Subcritical carbon dioxide supply system for chip cleaning

Abstract

The present application relates to a kind of chip cleaning subcritical carbon dioxide supply system, in the direction of input to output, in turn including raw material tank, booster pump, buffer tank, heating device and purification device, the raw material tank is used to store liquid carbon dioxide, the booster pump is used to transport the liquid carbon dioxide of the raw material tank to the buffer tank and pressurization, the heating device is connected the output end of buffer tank, for the liquid carbon dioxide of buffer tank output is heated and gasified, the purification device is used to the gaseous carbon dioxide of heating device output is purified, remove the impurity in gaseous carbon dioxide.The chip cleaning subcritical carbon dioxide supply system provided by the present application, more stronger continuous supply and stability.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide supply technology for chip cleaning, and more specifically to a subcritical carbon dioxide supply system for chip cleaning. Background Technology

[0002] Semiconductor technology and industry are undergoing rapid and repeated development. The aggregation technology used by small and medium-sized enterprises (SMEs) is becoming increasingly complex. This allows for the rapid collection of large amounts of data. However, this also necessitates higher-performance computers in fields such as high-performance computing, large-scale multimedia data processing, precision measurement, and guidance, thus constantly demanding high-density device technology. Increased device density means narrower linewidths. In other words, the chip manufacturing process becomes more refined and precise. During the semiconductor manufacturing process on wafers, surface contaminants increase exponentially over time, causing a sharp decline in the yield rate of semiconductor devices. While the ideal solution is to gradually adopt cleaning processes to perfectly remove all contaminants from the wafer surface, this is virtually impossible. Therefore, the performance, reliability, and production yield of high-density circuits are determined by unwanted impurities in the physicochemical composition of the wafers used during manufacturing or present on the surface of the components after manufacturing. Even with advanced ultra-fine processing technology, functional components cannot be obtained if the cleaning process is imperfect. In other words, cleaning technology is not about cleaning semiconductor devices, but rather about the manufacturing technology of semiconductor devices.

[0003] As the feature size of integrated circuits gradually decreases, the device structure requires a higher aspect ratio. Conventional wet cleaning methods, due to surface tension, have difficulty penetrating the deep trench structure of the wafer, failing to meet the requirements of finer line processes and high aspect ratio structures, directly affecting the removal effect of contaminants in the trench. Conventional wet etching suffers from poor anisotropy, severe structural collapse, and insignificant deep trench etching effect. In contrast, plasma dry etching has a series of problems such as slow etching rate, photoresist shedding and adhesion, structural damage, and waste gas treatment.

[0004] Currently, using supercritical carbon dioxide fluid for chip cleaning can better solve the above problems. Carbon dioxide reaches a supercritical state at 7.39 MPa and 31℃, and it has the characteristics of high density, strong dissolving power, and high mass transfer rate. It also has the advantages of abundant reserves, low cost, non-toxicity, inertness, and easy recycling. Specifically, Chinese Patent Publication No. CN 209000881 U discloses a Si-based HgCdTe chip cleaning device before passivation, which uses carbon dioxide as the cleaning agent. Its low surface tension, high diffusivity, and excellent dissolving power for organic matter improve the cleaning efficiency of contaminants and shorten the cleaning time.

[0005] In the field of chip cleaning, chips are relatively precise components. During chip manufacturing, they are affected by environmental contaminants (generated in other processes, byproducts of dry etching, oxidation / deposition processes, and polishing slurries; the main contaminants include particles, native oxide layers, metal contamination, organic matter, sacrificial layers, polishing residues, etc.). Therefore, continuous cleaning is required during the cleaning process. If the cleaning is interrupted or stopped for other reasons, the contaminants inside the chip will remain, which may lead to short circuits or electrical failures of the internal components. Therefore, to ensure the chip cleaning process, the delivery of carbon dioxide also needs to be continuous and stable (due to the three states of carbon dioxide, phase transitions can occur under the influence of temperature and pressure). However, most chip cleaning currently uses pre-fabricated supercritical carbon dioxide directly. This state of carbon dioxide requires specific equipment for front-end carbon dioxide treatment, which increases manufacturing costs to some extent. At the same time, the continuous supply and stability of supercritical carbon dioxide delivery are not high (it is easily affected by external factors and can cause phase transitions), which will affect the overall efficiency of the back-end chip cleaning. Summary of the Invention

[0006] To achieve the objectives of this invention, a subcritical carbon dioxide supply system for chip cleaning is provided. From input to output, the system comprises, in sequence, a raw material tank, a booster pump, a buffer tank, a heating device, and a purification device. The raw material tank stores liquid carbon dioxide. The booster pump delivers the liquid carbon dioxide from the raw material tank to the buffer tank and pressurizes it. The heating device is connected to the output of the buffer tank and heats and vaporizes the liquid carbon dioxide output from the buffer tank. The purification device purifies the gaseous carbon dioxide output from the heating device, removing impurities from the gaseous carbon dioxide.

[0007] Preferably, a cold insulation component is provided on the pipeline between the raw material tank and the buffer tank, and the booster pump is a diaphragm pump.

[0008] Preferably, an online impurity detection device is provided after the purification device. The online impurity detection device is used to detect the impurity content in the gaseous carbon dioxide output by the purification device, and issues a prompt message when the impurity content meets the preset conditions.

[0009] Preferably, a pre-filter is provided between the heating device and the purification device to filter impurities in the gaseous carbon dioxide; and / or, a post-filter is provided between the purification device and the online impurity detection device to filter impurities in the gaseous carbon dioxide.

[0010] Preferably, the online impurity detection device includes multiple impurity detection units connected in parallel, each used to detect different impurity contents.

[0011] Preferably, a pressure regulating device is provided between the heating device and the purification device, and the pressure regulating device is used to adjust the pressure of the gaseous carbon dioxide output by the heating device.

[0012] Preferably, a heat insulation component is provided on the pipeline between the heating device and the purification device.

[0013] Preferably, the heating device is a water bath heating device, and the heat preservation component includes multiple electric heating devices for heating the pipeline, and the multiple electric heating devices are spaced apart along the length of the pipeline.

[0014] Preferably, a self-pressurizing device is provided between the buffer tank and the heating device. The self-pressurizing device includes a heating device, which is used to vaporize the liquid carbon dioxide in the buffer tank. The self-pressurizing device is used to regulate the pressure in the buffer tank so that the liquid carbon dioxide in the buffer tank can be discharged normally.

[0015] The beneficial effects of the present invention are as follows: The subcritical carbon dioxide supply system provided by the present invention keeps the liquid delivery pipeline cold and the gaseous delivery pipeline hot, so that the carbon dioxide remains in a constant state during the delivery process and does not undergo phase change. Compared with the traditional carbon dioxide supply and delivery, it has better stability, stronger continuity in the delivery process, and is more suitable for chip cleaning. Attached Figure Description

[0016] The above and other objects, features, and advantages of the invention will become clearer through a more detailed description of the preferred embodiments illustrated in the accompanying drawings. The same reference numerals denote the same parts throughout the drawings, and the drawings are not intentionally drawn to scale with actual dimensions; the focus is on illustrating the gist of the invention.

[0017] Figure 1 This is a schematic diagram of the specific process of the subcritical carbon dioxide supply system provided in an embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of the specific structure of the subcritical carbon dioxide supply system provided in an embodiment of the present invention;

[0019] Figure 3 for Figure 2 A magnified view of part A in the middle;

[0020] Figure 4 for Figure 2 A magnified view of part B in the middle section;

[0021] Figure 5 for Figure 2 A magnified view of part C in the middle;

[0022] Figure 6This is a schematic diagram of the specific structure of the refrigerant pipeline provided in an embodiment of the present invention;

[0023] Figure 7 This is a schematic diagram showing the connection between the refrigeration unit and the diaphragm pump provided in an embodiment of the present invention;

[0024] In the diagram: 1-Raw material tank, 2-Buffer tank, 3-Diaphragm pump, 4-Return pipe, 5-Heating device, 51-Liquid delivery pipe, 521-Refrigerant outlet pipe, 522-Refrigerant return pipe, 6-Pressure regulating device, 7-Pre-filter device, 8-Insulation component, 81-Purification device, 82-Post-filter device. Detailed Implementation

[0025] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0026] Please refer to Figure 1-7 This invention provides a subcritical carbon dioxide supply system for chip cleaning, which, in the direction from input to output, includes a raw material tank 1, a booster pump, a buffer tank 2, a heating device 5, and a purification device 81. The raw material tank 1 is used to store liquid carbon dioxide. The booster pump is used to transport the liquid carbon dioxide from the raw material tank 1 to the buffer tank 2 and pressurize it. The heating device 5 is connected to the output end of the buffer tank 2 and is used to heat and vaporize the liquid carbon dioxide output from the buffer tank 2. The purification device 81 is used to purify the gaseous carbon dioxide output from the heating device 5 and remove impurities from the gaseous carbon dioxide.

[0027] Please refer to Figure 1-7 In a preferred embodiment, a cold insulation component is installed on the pipeline between the raw material tank 1 and the buffer tank 2, and the booster pump is a diaphragm pump 3; the booster pump adopts a redundant configuration, with a total of 4 units (1 in use and 3 on standby), each with a capacity of 300 Nm3 / hr, to ensure stable supply pressure, thereby ensuring the stability and continuous supply of carbon dioxide during the transportation process, and ensuring that carbon dioxide does not undergo phase change during transportation.

[0028] The working pressure fluctuation of the first delivery pipeline between the high-purity buffer tank 2 and the diaphragm pump 3 shall not exceed ±3 barg, and the working pressure fluctuation of the first delivery pipeline between the diaphragm pump 3 and the medium-pressure buffer tank 2 shall not exceed ±3 barg. At least one section of the first delivery pipeline between the high-purity buffer tank 2 and the diaphragm pump 3 shall be a cooling pipeline. The temperature of the liquid carbon dioxide near the diaphragm pump 3 in the cooling pipeline shall be controlled between -24°C and -26°C. The cooling pipeline includes a liquid delivery pipeline and a refrigerant pipeline located outside the liquid delivery pipeline. The refrigerant pipeline is connected to the refrigeration unit. Liquid carbon dioxide is delivered in the liquid delivery pipeline, and ethylene glycol refrigerant flows in the refrigerant pipeline.

[0029] Please refer to Figure 1 Section A extends from the liquid carbon dioxide receiving tank (raw material tank 1) (2*60m3) to the booster pump, with a working pressure of 19 barg. The entire pipe section adopts strict pipe insulation measures to ensure that the temperature is around -21 degrees Celsius and that the liquid is in a supercooled state.

[0030] Section B runs from the booster pump to the intermediate tank (buffer tank 2) (2*20m3), with a working pressure of 62 barg. The entire pipe section adopts strict pipe insulation measures to ensure that the temperature is around -21 degrees Celsius and that the liquid is in a supercooled state.

[0031] Section C, from the intermediate tank (2*20m3) to the heating device 5, operates at a pressure of 62 barg. The entire section of pipe is protected against freezing and kept cold.

[0032] ④The D&E section, from the outlet of heating device 5 to the delivery point, adopts the form of heat preservation and electric heat tracing to control the gas temperature between 30 and 40 degrees Celsius, ensuring a stable supply of gaseous carbon dioxide. Heating device 5 is configured as 2*750Nm3 / hr, which meets the N+N configuration requirements.

[0033] The pre-filter uses 2*750Nm3 / hr pre-filters; the post-filter uses 4*250Nm3 / hr terminal filters, with redundant configuration to ensure continuous supply and stability of gaseous carbon dioxide.

[0034] In this embodiment, the carbon dioxide used for chip cleaning employs a cooling system that first uses a diaphragm pump 3 to pressurize the supply, providing pressurized liquid carbon dioxide to the downstream end. This ensures a certain pressure for the carbon dioxide supply, allowing for rapid conversion to supercritical carbon dioxide when chip cleaning is required. The use of the diaphragm pump 3 for pressurization in this embodiment, as tested, ensures that the supplied carbon dioxide meets the requirements for metal ions, resulting in better cleaning performance as the raw material for chip cleaning.

[0035] Considering the issue of stable system delivery, to ensure that the diaphragm pump 3 can be started at any time when needed, it is necessary to ensure that the liquid carbon dioxide is sufficiently liquid before the diaphragm pump 3. This ensures a continuous supply of carbon dioxide. In this embodiment, a cooling pipeline is installed on the delivery pipeline between the raw material tank 11 and the diaphragm pump 33. Under stable pressure, the temperature of the liquid carbon dioxide is controlled between -24°C and -26°C, ensuring that the liquid carbon dioxide is sufficiently liquid. Considering that this temperature control is relatively low, the refrigerant needs to have good refrigeration efficiency and a certain antifreeze effect. Therefore, ethylene glycol refrigerant is selected as ethylene glycol solution. Using ethylene glycol solution to keep the liquid carbon dioxide transported in the pipeline cold ensures that the liquid carbon dioxide is sufficiently liquid before the diaphragm pump 3. When needed, the diaphragm pump 3 can be started at any time to ensure a stable and continuous supply of carbon dioxide.

[0036] In a preferred embodiment, the temperature of the liquid carbon dioxide at the inlet of raw material tank 1 is between -19°C and -22°C. In this embodiment, the incoming temperature of the liquid carbon dioxide is between -19°C and -22°C to provide a more stable supply at the upstream end. At this temperature, there is a risk of vaporization of the liquid carbon dioxide. After entering the cooling pipeline of this embodiment, the liquid carbon dioxide needs to be cooled to between -24°C and -26°C. At this temperature, the incoming material is a heat source, so the cooling system of this embodiment needs to select a cold source while also considering antifreeze protection. By selecting an ethylene glycol solution, which has a certain viscosity and antifreeze properties, it has a very good effect on cooling the liquid carbon dioxide.

[0037] Considering the effects of cooling capacity and viscosity, the ratio of ethylene glycol to water in the ethylene glycol solution is controlled to be 1:(1.21-1.23).

[0038] When an ethylene glycol solution with a ratio of 40% ethylene glycol and 60% water is used, it can achieve antifreeze protection at -25°C. However, it cannot further cool down the liquid carbon dioxide, which has a feed temperature of -19°C to -22°C, and maintain it at -24°C to -26°C. If the ratio of ethylene glycol to water is adjusted to 1:1.1, the amount of ethylene glycol used is too high, resulting in a higher overall viscosity of the ethylene glycol solution. This leads to greater flow resistance in the pipeline, which negatively impacts the cooling and insulation effect. Therefore, in this embodiment, the ratio of ethylene glycol to water is controlled at 1:(1.21-1.23). Under this ratio, the ethylene glycol solution has a suitable cooling capacity and a certain viscosity, providing excellent insulation for liquid carbon dioxide.

[0039] In a preferred embodiment, the refrigerant piping includes a working group piping and a standby group piping. The working group piping and the standby group piping do not operate simultaneously; one is used as a backup. Both the working group piping and the standby group piping include a refrigerant outlet pipe 521 and a refrigerant return pipe 522. Both the refrigerant outlet pipe 521 and the refrigerant return pipe 522 are connected to the refrigeration unit. Ethylene glycol refrigerant flows from the refrigeration unit through the refrigerant outlet pipe 521 to the diaphragm pump 3, and then flows back to the refrigeration unit through the refrigerant return pipe.

[0040] In a further preferred embodiment, a pre-pump reflux pipeline is also provided between the raw material tank 1 and the diaphragm pump 3. The pre-pump reflux pipeline includes a cooling pipeline as described in the previous embodiment. In this embodiment, the pre-pump reflux pipeline is also equipped with a cooling system, so that the refluxed liquid carbon dioxide can further cool the liquid carbon dioxide in the buffer tank 2, thereby ensuring that the outflowing carbon dioxide is completely liquid.

[0041] In a further preferred embodiment, both the raw material tank 1 and the buffer tank 2 are equipped with multiple pressure control valves to ensure the stability of the liquid delivery pressure.

[0042] Please refer to Figure 1-7 In a preferred embodiment, an online impurity detection device is provided after the purification device 81. The online impurity detection device is used to detect the impurity content in the gaseous carbon dioxide output by the purification device 81, and issues a prompt message when the impurity content meets the preset conditions.

[0043] Specifically, in a preferred embodiment, issuing a prompt message when the detected impurity content is at a preset value specifically includes:

[0044] When the total impurity content detected is within the first preset value, a first warning message is issued; when the total impurity content is too high, it can be filtered or purified again through back-end equipment.

[0045] Specifically, in a preferred embodiment, the subcritical carbon dioxide purification supply system further includes a circulation pipeline, one end of which is connected to an online impurity detection device, and the other end of which is connected to the purification device 81.

[0046] When the impurity content (here, impurity content refers to the total impurity content or the content of individual impurities) reaches the first preset value, the first prompt message is issued to remind the staff to perform a second purification or filtration process (the impurities are filtered again through the purification device 81 and the filtration device until the impurities in the gaseous carbon dioxide meet the standard).

[0047] Alternatively, when the impurity content exceeds the first preset value (when the impurity content is too high relative to the standard value), a first prompt message is issued to remind the staff to release the gaseous carbon dioxide into the corresponding treatment equipment, so as to finally achieve the venting of gaseous carbon dioxide or the application of gaseous carbon dioxide with impurities exceeding the first preset value to other processes. No specific limitation is made here.

[0048] Alternatively, when the detected impurity content is equal to a second preset value, a second prompt message will be issued (the first prompt message may be the same as the second prompt message).

[0049] In this embodiment, the preset number of impurities can be randomly selected. Specifically, it can be selected based on the composition of the impurities. For example, two elements or two compounds can be selected, and the four impurities can be detected accordingly to determine whether their content is the second preset value. Alternatively, all impurities can be selected from elements or compounds. Alternatively, multiple impurities with high content can be selected, or the content of multiple impurities can be averaged, and the standard (the standard for impurity content in subcritical carbon dioxide) can be determined based on the specific value of the average. This method is more efficient and accurate than the traditional method of calculating whether each impurity component meets the standard, and it is also more suitable for the supply of subcritical carbon dioxide for chip cleaning.

[0050] The prompt message issued when the detected impurity content is within the preset value also includes:

[0051] The system classifies impurities into elements and compounds based on their composition, and determines the composition based on the sum of the percentages of elements and compounds. When the sum of these percentages reaches a third preset value, a second prompt is issued. The formula for calculating the sum of these percentages is as follows:

[0052]

[0053] Among them, P 1预 P is a preset quantity of the element. 2预 P is a preset quantity of compounds. 1总 P represents the total quantity of elements. 2总 This represents the total number of compounds.

[0054] In a preferred embodiment, issuing a prompt message when the detected impurity content is at a preset value further includes:

[0055] The impurities are classified based on their content (by setting a gas pressure detector on the front-end gas delivery pipeline to calculate the impurity content of the gaseous carbon dioxide delivered at the front end), and impurities with content below a preset value and impurities with content above a preset value are classified (for example: content value is 1-3 ppb, preset value can be set to 2, impurities with content of [1-2] ppb are classified as the first category, and impurities with content of (2-3] ppb are classified as the second category), and the formula for calculating the sum of their proportions is the same as in the above embodiment;

[0056] In a preferred embodiment, issuing a prompt message when the detected impurity content is at a preset value further includes:

[0057] The impurities in subcritical carbon dioxide are classified according to their standard values. Impurities with a standard value of (0.01-0.5) are classified as Category 1, and impurities with a standard value of (0.5-1) are classified as Category 2. The formula for calculating the sum of their proportions is the same as in the above embodiment, and will not be repeated here.

[0058] In this embodiment, the above-described multiple embodiments are used to detect whether impurities meet the standards, so as to ensure that the content of each impurity in the final output subcritical carbon dioxide meets the standards, thereby ensuring the cleaning efficiency of the back-end chip cleaning.

[0059] Please refer to Figure 1-5 In a preferred embodiment, a pre-filter 7 is provided between the heating device 5 and the purification device 81 to filter impurities in gaseous carbon dioxide; and / or, a post-filter 82 is provided between the purification device 81 and the online impurity detection device to filter impurities in gaseous carbon dioxide.

[0060] Please refer to Figure 1-5 In a preferred embodiment, the online impurity detection device includes multiple impurity detection units connected in parallel, each used to detect different impurity contents.

[0061] Examples of various impurity detection processes and equipment are provided below:

[0062] The 5900-HP2 instrument was used to detect impurities H2, Ar+O2, N2, and CO. The detection principle is as follows: GC-PDHID, the chromatographic column separates H2, Ar+O2, N2, and CO from CO2 and then sends them to PDHID (helium ionization detector) for analysis. The stable low-power pulsed discharge in helium is used as an ionization source to ionize the analyte and generate a signal.

[0063] The 5900-D091 instrument was used to detect impurities CH4, NMHC, and TVOC. The GC-FID column separated CH4 and NMHC from CO2, which were then ionized by combustion in the FID to generate signals. Since TVOC concentration was low, the sample was first concentrated and enriched. Different species were separated by the chromatographic column and sent to the FID for combustion to generate ionization signals. Finally, these signals were summed to obtain the TVOC value.

[0064] The Tigeroptics HALO 3 instrument is used to detect H2O impurities. When light passes through the sample, it will attenuate due to energy absorption. The sample cavity has mirrors on both sides to reflect the light back and forth, which lengthens the optical path. The time required for the light intensity to decrease to 1 / e of the previous intensity is called the "wave-down time", which can be used to calculate the concentration of light-absorbing substances in the cavity.

[0065] The MultiExact4100 instrument is used to detect CO2 purity. A pair of filters are mounted on a rotating disk, allowing an infrared (IR) beam to pass through them alternately. One filter (the measurement filter) allows only the wavelengths absorbed by the analyte gas to pass through, while the other filter (the reference filter) allows wavelengths unaffected by the analyte gas to pass through. By measuring the difference in absorbance between the two filters using a detector, the gas concentration can be directly output.

[0066] The detection instrument 17i is used to detect impurities NH3. NH3 is converted into NO under the action of a high-temperature combustion furnace. NO reacts with O3 (with built-in O3 generator) to form excited state NO2, which then returns to the ground state and emits light. The ion concentration is calculated using the intensity of the emitted light.

[0067] The 43i-TLE instrument is used for SO2 detection. SO2 molecules absorb ultraviolet (UV) light, are excited at a certain wavelength, then decay to a lower energy state and emit UV light at a different wavelength. The concentration value is calculated using the intensity of the emitted UV light.

[0068] The 5900-HP3 instrument is used to detect Ar+, O2, and CO impurities. It employs GC-PED, where the carrier gas carries the components separated by the chromatographic column into the detector. Under high pressure and a strong electromagnetic field, the carrier gas and components are ionized together to form plasma. Different components emit light radiation of different wavelengths in the plasma. After filtering and photoelectric conversion, a chromatographic signal is obtained, and the signal is proportional to the content of the gaseous standard component.

[0069] The 5900-A6 detection instrument is used for GC-FID detection of CH4 and NMHC impurities. The sample is first concentrated and enriched, and then heated and desorbed into the chromatographic column. The chromatographic column separates CH4 and NMHC and then the sample is burned and ionized by FID to generate a signal.

[0070] The Tigeroptics HALO KA instrument is used for H2O impurity detection. When light passes through the sample, it will attenuate due to energy absorption. The sample cavity has mirrors on both sides to reflect the light back and forth, which lengthens the optical path. The time required for the light intensity to decrease to 1 / e of the previous intensity is called the "wave-down time" and can be used to calculate the concentration of light-absorbing substances in the cavity.

[0071] The ICP-MS and IC detectors are used for the detection of metal ions and cations / anions (analysis of metal ions and anions is performed offline). ICP-MS is a mass spectrometry technique that uses plasma as the ion source. It features rapid, sensitive, and simultaneous multi-element determination. The sample is broken down into ionic forms by high-temperature plasma. The ions are transported through a sampling cone and a vacuum interface into the mass spectrometer. After the mass analyzer analyzes ions with specific charge-to-mass ratios (m / z), they enter the detector for qualitative and quantitative analysis, thus performing mass spectrometry analysis (metal ions). Ion chromatography works by using a chromatography column filled with ion exchange resin to separate ionic components. As the eluent flows through, the ions move within the column to a conductivity detector. The detector only detects ionized components in the liquid between the electrodes within the detector container. Conductivity is the reciprocal of resistance, measured in S / m. The strength of the conductivity signal depends on the type of component and its dissociation state (cations / anions).

[0072] Please refer to Figure 1-5 In a preferred embodiment, a pressure regulating device 6 is provided between the heating device 5 and the purification device 81. The pressure regulating device 6 is used to regulate the pressure of the gaseous carbon dioxide output by the heating device 5.

[0073] Specifically, the pressure regulating pipeline includes a first pressure regulating pipeline, a second pressure regulating pipeline, and a third pressure regulating pipeline. Based on the control method, the pipeline with the highest priority is used for carbon dioxide transportation. The first, second, and third pressure regulating pipelines are all connected in parallel. The first pressure regulating pipeline adopts a pneumatic-electric control method, the second pressure regulating pipeline adopts a pneumatic-pneumatic control method, and the third pressure regulating pipeline adopts a self-regulating control method.

[0074] The three-channel pressure regulation system (with different control methods for the first, second, and third pressure regulating pipelines; to ensure a continuous supply of carbon dioxide, the pneumatic-electrically controlled pressure regulating pipeline (controlled by an external program) is used first; if the first pressure regulating pipeline malfunctions or cannot continue supplying, the system switches to the second pressure regulating pipeline (pneumatic-controlled); if the second pressure regulating pipeline also has the aforementioned problems, the system switches to the third pressure regulating pipeline (self-regulating) for carbon dioxide supply). Because the self-regulating system withstands lower mechanical pressure and has a more stable control method, this three-channel pressure regulation control system ensures a continuous supply of carbon dioxide gas, thereby guaranteeing a continuous supply during the chip cleaning process.

[0075] In a further embodiment, the first and second pressure regulating pipelines simultaneously deliver carbon dioxide gas, and a third pressure regulating pipeline is used as a backup continuous supply pipeline (gas delivery pipeline). When the first or second pressure regulating pipeline malfunctions, the first and third pressure regulating pipelines are used for simultaneous delivery, or the second and third pressure regulating pipelines are used for simultaneous delivery; this ensures a continuous supply of gaseous carbon dioxide and provides higher stability (when each pressure regulating pipeline delivers gas based on the priority of the control method, the pressure values ​​of each pressure regulating pipeline are the same).

[0076] Preferably, in the second embodiment, the carbon dioxide transport via the pressure regulating pipeline can also be based on the pressure values ​​of each pressure regulating pipeline; for example: the pressure value of the first pressure regulating pipeline is 5.7 MPa; the pressure value of the second pressure regulating pipeline is 5.5 MPa; the pressure value of the third pressure regulating pipeline is 5.4 MPa; when the pressure value of the gas transported by the pipeline is close to the pressure value of a certain pressure regulating pipeline, the corresponding pressure regulating pipeline is opened to transport carbon dioxide gas; specifically, the pressure value ratio of the first pressure regulating pipeline, the second pressure regulating pipeline, and the third pressure regulating pipeline is (1-1.5):(1-1.55):(1-1.6) or (1-1.5):(1-1.45):(1-1.4) or 1:1.1:1.2. The ratio of the pressure values ​​of each pipeline is mainly to ensure the continuous supply of carbon dioxide gas.

[0077] Specifically, in order to ensure a continuous supply of gaseous carbon dioxide, other settings can be used for various control methods and pressure values ​​of the pressure regulating pipeline. There are no restrictions on other settings here, as long as they can achieve a continuous supply and stable delivery of carbon dioxide.

[0078] Please refer to Figure 1-7 In a preferred embodiment, a heat insulation component 8 is provided on the pipeline between the heating device 5 and the purification device 81;

[0079] Please refer to Figure 1-5 In a preferred embodiment, the heating device 5 is a water bath heating device 5 (specifically, the heating device 5 is equipped with a liquid level control valve and an external water supply port). The heat preservation component 8 includes multiple electric heating devices 5 for heating the pipeline, and the multiple electric heating devices 5 are spaced apart along the length of the pipeline, with a spacing of 30-50m, preferably 50m. Specifically, the electric heating devices 5 can be multiple heating tapes arranged in pairs, with different temperatures between adjacent heating tapes. For example, the temperature of the first and third heating tapes is higher than the temperature of the second and fourth heating tapes, or the temperature of the first and third heating tapes is lower than the temperature of the second and fourth heating tapes (specifically, the temperature of the first and third heating tapes can be 34°C, and the temperature of the second and fourth heating tapes can be 38°C). By setting them apart and with different temperatures, the gaseous carbon dioxide can maintain its current state during transportation, thus preventing a phase change. Each heating tape is controlled by a separate heat tracing controller, which to a certain extent ensures the stability of the gaseous carbon dioxide.

[0080] Please refer to Figure 1-5 In a preferred embodiment, a self-pressurizing device is provided between the buffer tank 2 and the heating device 5. The self-pressurizing device includes the heating device 5, which is used to vaporize the liquid carbon dioxide in the buffer tank 2. The self-pressurizing device is used to regulate the pressure in the buffer tank 2 so that the liquid carbon dioxide in the buffer tank 2 can be discharged normally.

[0081] Specifically, the self-pressurizing device includes a vaporization pipe and a return pipe 4; the two ends of the heating device 5 are connected to the buffer tank 2 and the return pipe 4 respectively, and the output end of the return pipe 4 is connected to the buffer tank 2; when the liquid level in the buffer tank 2 is lower than the first preset value, a portion of the liquid in the buffer tank 2 is transported to the heating device 5 on the vaporization pipe for vaporization, and the vaporized carbon dioxide is transported to the buffer tank 2 through the return pipe 4 for self-pressurization, thereby ensuring that the liquid carbon dioxide in the buffer tank 2 is discharged normally.

[0082] In a preferred embodiment, the return pipe 4 includes a first pipe and a second pipe, which are connected in parallel and both ends are connected to the heating device 5 and the buffer tank 2. The buffer tank 2 is equipped with a first pressure detector, the first pipe is equipped with a control valve, and the heating device 5 is equipped with a second pressure detector. When the liquid level is lower than a first preset value and the first value (the value detected by the first pressure detector) is a second preset value, the gas vaporized by the heating device 5 is transported to the buffer tank 2 through the first pipe. The replenished pressure is determined by the following calculation formula:

[0083]

[0084] Wherein, P2 is the gas pressure value after vaporization by heating device 5 or the gas pressure value added to buffer tank 2, PH is the upper limit value of gas pressure in buffer tank 2, and P1 is the current gas pressure value or the first value in buffer tank 2. The numerical range is [5%-10%].

[0085] In this embodiment, The specific values ​​can be set according to the current air pressure in buffer tank 2, or they can be set to standard values ​​of 5%-6.5%, 7%-9%, or 5.5%-10%. When the liquid level in buffer tank 2 is lower than the preset value, the amount of air pressure that needs to be added to buffer tank 2 is calculated based on the current air pressure in buffer tank 2 and the standard upper limit air pressure of buffer tank 2. Then, the corresponding carbon dioxide liquid is controlled to flow out and vaporize by controlling the valve. This ensures that the liquid in buffer tank 2 can be discharged normally, and the air pressure in buffer tank 2 is kept at a stable value. This ensures the normal use of buffer tank 2 to a certain extent and avoids the air pressure in buffer tank 2 reaching the upper or lower limit value, thus improving safety.

[0086] In this embodiment, the gas pressure value in the buffer tank 2 can also be detected first. When the gas pressure value begins to decrease or is about to reach the second preset value, carbon dioxide is vaporized by self-pressurization and transported to the buffer tank 2 through the return pipe 4 for self-pressurization to ensure the normal discharge of the buffer tank 2. This technical means can also be used for gas pressure release in the following embodiments, so it will not be described in detail.

[0087] In a preferred embodiment, the second pipeline is provided with a control valve and a first storage tank connected to the control valve for storing the gas vaporized by the heating device 5; the first storage tank is provided with a third pressure detector for detecting the gas pressure value in the first storage tank.

[0088] When the gas pressure of the vaporized carbon dioxide is too high (approaching the upper limit of the gas pressure in buffer tank 2), the fourth valve is opened to deliver the gas to the first storage tank. The gas pressure is detected by the third pressure detector, and the first storage tank is controlled to deliver part of the gas to buffer tank 2, while the remaining gas is kept in the first storage tank for backup. A vent valve can also be installed on the first storage tank to release the gas when the interval between gas releases in the first storage tank is too long. The first storage tank is also equipped with a heat tracing and insulation component 8 to ensure the stability of the carbon dioxide gas and ensure that it does not undergo a phase change.

[0089] The first storage tank can be equipped with multiple storage chambers, which are spaced apart and each has a gas inlet and outlet. When the pressure of the liquefied gas is too high, the gas enters the first storage tank and then enters multiple storage chambers in sequence (the pressure setting value in each storage chamber can be set to the same value, or it can be divided according to level or ratio: level division: 1Mpa, 2Mpa, 3Mpa, etc.; ratio division: the ratio of the upper limit value to the lower limit value of the gas pressure in multiple storage chambers is (1-1.1):(0.8-1)). The storage chambers are opened as needed to deliver the gas to the buffer tank 2 for pressurization.

[0090] Please refer to Figure 1-7 In a further preferred embodiment, the self-pressurization system also includes a venting pipe connected to the buffer tank 2. The venting pipe is equipped with a venting valve and a second storage tank (the second storage tank and the first storage tank have the same structure, both for storing gas; see the previous embodiment for details). The buffer tank 2 is equipped with a first pressure detector, and the second storage tank is equipped with a fourth pressure detector. When the first value is a third preset value, the venting valve is opened to discharge the gas in the buffer tank 2 to the second storage tank. The discharged pressure is determined by the following calculation formula:

[0091]

[0092] Wherein, P3 is the gas pressure value to be released or the gas pressure value detected by the fourth gas pressure detector; PL is the lower limit value of the gas pressure in buffer tank 2; P1 is the current gas pressure value or the first value in buffer tank 2. The value range is [30%-50%], and the specific value range can also be 30%-35%, 35%-50%, or 40%-45%. The gas that needs to be discharged from the buffer tank 2 is calculated based on the lower limit pressure value of the buffer tank 2. While ensuring the normal operation of the buffer tank 2, it can also ensure the normal outflow of liquid in the buffer tank 2, and the gas pressure in the buffer tank 2 can also be kept constant, which improves safety to a certain extent.

[0093] In a further preferred embodiment, the return pipe 4 includes a first pipe and a second pipe. The second pipe is equipped with a first storage tank, a vent valve connected to the self-pressurization system and the buffer tank 2, and the second storage tank. The second storage tank is connected to the first storage tank through a third pipe (to store the gas discharged from the buffer tank 2; when the gas pressure in the buffer tank 2 is too low and the gas in the first storage tank is used up, the gas in the second storage tank is transported to the first storage tank and then transported back to the buffer tank 2 for pressurization). The third pipe is equipped with a control valve. The first, second, and third pipes are all equipped with heat tracing and insulation components 8 (mainly used to ensure that there is no phase change in carbon dioxide gas and to ensure stable carbon dioxide transport). The conveying pipe at the front end of the first heater and the vaporization pipe at the front end of the second heater are equipped with insulation components 8 (mainly used to ensure that there is no phase change in carbon dioxide gas and to ensure stable transport and continuous supply of carbon dioxide).

[0094] The subcritical carbon dioxide supply system provided by this invention is mainly applied in the field of chip cleaning. Specifically, liquid carbon dioxide is received through a raw material tank 1 and transported through a booster pump and a liquid transport pipeline 51 (the pipeline between the raw material tank 1 and the buffer tank 2 is called the liquid transport pipeline 51). By setting a cold insulation component between the two, the state of the liquid carbon dioxide during the transport process is ensured to be stable and not affected by environmental factors. Both the raw material tank 1 and the buffer tank 2 are equipped with self-pressurization devices to ensure the normal discharge of liquid carbon dioxide from the raw material tank 1 and the buffer tank 2.

[0095] The liquid in the buffer tank 2 is vaporized by the heating device 5 and transported to the pressure regulating device 6 through a gaseous delivery pipeline. The gaseous carbon dioxide is prioritized according to the control method of the pressure regulating device 6, ensuring normal delivery even in the event of hardware malfunctions or other technical problems during pipeline transport (one pressure regulating pipeline uses a self-regulating control method for enhanced stability). The gaseous delivery pipeline is heated or insulated using heat tracing or insulation components 8 (to maintain a constant state of gaseous carbon dioxide during transport and prevent phase change). Impurities in the gaseous carbon dioxide are filtered and detected by the filtration and purification devices 81, ensuring that the impurity content in the final output subcritical carbon dioxide reaches a preset value, guaranteeing the concentration of the subcritical carbon dioxide output at the back end (temperature 32±4℃; pressure 55±4 barg), thus ensuring the cleaning efficiency of the final chip cleaning process.

[0096] The beneficial effects of this invention are as follows: by keeping the liquid conveying pipeline cold and the gaseous conveying pipeline heated, the carbon dioxide remains in a constant state during the conveying process and does not undergo a phase change. Compared with traditional carbon dioxide supply and conveying, it has better stability, stronger continuity in the conveying process, and is more suitable for chip cleaning.

[0097] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A subcritical carbon dioxide supply system for chip cleaning, characterized in that, In the input-to-output direction, the system includes, in sequence, a raw material tank, a booster pump, a buffer tank, a heating device, and a purification device. The raw material tank is used to store liquid carbon dioxide. The booster pump is used to transport the liquid carbon dioxide from the raw material tank to the buffer tank and pressurize it. The heating device is connected to the output end of the buffer tank and is used to heat and vaporize the liquid carbon dioxide output from the buffer tank. The purification device is used to purify the gaseous carbon dioxide output from the heating device and remove impurities from the gaseous carbon dioxide. A cold insulation component is installed on the pipeline between the raw material tank and the buffer tank, and the booster pump is a diaphragm pump; a heat insulation component is installed on the pipeline between the heating device and the purification device; the heating device is a water bath heating device, and the heat insulation component includes multiple electric heating devices for heating the pipeline, and the multiple electric heating devices are spaced apart along the length of the pipeline. The working pressure fluctuation of the first delivery pipeline between the raw material tank and the diaphragm pump shall not exceed ±3 barg, and the working pressure fluctuation of the first delivery pipeline between the diaphragm pump and the buffer tank shall not exceed ±3 barg. At least one section of the first delivery pipeline between the raw material tank and the diaphragm pump shall be a cooling pipeline. The temperature of the liquid carbon dioxide near the diaphragm pump in the cooling pipeline shall be controlled between -24°C and -26°C. The cooling pipeline includes a liquid delivery pipeline and a refrigerant pipeline located outside the liquid delivery pipeline. The refrigerant pipeline is connected to the refrigeration unit. Liquid carbon dioxide is delivered in the liquid delivery pipeline, and ethylene glycol refrigerant flows in the refrigerant pipeline. A pressure regulating device is provided between the heating device and the purification device. The pressure regulating device is used to regulate the pressure of the gaseous carbon dioxide output by the heating device. The pressure regulating device includes a pressure regulating pipeline, which includes a first pressure regulating pipeline, a second pressure regulating pipeline, and a third pressure regulating pipeline. The pipelines are prioritized based on the control method, and the pressure regulating pipeline with the highest priority is used for carbon dioxide delivery. The first pressure regulating pipeline, the second pressure regulating pipeline, and the third pressure regulating pipeline are all connected in parallel. The first pressure regulating pipeline adopts a pneumatic-electric control method, the second pressure regulating pipeline adopts a pneumatic-pneumatic control method, and the third pressure regulating pipeline adopts a self-regulating control method.

2. The subcritical carbon dioxide supply system for chip cleaning according to claim 1, wherein An online impurity detection device is installed after the purification device. The online impurity detection device is used to detect the impurity content in the gaseous carbon dioxide output by the purification device, and issues a prompt message when the impurity content meets the preset conditions.

3. The subcritical carbon dioxide supply system for chip cleaning according to claim 2, wherein A pre-filter is provided between the heating device and the purification device to filter impurities in gaseous carbon dioxide; and / or, a post-filter is provided between the purification device and the online impurity detection device to filter impurities in gaseous carbon dioxide.

4. The subcritical carbon dioxide supply system for chip cleaning according to claim 2, wherein The online impurity detection device includes multiple impurity detection units connected in parallel, each used to detect different impurity contents.

5. The subcritical carbon dioxide supply system for chip cleaning according to claim 1, wherein A self-pressurizing device is provided between the buffer tank and the heating device. The self-pressurizing device includes a heating device, which is used to vaporize the liquid carbon dioxide in the buffer tank. The self-pressurizing device is used to regulate the pressure in the buffer tank so that the liquid carbon dioxide in the buffer tank can be discharged normally.

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