components, each of which can be implemented through any combination of hardware, software, and firmware. Program code or instructions for enabling processor 165 to perform various methods and functions can be stored in a readable storage medium such as memory.

[0039] If system 100 comprises more than one subsystem, then different processors 165 can be coupled to each other, enabling the transmission of images, data, information, instructions, etc., between the subsystems. For example, a subsystem can be coupled to an additional subsystem via any suitable transmission medium (which may include any suitable wired and / or wireless transmission media known in the art). Two or more of these subsystems can be effectively coupled by sharing a computer-readable storage medium (not shown).

[0040] Processor 165 can be configured to perform several functions using the output of system 100 or other outputs. For example, processor 165 can be configured to send outputs to an electronic data storage unit or another storage medium. Processor 165 can be further configured as described herein.

[0041] Processor 165 may be configured according to any of the embodiments described herein. Processor 165 may also be configured to perform other functions or additional steps using the output of system 100 or using images or data from other sources.

[0042] Processor 165 can be communicatively coupled to any of the various components or subsystems of system 100 in any manner known in the art. Furthermore, processor 165 can be configured to receive and / or acquire data or information from other systems (e.g., inspection results from an inspection system (e.g., a re-inspection tool), a remote database containing design data, etc.) via a transmission medium that may include wired and / or wireless portions. In this way, the transmission medium can act as a data link between processor 165 and other subsystems of system 100 or systems external to system 100. The various steps, functions, and / or operations of system 100 and methods disclosed herein are implemented by one or more of the following: electronic circuits, logic gates, multiplexers, programmable logic devices, ASICs, analog or digital controls / switches, microcontrollers, or computing systems. Program instructions implementing the methods (e.g., the methods described herein) can be transmitted via or stored on a carrier medium. The carrier medium may include storage media such as read-only memory, random access memory, magnetic disk or optical disk, non-volatile memory, solid-state memory, magnetic tape, etc. The carrier medium may include transmission media such as wires, cables, or wireless transmission links. For example, the various steps described throughout this disclosure may be implemented by a single processor 165 (or computer subsystem) or alternatively by multiple processors 165 (or multiple computer subsystems). Furthermore, different subsystems of system 100 may include one or more computing systems or logic systems. Therefore, the above description should not be construed as a limitation of this disclosure but is merely illustrative.

[0043] Processor 165 can communicate electronically with each valve of system 100. For example, processor 165 can be configured to send a command to outlet valve 112 to open and direct gas to outlet port 102, and processor 165 can be configured to send a command to exhaust valve 113 to open and direct gas to exhaust port 103. Processor 165 can similarly be configured to send commands to outlet valve 112 and exhaust valve, respectively, to close outlet port 102 and exhaust port 103 to limit the gas flow from outlet port 102 and exhaust port 103.

[0044] The processor 165 can communicate electronically with each pressure indicator of the system 100. For example, the processor 165 can be configured to receive pressure measurements from an input pressure indicator 115 used to receive measurements of the pressure of the air column 120.

[0045] The processor 165 can communicate electronically with the input mass flow controller 110 and the output mass flow controller 130. For example, the processor 165 can be configured to send commands to the input mass flow controller 110 and the output mass flow controller 130 to control the gas input and output from the gas column 120.

[0046] Processor 165 can communicate electronically with pump 140. For example, processor 165 can be configured to send instructions to pump 140 to operate or stop operation. In some embodiments, pump 140 can operate throughout the entire process of purifying gas through system 100, or pump 140 can be turned on and off by processor 165 at various times during the process of purifying gas through system 100.

[0047] Processor 165 can communicate electronically with RGA 155. For example, processor 165 can be configured to receive a concentration measurement of the output gas from RGA 155. Processor 165 can be configured to determine the purified gas as having an Ar concentration of less than 0.01%, which can produce a purified gas comprising at least 99.99% Xe. In some embodiments, the purified gas may comprise at least 99.999% Xe (i.e., an Ar concentration of less than 0.001%).

[0048] In some embodiments, processor 165 may be configured to use a timer to determine that the purified gas comprises at least 99.99% Xe. For example, within a preset duration, processor 165 may be configured to send an instruction to discharge valve 113 to open to direct gas to discharge port 103 (with outlet valve 112 closed), and after the preset duration, processor 165 may be configured to send an instruction to outlet valve 112 to open to direct gas to outlet port 102 (with discharge valve 113 closed).

[0049] The purified gas can be delivered to the outlet port 102 by closing the discharge valve 113 and opening the outlet valve 112.

[0050] System 100 may include any additional pumps, valves, fittings or other fluid devices for controlling the following: gas input to inlet port 101, gas output from outlet port 103, purified gas output to outlet port 102, and the movement of gas through gas column 120 and through other components of system 100.

[0051] although Figure 1 The system 100 illustrated herein includes a single air column 120, but in some embodiments, the system 100 may include two or more air columns 120 operating in parallel. For example, as Figure 2 As shown, system 100 may include a first air column 120a and a second air column 120b.

[0052] System 100 may further include a first inlet valve 111a and a second inlet valve 111b, the first inlet valve 111a being configured to control gas input from the input mass flow controller 110 to the first gas column 120a, and the second inlet valve 111b being configured to control gas input from the input mass flow controller 110 to the second gas column 120b. System 100 may further include a first outlet valve 112a and a second outlet valve 112b, the first outlet valve 112a being configured to control gas output from the first gas column 120a to the outlet port 102, and the second outlet valve 112b being configured to control gas output from the second gas column 120b to the outlet port 102. System 100 may further include a first exhaust valve 113a and a second exhaust valve 113b, the first exhaust valve 113a being configured to control gas output from the first gas column 120a to the exhaust port 103, and the second exhaust valve 113b being configured to control gas output from the second gas column 120b to the exhaust port 103. Processor 165 may electronically communicate with each of the first inlet valve 111a, the second inlet valve 111b, the first outlet valve 112a, the second outlet valve 112b, the first exhaust valve 113a, and the second exhaust valve 113b to control the opening and closing of each valve to control the gas flow through the first gas column 120a and the second gas column 120b to the outlet port 102 and the exhaust port 103.

[0053] System 100 may further include a first pressure indicator 115a and a second pressure indicator 115b, the first pressure indicator 115a being configured to measure the pressure in a first air column 120a, and the second pressure indicator 115b being configured to measure the pressure in a second air column 120b. Processor 165 is capable of electronic communication with the first pressure indicator 115a and the second pressure indicator 115b to receive the pressure measurements from the first air column 120a and the second air column 120b.

[0054] System 100 may further include a first output mass flow controller 130a and a second output mass flow controller 130b. The first output mass flow controller 130a is disposed in the path of the output gas from the first gas column 120a and the second gas column 120b to the discharge port 103, and the second output mass flow controller 130b is disposed in the path of the output gas from the first gas column 120a and the second gas column 120b to the outlet port 102. Processor 165 can electronically communicate with the first output mass flow controller 130a and the second output mass flow controller 130b to control the gas output from the first gas column 120a and the second gas column 120b to the outlet port 102 and the discharge port 103.

[0055] Optionally, system 100 may further include a first pump 140a configured to draw gas from a first gas column 120a and a second gas column 120b to an outlet port 103. System 100 may further include a second pump 140b configured to draw gas from the first gas column 120a and the second gas column 120b to an output port 102. Processor 165 may electronically communicate with the first pump 140a and the second pump 140b to control the drawing of gas from the first gas column 120a and the second gas column 120b to the outlet port 102 and the outlet port 103.

[0056] In some embodiments, the first gas column 120a and the second gas column 120b may operate asynchronously, which allows for a constant (or near-constant) input of gas with a high Ar content and an output of purified Xe gas. For example, the processor 165 may be configured to control the valves of the system 100 such that one of the first gas column 120a and the second gas column 120b is outputting purified gas to outlet port 102 or venting gas to outlet port 103, while the other of the first gas column 120a and the second gas column 120b is in the process of purifying the gas.

[0057] Another embodiment of this disclosure provides a method 200. For example... Figure 3 As shown in the document, method 200 may include the following steps, which have been described in conjunction with exemplary components of system 100 but are not limited herein.

[0058] At step 210, the gas column 120 is pressurized by supplying input gas from the input mass flow controller 110 and discharging output gas from the gas column 120 via the output mass flow controller 130. A pump 140 may be configured to induce gas flow through the gas column 120. The input gas may include at least 99.9% Xe and 0.05% to 0.1% Ar. The input gas may be supplied to the gas column 120 at an inlet pressure of 3 bar absolute to 6 bar absolute. Since the input mass flow rate of the input mass flow controller 110 is higher than the output mass flow rate of the output mass flow controller 130, the pressure in the gas column may be gradually increased. As the pressure increases, Xe may be preferentially adsorbed into the adsorbent contained in the gas column 120. Therefore, the output gas discharged from the gas column 120 has a higher Ar content than the input gas supplied to the gas column 120.

[0059] At step 220, in response to the gas column 120 reaching its maximum pressure, the supply of input gas to the gas column 120 is stopped, and output gas is purged from the gas column 120. In some embodiments, the maximum pressure reached in the gas column may be up to 5 bar absolute. When the maximum pressure is reached in the gas column 120, the input gas flowing into the gas column 120 has a similar rate to the output gas flowing out of the gas column 120, and Xe may be hardly adsorbed into the adsorbent. Therefore, the input gas flow can drive the output gas flow out to purge gas with a high Ar content. The output gas may include less than 99.9% Xe and more than 0.1% Ar. The input mass flow controller 110 may be controlled to stop the supply of input gas to the gas column 120. In some embodiments, the input gas may be shut off upstream of the input mass flow controller 110. In some embodiments, the output gas may be purged using input gas from the previous cycle or purified gas. The output gas may be purged to the discharge port 103. In some embodiments, the discharge port 103 may be connected to a recirculation system 150, which may direct the output gas back to a gas recovery system (e.g., XRS) for reprocessing of the high Ar content output gas.

[0060] In some embodiments, steps 210 and 220 may be optimized such that the partial pressure of Ar in the outlet stream is low enough to prevent excessive Ar from being adsorbed into the adsorbent, while minimizing the amount of Xe released to the discharge port 103. It should be understood that the optimized flow rate may be varied throughout steps 210 and 220. The flow rate may also depend on the temperature and volume of the gas column 120.

[0061] At step 260, purified gas is drawn from gas column 120. The purified gas may be drawn from outlet port 102 into storage tank 160, into testing tools, or into another tool or for another purpose, depending on the specific application.

[0062] In some embodiments, prior to step 260, method 200 may further include steps 230 and 240.

[0063] At step 230, RGA 155 receives a gas sample of the output gas purged from gas column 120.

[0064] At step 240, the RGA 155 measures the Ar concentration of the gas sample. As the output gas is purged from the gas column 120, the pressure in the gas column 120 decreases, causing Xe to desorb from the adsorbent. Therefore, in each consecutive gas sample measured by the RGA 155, the Xe concentration in the output gas will increase and the Ar concentration in the output gas will decrease. The RGA 155 can transmit the measured values ​​to the processor 165.

[0065] At step 250, in response to the Ar concentration of the gas sample being less than 0.01%, the output gas from gas column 120 is redirected from discharge port 103 to outlet port 102. When processor 165 determines that the Ar concentration of the gas sample is less than 0.01%, the output gas can be considered as purified gas with an Xe concentration of 99.99% or greater. Under the control of processor 165, outlet valve 112 can be opened and discharge valve 113 can be closed to direct the output gas to outlet port 102 instead of discharge port 103.

[0066] In some embodiments, the verification process of steps 230 to 250 may be performed downstream, and the RGA 155 may be external to other components of the system 100. In either case (i.e., the RGA 155 is integrated with the system 100 or is an external component), the RGA 155 may be used to control the progress of the method 200, or the RGA 155 may be used as a verification process before or after the steps of the method 200.

[0067] In some embodiments, method 200 may proceed from step 220 to step 260 after a preset duration without performing the verification process of steps 230 to 250 (e.g., without RGA 155). For example, after purging the output gas from gas column 120 for a preset duration in step 220, purified gas may be drawn from gas column 120 in step 260. For example, after the preset duration, processor 165 may be configured to send an instruction to outlet valve 112 to open to direct gas to outlet port 102 (with exhaust valve 113 closed).

[0068] Figure 4 and Figure 5 The illustration shows exemplary test data for Xe gas purification using the system 100 and method 200 described above. Specifically, Figure 4 The diagram illustrates the gas flow rate and pressure measurements of gas column 120, and... Figure 5 The diagram illustrates the Ar concentration measurements for RGA155. The test utilized an input gas of 640 ppm Ar (i.e., approximately 99.936% Xe) and approximately 1 L of 1.2 mm to 2 mm (approximately 700 g) Kostrolith NaMSXK adsorbent in a gas column of 120.

[0069] Under initial conditions t0, the pressure in the gas column 120 is 0.1 bar absolute, the input mass flow rate of the input mass flow controller 110 is 1 slm, and the output mass flow rate of the output mass flow controller 130 is 0.25 slm. After 53 minutes, at t1, the pressure in the gas column 120 is 4.9 bar absolute, the input mass flow rate is 0.35 slm, and the output mass flow rate is 0.25 slm. The time between t0 and t1 corresponds to the pressurization in step 210. Figure 4 As shown, the pressure in gas column 120 gradually increases until it reaches its maximum pressure. During this time, Xe is adsorbed into the adsorbent, resulting in an average Ar concentration of 1500 ppm in the output gas.

[0070] At 1:06, i.e., t2, the pressure in gas column 120 is 4.9 bar absolute, the input mass flow rate is 0.0 slm, and the output mass flow rate is 0.25 slm. At this time, an estimated amount of 41 L of Xe is adsorbed into the adsorbent, and the input gas flow is stopped corresponding to the stopping portion of step 220.

[0071] After 2:56 hours, at t3, the pressure in gas column 120 is 0.16 bar absolute, the input mass flow rate is 0.0 slm, and the output mass flow rate decreases to 0.0 slm. After 3:20 hours, at t4, the pressure in gas column 120 is 0.1 bar absolute, and the test stops. The time between t2 and t4 corresponds to the purge portion of step 220. During this time, the Ar concentration of the output gas decreases to an average of 85 ppm at 65% throughput and to an average of 10 ppm at 40% throughput to produce purified Xe gas (i.e., approximately 99.9915% Xe to approximately 99.999% Xe).

[0072] The results of the above experiments indicate that method 200 can be configured to produce a purified gas containing at least 99.99% Xe (containing 99.999% or more Xe) without mixing with fresh, clean, purified Xe gas. Furthermore, the high Ar content gas emitted using method 200 can be recycled through the XRS, minimizing Xe gas loss. Therefore, system 100 and method 200 provide an improved gas purification process with low cost and complexity, suitable for both small-batch and large-batch applications.

[0073] Although this disclosure has been described with respect to one or more specific embodiments, it should be understood that other embodiments of this disclosure may be made without departing from the scope of this disclosure. Therefore, this disclosure is to be considered limited only by the appended claims and their reasonable interpretation.

Claims

1. A method comprising: The gas column is pressurized by supplying input gas from an input mass flow controller and discharging output gas from the gas column via an output mass flow controller, wherein the input gas comprises at least 99.9% Xe and 0.05% to 0.1% Ar, the gas column contains an adsorbent, and the input mass flow rate of the input mass flow controller is greater than the output mass flow rate of the output mass flow controller to adsorb Xe into the adsorbent; In response to the gas column reaching its maximum pressure, the supply of the input gas to the gas column is stopped and the output gas is purged from the gas column, wherein the output gas comprises less than 99.9% Xe and greater than 0.1% Ar; and Purified gas is drawn from the gas column to desorb Xe from the adsorbent, wherein the purified gas comprises at least 99.99% Xe.

2. The method of claim 1, wherein before extracting the purified gas from the gas column, the method further comprises: A gas sample of the output gas purged from the gas column is received using a residual gas analyzer; The Ar concentration of the gas sample was measured using the residual gas analyzer. as well as In response to the Ar concentration of the gas sample being less than 0.01%, the output gas is redirected from the emission port to the outlet port.

3. The method of claim 2, wherein the emission port is connected to a gas recovery system configured to increase the Xe concentration of the output gas to up to 99.9% Xe.

4. The method of claim 2, wherein the outlet port is connected to a storage tank configured to store the purified gas.

5. The method of claim 2, wherein the outlet port is connected to a semiconductor testing system configured to supply the purified gas.

6. The method of claim 1, wherein the input gas supplied to the gas column via the input mass flow controller is connected to a gas recovery system configured to reduce the Ar concentration of the input gas to 0.05% to 0.1% Ar.

7. The method of claim 1, wherein the output gas is purged from the gas column by vacuum pressure from a vacuum pump.

8. The method of claim 1, wherein the purified gas comprises at least 99.999% Xe.

9. The method of claim 1, wherein the adsorbent is configured to preferentially adsorb Xe compared to Ar.

10. The method of claim 1, wherein the step of extracting the purified gas from the gas column is performed after the output gas has been purged from the gas column for a predetermined duration.

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