Supercritical fluid cleaning system and cleaning method

Abstract

The present invention provides a supercritical fluid cleaning system and a cleaning method. The supercritical fluid cleaning system includes a cleaning chamber that contains a sample to be cleaned having a liquid to be cleaned attached to at least a part of its surface, and a supercritical cleaning fluid supply device that supplies a cleaning fluid required for cleaning, drives the cleaning fluid to enter the cleaning chamber so that the pressure of the cleaning fluid increases to a level higher than the supercritical pressure and the temperature increases to a level higher than the supercritical temperature, oscillatingly cleans the sample to be cleaned by the action of the fluctuating pressure, and drives the supercritical cleaning fluid to flow out of the cleaning chamber so that the pressure does not decrease to below the supercritical pressure. The present invention changes the pressure of the cleaning fluid, so that the cleaning fluid oscillates and cleans the sample to be cleaned by the pressure fluctuation method, improves the dissolution rate of the supercritical cleaning fluid in the liquid to be cleaned during the pressurization process, and can carry out the liquid to be cleaned during the depressurization process, thereby improving the cleaning efficiency and being suitable for cleaning a large amount of samples to be cleaned at once.

Description

[Technical field]

[0001] The present invention relates to the technical field of cleaning equipment, and more particularly to a supercritical fluid cleaning system and method. [Background technology]

[0002] Semiconductor wafers are the most important materials in the semiconductor industry, and the requirements for their surface cleanliness are quite strict. In the cleaning process of semiconductor wafers, the drying process of the wafer surface is an essential part. Even after the wafer cleaning process is completed, a small amount of liquid (usually water) remains on the wafer surface. Therefore, by thoroughly removing the liquid on the wafer surface through drying, it is possible to prevent recontamination of the wafer surface and the occurrence of defects such as "watermarks", which will affect the performance of the wafer and reduce its yield.

[0003] Currently, many drying techniques for wafer surfaces have been developed, mainly including centrifugal dehydration drying, Marangoni drying, and drying using isopropyl alcohol (IPA). IPA drying is mainly used for wafers that are batch cleaned, and in this method, the wafer must be immersed in IPA liquid before drying. Due to their mutual solubility, the water on the wafer surface dissolves in IPA and becomes liquid IPA. IPA is separated from the wafer surface by multiple actions such as gravity, surface tension, and volatilization, achieving the drying of the wafer surface.

[0004] In the field of wafer cleaning, as semiconductor process nodes continue to shrink and pattern aspect ratios become larger and larger, when IPA separates from the wafer surface, the surface tension will destroy the wafer pattern structure, and even cause sticking, collapse, etc. in the structure, resulting in the failure of the wafer product.

[0005] In the conventional method of dealing with residual IPA on the wafer surface, the IPA on the wafer surface is gradually dissolved using supercritical carbon dioxide fluid, which has a surface tension of almost zero, and finally all of the IPA on the wafer surface is replaced with supercritical carbon dioxide fluid, and finally the supercritical carbon dioxide fluid on the wafer surface is evaporated and removed from the wafer surface by lowering the temperature and reducing the pressure. However, this method is limited by the dissolution rate of IPA in supercritical carbon dioxide, and it is not possible to dry a large number of wafers at once in a short period of time, resulting in poor drying efficiency. Summary of the Invention

[0006] In response to the above problems, the present invention provides a supercritical fluid cleaning system and cleaning method that allows the cleaning fluid to perform cleaning in the form of oscillation by changing the pressure of the cleaning fluid through pressurization or depressurization, improves the dissolution rate of the supercritical cleaning fluid in the liquid to be cleaned during the pressurization process, and can carry out the liquid to be cleaned during the depressurization process, improving cleaning efficiency and suitable for cleaning samples to be cleaned all at once.

[0007] The present invention provides a supercritical fluid cleaning system including a cleaning chamber for accommodating a sample to be cleaned having a liquid to be cleaned adhering to at least a portion of its surface, and a supercritical cleaning fluid supply device for supplying cleaning fluid required for cleaning, driving the cleaning fluid to enter the cleaning chamber so that the pressure of the cleaning fluid increases and becomes higher than the supercritical pressure and the temperature of the cleaning fluid increases and becomes higher than the supercritical temperature, oscillatingly cleaning the sample to be cleaned by the action of the fluctuating pressure, and driving the supercritical cleaning fluid to flow out of the cleaning chamber so that the pressure does not decrease below the supercritical pressure.

[0008] The present invention changes the pressure of the cleaning fluid, so that the cleaning fluid oscillates and cleans the sample to be cleaned by a pressure fluctuation method, improves the dissolution rate of the supercritical cleaning fluid in the liquid to be cleaned during the pressurization process, and carries out the liquid to be cleaned during the depressurization process, thereby improving the cleaning efficiency and being suitable for cleaning a large number of samples to be cleaned at once.

[0009] In a preferred technical solution of the present invention, the supercritical cleaning fluid supplying device includes a cavity, a heating device and a cooling device, the outlet of the cavity is connected to the inlet of the heating device, the outlet of the heating device is connected to the inlet of the cleaning chamber, the outlet of the cleaning chamber is connected to the outlet of the cooling device, and the outlet of the cooling device is connected to the inlet of the cavity; The cavity contains a cleaning fluid, a piston is provided within the cavity, one side of the piston is connected to a drive device, a space occupied by the cleaning fluid is formed between the side of the piston away from the drive device and the inner wall of the cavity, and the piston is driven by the drive device to move along the inner wall of the cavity to increase or decrease the pressure of the cleaning fluid, The heating device heats the cleaning fluid to make it a supercritical cleaning fluid; The cooling device cools the supercritical cleaning fluid in which the liquid to be cleaned is dissolved, which flows out of the cleaning chamber.

[0010] In a preferred technical solution of the present invention, the present invention further includes a separator for separating the washing fluid from the liquid to be washed, the separator includes a first connection port, a second connection port and a third connection port, the cavity is provided with a first inlet and a first outlet, the first inlet and the first outlet are respectively located at both ends of the cavity, the first inlet is provided relatively far from the piston, and the first outlet is relatively close to the piston, the first connection port is connected to the first outlet through a first pipe, and the second connection port is connected to the first outlet through a second pipe. the first pipe is provided with a first check valve for controlling one-way flow of fluid from the cavity to the separator, and the second pipe is provided with a second check valve for controlling one-way flow of cleaning fluid from the separator to the cavity; when the piston is located on a side of the first outlet away from the first inlet, the separator is in communication with the space occupied by the cleaning fluid, and when the piston is located between the first inlet and the first outlet, the separator is not in communication with the space occupied by the cleaning fluid.

[0011] According to this technical solution, the separator is connected to the cavity through two pipelines, and the first and second check valves control the flow direction of the fluid, thereby realizing convenient and controllable circulation of the cleaning fluid and simplifying the structure of the supercritical fluid cleaning system. In addition, by changing the position of the piston, the separator can be connected or disconnected from the space occupied by the fluid, resulting in a simple structure, convenient operation, and simplified system configuration.

[0012] In a preferred technical solution of the present invention, the system further includes a third check valve installed between the cavity and the heating device, a fourth check valve installed between the heating device and the cleaning chamber, and a fifth check valve installed between the cooling device and the cavity. According to this technical solution, the installation of a check valve can prevent the liquid from circulating and affecting the cleaning effect.

[0013] In a preferred technical solution of the present invention, the cleaning fluid refilling pipe is further included, the outlet of the cleaning fluid refilling pipe is connected to the pipe between the outlet of the cavity and the inlet of the heating device, and the cleaning fluid refilling pipe is further provided with an on-off valve.

[0014] According to this technical solution, the cleaning fluid refilling pipe has a simple structure, and can refill the fluid in the fluid supply device as needed to meet the cleaning fluid required for cleaning. In a preferred technical solution of the present invention, the drive device is an electric drive rod or a flywheel in a Stirling cycle system drivingly connected to the piston via a link.

[0015] According to this technical solution, the volume of the cavity is changed by driving the piston with an electric driving rod, which is simple and easy to operate, and the operation efficiency of the cleaning system is improved by the electric driving.The volume of the cavity is changed by driving the piston with a link using a flywheel in the Stirling cycle system, so as long as there is a specific external heat source, there is no need to separately arrange a power source to move the piston in the cavity.

[0016] In a preferred technical solution of the present invention, the supercritical cleaning fluid supply device is one or more.

[0017] According to this technical solution, by arranging a supercritical fluid supply device in one cleaning chamber, oscillatory cleaning can be realized under different pressure fluctuation ranges, thereby improving the applicability of the cleaning system to different supercritical cleaning fluids and liquids to be cleaned, and improving the cleaning efficiency. In a preferred technical solution of the present invention, the supercritical cleaning fluid supplying device includes an expansion chamber, a heating device, a regenerator, a cooling device and a compression chamber, which are connected in sequence to form a Stirling cycle, and the inlet of the cleaning chamber is connected to a pipe between the outlet of the heating device and the regenerator, and the outlet of the cleaning chamber is connected to a pipe between the regenerator and the cooling device.

[0018] In a preferred technical solution of the present invention, the cleaning fluid is carbon dioxide and the sample to be cleaned is a wafer.

[0019] According to this technical solution, supercritical carbon dioxide, which has a surface tension of almost zero, is used as a cleaning fluid and combined with oscillation caused by pressure fluctuations to clean wafers, thereby solving the problems of reduced IPA dissolution efficiency and easy damage to wafer structures in conventional wafer cleaning.

[0020] The present invention provides a method for cleaning a supercritical fluid cleaning system, comprising the steps of: a pressurizing step of driving the cleaning fluid to flow through the cleaning chamber at an increasing pressure above supercritical pressure; a heating step of heating the cleaning fluid to a supercritical cleaning fluid; A cleaning step in which the supercritical cleaning fluid oscillates and cleans the sample to be cleaned under the action of a fluctuating pressure; a depressurizing step of driving the supercritical cleaning fluid having the liquid to be cleaned dissolved therein to flow out of the cleaning chamber so that the pressure of the supercritical cleaning fluid does not drop below the supercritical pressure; The present invention further provides a method for cleaning a supercritical fluid cleaning system, comprising a cooling step of cooling the supercritical cleaning fluid having the liquid to be cleaned dissolved therein to obtain the liquid to be cleaned and the cleaning fluid. [Brief description of the drawings]

[0021] [Figure 1] 1 is a structural schematic diagram of a supercritical fluid cleaning system according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram of a first type pressure change law in the first embodiment of the present invention. [Diagram 3] FIG. 4 is a schematic diagram of a second type pressure change law in the first embodiment of the present invention. [Figure 4] FIG. 4 is a schematic diagram of a third type of pressure change law in the first embodiment of the present invention. [Diagram 5] FIG. 5 is a structural schematic diagram of a supercritical fluid cleaning system according to a second embodiment of the present invention. [Figure 6] FIG. 11 is a schematic diagram showing an example of a pressure change law in the second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The technical solutions in the embodiments of the present invention will be described below clearly and completely in accordance with the drawings in the embodiments of the present invention, but it is clear that the described embodiments are only a part of the embodiments of the present invention, and are not all of the embodiments. Based on the embodiments of the present invention, all other embodiments that a person skilled in the art can obtain without creative work are all within the protection scope of the present invention.

[0023] (First embodiment) The present invention provides a supercritical fluid cleaning system including one or more medium circulation circuits. Each medium circulation circuit includes a cavity 1, a heating device 2, a cleaning chamber 3, and a cooling device 4, which are connected in sequence via a pipe. The heating device 2 is used to heat the cleaning fluid to make it a supercritical cleaning fluid. The cleaning chamber 3 contains a sample to be cleaned (not shown) having a liquid to be cleaned attached to at least a part of its surface and a supercritical cleaning fluid, and the supercritical cleaning fluid oscillates and cleans the sample to be cleaned under the action of a fluctuating pressure. The cooling device 4 is used to cool the supercritical cleaning fluid that dissolves the liquid to be cleaned and flows out of the cleaning chamber 3. A piston 13 is provided in the cavity 1, and one side of the piston 13 is connected to a driving device. A space occupied by the cleaning fluid is formed between the side of the piston 13 away from the driving device and the inner wall of the cavity 1, and the piston 13 is driven by an electric driving rod 14 to move along the inner wall of the cavity 1 to increase or decrease the pressure of the cleaning fluid, thereby changing the size of the space occupied by the cleaning fluid.

[0024] The present invention changes the pressure of the cleaning fluid by using a means for changing the space occupied by the cleaning fluid in the cavity 1, thereby providing a driving force for the cleaning fluid to flow, and the cleaning fluid oscillates and cleans the sample to be cleaned by the method of pressure fluctuation, thereby improving the dissolution rate of the supercritical cleaning fluid in the liquid to be cleaned during the pressurization process and carrying out the liquid to be cleaned during the depressurization process, thereby improving the cleaning efficiency and being suitable for cleaning a large number of samples to be cleaned at once.

[0025] Specifically, in the embodiment of the present invention, there is no need for pre-heating the cleaning fluid before it enters the medium circulation circuit, and the system configuration in the front stage of the cavity 1 is simplified. In addition, compared to the form in which the cleaning fluid is heated before it enters the medium circulation circuit, the heating device 2 is provided in the pipeline between the outlet of the cavity 1 and the inlet of the cleaning chamber 3, and in cooperation with the cooling device 4, a circulation process of pressurizing, heating, cleaning, decompressing, and cooling the cleaning fluid can be realized, and the sample to be cleaned can be cleaned multiple times by oscillation. Furthermore, the heating device 2 equipped with an automatic temperature control device (not shown) heats the cleaning fluid at the outlet of the cavity 1, and controls the temperature of the cleaning fluid in the heating device 2 to be close to the set temperature, thereby maintaining a constant temperature in the cleaning chamber 3. In the embodiment of the present invention, the pressure of the system (the pressure at each point in the system is the same) does not fall below the supercritical pressure of the cleaning fluid, and both pressurization and decompression are performed on the premise that they do not fall below the supercritical pressure, and the temperature in the cleaning chamber 3 is also prevented from falling below the supercritical temperature of the cleaning fluid. By heating the washing chamber 3, the temperature therein can be maintained above the supercritical temperature of the washing fluid. By installing a pressure sensor in the washing chamber 3 to monitor the pressure therein, the control module can be arranged to increase the pressure in the entire system by replenishing the washing fluid via refill line 71 if the minimum pressure in the washing chamber 3 falls below the supercritical pressure of the washing fluid.

[0026] In a preferred embodiment of the present invention, the driving device is an electric driving rod 14 or a flywheel (not shown) in a Stirling cycle system connected to the piston 13 via a link. Driving the piston with the electric driving rod 14 to change the volume of the cavity 1 is simple and easy to operate, and the electric drive improves the operating efficiency of the cleaning system. Using a flywheel in a Stirling cycle system to drive the piston with a link to change the volume of the cavity requires only a specific external heat source (e.g., a heating device), and does not require a separate power source to move the piston within the cavity 1. The heating device 2 may be in the form of electric heating, solar heating, etc., and the present invention does not limit the heating means.

[0027] Specifically, as shown in FIG. 2, by changing the space occupied by the cleaning fluid in the cavity 1, the pressure variation law of the cleaning fluid in the cavity 1 is as shown in FIG. 2. The section P1-P2 of the pressure variation should be equal to or higher than the supercritical pressure of the cleaning fluid. In the time period t1-t2, the space occupied by the cleaning fluid is increased to realize decompression, and in the time period t2-t3, the space occupied by the cleaning fluid is decreased to realize pressure increase, and one cycle is completed through pressure increase and decompression. The time length of pressure increase and the time length of decompression may be the same or different, and are adjusted according to actual needs. The pressure fluctuates between P1-P2. As shown in FIG. 3, the pressure variation law includes pressure hold in addition to pressure increase and decompression, that is, pressure is held for a certain period of time after pressure increase to a certain pressure, and pressure is held for a certain period of time after pressure reduction to a certain pressure, and the system completes one cycle after pressure increase, pressure hold, pressure reduction, and pressure hold. In the pressure holding mode, the position of the piston 13 is unchanged, and the pressure of the system is also unchanged, so that the supercritical cleaning fluid and the liquid to be cleaned can be better mutually dissolved, and more liquid to be cleaned can be taken out during decompression, improving the cleaning efficiency. The purpose of making the pressure constant is to make the supercritical cleaning fluid and the liquid to be cleaned more mutually dissolved. As shown in FIG. 4, the pressure change law may be such that the pressure is increased or decreased to a predetermined pressure, and then pressure is held, and the system completes one cycle through pressure increase, pressure holding, and pressure reduction. Although not shown, the pressure change law may be such that one cycle is completed through pressure increase, pressure reduction, and pressure holding. Among them, the time order of pressure increase and pressure reduction in one cycle is not limited, and pressure may be increased and then pressure reduced, or pressure may be increased and then pressure reduced, but the pressure change law may be adjusted according to the actual situation by those skilled in the art, and is not limited to the example exemplified in the embodiment of the present invention. In addition, in FIG. 2, FIG. 3, and FIG. 4, the pressure increase and pressure reduction are shown to increase and decrease linearly, but are not limited thereto, and the pressure change curve may change in a sine function, a cosine function, or in other manners.

[0028] In a preferred embodiment of the present invention, the supercritical fluid cleaning system further includes one or more separators 5. The separator 5 is connected to the cavity 1 and is used to separate the cleaning fluid flowing out of the cleaning chamber 3 from the liquid to be cleaned. When the space occupied by the cleaning fluid is expanded, the separator 5 communicates with the space occupied by the cleaning fluid, but when the space occupied by the cleaning fluid is reduced, the separator 5 does not communicate with the space occupied by the cleaning fluid. Furthermore, depending on the state in which the cleaning fluid returns to the cavity 1 after being cooled, the separator 5 may be a gas-liquid separator or a liquid-liquid separator, etc., and the structure of the gas-liquid separator and the liquid-liquid separator can be referred to the normal mechanism of the prior art, and the description will be omitted here. The separated cleaning fluid can be used repeatedly, reducing the cleaning cost. Furthermore, the fluid from which the liquid to be cleaned is separated re-enters the system and circulates, improving the cleanliness of the cleaning fluid and avoiding cleaning the sample to be cleaned with the cleaning fluid contaminated by the liquid to be cleaned. The cleaning fluid of the present invention performs cleaning in a circulating form, realizing the continuity and repeatability of the sample oscillation cleaning, which is advantageous for improving the cleaning efficiency.

[0029] Specifically, each separator 5 includes a first connection port 51, a second connection port 52, and a third connection port 53, the cavity 1 is provided with a first inlet 12 and a first outlet 11, the first inlet 12 and the first outlet 11 are located at both ends of the cavity 1, respectively, the first inlet 12 is provided relatively far from the piston 13, and the first outlet 11 is relatively close to the piston 13, the first connection port 51 is connected to the first outlet 11 via a first pipeline, the second connection port 52 is connected to the first inlet 12 via a second pipeline, the third connection port 53 is an outlet, the first pipeline is provided with a first check valve 61 for controlling the unidirectional flow of fluid from the cavity 1 to the separator 5, and the second pipeline is provided with a second check valve 62 for controlling the unidirectional flow of cleaning fluid from the separator 5 to the cavity 1. When the piston 13 is moved to the first outlet 11 and positioned on the side of the first outlet 11 away from the first inlet (on the left side of the piston 13 in the figure), the separator 5 communicates with the space occupied by the cleaning fluid. At that time, the space occupied by the cleaning fluid expands, and the pressure drops. When the piston 13 is moved to the first inlet 12 and positioned between the first inlet 12 and the first outlet 11, the separator 5 does not communicate with the space occupied by the cleaning fluid. In the embodiment of the present invention, the separator 5 is connected to the cavity 1 through two pipes, and the one-way flow of the fluid is controlled by the first check valve 61 and the second check valve 62, thereby realizing convenient and controllable circulation of the cleaning fluid and simplifying the structure of the supercritical fluid cleaning system. In addition, since the communication or non-communication between the separator 5 and the space occupied by the cleaning fluid is controlled by moving the piston 13, an opening and closing valve is omitted, the structure of the system is simplified, and the cost is reduced.

[0030] In a preferred embodiment of the present invention, two or more medium circulation circuits share one cleaning chamber 3. That is, two or more medium circulation circuits can be arranged for one cleaning chamber 3, so that oscillation cleaning in different pressure fluctuation ranges can be realized and cleaning efficiency and cleaning effect can be improved. The medium circulation circuit is formed by sequentially connecting at least a cavity 1, a heating device 2, a cleaning chamber 3, and a cooling device 4. FIG. 1 shows that two medium circulation circuits are arranged for one cleaning chamber 3, including two cavities 1, two pistons 13, etc. When the system includes multiple medium circulation circuits, the range and rate of pressure change of the system are jointly determined by the scavenging volume, phase difference (0-180°) and moving speed of the piston 13 in the multiple cavities 1, and those skilled in the art can adjust parameters such as the scavenging volume, phase difference, and moving speed of the piston 13 according to the actual situation, and the embodiment of the present invention is not limited thereto. In a preferred embodiment of the present invention, the cleaning fluid refill line 71 is further included, the outlet of which is connected to the line between the outlet of the cavity 1 and the inlet of the heating device 2, and the cleaning fluid refill line 71 is further provided with an on-off valve.

[0031] According to this technical solution, the cleaning fluid can be replenished into the cavity 1 as needed to meet the cleaning fluid required for cleaning. Compared with the case where the supercritical cleaning fluid is directly replenished into the cleaning chamber 3, the cleaning fluid replenishment pipe 71 is installed before the heating device 2, so that the cleaning fluid is heated before being transported into the cleaning chamber 3, and the temperature and pressure of the supercritical cleaning fluid in the cleaning chamber 3 can be guaranteed to be consistent with those of the supercritical cleaning fluid at the outlet of the heating device, which is also advantageous for simplifying the system structure.

[0032] In a preferred embodiment of the present invention, the system further includes a third check valve 63 installed between the cavity 1 and the heating device 2, a fourth check valve 64 installed between the heating device 2 and the cleaning chamber 3, and a fifth check valve 65 installed between the cooling device 4 and the cavity 1. The above means can prevent the liquid from circulating and affecting the cleaning effect.

[0033] In a preferred embodiment of the present invention, the cleaning fluid is carbon dioxide, and the sample to be cleaned is a wafer. The supercritical fluid cleaning system according to the embodiment of the present invention can be applied to cleaning a wafer, and employs supercritical carbon dioxide, which has a surface tension of almost zero, as a cleaning fluid, and cleans the wafer in combination with oscillation due to pressure fluctuation, thereby solving the defects of the conventional wafer cleaning, that is, the efficiency of dissolving IPA is reduced and the wafer structure is easily damaged. Although the present invention has been illustrated by the above example, there is no limitation on the type of cleaning fluid and the type of sample to be cleaned, and those skilled in the art may select other cleaning fluids and samples to be cleaned according to actual needs.

[0034] The present invention provides a method of operating a supercritical fluid cleaning system, comprising the steps of: a pressurizing step of driving the cleaning fluid out of the cavity 1 at an increasing pressure above the supercritical pressure; a heating step in which the pressurized cleaning fluid is heated to a supercritical cleaning fluid, the supercritical cleaning fluid entering the cleaning chamber 3 at varying pressures; A cleaning step in which the supercritical cleaning fluid oscillates and cleans the sample to be cleaned under the action of a fluctuating pressure; a depressurizing step of driving the supercritical cleaning fluid having the liquid to be cleaned dissolved therein to flow out of the cleaning chamber 3 so that the pressure does not drop below the supercritical pressure; a cooling step of cooling the supercritical cleaning fluid in which the liquid to be cleaned is dissolved to obtain the liquid to be cleaned and the cleaning fluid; There is further provided a method of operating a supercritical fluid cleaning system, comprising:

[0035] In a preferred embodiment of the present invention, the method further includes the step of separating the liquid to be washed and the washing fluid, as described below: adjusting the position of the piston 13 so that the piston 13 is located to the left of the first outlet, and the space occupied by the washing fluid communicates with the separator 5, so that the washing fluid and the liquid to be washed in the washing chamber 3 enter the separator 5 through the first outlet 111, the liquid to be washed is discharged from the outlet, and the washing fluid flows into the cavity 1 through the first inlet 112.

[0036] Second embodiment The second embodiment of the present invention provides a supercritical fluid cleaning system. The difference from the first embodiment is that in the first embodiment, the system pressure is reduced by the combined effect of an increase in the volume occupied by the cleaning fluid in the cavity and a decrease in temperature. However, in the second embodiment, the system volume is unchanged, and the pressure is reduced mainly by a decrease in temperature, and circulatory cleaning can be achieved with only an external heat source without requiring a power source. The pressure change law in the second embodiment of the present invention is shown in FIG. 6, but since it is basically the same as the pressure change tendency in the first embodiment, a description thereof will be omitted here.

[0037] Specifically, the supercritical cleaning fluid supply device includes an expansion chamber 81, a heating device 2, a regenerator 82, a cooling device 4 and a compression chamber 83, which are sequentially connected to form a Stirling cycle, and the inlet of the cleaning chamber 3 is connected to a pipeline between the outlet of the heating device 2 and the regenerator 82, and the outlet of the cleaning chamber 3 is connected to a pipeline between the regenerator 82 and the cooling device 4. Furthermore, a sixth check valve 66 is provided in the inlet pipeline of the cleaning chamber 3, and a seventh check valve 67 is provided in the outlet pipeline of the cleaning chamber 3, and the sixth check valve 66 controls the one-way flow of the cleaning fluid from the heating device 2 to the cleaning chamber 3, and the seventh check valve 67 controls the one-way flow of the cleaning fluid from the cleaning chamber 3 to the cooling device 4.

[0038] In the second embodiment of the present invention, the separator 5 is further included. A first connection port and a second connection port of the separator 5 communicate with a pipeline between the cooling device 4 and the compression chamber 83 via a pipeline, and a first check valve 61 and a second check valve 62 are provided in the pipeline corresponding to the first connection port and the second connection port, respectively, to prevent the cleaning fluid dissolving the liquid to be cleaned from entering the compression chamber 83 without passing through the separator.

[0039] In a preferred embodiment of the present invention, the Stirling cycle system is of alpha, beta or gamma type and may be single or double acting.

[0040] Taking the combined system of an α-type Stirling cycle system and a cleaning chamber as an example, in the cleaning method corresponding to the second embodiment of the present invention, in the process of heating up the Stirling cycle at constant volume, the left and right pistons move synchronously to the left, the low-temperature cleaning fluid passes through the regenerator 82 and is heated and pressurized to become a supercritical cleaning fluid, and some of the supercritical cleaning fluid enters the cleaning chamber 3. In the process of cooling down the Stirling cycle at constant volume, the left and right pistons move synchronously to the right, the supercritical cleaning fluid flows out of the cleaning chamber 3 and enters the cooling device 4, the temperature of the supercritical cleaning fluid decreases, and the pressure also decreases. The pressure fluctuation law in the entire circulation process is shown in FIG. 6. During the above operation, the pressure fluctuation range can be adjusted by designing the volume ratio of the two piston cylinders and the phase difference between the two pistons.

[0041] The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. [Explanation of symbols]

[0042] 1 Cavity 11 Exit 1 12 First Entrance 13 Piston 14 Electric drive rod 2 Heating device 3. Washing chamber 4 Cooling device 5 Separator 51 First connection port 52 Second connection port 53 Third Connection Port 61 First check valve 62 Second check valve 63 Third check valve 64 4th check valve 65 5th check valve 66 6th check valve 67 7th check valve 71 Cleaning fluid refill line 81 Expansion chamber 82 Regenerator 83 Compression Chamber

Claims

1. a cleaning chamber for accommodating a sample to be cleaned having a liquid to be cleaned adhering to at least a portion of its surface; and a supercritical cleaning fluid supply device for supplying a cleaning fluid necessary for cleaning, driving the cleaning fluid to enter the cleaning chamber so that the pressure of the cleaning fluid increases to a level higher than the supercritical pressure and the temperature of the cleaning fluid increases to a level higher than the supercritical temperature, oscillatingly cleaning the sample to be cleaned by the action of the fluctuating pressure, and driving the supercritical cleaning fluid to flow out of the cleaning chamber so that the pressure does not decrease to a level lower than the supercritical pressure, the supercritical cleaning fluid supply device includes a cavity, a heating device, and a cooling device, the outlet of the cavity is connected to the inlet of the heating device, the outlet of the heating device is connected to the inlet of the cleaning chamber, the outlet of the cleaning chamber is connected to the outlet of the cooling device, and the inlet of the cooling device is connected to the inlet of the cavity; the cavity accommodates a cleaning fluid, a piston is provided within the cavity, one side of the piston is connected to a driving device, a space occupied by the cleaning fluid is formed between the side of the piston away from the driving device and an inner wall of the cavity, and the piston is driven by the driving device to move along the inner wall of the cavity, thereby increasing or decreasing the pressure of the cleaning fluid; The heating device heats the cleaning fluid to make it a supercritical cleaning fluid, 2. A supercritical fluid cleaning system, comprising: a cooling device for cooling a supercritical cleaning fluid in which the liquid to be cleaned is dissolved and which flows out of the cleaning chamber.

2. The cleaning fluid further includes a separator for separating the cleaning fluid from the liquid to be cleaned, the separator including a first connection port, a second connection port, and a third connection port, the cavity is provided with a first inlet and a first outlet, the first inlet and the first outlet are located at both ends of the cavity, respectively, the first inlet is provided relatively far from the piston, the first outlet is relatively close to the piston, the first connection port is connected to the first outlet via a first pipe line, the second connection port is connected to the first inlet via a second pipe line, and the third connection port is connected to the first outlet via a second pipe line. the connection port is a discharge port, the first pipe is provided with a first check valve for controlling one-way flow of fluid from the cavity to the separator, and the second pipe is provided with a second check valve for controlling one-way flow of cleaning fluid from the separator to the cavity, and when the piston is located on a side of the first outlet away from the first inlet, the separator communicates with a space occupied by the cleaning fluid, and when the piston is located between the first inlet and the first outlet, the separator does not communicate with the space occupied by the cleaning fluid.

2. The supercritical fluid cleaning system according to claim 1.

3. The cleaning apparatus further includes a third check valve installed between the cavity and the heating device, a fourth check valve installed between the heating device and the cleaning chamber, and a fifth check valve installed between the cooling device and the cavity.

3. The supercritical fluid cleaning system according to claim 2.

4. The cleaning fluid supply pipe further includes a cleaning fluid supply pipe, an outlet of the cleaning fluid supply pipe communicates with a pipe between the outlet of the cavity and the inlet of the heating device, and the cleaning fluid supply pipe is further provided with an on-off valve.

2. The supercritical fluid cleaning system according to claim 1.

5. the drive device is an electric drive rod or a flywheel in a Stirling cycle system drivingly connected to the piston via a link; 5. The supercritical fluid cleaning system according to claim 1, wherein the supercritical fluid cleaning system comprises a first insulating layer and a second insulating layer.

6. The supercritical cleaning fluid supply device is one or more.

5. The supercritical fluid cleaning system according to claim 1, wherein the supercritical fluid cleaning system comprises a first insulating layer and a second insulating layer.

7. The cleaning fluid is carbon dioxide and the sample to be cleaned is a wafer.

2. The supercritical fluid cleaning system according to claim 1.

8. a pressurizing step of driving the cleaning fluid to flow through the cleaning chamber at a pressure above supercritical pressure; heating said pressurized cleaning fluid to a supercritical cleaning fluid, the supercritical cleaning fluid entering a cleaning chamber at varying pressures; a cleaning step in which the supercritical cleaning fluid oscillates and cleans the sample to be cleaned under the action of a fluctuating pressure; a depressurizing step of driving the supercritical cleaning fluid having the liquid to be cleaned dissolved therein to flow out of the cleaning chamber so that the pressure does not drop below the supercritical pressure; A cooling step of cooling the supercritical cleaning fluid in which the liquid to be cleaned is dissolved to obtain the liquid to be cleaned and the cleaning fluid.

8. The method for cleaning a supercritical fluid cleaning system according to claim 1,

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