A substrate supercritical processing apparatus and processing method

Abstract

The present application relates to a kind of substrate supercritical processing device and the method for processing substrate, the substrate supercritical processing device includes carbon dioxide supply device, CO2 storage chamber, supercritical processing chamber, CO2 recovery device, wherein CO2 storage chamber is provided 2 or more, carbon dioxide supply device is provided one or 2 or more, one carbon dioxide supply device can be connected with one or two or more CO2 storage chamber by liquid CO2 supply pipeline, CO2 storage chamber is connected with supercritical processing chamber by supercritical CO2 supply pipeline;The processing device can convert liquid CO2 into supercritical CO2 state by being provided with two or more parallel CO2 storage chamber, in the process of carrying out substrate processing, by the repeated switching between CO2 storage chamber, it can uninterruptedly supply supercritical state CO2 fluid to subsequent supercritical processing chamber, to realize the continuous processing of substrate in supercritical processing chamber.

Description

Technical Field

[0001] This invention relates to the technical field of integrated circuit manufacturing, and in particular to a substrate / wafer supercritical processing apparatus and processing method. Background Technology

[0002] In the manufacturing process of semiconductor wafers and other substrates, their surfaces require chemical cleaning or wet etching. If traditional drying methods, such as spin drying, are used, the liquid in the surface microstructure may cause the pattern to collapse or bend due to surface tension during evaporation, especially in advanced integrated circuit processes with high aspect ratio patterns. Supercritical fluid drying technology is a technique for drying materials when the drying medium is at its critical temperature and pressure. When the temperature and pressure of a substance exceed its critical temperature and pressure, the substance transforms into a supercritical state. In the supercritical state, the fluid exhibits the dual characteristics of both gas and liquid phases, possessing the high diffusion capacity and low viscosity of a gas and the high density and solvation capacity of a liquid. Commonly used supercritical fluids include carbon dioxide (CO2), nitrogen (N2), nitrous oxide (N2O), and ethylene (C2H4). Among these, CO2 is the most common, as it has a relatively low critical temperature and pressure, is inexpensive, non-toxic, and has low reactivity. The critical temperature of CO2 is 31.1℃, and its critical pressure is 7.38 MPa. First, the drying medium, in a supercritical state, enters the material being dried and undergoes a gentle and rapid exchange with solvent molecules, displacing the solvent. Then, by changing conditions such as temperature and pressure, the mixed processing fluid is converted from a supercritical state to a gas, releasing the solvent from the raw material and achieving the drying effect. Supercritical fluids have low surface tension, meaning that materials dried using supercritical fluid drying technology do not shrink or break down, largely maintaining the structure and state of the dried material and effectively preventing agglomeration and coagulation. This technology is widely used in aerogel drying, medical material preparation, catalyst preparation, and ultrafine material preparation, among other fields. In the semiconductor industry, using supercritical fluids to dry wafer surfaces effectively prevents the collapse and distortion of microstructures on the wafer surface. Besides wafer drying, supercritical fluid processing technology can also be used for surface treatments such as cleaning or rinsing wafer surfaces.

[0003] To avoid the collapse and disintegration of microstructures on the substrate surface caused by traditional drying methods, supercritical fluid displacement drying technology is currently used to remove liquid from the substrate surface and dry the substrate. Samsung-US20230046595A1 and Samsung-US11227761B2 employ a gaseous carbon dioxide source. The supplied gaseous CO2 is liquefied into liquid CO2 by a liquefaction device and then enters a storage tank. This storage tank pre-treats the liquid CO2 to a supercritical state (SCC state, CO2 critical temperature: 31.1℃, critical pressure: 7.38MPa) by heating. The supercritical CO2 is then introduced into a subsequent supercritical processing chamber (processing chamber) to displace the liquid (IPA liquid film, IPA slurry) on the substrate surface within the processing chamber, thus achieving wafer drying. However, this patent only sets up one storage chamber for the preparation and storage of supercritical CO2. As the drying process progresses, when the amount of supercritical CO2 in this chamber becomes insufficient to meet the needs of subsequent drying processes, it is necessary to resupply the storage chamber with liquid CO2 and reprocess it into supercritical CO2 by heating it up, in order to carry out the next round of supercritical drying. This method results in a long system waiting time, making it difficult to meet the requirements of high efficiency and high production capacity.

[0004] The carbon dioxide fluid supply devices in TEL-CN114496837A and TEL-CN110957239A have the ability to maintain pressure output of CO2 in a supercritical state. Subsequently, the supercritical CO2 fluid is introduced into the subsequent drying chamber via known structures such as heaters, throttle valves, and filters, achieving IPA liquid film replacement on the substrate surface and drying of the substrate. In TEL's technical approach, the processing fluid supply device is equipped with a circulation path, which includes a cooling section (such as a compressor and its associated cooling water system), a pump, a heating section (spiral heater), and a pressure regulating section (back pressure stabilizing valve). The entire processing fluid supply device contains many sub-components, leading to: 1. Increased contact between moving parts such as the compressor and delivery pump and CO2, increasing the possibility of particulate contamination on the substrate surface. Furthermore, the pulsation of the pump may cause damage to the pump or piping, or shorten the lifespan of the pump or piping; 2. High system complexity and poor integration, making it difficult to integrate into key semiconductor equipment such as cleaning machines. Its fluid supply device can only be configured separately, far away from equipment such as the cleaning machine, and connected to the drying area through a long connection passage. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a substrate supercritical processing apparatus and method. This processing apparatus, by setting up two or more parallel CO2 storage chambers, converts liquid CO2 into a supercritical CO2 state. Through repeated switching between the CO2 storage chambers, supercritical CO2 fluid can be continuously supplied to the subsequent supercritical processing chambers, thereby achieving continuous processing of the substrate / wafer located in the supercritical processing chamber.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A supercritical substrate processing apparatus, the processing apparatus comprising a carbon dioxide supply device, a CO2 storage chamber, a supercritical processing chamber, and a CO2 recovery device;

[0008] Two or more CO2 storage chambers are provided. An on / off valve V2 is installed at the inlet of the CO2 storage chamber, and the inlet of the CO2 storage chamber is connected to the outlet of the on / off valve V2. An on / off valve V3 is installed at the outlet of the CO2 storage chamber, and the outlet of the CO2 storage chamber is connected to the inlet of the on / off valve V3. Preferably, two CO2 storage chambers are provided.

[0009] One or more carbon dioxide supply devices are provided, preferably two or more; an on / off valve V1 is provided at the outlet of the carbon dioxide supply device, and the outlet of the carbon dioxide supply device is connected to the inlet of the on / off valve V1.

[0010] When two or more carbon dioxide supply devices are installed, each carbon dioxide supply device is connected to the inlet of one or more CO2 storage chambers via a liquid CO2 supply pipeline through the outlet of the on / off valve V1. Each liquid CO2 supply pipeline is equipped with a first mass flow meter, a first pressure sensor and a first safety valve.

[0011] Alternatively, when there is one carbon dioxide supply device, the carbon dioxide supply device is connected to each CO2 storage chamber via an on / off valve V1, a liquid CO2 supply pipeline and branch pipelines, and an on / off valve V2 respectively; one end of the liquid CO2 supply pipeline is connected to the outlet of the on / off valve V1, and the other end is connected to the inlet of the on / off valve V2 at the inlet of each CO2 storage chamber via a branch pipeline; the liquid CO2 supply pipeline is equipped with a first mass flow meter, a first pressure sensor, and a first safety valve.

[0012] A supercritical CO2 supply pipeline and branch pipelines are provided between the CO2 storage chamber and the supercritical processing chamber. One end of the supercritical CO2 supply pipeline is connected to the inlet of the supercritical processing chamber, and the other end is connected to the outlet of the on / off valve V3 at the outlet of each CO2 storage chamber through the branch pipeline of the supercritical CO2 supply pipeline. A second temperature sensor, a filter, a pressure regulating valve V4 and a second mass flow meter are provided on the supercritical CO2 supply pipeline.

[0013] The supercritical processing chamber is equipped with a third pressure sensor, a third temperature sensor, a heating device H, and a second safety valve. An exhaust pipe is provided between the supercritical processing chamber and the CO2 recovery device. One end of the exhaust pipe is connected to the outlet of the supercritical processing chamber, and the other end is connected to the inlet of the CO2 recovery device. An on-off valve V5, a pressure regulating valve V6, an on-off valve V7, and a first check valve are provided on the exhaust pipe.

[0014] Furthermore, the CO2 storage chamber is a closed chamber with a volume of 2–50 L, preferably 10–40 L. The CO2 storage chamber can store liquid CO2 and prepare supercritical CO2 by heating (raising the temperature within the closed storage chamber) or pressurizing with a pressure pump. The supercritical CO2 is then introduced into the subsequent supercritical processing chamber. Specifically, while one CO2 storage chamber is introducing supercritical CO2 into the supercritical processing chamber, another CO2 storage chamber is in a standby state of either receiving liquid CO2 or preparing supercritical CO2. When the supercritical CO2 in the first CO2 storage chamber is depleted or no longer meets the requirements of subsequent processes, the chamber switches to another standby CO2 storage chamber to continue supplying supercritical CO2 to the supercritical processing chamber. Through repeated switching between two or more CO2 storage chambers, a continuous supply of supercritical CO2 to the supercritical processing chamber is achieved without interruption.

[0015] Each CO2 storage chamber is equipped with a second pressure sensor and a first temperature sensor to monitor the pressure and temperature inside the CO2 storage chamber; each CO2 storage chamber is equipped with a temperature control device; the temperature control device configured in the CO2 storage chamber can be one or more of the following: water bath, oil bath, electric heating wire, electric heating belt or other heat exchange device for cold and hot media, and the temperature adjustment range can be 0 to 150℃.

[0016] Furthermore, the CO2 supply device supplies and outputs liquid CO2, with the temperature of the output liquid CO2 stabilized at 20–25°C; the CO2 supply device can be a high-pressure liquid CO2 storage tank or cylinder, or a liquid CO2 storage tank or cylinder equipped with a transfer pump / high-pressure transfer pump; or a liquid CO2 conversion device consisting of a CO2 gas source, a gas purifier, a flow meter, a filter, and a condenser, or a liquid CO2 conversion device consisting of a CO2 gas source, a flow meter, a filter, and a condenser; the CO2 gas source in the liquid CO2 conversion device Gaseous CO2 at 5–7 MPa is provided and converted into liquid CO2 using filters, condensers, or compressors. The condenser can operate at -50–-10°C, the liquid CO2 produced can be at -10–10°C, and the liquid CO2 produced can be at 3–7 MPa. In the downstream pipeline of the CO2 supply device, the temperature of the output liquid CO2 can be restored and stabilized at 20–25°C at room temperature, or the temperature of the output liquid CO2 can be stabilized at 20–25°C through a pipeline heating device.

[0017] A CO2 transfer pump / high-pressure transfer pump can also be installed after the condenser in the liquid CO2 conversion unit to increase the output capacity of liquid CO2.

[0018] Furthermore, the supercritical processing chamber is an openable and closable sealed chamber with a volume of 0.4 to 1.5 L. Its material can be stainless steel or other high-pressure resistant metals. The inner wall of the chamber can be treated by electroplating or polishing. The supercritical processing chamber has one or more trays inside, with a substrate or wafer placed on each tray. The heating device installed on the supercritical processing chamber can be an electric heating wire, an electric heating belt, or an electric heating blanket.

[0019] Furthermore, two branch exhaust pipes are provided on the exhaust pipe, parallel to the on / off valve V7 and the check valve. One end of one branch exhaust pipe is connected to the outlet of the pressure regulating valve V6, and the other end is connected to the inlet of the CO2 recovery device via the first throttle valve, the on / off valve V8, and the second check valve. One end of the other branch exhaust pipe is connected to the outlet of the pressure regulating valve V6, and the other end is connected to the inlet of the CO2 recovery device via the second throttle valve and the on / off valve V9.

[0020] Furthermore, the CO2 recovery device may be a CO2 storage tank / cylinder, or a CO2 storage tank / cylinder including a gas-liquid separation device, a filter, and a condenser.

[0021] Furthermore, the first safety valve and the second safety valve are used to relieve pressure in the system when the system pressure is unexpectedly too high. The pressure relief threshold range of the safety valves is 15 to 30 MPa.

[0022] Furthermore, when there are three or more CO2 storage chambers, the number of supercritical processing chambers can be increased. For example, four CO2 storage chambers correspond to two supercritical processing chambers, five CO2 storage chambers correspond to three supercritical processing chambers, etc., which can further improve the efficiency of substrate processing.

[0023] Another objective of this invention is to provide a method for processing a substrate using the aforementioned supercritical substrate processing apparatus, the processing procedure of which is as follows:

[0024] (1) Select any one or two CO2 storage chambers to convert liquid CO2 into supercritical CO2: First, maintain the temperature in the selected CO2 storage chamber at the initial temperature (2-15℃) using a temperature control device; then, open the on / off valves V1 and V2 between the carbon dioxide supply device and the selected CO2 storage chamber. Liquid CO2 is supplied to the CO2 storage chamber via the CO2 supply device through the on / off valves V1 and V2 and the first mass flow meter. When the volume of liquid CO2 in the CO2 storage chamber (volume V) reaches 0.3-0.95V (preferably 0.45-0.95V), close the on / off valves V1 and V2; set the temperature of the temperature control device to 35-150℃ (preferably 80-120℃), and heat the selected CO2 storage chamber through the temperature control device to convert all the CO2 inside into supercritical CO2 (SCC) state for later use.

[0025] (2) Place the substrate / wafer to be processed onto the tray in the supercritical processing chamber;

[0026] (3) The supercritical processing chamber is preheated to 80-100°C. Select any spare CO2 storage chamber and open the on / off valve V3 between the selected CO2 storage chamber and the supercritical processing chamber. The supercritical CO2 in the CO2 storage chamber enters the supercritical processing chamber through the filter, pressure regulating valve V4, and second mass flow meter to process the substrate / wafer. After processing is completed, the supercritical processing chamber is vented and depressurized. The processed substrate / wafer is taken out and a new substrate / wafer to be processed is transferred.

[0027] (4) While performing any of the steps (1), (2) or (3), at least one other CO2 storage chamber is converted from liquid CO2 to supercritical CO2 state according to the operation of step (2), so that the other CO2 storage chamber enters the standby state.

[0028] (5) During the substrate processing, when the pressure in the operating CO2 storage chamber drops to 10-25MPa, the on / off valve V3 between the operating CO2 storage chamber and the supercritical processing chamber is closed, and at the same time, the on / off valve V3 between any standby CO2 storage chamber and the supercritical processing chamber is opened to realize the switching between CO2 storage chambers, and the switched CO2 storage chamber is used to supply the supercritical processing chamber SCC.

[0029] Further, the substrate / wafer processing in step (3) is as follows: supercritical CO2 enters the supercritical processing chamber, and the supercritical processing chamber enters the intake pressurization process, called the T1 pressurization stage. When the pressure inside the supercritical processing chamber rises to 8-18 MPa (preferably 15-18 MPa), the on / off valve V3 is closed, the supply of SCC is stopped, the T1 pressurization stage ends, and the T2 settling stage begins. The pressure inside the supercritical processing chamber stabilizes at 8-18 MPa and is maintained for 1-60 seconds. The substrate / wafer and supercritical CO2 have sufficient contact and replacement. The T2 settling stage ends, and at the same time, the on / off valve V3 between the CO2 storage chamber and the supercritical processing chamber, the pressure regulating valve V4, and the opening valve on the exhaust pipe are opened. The supercritical processing chamber enters the T3 flow replacement stage after the closing valve V5, pressure regulating valve V6, on / off valve V7, and check valve are connected. During this stage, the opening of the pressure regulating valve V6 is adjusted by the control system feedback to maintain the pressure in the supercritical processing chamber at 8-18 MPa (preferably 14-18 MPa) for 0.5-2 minutes. After the substrate wafer processing is completed, the on / off valve V3 and pressure regulating valve V4 between the CO2 storage chamber and the supercritical processing chamber are closed, the T3 flow replacement stage ends, and the supercritical processing chamber enters the T4 exhaust stage. The supercritical processing chamber is depressurized by exhausting gas through the exhaust pipe until the pressure inside the supercritical processing chamber drops to atmospheric pressure. The above process may or may not include the T2 settling stage.

[0030] Furthermore, the T3 flow replacement stage can be a stable replacement process with constant pressure, a pressure reduction-pressure increase cycle process, a pressure reduction-settling-pressure increase cycle process, or one or more of the following: a pressure reduction-pressure increase-settling cycle process.

[0031] Furthermore, the above processing method can be used for drying, cleaning, and rinsing of substrates / wafers. Before supercritical processing, a liquid film can be coated on the surface of the substrate / wafer. The liquid film can be one or more of alcohol or alkane liquid films, such as an isopropanol liquid film, and the thickness of the liquid film can be 0.05–0.5 mm, for example, 0.1 mm.

[0032] Compared with the prior art, the advantages of the present invention are: 1. By switching between two or more CO2 storage chambers, supercritical CO2 can be continuously and uninterruptedly supplied to the processing chamber, which can meet the requirements of high production capacity and high processing efficiency; 2. The CO2 supply device does not need to be equipped with mechanical components such as pressurizing pumps with large pressure fluctuation ranges. The system structure is simple, the cost is low, it is not easy to be damaged, and it is more conducive to later maintenance. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a supercritical substrate processing device provided by the present invention; wherein a represents two or more carbon dioxide supply devices; and b represents one carbon dioxide supply device.

[0034] Figure 2 This is a schematic diagram of a substrate supercritical processing device provided in Example 1, where a is the O2 storage chamber 200a completing the conversion of liquid CO2 to the supercritical state, and b is the CO2 storage chamber 200b completing the conversion of liquid CO2 to the supercritical state.

[0035] Figure 3 This is a schematic diagram of a substrate supercritical processing device provided in Example 2, where a represents the CO2 storage chamber 200a where liquid CO2 is converted to a supercritical state, and b represents the CO2 storage chamber 200b where liquid CO2 is converted to a supercritical state.

[0036] Figure 1 , Figure 2 and Figure 3 In the middle, 100-CO2 supply device, 401-on / off valve V1, 402-liquid CO2 supply pipeline, 403-first mass flow meter, 404-on / off valve V2, 405-first pressure sensor, 406-first safety valve, 407-first temperature sensor, 408-second pressure sensor, 20-CO2 storage chamber, 200-temperature control device, 409-second temperature sensor, 410-filter, 411-supercritical CO2 supply pipeline, 412-on / off valve V3, 413-pressure regulating valve V4, 414 - Second mass flow meter, 415 - Third temperature sensor, 416 - Third pressure sensor, 417 - Substrate / wafer, 418 - Heating device, 419 - Second safety valve, 40 - Supercritical processing chamber, 420 - On / off valve V5, 421 - Pressure regulating valve V6, 422 - Exhaust pipe, 423 - On / off valve V7, 424 - First check valve, 425 - First throttle valve, 426 - On / off valve V8, 427 - Second check valve, 428 - Second throttle valve, 429 - On / off valve V9, 300 - CO2 recovery device.

[0037] Figure 4This is a schematic diagram of the carbon dioxide supply device 100 used in Examples 1 and 2, wherein 10 is a CO2 gas source, 11 is a mass flow meter, 12 is a filter, and 13 is a condenser.

[0038] Figure 5 This is a schematic diagram of the CO2 recovery device 300 used in Examples 1 and 2, wherein 30 is the end pipeline of the CO2 exhaust line, 31 is the gas-liquid separation device, 32 is the filter, 33 is the condenser, and 34 is the CO2 storage tank.

[0039] Figure 6 The temperature control device configured for the CO2 storage chamber in Examples 1 and 2 includes: 20 - CO2 storage chamber, 21 - water bath thermostat, 22 - water bath delivery pipe, 23 - water bath coil, 24 - electric heating wire, and 25 - water bath tank.

[0040] Figure 7 This is a graph showing the pressure changes at each stage (T1, T2, T3, and T4) in the supercritical processing chamber during the drying process of the wafer in the substrate supercritical processing device in Example 3.

[0041] Figure 8 This is a graph showing the pressure changes at stages T1, T3, and T4 in the supercritical processing chamber during the drying process of the wafer in the substrate supercritical processing device in Example 4.

[0042] Figure 9 This is a flowchart illustrating the overall process of processing the substrate using a supercritical substrate treatment device according to the present invention. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] Example 1

[0045] like Figure 2 As shown, a supercritical substrate processing device includes two carbon dioxide supply devices 100a and 100b, two CO2 storage chambers 20a and 20b, a supercritical processing chamber 40, and a CO2 recovery device 300.

[0046] An on / off valve 401a is installed at the outlet of the carbon dioxide supply device 100a, and the outlet of the carbon dioxide supply device 100a is connected to the inlet of the on / off valve 401a. An on / off valve 404a is installed at the inlet of the CO2 storage chamber 20a, and the inlet of the CO2 storage chamber 20a is connected to the outlet of the on / off valve 404a. One end of the liquid CO2 supply pipeline 402a is connected to the outlet of the on / off valve 401a, and the other end is connected to the inlet of the on / off valve 404a. A first mass flow meter 403a, a first pressure sensor 405a, and a first safety valve 406a are installed on the liquid CO2 supply pipeline 402a.

[0047] An on / off valve 401b is installed at the outlet of the carbon dioxide supply device 100b, and the outlet of the carbon dioxide supply device 100b is connected to the inlet of the on / off valve 401b. An on / off valve 404b is installed at the inlet of the CO2 storage chamber 20b, and the inlet of the CO2 storage chamber 20b is connected to the outlet of the on / off valve 404b. One end of the liquid CO2 supply pipeline 402b is connected to the outlet of the on / off valve 401b, and the other end is connected to the inlet of the on / off valve 404b. A first mass flow meter 403b, a first pressure sensor 405b, and a first safety valve 406b are installed on the liquid CO2 supply pipeline 402b.

[0048] Among them, carbon dioxide supply devices 100a and 100b are liquid CO2 conversion devices consisting of a gaseous CO2 cylinder, a mass flow meter, a filter, and a condenser (e.g., Figure 4 As shown, the gaseous CO2 cylinder outputs 5MPa of gaseous CO2. The mass flow meter is a Coriolis mass flow meter. The working temperature of the condenser can be -30℃. The output liquid CO2 is warmed back to room temperature in the output pipeline. The output liquid CO2 pressure is 6MPa.

[0049] CO2 storage chamber 20a is equipped with a second pressure sensor 408a and a first temperature sensor 407a. An on / off valve 412a is installed at the outlet of CO2 storage chamber 20a, and the outlet of CO2 storage chamber 20a is connected to the inlet of on / off valve 412a. CO2 storage chamber 20b is equipped with a second pressure sensor 408b and a first temperature sensor 407b. An on / off valve 412b is installed at the outlet of CO2 storage chamber 20b, and the outlet of CO2 storage chamber 20b is connected to the inlet of on / off valve 412b. Both CO2 storage chambers 20a and 20b are cylindrical sealed chambers with a volume of 30L. CO2 storage chamber 20a is equipped with a temperature control device 200a, which includes a water bath thermostat 21, a water bath delivery pipe 22, a water bath coil 23, an electric heating wire 24, and a water bath 25.

[0050] The supercritical processing chamber 40 is a hollow, stainless steel sealed cavity with an internal volume of 0.7L. It contains a tray for placing substrates / wafers. The inlet of the supercritical processing chamber 40 is connected to one end of the supercritical CO2 supply pipeline 411. The other end of the CO2 supply pipeline 411 is connected to two branch pipelines through a tee connector, which are respectively connected to the outlets of the on-off valves 412a and 412b. The supercritical CO2 supply pipeline 411 is equipped with a second temperature sensor 409, a filter 410, a pressure regulating valve 413, and a second mass flow meter 414. The first mass flow meters 403a and 403b and the second mass flow meter 414 are all Coriolis mass flow meters.

[0051] The supercritical processing chamber 40 is equipped with an electric heating element 418 at its bottom. The supercritical processing chamber 40 is equipped with a third pressure sensor 416 and a third temperature sensor 415 for detecting the pressure and temperature inside the chamber. The supercritical processing chamber 40 is equipped with a second safety valve 419. The outlet of the supercritical processing chamber 40 is connected to one end of the exhaust pipe 422, and the other end of the exhaust pipe 422 is connected to the inlet of the CO2 recovery device 300. The exhaust pipe 422 is equipped with an on / off valve 420, a pressure regulating valve 421, an on / off valve 423, and a check valve 424.

[0052] The CO2 recovery unit 300 consists of a gas-liquid separator, a filter, a condenser, and a CO2 storage tank.

[0053] Example 2

[0054] like Figure 2 As shown, a supercritical substrate processing device includes a carbon dioxide supply device 100, two CO2 storage chambers 20a and 20b, a supercritical processing chamber 40, and a CO2 recovery device 300; the carbon dioxide supply device 100 is connected to the two CO2 storage chambers 20a and 20b respectively through a liquid CO2 supply pipeline 402.

[0055] A shut-off valve 401 is installed at the outlet of the carbon dioxide supply device 100, and the outlet of the carbon dioxide supply device 100 is connected to the inlet of the shut-off valve 401. A shut-off valve 404a is installed at the inlet of the CO2 storage chamber 20a, and the inlet of the CO2 storage chamber 20a is connected to the outlet of the shut-off valve 404a. A shut-off valve 404b is installed at the inlet of the CO2 storage chamber 20b, and the inlet of the CO2 storage chamber 20b is connected to the outlet of the shut-off valve 404b.

[0056] A liquid CO2 supply pipeline 402 is provided between the carbon dioxide supply device 100 and the CO2 storage chambers 20a and 20b. One end of the liquid CO2 supply pipeline 402 is connected to the outlet of the on-off valve 401, and the other end is connected to the inlet of the on-off valve 404a and the on-off valve 404b respectively through two branch pipelines branched off by a tee connector. A first mass flow meter 403, a first pressure sensor 405 and a first safety valve 406 are provided on the liquid CO2 supply pipeline 402.

[0057] Among them, carbon dioxide supply devices 100a and 100b are liquid CO2 conversion devices consisting of a gaseous CO2 cylinder, a mass flow meter, a filter, and a condenser (e.g., Figure 4 As shown, the gaseous CO2 cylinder outputs 5MPa of gaseous CO2. The mass flow meter is a Coriolis mass flow meter. The working temperature of the condenser can be -30℃. The prepared liquid CO2 is warmed back to room temperature in the output pipeline. The output liquid CO2 pressure is 6MPa.

[0058] CO2 storage chamber 20a is equipped with a second pressure sensor 408a and a first temperature sensor 407a. An on / off valve 412a is installed at the outlet of CO2 storage chamber 20a, and the outlet of CO2 storage chamber 20a is connected to the inlet of on / off valve 412a. CO2 storage chamber 20b is equipped with a second pressure sensor 408b and a first temperature sensor 407b. An on / off valve 412b is installed at the outlet of CO2 storage chamber 20b, and the outlet of CO2 storage chamber 20b is connected to the inlet of on / off valve 412b. Both CO2 storage chambers 20a and 20b are cylindrical sealed chambers with a volume of 30L. CO2 storage chamber 20a is equipped with a temperature control device 200a, which includes a water bath thermostat 21, a water bath delivery pipe 22, a water bath coil 23, an electric heating wire 24, and a water bath 25.

[0059] The supercritical processing chamber 40 is a hollow, stainless steel sealed cavity with a volume of 0.7L. Inside, there is a tray for placing substrates / wafers. The inlet of the supercritical processing chamber 40 is connected to one end of the supercritical CO2 supply pipeline 411. The other end of the CO2 supply pipeline 411 is connected to two branch pipelines through a tee connector, which are respectively connected to the outlets of the on-off valves 412a and 412b. The supercritical CO2 supply pipeline 411 is equipped with a second temperature sensor 409, a filter 410, a pressure regulating valve 413, and a second mass flow meter 414. The first mass flow meters 403a and 403b and the second mass flow meter 414 are all Coriolis mass flow meters.

[0060] The supercritical processing chamber 40 is equipped with an electric heating belt 418 at its bottom. A third pressure sensor 416 and a third temperature sensor 415 are installed on the supercritical processing chamber 40 to detect the pressure and temperature within the chamber. A second safety valve 419 is also installed on the supercritical processing chamber 40. The outlet of the supercritical processing chamber 40 is connected to one end of an exhaust pipe 422, and the other end of the exhaust pipe 422 is connected to the inlet of the CO2 recovery device 300. An on / off valve 420, a pressure regulating valve 421, an on / off valve 423, and a check valve 424 are installed on the exhaust pipe 422. The CO2 recovery device 300 consists of a gas-liquid separator, a filter, a condenser, and a CO2 storage tank.

[0061] Example 3

[0062] The 12-inch wafer was dried using the supercritical processing device described in Example 1. The specific process is as follows:

[0063] First, check that all components of the supercritical treatment unit are in normal condition and that all valves are closed.

[0064] (1) Turn on the heating device 418 to preheat the supercritical processing chamber 40 to 90°C and maintain that temperature.

[0065] (2) Set the temperature of the temperature control device 200a to 5℃, adjust and maintain the temperature of the CO2 storage chamber 20a at the initial temperature of 5℃, and then open the on / off valves 401a and 404a. The liquid CO2 output by the carbon dioxide supply device 100a is transported to the CO2 storage chamber 20a through the liquid CO2 supply pipeline 402a, passing sequentially through the on / off valve 401a, the first mass flow meter 403a, and the on / off valve 404a. When the liquid CO2 in the CO2 storage chamber 20a... When the CO2 concentration reaches 15L, the on / off valves 401a and 404a are closed, and the temperature control device 200a is set to 90℃ to heat the CO2 storage chamber 20a. The temperature and pressure inside the CO2 storage chamber 20a are monitored by the first temperature sensor 407a and the second pressure sensor 408a. When the temperature reaches 90℃ and the pressure reaches 20MPa, all the CO2 inside the CO2 storage chamber 20a becomes supercritical (SCC state). Figure 2 As shown in a.

[0066] (3) Place a 12-inch wafer coated with an IPA (isopropanol) liquid film on a tray in the supercritical processing chamber.

[0067] (4) Open the on / off valve 412a and the pressure regulating valve 413. The SCC in the CO2 storage chamber 20a passes through the on / off valve 412a, the filter 410, the pressure regulating valve 413, and the second mass flow meter 414 in sequence before entering the supercritical treatment chamber 40. The gas pressure in the supercritical treatment chamber 40 will start to rise from atmospheric pressure. The gas pressure rise process in the supercritical treatment chamber 40 is called the T1 pressure rise stage (e.g., Figure 7 As shown, when the pressure inside the supercritical processing chamber 40 rises to the supercritical processing pressure P1 = 16 MPa, the on / off valve 412a and the pressure regulating valve 413 are closed, the supply of SCC is stopped, the T1 pressure rise stage ends, and the T2 settling stage begins. The pressure inside the supercritical processing chamber 40 stabilizes at 16 MPa and is maintained for 10 seconds. During the T2 settling stage, the SCC inside the supercritical processing chamber 40 will displace the IPA liquid film on the wafer surface, and the IPA liquid film on the substrate surface will gradually dissolve in the SCC. The T2 settling stage ends, and the on / off valve 412a is opened. The supercritical processing chamber 40 is equipped with pressure regulating valves 413, 420, 421, 423, and 424. During the T3 flow-displacement stage, the control system adjusts the opening of pressure regulating valve 421 based on pressure data detected by pressure sensor 416, maintaining the pressure in the supercritical processing chamber 40 at P1 = 16 MPa. In the T3 flow-displacement stage, the supercritical processing chamber 40 discharges a mixed fluid containing IPA through exhaust pipe 422. The discharged mixed fluid ultimately flows into the recovery device 300 for recycling. During the T3 flow-displacement stage, opening and closing valves 412a and 413 remain open, continuously replenishing the supercritical processing chamber 40 with fresh, pure SCC. By simultaneously supplying SCC to the supercritical processing chamber 40 and discharging the mixed processing fluid, the replacement and drying of IPA on the wafer surface is achieved, while the pressure within the supercritical processing chamber 40 is maintained at 16 MPa, ensuring the mixed fluid remains in a supercritical state and preventing localized gas-liquid phase transitions. The T3 flow-displacement stage lasts for 1 minute, during which the IPA on the wafer surface is completely replaced by the supercritical fluid, and the drying process on the wafer surface is completed. The on / off valve 412a and the pressure regulating valve 413 are then closed, ending the T3 flow-displacement stage. The supercritical processing chamber 40 then enters the T4 exhaust stage, where the processing fluid inside the supercritical processing chamber 40 is discharged through the exhaust line until the internal pressure drops to atmospheric pressure. The dried wafer is then removed and a new wafer with an IPA liquid film on its surface is transferred for the next supercritical fluid drying process.

[0068] (5) While the wafers in the supercritical processing chamber 40 begin drying, the temperature of the temperature control device 200b is set to 5°C. The temperature of the CO2 storage chamber 20b is maintained at its initial temperature of 5°C under the action of the temperature control device 200b. Then, the on / off valves 401b and 404b are opened, and the liquid CO2 in the carbon dioxide supply device 100b is transported to the CO2 storage chamber 20b through the liquid CO2 supply pipeline 402b, sequentially via the on / off valve 401b, the first mass flow meter 403b, and the on / off valve 404b. When the CO2 in the CO2 storage chamber 20b... When the liquid CO2 reaches 15L, the on / off valves 401 and 404b are closed, and the temperature of the temperature control device 200b corresponding to the CO2 storage chamber 20b is set to 90℃. The CO2 storage chamber 20b is heated, and the temperature and pressure inside the CO2 storage chamber 20b are monitored by the first temperature sensor 407b and the second pressure sensor 408b. When the temperature reaches 90℃ and the pressure reaches 20MPa, all the CO2 inside the CO2 storage chamber 20b becomes supercritical (SCC state), and the CO2 storage chamber 20b enters standby mode (e.g., ...). Figure 2 (as shown in b);

[0069] (6) When the pressure inside the supercritical processing chamber 40a drops to less than 16MPa, the on-off valve 412a is closed and the on-off valve 412b is opened at the same time, so that SCC is supplied from the CO2 storage chamber 20b to the supercritical processing chamber 40, thereby realizing the switching between the CO2 storage chambers and realizing the continuous supply of SCC to the supercritical processing chamber 40.

[0070] Example 4

[0071] The 12-inch wafer was dried using the supercritical processing apparatus described in Example 1.

[0072] This embodiment is a variation of embodiment 3. The specific process is the same as in embodiment 3, except that the pressure change process in the supercritical fluid chamber in step (4) of this embodiment adopts a depressurization-increase cycle process (e.g., Figure 8 As shown), the details are as follows:

[0073] (4) Open the on / off valve 412a and the pressure regulating valve 413. The SCC in the CO2 storage chamber 20a passes through the on / off valve 412a, the filter 410, the pressure regulating valve 413, and the second mass flow meter 414 in sequence before entering the supercritical treatment chamber 40. The gas pressure in the supercritical treatment chamber 40 will start to rise from atmospheric pressure. The gas pressure rise process in the supercritical treatment chamber 40 is called the T1 pressure rise stage (e.g., Figure 8As shown, when the pressure inside the supercritical processing chamber 40 rises to the supercritical processing pressure P1 = 16 MPa, the on / off valve 412a and pressure regulating valve 413 are closed, the supply of SCC is stopped, the T1 pressure rise stage ends, and the T3 flow replacement stage begins. Simultaneously, the on / off valve 420, pressure regulating valve 421, on / off valve 423, and check valve 424 are opened to discharge some of the mixed processing fluid. The pressure inside the supercritical processing chamber 40 will decrease as the processing fluid is discharged. When the pressure inside the supercritical processing chamber 40 decreases to P2 = 14 MPa, the on / off valve 420 and pressure regulating valve 423 are closed, and the on / off valve 412a and pressure regulating valve 413 are opened. The pressure inside the supercritical processing chamber 40 will rise as SCC is replenished. When the pressure inside the supercritical processing chamber 40 rises to P1 = 16 MPa, the on / off valve 412a and pressure regulating valve 413 are closed again to discharge some of the mixed processing fluid. This process is repeated sequentially in the supercritical processing chamber 40. The supercritical fluid processing chamber 40 undergoes a depressurization-boosting cycle. During each depressurization process, a mixed processing fluid containing dissolved IPA is discharged, and during each boosting process, fresh and pure SCC is added. This process replaces the IPA liquid film on the wafer surface and dries the wafer. The cycle is controlled by feedback from the control system, which adjusts the opening and closing of each valve and the opening degree of the pressure regulating valve based on the pressure data detected by the pressure sensor 416. The depressurization-boosting cycle is repeated 7 times (taking 1 minute). At the end of the T3 flow replacement stage, the opening and closing valve 412a and the pressure regulating valve 413 are closed, and the opening and closing valve 420, the pressure regulating valve 421, the opening and closing valve 423, and the check valve 424 are opened. The supercritical fluid processing chamber 40 then enters the T4 exhaust stage. The processing fluid in the supercritical fluid processing chamber 40 is discharged through the exhaust line until the internal pressure drops to atmospheric pressure. The dried wafer is then removed and a new wafer with an IPA liquid film on its surface is transferred for the next supercritical fluid drying process.

[0074] Reasonable modifications or alterations made based on this patent and its embodiments should also be protected under this patent. For example, increasing the number of supercritical processing chambers, such as four CO2 storage chambers corresponding to two supercritical processing chambers, six CO2 storage chambers corresponding to three supercritical processing chambers, etc.

Claims

1. A method for processing a substrate using a supercritical substrate processing device, characterized in that, The supercritical substrate processing device includes a carbon dioxide supply device, a CO2 storage chamber, a supercritical processing chamber, and a CO2 recovery device. Two or more CO2 storage chambers are provided. An on / off valve V2 is installed at the inlet of each CO2 storage chamber, and the inlet of the CO2 storage chamber is connected to the outlet of the on / off valve V2. An on / off valve V3 is installed at the outlet of each CO2 storage chamber, and the outlet of the CO2 storage chamber is connected to the inlet of the on / off valve V3. Each CO2 storage chamber is equipped with a temperature control device. One or more carbon dioxide supply devices are installed, and an on / off valve V1 is installed at the outlet of the carbon dioxide supply device. The outlet of the carbon dioxide supply device is connected to the inlet of the on / off valve V1. When two or more carbon dioxide supply devices are installed, each carbon dioxide supply device is connected to the inlet of one or more CO2 storage chambers via a liquid CO2 supply pipeline through the outlet of the on / off valve V1. The liquid CO2 supply pipeline is equipped with a first mass flow meter, a first pressure sensor, and a first safety valve. Alternatively, when there is one carbon dioxide supply device, the carbon dioxide supply device is connected to each CO2 storage chamber via an on / off valve V1, a liquid CO2 supply pipeline and branch pipelines, and an on / off valve V2 respectively; one end of the liquid CO2 supply pipeline is connected to the outlet of the on / off valve V1, and the other end is connected to the inlet of the on / off valve V2 at the inlet of each CO2 storage chamber via a branch pipeline; the liquid CO2 supply pipeline is equipped with a first mass flow meter, a first pressure sensor, and a first safety valve; a supercritical CO2 supply pipeline is provided between the CO2 storage chamber and the supercritical processing chamber; one end of the supercritical CO2 supply pipeline is connected to the inlet of the supercritical processing chamber, and the other end is connected to the outlet of the on / off valve V3 at the outlet of each CO2 storage chamber via a branch pipeline of the supercritical CO2 supply pipeline; the supercritical CO2 supply pipeline is equipped with a second temperature sensor, a filter, a pressure regulating valve V4, and a second mass flow meter. An exhaust pipe is provided between the supercritical processing chamber and the CO2 recovery device. One end of the exhaust pipe is connected to the outlet of the supercritical processing chamber and the other end is connected to the inlet of the CO2 recovery device. An on-off valve V5, a pressure regulating valve V6, an on-off valve V7, and a first check valve are installed on the exhaust pipe. The method for processing a substrate using a supercritical substrate processing device specifically includes the following steps: (1) Select any one or two CO2 storage chambers to convert liquid CO2 into supercritical CO2: First, maintain the temperature in the selected CO2 storage chamber at an initial temperature of 2~15℃ using a temperature control device; then, open the on / off valves V1 and V2 between the carbon dioxide supply device and the selected CO2 storage chamber. Liquid CO2 is supplied to the CO2 storage chamber via the CO2 supply device through the on / off valves V1, V2, and the first mass flow meter. When the volume of liquid CO2 in the CO2 storage chamber with a volume of V reaches 0.3~0.95V, close the on / off valves V1 and V2; set the temperature of the temperature control device to 35~150℃, and heat the selected CO2 storage chamber through the temperature control device to convert all the CO2 inside into supercritical CO2 state for later use. (2) Place the substrate to be processed onto the tray in the supercritical processing chamber; (3) The supercritical processing chamber is preheated to 80~100℃. Select any spare CO2 storage chamber and open the on / off valve V3 between the selected CO2 storage chamber and the supercritical processing chamber. The supercritical CO2 in the CO2 storage chamber enters the supercritical processing chamber through the filter, pressure regulating valve V4 and the second mass flow meter to process the substrate / wafer. After the processing is completed, the supercritical processing chamber is vented and depressurized. The processed substrate / wafer is taken out and a new substrate to be processed is transferred. (4) While performing any of the steps (1), (2) or (3), at least one other CO2 storage chamber is converted from liquid CO2 to supercritical CO2 state according to the operation of step (1), so that the other CO2 storage chamber enters the standby state. (5) During the substrate processing, when the pressure in the operating CO2 storage chamber drops to 10-25MPa, the on / off valve V3 between the operating CO2 storage chamber and the supercritical processing chamber is closed, and at the same time, the on / off valve V3 between any standby CO2 storage chamber and the supercritical processing chamber is opened to realize the switching between CO2 storage chambers, and the switched CO2 storage chamber is used to supply supercritical CO2 to the supercritical processing chamber.

2. The method according to claim 1, characterized in that, A second pressure sensor and a first temperature sensor are installed on the CO2 storage chamber to monitor the pressure and temperature inside the CO2 storage chamber. The volume of the CO2 storage chamber is 2~50 L. The temperature control device configured in the CO2 storage chamber is one or more of the following: water bath, oil bath, electric heating wire, electric heating belt or other heat exchange device for cold and hot media. The temperature adjustment range is 0~150℃.

3. The method according to claim 2, characterized in that, The CO2 supply device supplies and outputs liquid CO2, and the temperature of the output liquid CO2 is stabilized at 20~25 ℃; the carbon dioxide supply device is a high-pressure liquid CO2 storage tank or cylinder, or a liquid CO2 storage tank or cylinder equipped with a transfer pump or a high-pressure transfer pump; or a liquid CO2 conversion device consisting of a CO2 gas source, a gas purifier, a flow meter, a filter, and a condenser, or a liquid CO2 conversion device consisting of a CO2 gas source, a flow meter, a filter, and a condenser; the liquid CO2 conversion device is equipped with a transfer pump or a high-pressure transfer pump.

4. The method according to claim 1, characterized in that, The supercritical processing chamber is an openable and closable sealed chamber with a volume of 0.4~1.5L. The supercritical processing chamber is equipped with a third pressure sensor, a third temperature sensor, a heating device, and a second safety valve. Inside the supercritical processing chamber, there is one or more trays, each tray holding a substrate or wafer. The heating device installed on the supercritical processing chamber is an electric heating wire, an electric heating belt, or an electric heating blanket.

5. The method according to claim 1, characterized in that, Two branch exhaust pipes are provided on the exhaust pipe, parallel to the on / off valve V7 and the check valve. One end of one branch exhaust pipe is connected to the outlet of the pressure regulating valve V6, and the other end is connected to the inlet of the CO2 recovery device via the first throttle valve, the on / off valve V8 and the second check valve. One end of the other branch exhaust pipe is connected to the outlet of the pressure regulating valve V6, and the other end is connected to the inlet of the CO2 recovery device via the second throttle valve and the on / off valve V9.

6. The method according to claim 1, characterized in that, The first and second safety valves are used to relieve pressure in the system when the pressure is unexpectedly too high. The pressure relief threshold range of the safety valves is 15~30 MPa.

7. The method according to claim 1, characterized in that, In step (1), select any one or two CO2 storage chambers to convert liquid CO2 into supercritical CO2: First, use a temperature control device to maintain the temperature in the selected CO2 storage chamber at an initial temperature of 2~15℃; Then, open the on / off valves V1 and V2 between the carbon dioxide supply device and the selected CO2 storage chamber. Liquid CO2 is supplied to the CO2 storage chamber via the CO2 supply device through the on / off valves V1 and V2 and the first mass flow meter. When the volume of liquid CO2 in the CO2 storage chamber with a volume of V reaches 0.45~0.95 V, close the on / off valves V1 and V2. Set the temperature of the temperature control device to 80~120℃ and heat the selected CO2 storage chamber through the temperature control device to convert all the CO2 inside into a supercritical CO2 state for later use.

8. The method according to claim 1, characterized in that, In step (3), the substrate processing process is as follows: supercritical CO2 enters the supercritical processing chamber, and the supercritical processing chamber enters the intake pressurization process, which is called the T1 pressurization stage. When the pressure inside the supercritical processing chamber rises to 8~18 MPa, the on / off valve V3 is closed, the supply of SCC is stopped, the T1 pressurization stage ends and enters the T2 settling stage. The pressure inside the supercritical processing chamber is stabilized at 8-18 MPa and maintained for 1-60s. The substrate / wafer and supercritical CO2 have sufficient contact and replacement. The T2 settling stage ends. At the same time, the on / off valve V3, the pressure regulating valve V4 between the CO2 storage chamber and the supercritical processing chamber, and the on / off valve V5, the pressure regulating valve V6, the on / off valve V7 and the check valve on the exhaust pipe are opened, and the T3 flow replacement stage is entered. In this stage, the opening degree of the pressure regulating valve V6 is adjusted by the feedback of the control system so that the pressure inside the supercritical processing chamber is always maintained at 8~18 MPa for 0.5-2min. Once the substrate processing is complete, close the on / off valve V3 and pressure regulating valve V4 between the CO2 storage chamber and the supercritical processing chamber. The T3 flow replacement stage ends, and the supercritical processing chamber enters the T4 exhaust stage. The supercritical processing chamber is depressurized by exhausting through the exhaust pipe until the pressure inside the supercritical processing chamber drops to atmospheric pressure. The processing may or may not include the T2 settling stage.

9. The method according to claim 8, characterized in that, In step (3), the substrate processing process is as follows: supercritical CO2 enters the supercritical processing chamber, and the supercritical processing chamber enters the intake pressurization process, which is called the T1 pressurization stage. When the pressure inside the supercritical processing chamber rises to 15~18 MPa, the on / off valve V3 is closed, the supply of SCC is stopped, the T1 pressurization stage ends and enters the T2 settling stage. The pressure inside the supercritical processing chamber is stabilized at 8-18 MPa and maintained for 1-60s. The substrate / wafer has sufficient contact and replacement with supercritical CO2. The T2 settling stage ends. At the same time, the on / off valve V3 between the CO2 storage chamber and the supercritical processing chamber, the pressure regulating valve V4, and the on / off valve V5, pressure regulating valve V6, on / off valve V7 and check valve on the exhaust pipe are opened, and the T3 flow replacement stage is entered. In this stage, the opening degree of the pressure regulating valve V6 is adjusted by the feedback of the control system so that the pressure inside the supercritical processing chamber is always maintained at 14~18 MPa for 0.5-2min. Once the substrate processing is complete, close the on / off valve V3 and pressure regulating valve V4 between the CO2 storage chamber and the supercritical processing chamber. The T3 flow replacement stage ends, and the supercritical processing chamber enters the T4 exhaust stage. The supercritical processing chamber is depressurized through the exhaust pipe until the pressure inside the supercritical processing chamber drops to atmospheric pressure.

10. The method according to claim 7, characterized in that, The T3 flow replacement stage in step (3) is a stable replacement process with constant pressure, or a pressure reduction-pressure increase cycle process, or a pressure reduction-stagnation-pressure increase-stagnation cycle process, or a combination of the above processes, wherein the number of cycles is 2 to 50.

11. The method according to claim 1, characterized in that, This processing method is used to dry, clean, and rinse the substrate.

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