A supercritical carbon dioxide drying apparatus

Abstract

This application provides a supercritical carbon dioxide drying device, relating to the field of precision cleaning and drying technology. The device includes a storage tank, a drying unit, a gas-liquid separator, and a compression subsystem. The drying unit includes a pressure tank and a vacuum tank. A cleaning cylinder is installed through the pressure tank, and the cleaning cylinder contains a control chamber and a cleaning chamber. The cleaning cylinder has a liquid inlet. A first piston in the control chamber, driven by a first driving component, can control the connection between the cleaning chamber and the pressure tank through the liquid inlet. The cleaning chamber is connected to the vacuum tank via a connecting pipe and a first control mechanism. A second control mechanism is installed on the air inlet connected to the cleaning chamber. The pressure tank is connected to the storage tank via a booster pump and a preheater. The vacuum tank is connected to the gas-liquid separator via a first control valve and a first vacuum pump. The cleaning cylinder has an venting pipe connected to the cleaning chamber, and a second control valve and a second vacuum pump are installed on the venting pipe. This device can achieve non-destructive drying with a short drying cycle.

Description

Technical Field

[0001] This invention relates to the field of precision cleaning and drying technology, specifically a supercritical carbon dioxide drying device. Background Technology

[0002] After wet cleaning of integrated circuits (ICs) and MEMS devices, drying wafers with high aspect ratio micro / nano structures (such as tendons and vias) without damage is a significant challenge. In the traditional isopropanol (IPA) displacement drying method, when IPA evaporates, the capillary forces (surface tension) at the gas-liquid interface can cause the delicate nanostructures to collapse, adhere, or be destroyed, and trace amounts of IPA residue may adversely affect the electrical performance of the devices.

[0003] Supercritical carbon dioxide drying technology is a high-end process that utilizes carbon dioxide in a special state to safely remove liquid solvents from materials without creating a gas-liquid interface, thus achieving zero-damage drying. It is a preferred approach for high aspect ratio micro / nano structure wafers. The core process of supercritical carbon dioxide drying involves placing the material to be dried in an autoclave, introducing liquid CO2, and heating and pressurizing it to above 31°C and 7.38 MPa. The supercritical CO2 dissolves and carries away the intermediate solvent in the pores. Then, while maintaining the temperature above the critical point, the pressure is slowly and controllably released, allowing the supercritical CO2 to directly transform into a gas and be discharged, with no gas-liquid interface throughout the entire process.

[0004] While this technology can solve the pain points of IPA drying, there are bottlenecks in its industrial application: the autoclave has extremely high requirements for sealing, while mass production requires frequent handling of wafers. Therefore, in actual work, the autoclave needs to be repeatedly depressurized, ventilated, and resealed for pressurization, which is time-consuming, inefficient, and difficult to adapt to the needs of large-scale mass production. Summary of the Invention

[0005] To address the bottlenecks of long drying time and low efficiency in the industrial application of supercritical carbon dioxide drying technology, this application provides a supercritical carbon dioxide drying device that can achieve non-destructive drying with a short drying cycle and high drying efficiency.

[0006] The technical solution adopted by this invention to solve its technical problem is: A supercritical carbon dioxide drying device includes a storage tank and a drying device, wherein the drying device includes a pressure tank and a vacuum tank, and the pressure tank contains carbon dioxide in a supercritical state or above. The pressure tank is provided with several cleaning cylinders, each of which includes a control chamber and a cleaning chamber. The cleaning cylinder is provided with a liquid inlet. The first piston in the control chamber can control the connection and disconnection between the cleaning chamber and the pressure tank under the drive of the first driving component. The vacuum tank includes several sub-spaces, and the cleaning chamber is connected to the corresponding sub-spaces through connecting pipes, and the connecting pipes are provided with a first control mechanism for controlling the opening and closing of the connecting pipes. The cleaning cylinder is provided with a second exhaust port and an air inlet that are connected to the cleaning chamber. The air inlet is provided with a second control mechanism for controlling the opening and closing of the air inlet. The pressure tank is connected to the liquid storage tank. The first exhaust port of the vacuum tank is equipped with a first control valve and a first vacuum pump, and the second exhaust port is equipped with a second control valve and a second vacuum pump.

[0007] Furthermore, it also includes a gas-liquid separator, a booster pump and a preheater are provided between the pressure tank and the storage tank, the first exhaust port is connected to the inlet of the gas-liquid separator through a first control valve and a first vacuum pump, and the outlet of the gas-liquid separator is connected to the storage tank through a compressor and a condenser.

[0008] Furthermore, the pressure vessel is covered with an insulation layer, and a heating element for heating carbon dioxide is installed inside the pressure vessel.

[0009] Furthermore, the internal space of the pressure vessel includes a first cavity and a second cavity. The second cavity is filled with carbon dioxide in a supercritical state or higher. The first cavity includes an inlet cavity and a return cavity. The pressure vessel is provided with a heat exchange inlet connected to the inlet cavity and a heat exchange outlet connected to the return cavity. A heat exchange tube is provided in the second cavity. One end of the heat exchange tube is connected to the inlet cavity, and the other end of the heat exchange tube is connected to the return cavity.

[0010] Furthermore, the cleaning chamber is provided with a wafer box for supporting the wafer to be cleaned. The wafer box includes two arc-shaped support plates with identical structures and symmetrically arranged. The two support plates are connected by a connecting plate to form a rigid frame. The inner side of the support plate is provided with a plurality of support grooves for accommodating the wafer. The upper end of the support plate is provided with a guide slide plate. The inner side wall of the cleaning chamber is provided with a guide groove that cooperates with the guide slide plate.

[0011] Furthermore, a connecting flange is provided at the second open end of the cleaning cylinder, and rotating slide rods are rotatably provided at the upper and lower ends of the cleaning cylinder, respectively. Through holes that cooperate with the rotating slide rods are provided at the upper and lower ends of the second sealing plate, respectively. Several locking rods are provided on the cleaning cylinder along the circumferential direction. One end of the locking rod is hinged to the cleaning cylinder, and a locking nut is provided at the other end of the locking rod. Grooves for accommodating the locking rods are provided at the edges of the connecting flange and the second sealing plate, and a fifth sealing gasket is provided between the second sealing plate and the connecting flange.

[0012] Furthermore, the first opening end of the cleaning cylinder is provided with a first sealing plate, and the first driving component is a first hydraulic cylinder disposed on the first sealing plate, with the piston rod of the first hydraulic cylinder connected and fixed to the first piston.

[0013] Furthermore, the cleaning cylinder is provided with a main pipe that communicates with the cleaning chamber, and the main pipe is provided with a first branch pipe that communicates with a corresponding subspace. The first control mechanism includes a second piston that is slidably disposed in the main pipe. The second piston, driven by the second oil cylinder, can control the opening and closing of the vacuum tank and the cleaning chamber.

[0014] Furthermore, the vacuum tank is located above the pressure tank, a first mounting base is provided on the lower side of the vacuum tank, and a second mounting base is provided on the upper side of the pressure tank. The first mounting base and the second mounting base are connected and fixed. The vacuum tank is provided with a second branch pipe that corresponds one-to-one with the first branch pipe. The second branch pipe is connected and fixed to the corresponding first branch pipe by means of a flange connection.

[0015] Furthermore, the air inlet includes an air inlet pipe body, and the second control mechanism includes a third piston slidably disposed within the air inlet pipe body. The air inlet pipe body is provided with air holes, and the third piston, driven by the third driving member, can control the opening and closing of the external atmosphere and the cleaning chamber.

[0016] The beneficial effects of this invention are: 1. The supercritical carbon dioxide drying equipment provided in this application uses supercritical carbon dioxide as the drying medium. Relying on its characteristics of zero surface tension, high diffusivity and high solubility, it can quickly penetrate into the interior of high aspect ratio micro-nano structures such as wafer trenches, fully replacing residual moisture and cleaning agents. This avoids defects such as structural collapse, adhesion and breakage caused by capillary forces in the traditional IPA displacement drying method. At the same time, after the supercritical carbon dioxide is vaporized and vacuumed, there are no trace residues, effectively avoiding the interference of residual substances on the electrical performance of devices, and significantly improving the production yield and long-term reliability of integrated circuits (ICs) and MEMS devices. 2. The supercritical carbon dioxide drying equipment provided in this application adopts a separate design of a pressure tank and a through-type cleaning cylinder. Combined with piston switching control and vacuum tank auxiliary recovery, the wafer loading and unloading operation can be completed without depressurizing or venting the entire pressure tank. This eliminates the cumbersome process of repeated sealing, pressurization, and depressurization, shortens the production cycle of single batch wafer drying, and realizes efficient continuous wafer processing, which can adapt to the needs of large-scale mass production.

[0017] 3. The supercritical carbon dioxide drying equipment provided in this application realizes closed-loop recovery and utilization of carbon dioxide, which greatly reduces the consumption and loss of carbon dioxide. It not only conforms to the green and low-carbon development trend of the semiconductor industry, but also reduces the input of raw material costs and improves the economic efficiency of equipment operation, thus combining environmental protection and economy. Attached Figure Description Figure 1 This is a three-dimensional structural diagram of the drying device; Figure 2 for Figure 1 A magnified structural diagram of part A in the middle; Figure 3 for Figure 1 A magnified structural diagram of part B in the middle section; Figure 4 This is a top view of the drying unit; Figure 5 for Figure 4 AA section view in the middle; Figure 6 for Figure 4 BB section view in the middle; Figure 7 for Figure 6 A magnified structural diagram of section C; Figure 8 This is a front view of the drying unit; Figure 9 for Figure 8 CC section view in the middle; Figure 10 This is a schematic diagram showing the positional relationship between the pressure tank, cleaning cylinder, and heat exchange tubes. Figure 11 for Figure 10 A magnified structural diagram of section D in the middle; Figure 12 A schematic diagram of a supercritical carbon dioxide drying device provided in an embodiment of this application; Figure 13 This is a schematic diagram of the three-dimensional structure of a wafer box; Figure 14 The working process of a supercritical carbon dioxide drying device provided in the embodiments of this application Figure 1 ; Figure 15 The working process of a supercritical carbon dioxide drying device provided in the embodiments of this application Figure 2 ; Figure 16 The working process of a supercritical carbon dioxide drying device provided in the embodiments of this application Figure 3 ; Figure 17 The working process of a supercritical carbon dioxide drying device provided in the embodiments of this application Figure 4; Figure 18 The working process of a supercritical carbon dioxide drying device provided in the embodiments of this application Figure 5 ; Figure 19 The working process of a supercritical carbon dioxide drying device provided in the embodiments of this application Figure 6 ; Figure 20 The working process of a supercritical carbon dioxide drying device provided in the embodiments of this application Figure 7 ; Figure 21 The working process of a supercritical carbon dioxide drying device provided in the embodiments of this application Figure 8 .

[0018] In the diagram: 1. Storage tank; 2. Drying device; 21. Pressure tank; 211. Medium inlet; 212. Second mounting base; 213. Base; 214. Second pressure gauge; 215. Thermometer; 216. Second baffle; 217. Third baffle; 2181. Heat exchange inlet; 2182. Heat exchange outlet; 219. Heat exchange tube; 22. Vacuum tank; 221. First baffle; 222. First mounting base; 223. Second branch pipe; 224. First exhaust port; 225. First pressure gauge; 23. Cleaning cylinder; 231. Liquid inlet; 232. Main pipe; 2321. First branch pipe; 2322. Second limiting protrusion 233. Second exhaust port; 234. Intake pipe body; 2341. Air vent; 2342. Third limiting boss; 235. First limiting boss; 236. Guide boss; 237. Connecting flange; 238. Insert block; 241. First sealing plate; 242. First piston; 243. First hydraulic cylinder; 251. Second sealing plate; 252. Rotating slide rod; 2521. Limiting nut; 253. Locking rod; 2531. Locking nut; 261. Third sealing plate; 262. Second piston; 263. Second hydraulic cylinder; 271. Fourth sealing plate; 272. Third piston; 273. Third hydraulic cylinder; 3. Gas-liquid separator; 4. First pipeline; 41. Booster pump; 42. Preheater; 43. Third control valve; 44. Fourth control valve; 5. Second pipeline; 51. First control valve; 52. First vacuum pump; 6. Evacuation pipeline; 61. Second control valve; 62. Second vacuum pump; 7. Third pipeline; 71. Compressor; 72. Condenser; 73. Fifth control valve; 81. Wafer; 82. Wafer box; 821. Connecting plate; 822. Support plate; 8221. Support groove; 8222. Guide slide plate. Detailed Implementation

[0019] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be described in detail below with reference to the accompanying drawings. The described embodiments are merely a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort should fall within the protection scope of this application.

[0020] To facilitate understanding of the specific embodiments of this application, a coordinate system is first defined for the drying device 2 as follows: Figure 1 As shown, the left and right directions are horizontal, the front and back directions are vertical, and the up and down directions are vertical.

[0021] like Figure 12 As shown, a supercritical carbon dioxide drying device includes a storage tank 1, a drying device 2, and a gas-liquid separator 3.

[0022] like Figure 1 , Figure 8 and Figure 9 As shown, the drying device 2 includes a pressure tank 21 and a vacuum tank 22.

[0023] The pressure tank 21 is filled with carbon dioxide in a supercritical state (i.e., pressure greater than 7.38 MPa and temperature greater than 31.1°C). The pressure tank 21 is equipped with a medium inlet 211, which is connected to a storage tank 1 for storing carbon dioxide via a first pipeline 4. A booster pump 41 and a preheater 42 are sequentially arranged along the flow direction of the carbon dioxide on the first pipeline 4. The booster pump 41 pressurizes the carbon dioxide to a set pressure and pumps it into the pressure tank 21; the preheater 42 heats the carbon dioxide. Under the action of the booster pump 41 and the preheater 42, the temperature and pressure of the carbon dioxide in the pressure tank 21 exceed the critical point (i.e., pressure greater than 7.38 MPa and temperature greater than 31.1°C), thus reaching a supercritical state.

[0024] Multiple cleaning cylinders 23 are evenly distributed along the axial direction on the pressure tank 21, and the cleaning cylinders 23 penetrate the pressure tank 21. The pressure tank 21 and the cleaning cylinders 23 are connected and fixed by welding. Preferably, the cleaning cylinders 23 are horizontal, and the multiple cleaning cylinders 23 are arranged in parallel.

[0025] As one specific implementation method, according to Figure 1In the coordinate system shown, the axis of the pressure tank 21 in this embodiment extends laterally, and the medium inlet 211 is located at the right end of the pressure tank 21. Four cleaning cylinders 23 extending in the front-to-back direction are evenly distributed laterally on the pressure tank 21, and the cleaning cylinders 23 penetrate the pressure tank 21 in the front-to-back direction. The pressure tank 21 is provided with through holes for accommodating the cleaning cylinders 23. The front and rear ends of the cleaning cylinders 23 are respectively connected and fixed to the side wall of the pressure tank 21 by welding, and the welded joints can reliably withstand the preset pressure of the pressure tank 21.

[0026] like Figure 9 , Figure 10 and Figure 11 As shown, the first opening end of the cleaning cylinder 23 is provided with a first sealing plate 241 for sealing the cleaning cylinder 23, and the second opening end of the cleaning cylinder 23 is provided with a second sealing plate 251 for sealing the cleaning cylinder 23. The second sealing plate 251 is detachably connected and fixed to the cleaning cylinder 23. The internal space of the cleaning cylinder 23 is divided into a control chamber and a cleaning chamber in sequence from the first opening end to the second opening end. The cleaning chamber is used to place the wafer 81 to be cleaned. The control chamber is provided with a first piston 242, which can reciprocate back and forth along the control chamber under the drive of a first driving member. The cleaning cylinder 23 is provided with a liquid inlet 231. When the first piston 242 is in the first working position, the pressure tank 21 is connected to the cleaning chamber through the liquid inlet 231. At this time, the cleaning medium (carbon dioxide in a supercritical state or above) in the pressure tank 21 can enter the cleaning chamber through the liquid inlet 231. When the first piston 242 is in the second working position, the liquid inlet 231 is blocked by the first piston 242, and the pressure tank 21 is not connected to the cleaning cylinder 23.

[0027] In one specific embodiment, the first opening end is located at the rear end of the cleaning cylinder 23, and the second opening end is located at the front end of the cleaning cylinder 23. The first sealing plate 241 is connected and fixed to the cleaning cylinder 23 by a flange connection, and a first sealing gasket is provided between the first sealing plate 241 and the flange plate at the first opening end. The first driving component is a first hydraulic cylinder 243. The cylinder body of the first hydraulic cylinder 243 is fixed to the first sealing plate 241 by bolts, and the piston rod of the first hydraulic cylinder 243 passes through the first sealing plate 241 and is detachably connected and fixed to the first piston 242. The first piston 242 includes a first structure with a cylindrical structure. Multiple (at least two) first sealing rings are sleeved on the outside of the first structure, and the first structure is provided with a groove for accommodating the first sealing rings.

[0028] Here, the first hydraulic cylinder 243 can also be disposed inside the control cavity. When the first hydraulic cylinder 243 is disposed inside the control cavity, the tail end of the cylinder body of the first hydraulic cylinder 243 (i.e., the end facing away from the rod cavity) is fixedly connected to the first sealing plate 241 by bolts.

[0029] like Figure 4 and Figure 5 As shown, the vacuum tank 22 is provided with a plurality of first partitions 221, which divide the internal space of the vacuum tank 22 into a plurality of subspaces. The number of subspaces is the same as the number of cleaning cylinders 23, and they correspond one-to-one.

[0030] In one specific implementation, the vacuum tank 22 described in this embodiment is provided with three first partitions 221 along the axial direction. The first partitions 221 divide the internal space of the vacuum tank 22 into four sub-spaces that correspond one-to-one with the cleaning cylinder 23.

[0031] like Figure 6 and Figure 9 As shown, the cleaning chamber of the cleaning cylinder 23 is connected to the corresponding subspace of the vacuum tank 22 via a connecting pipe, and a first control mechanism for controlling the opening and closing of the connecting pipe is provided on the connecting pipe.

[0032] As one specific implementation method, according to Figure 1 The coordinate system shown is as follows: Figure 3 and Figure 8In this embodiment, the vacuum tank 22 is located above the pressure tank 21. A plurality of first mounting seats 222 are evenly distributed along the axial direction on the lower side of the vacuum tank 22, and these first mounting seats 222 are welded to the bottom surface of the vacuum tank 22. A plurality of second mounting seats 212, corresponding one-to-one with the first mounting seats 222, are axially arranged on the upper side of the pressure tank 21, and these second mounting seats 212 are welded to the upper surface of the pressure tank 21. The first mounting seats 222 are connected to the corresponding second mounting seats 212 by bolt assemblies, and the vacuum tank 22 and the pressure tank 21 are connected to form a rigid whole. A main pipe 232 extending vertically is provided on the front side of the pressure tank 21 on the cleaning cylinder 23. The lower end of the main pipe 232 is welded to the cleaning cylinder 23, and the main pipe 232 is connected to the cleaning chamber of the cleaning cylinder 23. The main pipe 232 is provided with a horizontally arranged first branch pipe 2321 with its opening facing the vacuum tank 22. The end of the first branch pipe 2321 facing the main pipe 232 is connected and fixed to the main pipe 232 by welding, and the first branch pipe 2321 is connected to the internal space of the main pipe 232. The vacuum tank 22 is provided with a plurality of second branch pipes 223 corresponding one-to-one with the first branch pipes 2321. The end of the second branch pipe 223 facing the vacuum tank 22 is connected and fixed to the vacuum tank 22 by welding, and is connected to the corresponding subspace. The end of the second branch pipe 223 facing away from the vacuum tank 22 is connected and fixed to the corresponding first branch pipe 2321 by flange connection. A second sealing gasket is provided between the flange plate of the first branch pipe 2321 and the flange plate of the second branch pipe 223. The main pipe 232, the first branch pipe 2321 and the second branch pipe 223 together form the connecting pipe. The first control mechanism includes a second piston 262 slidably disposed within the main pipe 232. Driven by a second driving component, the second piston 262 can reciprocate axially along the main pipe 232. When the second piston 262 is in the first working position, it is located above the first branch pipe 2321, and the cleaning chamber is connected to the corresponding subspace within the vacuum tank 22 via a connecting pipe. When the second piston 262 is in the second working position, it is flush with or below the first branch pipe 2321, the connecting pipe is closed, and the cleaning chamber is not connected to the corresponding subspace within the vacuum tank 22.

[0033] In one specific embodiment, the pressure tank 21 in this embodiment has several bases 213 evenly distributed along the axial direction at its bottom. The bases 213 are fixedly connected to the pressure tank 21 by welding, and the bottom plate of the bases 213 is fixed to the ground by anchor bolts.

[0034] In one specific embodiment, a third sealing plate 261 is provided at the upper opening of the main pipe 232, and the third sealing plate 261 is connected and fixed to the main pipe 232 by a flange connection. A third sealing gasket is provided between the third sealing plate 261 and the flange plate of the main pipe 232. The second driving component is a second hydraulic cylinder 263. The cylinder body of the second hydraulic cylinder 263 is fixed to the third sealing plate 261 by bolts. The piston rod of the second hydraulic cylinder 263 passes through the third sealing plate 261 and is detachably connected and fixed to the second piston 262. The second piston 262 includes a second structure with a cylindrical structure. Multiple (at least two) second sealing rings are sleeved on the outside of the second structure, and the second structure is provided with a groove for accommodating the second sealing rings.

[0035] Similarly, the second hydraulic cylinder 263 can also be installed inside the main pipe 232. When the second hydraulic cylinder 263 is installed inside the main pipe 232, the tail end of the cylinder body of the second hydraulic cylinder 263 (i.e., the end facing away from the rod cavity) is fixedly connected to the third sealing plate 261 by bolts.

[0036] like Figure 5 , Figure 6 and Figure 9 As shown, the vacuum tank 22 is provided with a plurality of first exhaust ports 224 corresponding one-to-one with the subspaces, and the first exhaust ports 224 are connected to the corresponding subspaces. The cleaning cylinder 23 is provided with a second exhaust port 233 connected to the cleaning chamber. For example, according to... Figure 1 In the coordinate system shown, the first exhaust port 224 is located on the rear side of the vacuum tank 22, and the second exhaust port 233 is located on the lower side of the cleaning cylinder 23.

[0037] like Figure 12As shown, the first exhaust port 224 is connected to the inlet of the gas-liquid separator 3 via a second pipeline 5, and a first control valve 51 and a first vacuum pump 52 are sequentially arranged on the second pipeline 5 along the flow direction of the medium. A venting pipeline 6 is provided on the second exhaust port 233, and a second control valve 61 and a second vacuum pump 62 are sequentially arranged on the venting pipeline 6 in the direction away from the second exhaust port 233. The gas outlet of the gas-liquid separator 3 is connected to the return port of the liquid storage tank 1 via a third pipeline 7, and a compression subsystem is provided on the third pipeline 7. The compression subsystem is used to compress and liquefy the gaseous carbon dioxide separated by the gas-liquid separator 3. The compression subsystem includes a compressor 71 and a condenser 72 sequentially along the flow direction of the medium. A third control valve 43 is provided at the medium inlet 211 of the drying device 2, a fourth control valve 44 is provided on the first pipeline 4 upstream of the booster pump 41, and a fifth control valve 73 is provided on the third pipeline 7 upstream and downstream of the compression subsystem, respectively.

[0038] Here, multiple first exhaust ports 224 can share one first vacuum pump 52, or each first exhaust port 224 can be equipped with its own first vacuum pump 52. As a specific implementation, in this embodiment, multiple first exhaust ports 224 share one first vacuum pump 52, meaning the second pipeline 5 includes branch sections and a common section. Each branch section of the second pipeline 5 is equipped with a first control valve 51, and the first vacuum pump 52 is located on the common section of the second pipeline 5. Similarly, multiple second exhaust ports 233 can share one second vacuum pump 62, or each second exhaust port 233 can be equipped with its own second vacuum pump 62. As a specific implementation, in this embodiment, multiple second exhaust ports 233 share one second vacuum pump 62, meaning the venting pipeline 6 includes branch sections and a common section. Each branch section of the venting pipeline 6 is equipped with a second control valve 61, and the first vacuum pump 52 is located on the common section of the venting pipeline 6.

[0039] like Figure 6 and Figure 7 As shown, the cleaning cylinder 23 is also provided with an air inlet communicating with the cleaning chamber, and the air inlet is provided with a second control mechanism for controlling the opening and closing of the air inlet. For example, according to... Figure 1 In the coordinate system shown, the air inlet is located on the upper left side of the cleaning cylinder 23.

[0040] In one specific embodiment, the air inlet in this embodiment includes an air inlet pipe 234 disposed on the cleaning cylinder 23. One end of the air inlet pipe 23 facing the cleaning cylinder 23 is welded and fixed to the cleaning cylinder 23, and communicates with the cleaning chamber of the cleaning cylinder 23. The second control mechanism includes a third piston 272 slidably disposed within the air inlet pipe 234. The third piston 272 is capable of reciprocating along the axial direction of the air inlet pipe 234 under the drive of the third driving member. An air hole 2341 is provided on the air inlet pipe 234. When the third piston 272 is in the first working position, the third piston 272 is located on the side of the air hole 2341 away from the cleaning cylinder 23, and outside air can enter the cleaning chamber through the air hole 2341; when the third piston 272 is in the second working position, the third piston 272 is aligned with the air hole 2341 or located on the side of the air hole 2341 closer to the cleaning cylinder 23, and outside air cannot enter the cleaning chamber through the air hole 2341.

[0041] In one specific embodiment, a fourth sealing plate 271 is provided at the upper opening of the intake pipe body 234, and the fourth sealing plate 271 is connected and fixed to the intake pipe body 234 by a flange connection. A fourth sealing gasket is provided between the fourth sealing plate 271 and the flange plate of the intake pipe body 234. The third driving component is a third hydraulic cylinder 273. The cylinder body of the third hydraulic cylinder 273 is fixed to the fourth sealing plate 271 by bolts. The piston rod of the third hydraulic cylinder 273 passes through the fourth sealing plate 271 and is detachably connected and fixed to the third piston 272. The third piston 272 includes a cylindrical third structure. Multiple (at least two) third sealing rings are sleeved on the outside of the third structure, and the third structure is provided with a groove for accommodating the third sealing rings.

[0042] Similarly, the third hydraulic cylinder 273 can also be installed inside the intake pipe body 234. When the third hydraulic cylinder 273 is installed inside the intake pipe body 234, the tail end of the cylinder body of the third hydraulic cylinder 273 (i.e., the end facing away from the rod chamber) is fixedly connected to the fourth sealing plate 271 by bolts.

[0043] Furthermore, such as Figure 7 and Figure 9As shown, a first limiting boss 235 with an annular structure is provided on the inner wall of the cleaning cylinder 23 between the cleaning chamber and the control chamber. When the first piston 242 is in the second working position, the first piston 242 abuts against the first limiting boss 235. A second limiting boss 2322 with an annular structure is provided at the lower end of the inner wall of the main pipe 232. When the second piston 262 is in the second working position, the second piston 262 abuts against the second limiting boss 2322. A third limiting boss 2342 with an annular structure is provided on the inner wall of the air intake pipe 234. When the third piston 272 is in the second working position, the third piston 272 abuts against the third limiting boss 2342.

[0044] Furthermore, such as Figure 1 and Figure 8 As shown, the vacuum tank 22 is equipped with a first pressure sensor (not shown) and a first pressure gauge 225 for detecting the pressure in each sub-space. The pressure tank 21 is equipped with a second pressure sensor (not shown) and a second pressure gauge 214 for detecting the pressure inside the pressure tank 21. The cleaning cylinder 23 is equipped with a third pressure sensor (not shown) and a third pressure gauge (not shown) for detecting the pressure inside the cleaning chamber. By setting the first pressure gauge 225, the second pressure gauge 214, and the third pressure gauge, the pressure in each sub-space of the vacuum tank 22, the pressure tank 21, and the cleaning chamber can be directly observed, avoiding operational abnormalities caused by electronic feedback failure.

[0045] Furthermore, in order to reduce the temperature drop caused by heat loss from the pressure tank 21, the pressure tank 21 is covered with an insulation layer (not shown in the figure). The insulation layer can be made of cotton material or industrial insulation materials such as polyurethane.

[0046] Furthermore, the pressure tank 21 is equipped with a heating element for heating carbon dioxide, and the pressure tank 21 is also equipped with a temperature sensor (not shown in the figure) and a thermometer 215 for detecting the internal temperature. By setting the thermometer 215, the temperature of carbon dioxide inside the pressure tank 21 can be observed directly, avoiding abnormal operation caused by temperature sensor malfunction.

[0047] As one specific implementation method, such as Figure 1 , Figure 5 and Figure 10 As shown in this embodiment (according to) Figure 1(In the coordinate system shown), a second baffle 216 is fixedly installed at the end of the pressure tank 21 furthest from the medium inlet 211. The second baffle 216 divides the internal space of the pressure tank 21 into a first cavity and a second cavity. The second cavity is filled with carbon dioxide in a supercritical state or higher. A third baffle 217 is fixedly installed in the first cavity, dividing the first cavity into an inlet cavity and a return cavity. For example, the third baffle 217 is perpendicular to the second baffle 216 and divides the first cavity into an inlet cavity and a return cavity that are symmetrically arranged vertically. A heat exchange inlet 2181 connected to the inlet cavity and a heat exchange outlet 2182 connected to the return cavity are respectively provided at the left end of the pressure tank 21. The heating component consists of multiple heat exchange tubes 219 disposed in the second cavity. The heat exchange tubes 219 have a U-shaped structure, and the four cleaning cylinders 23 are all located inside the U-shaped structure of the heat exchange tubes 219. One end of the heat exchange tube 219 passes through the second partition 216 and is connected to the liquid inlet chamber, while the other end passes through the second partition 216 and is connected to the liquid return chamber. The heat exchange inlet 2181 is connected to the outlet of the heat source (not shown in the figure) via a pipeline (not shown in the figure), and the heat exchange outlet 2182 is connected to the heat source inlet via a pipeline. The heat exchange medium provided by the heat source can enter the heat exchange tube 219 through the heat exchange inlet 2181, thereby heating the carbon dioxide in the second chamber. After heat exchange, the heat exchange medium flows back to the heat source through the heat exchange outlet 2182 for reheating. A circulation pump (not shown in the figure) is installed on the pipeline connecting the pressure tank 21 and the heat source to drive the circulation of the heat exchange medium. The heat source can be a commonly used heat source in the prior art, such as waste heat generated in factory production or circulating hot water provided by a boiler, which will not be elaborated here.

[0048] The supercritical carbon dioxide drying equipment provided in this application also includes a control unit. In actual operation, the control unit can control the start and stop of the first vacuum pump 52 and the working state of each first control valve 51 according to the pressure data fed back by the first pressure sensor; the control unit can control the start and stop of the second vacuum pump 62 and the working state of each second control valve 61 according to the pressure data fed back by the third pressure sensor; the control unit can control the start and stop of the booster pump 41 and the working state of the third control valve 43 and the fourth control valve 44 according to the pressure data fed back by the second pressure sensor.

[0049] like Figure 6 , Figure 7 and Figure 13As shown, the cleaning chamber is equipped with a wafer cassette 82 for supporting the wafers 81 to be cleaned. The wafer cassette 82 includes two connecting plates 821. Between the two connecting plates 821 are two identical and symmetrically arranged arc-shaped support plates 822. The two ends of each support plate 822 are connected and fixed to the connecting plates 821, forming a rigid frame together. The inner surface of each support plate 822 (with the opposite side of the two support plates 822 as the inner surface) has a plurality of support grooves 8221 evenly distributed along its length to accommodate the wafers 81. The lower ends of the wafers 81 are inserted into the corresponding support grooves 8221 of the two support plates 822. The upper end of each support plate 822 has a guide slide plate 8222 extending horizontally outward (with the opposite side of the two support plates 822 as the inner surface). The cleaning chamber of the cleaning cylinder 23 has guide grooves on its left and right sides that mate with the guide slide plate 8222. For example, the cleaning chamber has guide bosses 236 on its left and right sides, and these guide bosses 236 have guide grooves that mate with the guide slide plate 8222.

[0050] Furthermore, since the second sealing plate 251 needs to be frequently opened and closed in actual operation, for ease of operation, such as Figure 2 and Figure 9As shown, the second open end of the cleaning cylinder 23 is provided with a connecting flange 237. Rotating slide rods 252 are respectively provided at the upper and lower ends of the cleaning cylinder 23, located behind the connecting flange 237. Each rotating slide rod 252 includes a vertical portion and a horizontal portion. The vertical portion is rotatably connected to the cleaning cylinder 23, and the horizontal portion is slidably connected to the second sealing plate 251. The upper and lower ends of the second sealing plate 251 are respectively provided with through holes that mate with the horizontal portion of the rotating slide rod 252. A limiting member is provided on the suspended end of the horizontal portion to prevent the second sealing plate 251 from slipping off the rotating slide rod 252. For example, insertion blocks 238 are welded to the upper and lower ends of the cleaning cylinder 23. Each insertion block 238 has an insertion hole for accommodating the vertical portion, and the limiting member is a limiting nut 2521. A plurality of locking rods 253 are evenly distributed circumferentially on the cleaning cylinder 23, located behind the connecting flange 237. One end of each locking rod 253 is hinged to the cleaning cylinder 23 via a hinge shaft, and the other end of each locking rod 253 is provided with a locking nut 2531. The edges of the connecting flange 237 and the second sealing plate 251 are both provided with slots for accommodating the locking rods 253. For example, six locking rods 253 are evenly distributed circumferentially on the cleaning cylinder 23, and the locking nuts 2531 are high-head knurled nuts. A fifth sealing gasket is provided between the second sealing plate 251 and the connecting flange 237, located inside the slot. For example, the connecting flange 237 is provided with a groove for accommodating the fifth sealing gasket, and the fifth sealing gasket is embedded in the groove.

[0051] The working process of a supercritical carbon dioxide drying device is as follows: First, such as Figure 14 As shown, the wafer cassette 82 containing the wafer 81 to be cleaned is placed into the cleaning chamber of the cleaning cylinder 23.

[0052] Second, such as Figure 15 As shown, rotate the second sealing plate 251 until the second sealing plate 251 is coaxially aligned with the cleaning cylinder 23.

[0053] Third, such as Figure 16 As shown, the second sealing plate 251 is pushed toward one side of the cleaning cylinder 23, so that the second sealing plate 251 slides relative to the rotating slide rod 252 until the second sealing plate 251 is in contact with the connecting flange 237.

[0054] Fourth, such as Figure 17 As shown, rotate the locking rod 253 forward so that it engages in the slot, and then tighten the locking nut 2531 to lock the second sealing plate 251 (i.e., Figure 2 (The state shown).

[0055] Fifth, such as Figure 18 As shown, the first piston 242, the second piston 262, and the third piston 272 are all in the second working position. Then, the first vacuum pump 52 and the second vacuum pump 62 are turned on to evacuate the vacuum tank 22 and the cleaning chamber. When the pressure detected by the first pressure sensor reaches a preset value (i.e., a preset vacuum level is reached), the first vacuum pump 52 and the first control valve 51 are closed; when the pressure detected by the third pressure sensor reaches a preset value (i.e., a preset vacuum level is reached), the second vacuum pump 62 and the second control valve 61 are closed.

[0056] Sixth, such as Figure 19 As shown, the first piston 242 is pulled backward by the first cylinder 243, placing it in the first working position. At this time, carbon dioxide in the pressure tank 21 enters the cleaning chamber through the liquid inlet 231 until the cleaning chamber is filled with carbon dioxide in a supercritical state, and this state is maintained for a set time. Supercritical carbon dioxide is a special fluid state that is neither gas nor liquid. In this state, carbon dioxide exhibits unique physical properties, possessing both the low viscosity and high diffusivity of a gas, allowing it to easily enter even the smallest pores of a material; at the same time, it possesses the high density and dissolving power of a liquid, dissolving and carrying away the original solvent in the pores like water dissolves sugar. More importantly, its surface tension is zero, thus enabling it to quickly penetrate into microporous structures. Based on these properties, supercritical carbon dioxide can rapidly penetrate the micro-nano structure of wafer 81 and dissolve the cleaning medium remaining on the surface and in the micro-nano structure of wafer 81 (i.e., the cleaning medium remaining during wet cleaning of wafer 81) in the supercritical carbon dioxide.

[0057] Seventh, such as Figure 20 As shown, the first piston 242 is pushed forward by the first cylinder 243, causing it to return to the second working position. Then, the second piston 262 is pulled upward by the second cylinder 263, causing it to slowly return to the first working position. When the second piston 262 returns to the first working position, the cleaning chamber is connected to the corresponding subspace of the vacuum tank 22 through a connecting pipe. At this moment, the volume instantly expands by a factor of 1, and the supercritical carbon dioxide carrying the cleaning medium is converted into gaseous carbon dioxide.

[0058] Eighth, the first control valve 51 is opened, and the first vacuum pump 52 is started. The first vacuum pump 52 delivers carbon dioxide gas to the gas-liquid separator 3. The pure carbon dioxide separated by the gas-liquid separator 3, along with the gas from the compressor 71 and condenser 72, flows into the storage tank 1. Only the first vacuum pump 52 and the first control valve 51 are opened here because some unvaporized carbon dioxide may exist at the bottom of the cleaning chamber.

[0059] Ninth, when the pressure detected by the first pressure sensor reaches the preset value (i.e., the preset vacuum level), the first vacuum pump 52 stops working and the first control valve 51 closes. At this time, the carbon dioxide completely evaporates without leaving any trace, ensuring the ultra-high purity and reliability of the device and solving the problem of chemical residue.

[0060] Tenth, the second piston 262 is pushed downward by the second cylinder 263 to the second working position, and the second piston 262 is stably maintained in the second working position by the second cylinder 263. Then, the third piston 272 is pulled upward by the third cylinder 273 to the first working position. At this time, outside air will enter the cleaning chamber through the air hole 2341, while the vacuum tank 22 is isolated by the second piston 262, so outside air cannot enter the vacuum tank 22, and the vacuum tank 22 will be in a stable vacuum state. In this way, it is not necessary to evacuate the vacuum tank 22 again during the next round of cleaning. It is only necessary to turn on the second vacuum pump 62 to evacuate the cleaning chamber, which can effectively save time and shorten the drying cycle.

[0061] Eleventh, after the pressure inside the cleaning chamber is balanced with the outside atmosphere, open the second sealing plate 251 and take out the wafer box 82 containing the wafer 81.

[0062] Since supercritical carbon dioxide stays in the cleaning chamber for a short time (generally 3-5 minutes), while the time for vacuuming after carbon dioxide vaporization (i.e., step 8) is relatively long, multiple cleaning cylinders 23 are set up to make reasonable use of this time difference, thereby making reasonable overall arrangements for time and improving work efficiency.

[0063] Preferably, the pressure of carbon dioxide in the pressure tank 21 is 15-20 MPa, and the temperature is 40-60°C. When the pressure detected by the second pressure sensor reaches the preset lower limit, the third control valve 43, the fourth control valve 44, the booster pump 41, and the preheater 42 open to supply carbon dioxide into the pressure tank 21 until the pressure in the pressure tank 21 reaches the preset upper limit. Similarly, when the temperature detected by the temperature sensor reaches the preset lower limit, the heating element is activated to heat the carbon dioxide in the pressure tank 21 through the heat exchange tube 219 until the temperature of the carbon dioxide in the pressure tank 21 reaches the preset upper limit.

[0064] Example 2 The vacuum tank 22 is located directly above the cleaning chamber of the cleaning cylinder 23. The connecting pipeline includes only the main pipeline 232, the lower end of which is welded to the cleaning chamber of the cleaning cylinder 23, and the upper end of which is sealed and fixedly connected to the connection port at the bottom of the vacuum tank 22 via a flange. The first control mechanism is a first shut-off valve located on the main pipeline 232. The first shut-off valve can be an electric shut-off valve or a manual shut-off valve. The remaining structure is the same as in Embodiment 1.

[0065] Example 3 Removing the vent 2341, the second control mechanism is a second shut-off valve installed on the inlet pipe body. One end of the second shut-off valve is sealed and fixedly connected to the open end of the inlet pipe body 234, and the other end of the second shut-off valve is directly connected to the atmosphere. The second shut-off valve can be an electric shut-off valve or a manual shut-off valve. The remaining structure is the same as in Embodiment 1.

[0066] Example 4 The heating element is a heating rod disposed on the pressure vessel 21. The heating rod is sealed and fixedly connected to the pressure vessel 21, and the heating end of the heating rod extends into the pressure vessel 21. Preferably, a plurality of heating rods are evenly distributed along the axial direction on the pressure vessel 21. The remaining structure is the same as in Embodiment 1.

[0067] Other embodiments obtained by those skilled in the art based on the embodiments provided in this application by combining, splitting, or reorganizing the embodiments of this application do not exceed the protection scope of this application.

[0068] The above detailed embodiments have provided a detailed explanation of the purpose, technical solutions, and beneficial effects of the embodiments of this application. The above are merely specific embodiments of the embodiments of this application and are not intended to limit the protection scope of the embodiments of this application. That is, any modifications, equivalent substitutions, improvements, etc., made on the basis of the embodiments of this application should be included within the protection scope of the embodiments of this application.

Claims

1. A supercritical carbon dioxide drying device, characterized in that: It includes a storage tank (1) and a drying device (2), wherein the drying device (2) includes a pressure tank (21) and a vacuum tank (22), wherein the pressure tank (21) contains carbon dioxide in a supercritical state or above; The pressure tank (21) is provided with a plurality of cleaning cylinders (23). The interior of the cleaning cylinder (23) includes a control chamber and a cleaning chamber. The cleaning cylinder (23) is provided with a liquid inlet (231). The first piston (242) in the control chamber can control the opening and closing of the cleaning chamber and the pressure tank (21) under the drive of the first driving member. The vacuum tank (22) includes several subspaces. The cleaning chamber is connected to the corresponding subspaces through connecting pipes, and a first control mechanism for controlling the opening and closing of the connecting pipes is provided on the connecting pipes. The cleaning cylinder (23) is provided with a second exhaust port (233) and an air inlet that are connected to the cleaning chamber. The air inlet is provided with a second control mechanism for controlling the opening and closing of the air inlet. The pressure tank (21) is connected to the liquid storage tank (1). The first exhaust port (224) of the vacuum tank (22) is equipped with a first control valve (51) and a first vacuum pump (52). The second exhaust port (233) is equipped with a second control valve (61) and a second vacuum pump (62).

2. The supercritical carbon dioxide drying equipment according to claim 1, characterized in that: It also includes a gas-liquid separator (3), a booster pump (41) and a preheater (42) are provided between the pressure tank (21) and the storage tank (1), the first exhaust port (224) is connected to the inlet of the gas-liquid separator (3) through the first control valve (51) and the first vacuum pump (52), and the outlet of the gas-liquid separator (3) is connected to the storage tank (1) through the compressor (71) and the condenser (72).

3. The supercritical carbon dioxide drying equipment according to claim 1, characterized in that: The pressure tank (21) is covered with an insulation layer, and a heating element for heating carbon dioxide is installed inside the pressure tank (21).

4. The supercritical carbon dioxide drying equipment according to claim 3, characterized in that: The internal space of the pressure tank (21) includes a first cavity and a second cavity. The second cavity is filled with carbon dioxide in a supercritical state or above. The first cavity includes an inlet cavity and a return cavity. The pressure tank (21) is provided with a heat exchange inlet (2181) connected to the inlet cavity and a heat exchange outlet (2182) connected to the return cavity. The second cavity is provided with a heat exchange tube (219). One end of the heat exchange tube (219) is connected to the inlet cavity, and the other end of the heat exchange tube (219) is connected to the return cavity.

5. The supercritical carbon dioxide drying equipment according to claim 1, characterized in that: The cleaning chamber is provided with a wafer box (82) for supporting the wafer (81) to be cleaned. The wafer box (82) includes two arc-shaped support plates (822) with the same structure and symmetrically arranged. The two support plates (822) are connected by a connecting plate (821) to form a rigid frame. The inner side of the support plate (822) is provided with a plurality of support grooves (8221) for accommodating the wafer (81). The upper end of the support plate (822) is provided with a guide plate (8222). The inner side wall of the cleaning chamber is provided with a guide groove that cooperates with the guide plate (8222).

6. The supercritical carbon dioxide drying equipment according to claim 1, characterized in that: The second opening end of the cleaning cylinder (23) is provided with a connecting flange (237). The upper and lower ends of the cleaning cylinder (23) are respectively provided with rotating slide rods (252). The upper and lower ends of the second sealing plate (251) are respectively provided with through holes that cooperate with the rotating slide rods (252). The cleaning cylinder (23) is provided with a number of locking rods (253) along the circumferential direction. One end of the locking rod (253) is hinged to the cleaning cylinder (23), and the other end of the locking rod (253) is provided with a locking nut (2531). The edges of the connecting flange (237) and the second sealing plate (251) are both provided with slots for accommodating the locking rods (253). A fifth sealing gasket is provided between the second sealing plate (251) and the connecting flange (237).

7. The supercritical carbon dioxide drying equipment according to claim 1, characterized in that: The first opening end of the cleaning cylinder (23) is provided with a first sealing plate (241), and the first driving component is a first oil cylinder (243) provided on the first sealing plate (241). The piston rod of the first oil cylinder (243) is connected and fixed to the first piston (242).

8. The supercritical carbon dioxide drying equipment according to claim 1, characterized in that: The cleaning cylinder (23) is provided with a main pipe (232) that is connected to the cleaning chamber. The main pipe (232) is provided with a first branch pipe (2321) that is connected to a corresponding subspace. The first control mechanism includes a second piston (262) that is slidably disposed in the main pipe (232). The second piston (262) can control the opening and closing of the vacuum tank (22) and the cleaning chamber under the drive of the second oil cylinder (263).

9. A supercritical carbon dioxide drying device according to claim 8, characterized in that: The vacuum tank (22) is located above the pressure tank (21). A first mounting base (222) is provided on the lower side of the vacuum tank (22), and a second mounting base (212) is provided on the upper side of the pressure tank (21). The first mounting base (222) and the second mounting base (212) are connected and fixed. A second branch pipe (223) is provided on the vacuum tank (22) that corresponds one-to-one with the first branch pipe (2321). The second branch pipe is connected and fixed to the corresponding first branch pipe (2321) through a flange connection.

10. A supercritical carbon dioxide drying device according to claim 1, characterized in that: The air inlet includes an air inlet pipe (234), and the second control mechanism includes a third piston (272) slidably disposed in the air inlet pipe (234). The air inlet pipe (234) is provided with an air hole (2341). The third piston (272) can control the opening and closing of the external atmosphere and the cleaning chamber under the drive of the third driving member.

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