Method and system for recovering supercritical wafer cleaning / drying media.

Abstract

To provide a supercritical wafer cleaning / drying medium recovery method and system that enables the continuous separation and recovery of high-purity cleaning / drying media in the field of wafer processing.SOLUTION: A method includes a cleaning / drying step of dissolving and removing an organic solvent attached on a wafer by a cleaning / drying medium in a supercritical state to obtain a mixed medium carrying the organic solvent, a depressurization step of reducing the pressure of the mixed medium to first pressure after the cleaning / drying step, and an adsorption step of heating the depressurized mixed medium to first temperature after the depressurization step to obtain a gaseous mixed medium, bringing the gaseous mixed medium into contact with an organic solvent adsorbent in an adsorber, and causing the organic solvent in the mixed medium to be adsorbed and concentrated by the organic solvent adsorbent and separated from the cleaning / drying medium.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to the field of wafer processing, and specifically, to a method and system for recovering a supercritical wafer cleaning / drying medium.

Background Art

[0002] Semiconductor wafers are the most important materials in the semiconductor industry, and the requirements for their surface cleanliness are quite strict. In the semiconductor wafer processing process, wafer surface cleaning and drying are essential processes to effectively remove the solvent on the wafer surface and keep the wafer surface clean. On the other hand, some supercritical media have the characteristic that their surface tension is zero, so they can smoothly enter through the pore structure on the wafer surface and achieve efficient removal of the solvent.

[0003] In the conventional cleaning and drying process using supercritical media, usually, the supercritical cleaning / drying medium is used as a "disposable" consumable. However, due to the large consumption of the supercritical cleaning / drying medium in the cleaning and drying process, the cost of wafer cleaning / drying becomes very high. Furthermore, under a specific temperature and / or pressure environment, there is a possibility that the solvent and the cleaning / drying medium are somewhat miscible, so it is difficult to separate and recover the cleaning / drying medium by simple separation means (such as gas-liquid separation or liquid-liquid separation), and often a large amount of solvent impurities remain in the recovered cleaning / drying medium, which may result in low purity.

[0004] Therefore, in this field, there is an urgent need for a high-purity supercritical wafer cleaning / drying medium recovery process to reduce the cleaning and drying costs of semiconductor wafers.

Summary of the Invention

Problems to be Solved by the Invention

[0005] In view of the above points, the present invention provides a method and system for recovering a supercritical wafer cleaning / drying medium that can achieve continuous separation and recovery of a high-purity cleaning / drying medium. [Means for solving the problem]

[0006] A first aspect of the present invention is a method for recovering a supercritical wafer cleaning / drying medium, A cleaning / drying step in which organic solvents adhering to a wafer are dissolved and removed using a supercritical cleaning / drying medium to obtain a mixed medium supporting the organic solvent, After the washing / drying step, a depressurization step is performed to reduce the pressure of the mixed medium to a first pressure, The present invention provides a supercritical wafer cleaning / drying medium recovery method comprising: a depressurization step, followed by an adsorption step in which the depressurized mixed medium is heated to a first temperature to obtain a gaseous mixed medium, the gaseous mixed medium comes into contact with an organic solvent adsorbent in an adsorbent, the organic solvent in the mixed medium is adsorbed and concentrated by the organic solvent adsorbent, and separated from the cleaning / drying medium.

[0007] According to this proposed technology, the organic solvents used in the wafer processing process are generally organic solvents that are relatively soluble in supercritical cleaning / drying media (e.g., alcohols, ketones, and ester-based organic solvents), and are difficult to separate from the supercritical cleaning / drying media. However, the organic solvent adsorbent is a material with high porosity, and can adsorb organic solvent gases onto its surface or pores through adsorption. As a result, the adsorption of the organic solvent can be achieved by reducing the pressure of the mixture of organic solvent and cleaning / drying media to a first pressure, raising the temperature to a first temperature to create a gaseous mixture, and then spraying this gaseous mixture onto the organic solvent adsorbent. Throughout the entire adsorption process, the cleaning / drying media is not blocked or concentrated, and the organic solvent adsorbent has high selectivity for organic solvents, thus reducing losses in the separation of the cleaning / drying media. Furthermore, the adsorption of organic solvents by the organic solvent adsorbent allows for continuous separation of the gaseous cleaning / drying media from the organic solvent, and enables the continuous flow of high-purity cleaning / drying media, thereby achieving the recovery of high-purity cleaning / drying media.

[0008] As a preferred technical proposal, a supercritical wafer cleaning / drying medium recovery method further includes: The process includes determining whether the organic solvent adsorbent in the first adsorbent has reached the adsorption threshold, and if so, switching the adsorbent from the first adsorbent to the second adsorbent in the adsorption step, and The process includes a desorption step, after the adsorbent switching step, in which the organic solvent adsorbent in the first adsorbent is heated to a second temperature, the organic solvent is desorbed from the organic solvent adsorbent in the first adsorbent, and then discharged from the first adsorbent and flowed into the organic solvent collection port.

[0009] According to this proposed technology, the adsorption step is performed by switching to the second adsorbent just before the organic solvent adsorbent in the first adsorbent reaches adsorption equilibrium, thereby continuously performing the adsorption step. Simultaneously, the temperature of the organic solvent adsorbent in the first adsorbent is increased in the desorption step, changing the adsorption equilibrium of the organic solvent adsorbent in the first adsorbent. This promotes the desorption of the organic solvent from the organic solvent adsorbent in the first adsorbent, ensuring that the separation of the washing / drying medium can be performed continuously and improving the separation and recovery efficiency of the washing / drying medium.

[0010] A preferred technical proposal is a supercritical wafer cleaning / drying medium recovery method, which further includes a purification step to remove organic solvent adsorbent pellets from the cleaning / drying medium separated in the adsorption step.

[0011] According to this proposed technology, since the organic solvent adsorbent in the adsorption step may detach during the adsorption / desorption process, a higher purity cleaning / drying medium can be obtained by removing the organic solvent adsorbent separated in the adsorption step from the cleaning / drying medium.

[0012] A preferred technical solution is an activated carbon adsorbent or a molecular sieve adsorbent with a pore size in the range of 0.7 nm to 0.9 nm as the organic solvent adsorbent, and carbon dioxide as the washing / drying medium.

[0013] According to this proposed technology, the surface tension of supercritical carbon dioxide becomes zero, allowing for the rapid dissolution of organic solvents. Furthermore, both the activated carbon adsorbent and the molecular sieve adsorbent with a pore size in the range of 0.7 nm to 0.9 nm have very high porosity, resulting in high adsorption rates for organic solvents. They can adsorb almost all alcohol, ketone, and ester-based organic solvent gases present within the carbon dioxide gas without affecting its passage.

[0014] A preferred technical configuration would be a first pressure of 3-9 MPa, a first temperature of 30-90°C, and a second temperature of 150-300°C.

[0015] According to this proposed technology, when the pressure of the mixed medium of carbon dioxide and organic solvent is within the range of 3-9 MPa and the temperature is within the range of 30-90°C, the carbon dioxide becomes a subcritical gas. At this time, carbon dioxide and the organic solvent are almost immiscible, and the organic solvent adsorbent exhibits a very high adsorption equilibrium concentration for the gaseous organic solvent. Therefore, the organic solvent adsorbent can almost completely separate and adsorb the gaseous organic solvent in the mixed medium that has passed through it, and the separated high-purity gaseous carbon dioxide can rapidly pass through the organic solvent adsorbent and flow out continuously. Subsequently, by further raising the temperature to 150-300°C, the adsorption equilibrium concentration of the organic solvent adsorbent for the organic solvent is reduced, promoting the desorption of the organic solvent from the organic solvent adsorbent. Furthermore, since activated carbon adsorbents and molecular sieve adsorbents with pore sizes in the range of 0.7 nm-0.9 nm do not chemically react with organic solvents, the desorbed organic solvent can be recovered through the organic solvent collection port and reused.

[0016] As a preferred technical proposal, a supercritical wafer cleaning / drying medium recovery method further includes: A gas supply step provides a supercritical cleaning / drying medium to be used in the cleaning / drying step by pressurizing and heating the gaseous cleaning / drying medium separated in the adsorption step and / or an external medium supplied from an external gas source to obtain a supercritical cleaning / drying medium, The process includes a pressure adjustment step in which the gaseous cleaning / drying medium obtained in the adsorption step is pressurized and transported, and the pressure of the pressurized cleaning / drying medium is adjusted to be the same as the pressure of the external medium before the gas supply step.

[0017] According to this proposed technology, since some of the cleaning / drying medium remains on the wafer surface, some loss of the cleaning / drying medium occurs during the cycle. However, by supplying a mixed gas from an external gas source and the gaseous cleaning / drying medium obtained in the adsorption step, it is possible to achieve the repeated use of the cleaning / drying medium and replenish the loss of the cleaning / drying medium during the cycle, thereby maintaining the amount of supercritical medium used for cleaning / drying in the cleaning / drying step after multiple cycles.

[0018] Furthermore, since the cleaning / drying medium obtained in the adsorption step is in a low-pressure gaseous state and flows slowly, the flow rate of the cleaning / drying medium can be accelerated by pressurizing it in the pressure adjustment step, and then the pressure before executing the gas supply step can be matched with the pressure of the external gas source by pressure adjustment, thereby stabilizing the pressure of the gaseous cleaning / drying medium entering the gas supply step. Here, the external medium stored in the external gas source may be a gaseous or liquid medium.

[0019] A second aspect of the present invention provides a supercritical wafer cleaning / drying medium recovery system comprising: a cleaning / drying device that houses a wafer and dissolves and removes organic solvents adhering to the wafer using a supercritical cleaning / drying medium to obtain a mixed medium carrying the organic solvent; a first pressure reducing valve communicating with the outlet of the cleaning / drying device for reducing the pressure of the mixed medium to a first pressure; and an adsorption / desorption unit that houses an organic solvent adsorbent and communicates with the outlet of the first pressure reducing valve, the adsorption / desorption unit having a first heating device for heating the mixed medium that has entered the adsorption / desorption unit to a first temperature to obtain a gaseous mixed medium, the gaseous mixed medium coming into contact with the organic solvent adsorbent, the organic solvent in the mixed medium being adsorbed and concentrated by the organic solvent adsorbent and separated from the cleaning / drying medium.

[0020] As a preferred technical solution, the adsorption / desorption unit includes a plurality of adsorbers containing an organic solvent adsorbent and a first heating device. The plurality of adsorbers are provided in parallel, the inlets of the plurality of adsorbers communicate with the outlet of the first pressure reducing valve, and an organic solvent collection port communicates with the solvent outlets of the plurality of adsorbers. The first heating device is provided around the plurality of adsorbers and is used to control the temperature of the plurality of adsorbers to a first temperature or a second temperature higher than the first temperature.

[0021] As a preferred technical solution, the supercritical wafer cleaning / drying medium recovery system further includes a purifier that communicates with the medium outlets of the plurality of adsorbers and removes the organic solvent adsorbent pellets in the cleaning / drying medium.

[0022] As a preferred technical solution, the supercritical wafer cleaning / drying medium recovery system further includes a gas supply unit that communicates with the medium outlet of the adsorption / desorption unit and the inlet of the cleaning / drying device, pressurizes and raises the temperature of the cleaning / drying medium flowing out of the adsorption / desorption unit to obtain a supercritical cleaning / drying medium for use in the cleaning / drying device, an external gas source whose outlet communicates with the inlet of the gas supply unit, and a pressure adjustment device that communicates with the medium outlet of the adsorption / desorption unit and the inlet of the external gas source and has a compressor and a second pressure reducing valve that communicate in sequence along the fluid flow direction.

Brief Description of the Drawings

[0023] [Figure 1] It is a flowchart of a supercritical wafer cleaning / drying medium recovery method according to an embodiment of the present invention. [Figure 2] It is a concentration diagram of isopropanol organic solvent in a mixed medium adsorbed on a NaY molecular sieve according to an embodiment of the present invention. [Figure 3] It is a structural schematic diagram of a supercritical wafer cleaning / drying medium recovery system applied to an embodiment of the present invention. [Figure 4] It is a flowchart of another supercritical wafer cleaning / drying medium recovery method according to an embodiment of the present invention. [Figure 5]This is a schematic diagram of the structure of another supercritical wafer cleaning / drying medium recovery system applied to embodiments of the present invention. [Modes for carrying out the invention]

[0024] The present invention will be described in more detail below with reference to specific embodiments and drawings. The realization of the present invention is not limited to the embodiments described below, and any modifications, substitutions, combinations, and improvements based on the technical idea of ​​the present invention, adopted within the scope of the knowledge of those skilled in the art, are all within the scope of protection of the present invention.

[0025] First Embodiment As shown in Figure 1, a first embodiment of the present invention is a method for recovering a supercritical wafer cleaning / drying medium, A cleaning / drying step S1 involves dissolving and removing organic solvents adhering to the wafer using a supercritical cleaning / drying medium to obtain a mixed medium supporting the organic solvent, After the washing / drying step S1, a depressurization step S2 is performed to reduce the pressure of the mixed medium to a first pressure, After the depressurization step S2, the depressurized mixed medium is heated to a first temperature to obtain a gaseous mixed medium, the gaseous mixed medium comes into contact with the organic solvent adsorbent in the adsorbent, the organic solvent in the mixed medium is adsorbed and concentrated by the organic solvent adsorbent, and separated from the washing / drying medium in the adsorption step S3. The process involves determining whether the organic solvent adsorbent in the first adsorbent has reached the adsorption threshold, and if it has, switching the adsorbent from the first adsorbent to the second adsorbent in the adsorption step S3 in an adsorbent switch step S4. After the adsorbent switching step S4, the organic solvent adsorbent in the first adsorbent is heated to the second temperature, and after the organic solvent is desorbed from the organic solvent adsorbent in the first adsorbent, it is discharged from the first adsorbent and flows into the organic solvent collection port in a desorption step S5. The process includes a purification step S6 to remove organic solvent adsorbent pellets in the washing / drying medium separated in the adsorption step S3.

[0026] In this invention, the "organic solvent adsorbent" may be any adsorbent that highly selectively adsorbs organic solvents. Preferably, an activated carbon adsorbent or a molecular sieve adsorbent with a pore size in the range of 0.7 nm to 0.9 nm may be selected. For example, if the washing / drying medium is carbon dioxide and the organic solvent is isopropanol (IPA), a NaY molecular sieve may be selected as the organic solvent adsorbent. The NaY molecular sieve has a very high adsorption rate for gaseous organic solvents. As shown in Figure 2, when the gaseous mixed medium passes through the NaY molecular sieve, the isopropanol concentration in the gaseous mixed medium rapidly decreases to almost zero. In other words, most of the isopropanol is adsorbed and concentrated on the NaY molecular sieve without affecting the normal passage of carbon dioxide gas, thereby achieving separation of gaseous carbon dioxide and gaseous isopropanol.

[0027] The supercritical cleaning / drying medium may be any medium capable of dissolving organic solvents on the wafer surface. Preferably, the cleaning / drying medium is carbon dioxide, as supercritical carbon dioxide has a surface tension of 0, which allows for good dissolution of organic solvents and removal of solvent residue from the wafer surface.

[0028] Here, the organic solvent can undergo adsorption and desorption with the organic solvent adsorbent under specific adsorption environmental parameters (an environment consisting of one or more elements such as specific pressure, temperature, and atmosphere). In this embodiment, the progress of adsorption and desorption of the organic solvent is preferably controlled by controlling the pressure and temperature. Specifically, the adsorption step S3 is performed at a first pressure and a first temperature, and the desorption step S5 is performed at a first pressure and a second temperature, where the second temperature is greater than the first temperature. More preferably, the first pressure in the adsorption step S3 is 3-9 MPa, the first temperature is 30-90°C, and the second temperature in the desorption step S5 is 150-300°C. At the first pressure and temperature, carbon dioxide in the mixed medium is in a subcritical gaseous state and is almost immiscible with the gaseous organic solvent, making it easy to separate from the carbon dioxide. In this case, the organic solvent adsorbent has a high adsorption equilibrium concentration with respect to the gaseous organic solvent, which makes it easier to almost completely separate and adsorb the gaseous organic solvent in the mixed medium with the organic solvent adsorbent. This reduces the loss of the washing / drying medium during separation and allows for the continuous separation and recovery of high-purity washing / drying medium. On the other hand, at the first pressure and second temperature, the adsorption equilibrium concentration of the organic solvent adsorbent with respect to the organic solvent decreases, promoting the desorption of the organic solvent from the organic solvent adsorbent. By simply maintaining the pressure and adjusting the temperature, the separation of the washing / drying medium and the adsorption of the organic solvent in the mixed medium can be achieved, allowing for more flexible control of the separation and recovery process.

[0029] Figure 3 shows a supercritical wafer cleaning / drying medium recovery system applied to the supercritical wafer cleaning / drying medium recovery method according to this embodiment. As shown in Figure 3, the supercritical wafer cleaning / drying medium recovery system includes a flow path in which a cleaning / drying device 4, a first pressure reducing valve 5, an adsorption / desorption unit 100, and a purifier 9 are sequentially connected.

[0030] Here, the cleaning / drying equipment 4 is a specific location where the cleaning or drying of the wafer is completed. For example, the cleaning / drying equipment 4 may be formed as a cleaning tank with openings at both ends, with a wafer mounting structure provided inside the tank, and a supercritical cleaning / drying medium flowing into the cleaning tank from one end opening, flowing over the surface of the wafer mounted inside the tank, and then flowing out from the other end of the cleaning tank.

[0031] The first pressure reducing valve 5, which is connected to the outlet of the washing / drying equipment 4, is a component that has the function of reducing the pressure of the fluid medium, and includes, but is not limited to, pressure reducing valves that can control the outlet pressure to a constant level in the conventional sense, and needle valves that have a throttling function.

[0032] The adsorption / desorption unit 100 is connected to the outlet of the first pressure reducing valve 5 and includes an adsorbent and a first heating device 6, with an organic solvent adsorbent built into the adsorbent. Preferably, the adsorption / desorption unit has a first adsorbent 7 and a second adsorbent 8 arranged in parallel, and the first heating device 6 is provided around the first adsorbent 7 and the second adsorbent 8 and is a component that has the function of raising the temperature of the fluid medium, and includes, but is not limited to, electric heating, fuel heating, and fluid heat exchange with the second medium.

[0033] The purifier 9 is connected to the medium outlets of the first adsorbent 7 and the second adsorbent 8 of the adsorption / desorption unit 100, and is used to purify the gaseous washing / drying medium after desorption and to filter out any remaining organic solvent adsorbent.

[0034] Specifically, the cleaning / drying equipment performs the cleaning / drying step S1, and the supercritical cleaning / drying medium enters the cleaning / drying equipment 4 containing the wafer, where the solvent on the wafer surface is cleaned and removed to obtain a mixed medium carrying the solvent. Next, the depressurization step S2 is performed, and the mixed medium that flows out of the cleaning / drying equipment first enters the first depressurization valve 5. The supercritical cleaning / drying medium is depressurized by the first depressurization valve 5 and then reaches a first pressure of 3-9 MPa at the outlet of the first depressurization valve 5. Subsequently, the adsorption step S3 is performed, introducing the mixed medium at a first pressure into the adsorption / desorption unit 100. The mixed medium is heated by the first heating device 6 in the adsorption / desorption unit 100 to a first temperature of 30-90°C. The gaseous mixed medium at the first pressure and temperature is then introduced into the first adsorbent 7 and brought into contact with the organic solvent adsorbent. The organic solvent is adsorbed onto the organic solvent adsorbent, and the cleaning / drying medium continuously passes through the organic solvent adsorbent. Finally, the purification step S6 is performed, and the cleaning / drying medium flows into the purifier 9 from the medium outlet of the first adsorbent 7 or the second adsorbent 8. The cleaning / drying medium separated in the adsorption step S3 is filtered, any detached adsorbent pellets are removed, and the separation of the high-purity cleaning / drying medium is completed.

[0035] After continuously performing the adsorption step S3 for a certain period of time, the adsorbent switching step S4 is performed to determine whether the organic solvent adsorbent in the first adsorbent 7 has reached the adsorption threshold. The adsorption threshold here may be the adsorption saturation amount of the organic solvent adsorbent in the first adsorbent 7, or the amount of adsorption when the adsorption rate of the organic solvent adsorbent decreases, and is not limited to this. If the organic solvent adsorbent in the first adsorbent 7 has reached the adsorption threshold, the adsorbent in the adsorption step S3 is switched to the second adsorbent 8. Simultaneously with the second adsorbent 8 performing the adsorption step S3, the first adsorbent 7 performs the desorption step S5, raising the temperature of the first adsorbent 7 to the second temperature of 150-300°C using the first heating device 6. At this time, the adsorption equilibrium concentration of the organic solvent adsorbent in the first adsorbent 7 decreases, and after the organic solvent is desorbed, it flows out from the organic solvent collection port 13 via the solvent outlet of the first adsorbent 7.

[0036] As described above, the washing / drying medium is not blocked or concentrated throughout the entire adsorption process, and the organic solvent adsorbent has high selectivity for organic solvents, allowing for almost complete adsorption of all organic solvents in the mixed medium. This ensures high purity in the separation of the washing / drying medium while reducing losses in the separation process.

[0037] Furthermore, by adsorbing organic solvents with an organic solvent adsorbent, and by switching between the first adsorbent 7 and the second adsorbent 8 in the adsorbent switching step S4, adsorption and desorption can be performed simultaneously in the first adsorbent 7 and the second adsorbent 8, improving the separation efficiency of the washing / drying medium and maintaining the continuous outflow of high-purity washing / drying medium, thereby realizing the sustained recovery of high-purity washing / drying medium.

[0038] Second Embodiment Preferably, Figure 4 shows a flowchart of another supercritical wafer cleaning / drying medium recovery method according to this embodiment. As shown in Figure 4, the supercritical wafer cleaning / drying medium recovery method further includes: The gas supply step S7 provides a supercritical cleaning / drying medium used in the cleaning / drying step S1 by pressurizing and heating the gaseous cleaning / drying medium separated in the adsorption step S3 and / or an external medium supplied from an external gas source to obtain a supercritical cleaning / drying medium, The process includes transporting the gaseous cleaning / drying medium obtained in the adsorption step S3 under pressure, and adjusting the pressure of the pressurized cleaning / drying medium to be the same as the pressure of the external medium before the gas supply step S7, in a pressure adjustment step S8.

[0039] Accordingly, Figure 5 is a schematic diagram of a preferred supercritical wafer cleaning / drying medium recovery system. As shown in Figure 5, the supercritical wafer cleaning / drying medium recovery system further includes a gas supply unit 200, an external gas source 1, and a pressure regulating device (including a compressor 10 and a second pressure reducing valve 11 connected in order). The gas supply unit 200 communicates with the medium outlet of the adsorption / desorption unit 100 and the inlet of the cleaning / drying equipment 4. The cleaning / drying medium flowing out from the medium outlet of the adsorption / desorption unit 100 is pressurized and heated to obtain a supercritical cleaning / drying medium for use in the cleaning / drying equipment 4. The outlet of the external gas source 1 communicates with the inlet of the gas supply unit 200, the compressor 10 in the pressure regulating device communicates with the outlet of the adsorption / desorption unit, and the second pressure reducing valve 11 communicates with the inlet of the external gas source 1.

[0040] Here, as shown in Figure 5, the gas supply unit 200 may be a unit combining a pressure boosting pump 2 and a second heating device 3. The pressure boosting pump 2 is a device that can increase the pressure of a fluid working medium and output it, and its form includes, but is not limited to, positive displacement pumps and reciprocating pumps.

[0041] The external gas source 1 is a gas source in a broad sense and can supply a gaseous or liquid working medium to the supercritical wafer cleaning / drying medium recovery system. In some embodiments, the external gas source 1 may be a gas supply passage formed by connecting a group of gas cylinders and a chiller, or in other embodiments, the external gas source 1 may be a gas supply system consisting of a storage tank and its attached cooling device. The pressure regulating device is a unit combining a compressor 10 and a second pressure reducing valve 11. The compressor 10 is a device that can increase the pressure of a gaseous medium, and its form includes, but is not limited to, a centrifugal compressor and an axial flow compressor. The outlet pressure of the compressor 10 is slightly higher than the starting pressure of the second pressure reducing valve 11, and the outlet pressure of the second pressure reducing valve 11 is the same as the pressure of the external medium supplied from the external gas source 1.

[0042] In this embodiment, the system's continuous circulating operation is maintained by replenishing the media loss in the system with the external gas source 1. Furthermore, the pressure increase by the compressor 10 promotes acceleration of the working medium, thereby facilitating backward flow. The second pressure reducing valve 11 controls the outlet pressure of the pressure regulating device to match the outlet pressure of the external gas source 1. As a result, the medium at the outlet of the pressure regulating device is mixed with the medium from the external gas source at equal pressure before being supplied to the gas supply unit 200, thus maintaining stable and safe operation of the system.

[0043] Specifically, the gas supply step S7 is executed starting from the external gas source 1, supplying the cleaning / drying medium into the system from the external gas source 1. The cleaning / drying medium is pressurized by the pressure boosting pump 2 and heated by the second heating device 3 to reach a supercritical state of high temperature and pressure. Subsequently, steps S1-S6 are executed sequentially in the same procedure as in the first embodiment, followed by the pressure adjustment step S8. The high-purity gaseous cleaning / drying medium flowing out of the purifier 9 flows through the compressor 10 and the second pressure reducing valve 11. The flow of the low-pressure gaseous medium is slow, but after being pressurized by the compressor, the rapid flow of the medium is promoted. The pressure is reduced to the same pressure as the external gas source 1 at the second pressure reducing valve 11, allowing the medium to enter the external gas source 1 stably. After mixing with the external medium supplied from the external gas source 1, the gas supply step S7 is executed cyclically again.

[0044] In another preferred embodiment of the present invention, the supercritical wafer cleaning / drying medium recovery system further includes a blowdown valve 12 provided in any of the system's pipelines for blowing down the medium in special or emergency situations.

[0045] The foregoing are merely preferred embodiments of the present invention and do not limit it. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are all included within the scope of protection of the present invention. [Explanation of symbols]

[0046] 100 Suction / Detachment Units 200 gas supply units 1. External gas source 2. Booster pump 3. Second heating device 4. Washing / Drying Equipment 5. First pressure reducing valve 6. First heating device 7. First adsorbent 8. Second adsorbent 9. Purifier 10 Compressors 11. Second pressure reducing valve 12 Blowdown valve 13. Organic solvent collection port.

Claims

1. A method for cleaning / drying a supercritical wafer and recovering the medium, A cleaning / drying step in which an organic solvent adhering to a wafer is dissolved and removed using a supercritical cleaning / drying medium to obtain a mixed medium supporting the organic solvent, After the washing / drying step, a depressurization step is performed to reduce the pressure of the mixed medium to a first pressure, After the vacuum step, the vacuum-reduced mixed medium is heated to a first temperature to obtain a gaseous mixed medium, the gaseous mixed medium comes into contact with an organic solvent adsorbent in an adsorbent, the organic solvent in the mixed medium is adsorbed and concentrated by the organic solvent adsorbent, and separated from the washing / drying medium in an adsorption step, A method for recovering a supercritical wafer cleaning / drying medium, characterized by including the following:

2. An adsorbent switching step is performed to determine whether the organic solvent adsorbent in the first adsorbent has reached an adsorption threshold, and if it has, to switch the adsorbent in the adsorption step from the first adsorbent to the second adsorbent, After the adsorbent switching step, the organic solvent adsorbent in the first adsorbent is heated to a second temperature, and after the organic solvent is desorbed from the organic solvent adsorbent in the first adsorbent, it is discharged from the first adsorbent and flows into the organic solvent collection port in a desorption step. The supercritical wafer cleaning / drying medium recovery method according to claim 1, further comprising the above.

3. The supercritical wafer cleaning / drying medium recovery method according to claim 1, further comprising a purification step of removing organic solvent adsorbent pellets in the cleaning / drying medium separated in the adsorption step.

4. The supercritical wafer cleaning / drying medium recovery method according to claim 2, characterized in that the organic solvent adsorbent is an activated carbon adsorbent or a molecular sieve adsorbent having a pore size in the range of 0.7 nm to 0.9 nm, and the cleaning / drying medium is carbon dioxide.

5. The supercritical wafer cleaning / drying medium recovery method according to claim 4, characterized in that the first pressure is 3-9 MPa, the first temperature is 30-90°C, and the second temperature is 150-300°C.

6. A gas supply step provides a gas that supplies the supercritical cleaning / drying medium used in the cleaning / drying step by pressurizing and heating the gaseous cleaning / drying medium separated in the adsorption step and / or an external medium supplied from an external gas source to obtain the cleaning / drying medium in a supercritical state, A pressure adjustment step is performed to pressurize and transport the gaseous cleaning / drying medium obtained in the adsorption step, and to adjust the pressure of the pressurized cleaning / drying medium to be the same as the pressure of the external medium before the gas supply step. The supercritical wafer cleaning / drying medium recovery method according to claim 1, further comprising the above.

7. A supercritical wafer cleaning / drying medium recovery system, A cleaning / drying apparatus that contains a wafer and uses a supercritical cleaning / drying medium to dissolve and remove organic solvents adhering to the wafer, thereby obtaining a mixed medium supporting the organic solvent, A first pressure reducing valve is connected to the outlet of the washing / drying equipment and reduces the pressure of the mixed medium to a first pressure, A supercritical wafer cleaning / drying medium recovery system comprising: an adsorption / desorption unit having an organic solvent adsorbent built in and communicating with the outlet of a first pressure reducing valve, the adsorption / desorption unit having a first heating device for heating the mixed medium that has entered the adsorption / desorption unit to a first temperature to obtain a gaseous mixed medium, the gaseous mixed medium coming into contact with the organic solvent adsorbent, the organic solvent in the mixed medium being adsorbed and concentrated by the organic solvent adsorbent, and separated from the cleaning / drying medium; and

8. The adsorption / desorption unit comprises a plurality of adsorbents, each containing the organic solvent adsorbent, and the first heating device. The supercritical wafer cleaning / drying medium recovery system according to claim 7, characterized in that a plurality of adsorbents are provided in parallel, the inlets of the plurality of adsorbents are connected to the outlets of the first pressure reducing valve, the solvent outlets of the plurality of adsorbents are connected to organic solvent collection ports, and the first heating device is provided around the plurality of adsorbents and is used to control the temperature of the plurality of adsorbents to a first temperature or a second temperature higher than the first temperature.

9. The supercritical wafer cleaning / drying medium recovery system according to claim 8, further comprising a purifier that communicates with the medium outlets of a plurality of adsorbents and removes organic solvent adsorbent pellets from the cleaning / drying medium.

10. A gas supply unit is connected to the media outlet of the adsorption / desorption unit and the inlet of the washing / drying equipment, and includes a pressure boosting pump and a second heating device. An external gas source whose outlet is connected to the inlet of the gas supply unit, A pressure regulating device having a compressor and a second pressure reducing valve, which are in communication with the medium outlet of the adsorption / desorption unit and the inlet of the external gas source, and which are in sequential communication along the direction of fluid flow, The supercritical wafer cleaning / drying medium recovery system according to claim 9, further comprising the above.

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