An on-line efficient cleaning system and method for single crystal silicon wafer oxidation furnace tube
Patent Information
- Application Number
- CN202610981543.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-02
- Publication Date
- 2026-09-08
AI Technical Summary
[0006]本申请提供了一种用于单晶硅片氧化炉管的在线高效清洗系统及方法，以至少解决现有技术中氧化炉管清洗需要拆装、清洗效率低、清洗后安装可能再次引入金属沾污的问题
通过构建包括MFC质量流量计、高速电磁阀和PLC控制的脉冲式氮气装置，并结合水浴加热装置和氧化炉管的一体式进气口结构，实现了氧化炉管无需拆卸的原位在线清洗，避免了传统拆装清洗法引入的二次沾污风险和人工安装成本。
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Figure CN122708548A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor single-crystal silicon wafer substrate manufacturing technology, and in particular to an online high-efficiency cleaning system and method for single-crystal silicon wafer oxidation furnace tubes. Background Technology
[0002] Fabricating high-performance MOSFET transistors requires growing a high-quality silicon oxide layer on a polished silicon substrate. Although the surface of the silicon wafer is smooth after polishing, dangling bonds, contaminants, and defects still exist at the atomic level. The core purpose of high-temperature wet oxidation is to grow a high-quality, dense silicon oxide layer (thermal oxide layer) on the surface of the polished silicon substrate. This thermal oxide layer is the heart of MOSFET transistor fabrication, and its quality directly determines the transistor's performance, power consumption, and reliability.
[0003] The quality of the thermal oxide layer directly depends on the anodizing furnace itself, and metal contamination directly affects its quality. Metal contamination reduces the insulation capacity of the oxide layer, causing it to break down under lower electric fields and leading to short-circuit failure. Metal contamination also increases the interface state density at the silicon substrate-silicon oxide layer interface, disrupting the atomic-level flatness of the interface and degrading device performance. Furthermore, metal contamination can diffuse from the oxide layer into the substrate silicon, inducing lattice defects and causing device leakage. In actual production, the thermal anodizing process of silicon wafers requires frequent opening of the furnace door, connecting the furnace atmosphere with the external atmosphere, which easily leads to the accumulation of metal contamination. Therefore, after processing a certain number of silicon wafers, the anodizing furnace tubes need to be cleaned regularly.
[0004] Currently, the mainstream method for cleaning oxidation furnace tubes is the disassembly and reassembly cleaning method: the oxidation furnace tubes are cooled and removed, sent to a specialized cleaning machine, and cleaned with chemical solutions. After cleaning, the furnace tubes still need to be manually reinstalled into the equipment. This method is difficult to disassemble and reassemble, time-consuming, and requires manual reinstallation of the cleaned furnace tubes, posing a risk of introducing secondary contamination.
[0005] Therefore, how to achieve efficient in-situ online cleaning without disassembling the oxidation furnace tube, while removing metal contaminants and residual dopant elements from the inner wall of the furnace tube and preventing secondary pollution during the cleaning process, is a technical problem that urgently needs to be solved in the field of semiconductor single crystal silicon wafer substrate manufacturing. Summary of the Invention
[0006] This application provides an online high-efficiency cleaning system and method for oxidation furnace tubes of monocrystalline silicon wafers, which at least solves the problems in the prior art of oxidation furnace tube cleaning, such as the need for disassembly and reassembly, low cleaning efficiency, and the possibility of re-introducing metal contamination during reinstallation after cleaning.
[0007] In a first aspect, this application provides an online high-efficiency cleaning system for oxidation furnace tubes of single crystal silicon wafers, including oxidation furnace tubes, water bath heating device and pulse nitrogen device; The oxidation furnace tube is made of high-purity quartz material, and its tail is a dome structure with an integrated air inlet at the center of the dome. The furnace inlet fixing flange of the oxidation furnace tube has a built-in tail gas treatment device. The water bath heating device is a quartz water bath with a heating base. The quartz water bath is connected to the air inlet at the tail of the furnace via a PFA gas pipe and a polytetrafluoroethylene fixing piece. The pulsed nitrogen device includes a gas source, a buffer valve, an MFC mass flow meter, a high-speed solenoid valve, and a gas consumption terminal connected in sequence. The high-speed solenoid valve is controlled to open and close by a PLC. When the gas consumption terminal needs nitrogen, the PLC controls the high-speed solenoid valve to open, and nitrogen is introduced into the gas consumption terminal through the MFC mass flow meter and the high-speed solenoid valve. When the gas consumption terminal stops using gas, the PLC controls the high-speed solenoid valve to close, and nitrogen is automatically switched to a bypass recovery pipeline to form a pulsed nitrogen with a fixed cycle frequency. The outlet of the pulsed nitrogen device is connected to the quartz water bath, and is used to introduce the pulsed nitrogen into the quartz water bath to carry steam through the air inlet into the oxidation furnace tube.
[0008] Optionally, the integrated air inlet at the tail of the oxidation furnace tube is a quartz tube with a diameter of 3cm to 6cm and a length of 10cm to 20cm, and the quartz tube is welded to the center of the dome.
[0009] Optionally, the volume of the quartz water bath is 25L to 40L, and the heating base is used to heat the liquid in the quartz water bath to 95℃ to 100℃.
[0010] Optionally, the flow rate of the pulsed nitrogen is 5slpm to 10slpm, the gas supply cycle is 50s to 100s, wherein the gas supply is 40s to 80s and the gas supply is 10s to 20s, and the pulse frequency is 0.01Hz to 0.02Hz.
[0011] Secondly, this application provides an online high-efficiency cleaning method for oxidation furnace tubes of single-crystal silicon wafers, applied to the online high-efficiency cleaning system provided in the first aspect above, the method comprising the following steps: S1: Seal the oxidation furnace tube and introduce nitrogen gas to cool it down to the cleaning temperature; S2: The pulsed nitrogen gas generated by the pulsed nitrogen device carries deionized water vapor to clean the oxidation furnace tube; S3: The pulsed nitrogen generated by the pulsed nitrogen device carries SC2 solution vapor, dilute hydrofluoric acid solution vapor and ozone aqueous solution vapor in sequence to clean the oxidation furnace tube. S4: The pulsed nitrogen gas generated by the pulsed nitrogen device carries the deionized water vapor to clean the oxidation furnace tube; S5: Perform metal characterization and testing on the oxidation furnace tube.
[0012] Optionally, the cleaning temperature in S1 is 50℃~150℃, and the nitrogen flow rate is 5slpm~10slpm.
[0013] Optionally, the method for preparing deionized water vapor in S2 and S4 includes the following steps: Deionized water is injected into the quartz water bath and heated to 95°C~100°C by the heating base to evaporate; wherein, the pulsed nitrogen gas carrying the deionized water vapor is circulated 10 to 20 times.
[0014] Optionally, the method for preparing the SC2 solution vapor in S3 includes the following steps: Hydrochloric acid and hydrogen peroxide are injected into the replaced deionized water to make the SC2 concentration in the mixed solution reach 2% to 3%, and the mixed solution is heated to 95°C to 100°C to generate SC2 solution vapor. The pulsed nitrogen gas carrying the SC2 solution vapor is circulated 15 to 30 times.
[0015] Optionally, the method for preparing the dilute hydrofluoric acid solution vapor in S3 includes the following steps: Hydrofluoric acid is injected into the replaced deionized water to make the concentration of hydrofluoric acid in the solution reach 1% to 2%, and the solution is heated to 95°C to 100°C to generate hydrofluoric acid vapor; wherein, the pulsed nitrogen gas carrying the dilute hydrofluoric acid solution vapor is circulated 10 to 20 times.
[0016] Optionally, the method for preparing ozone aqueous solution vapor in S3 includes the following steps: Ozone is introduced into the replaced deionized water to make the ozone content in the solution reach 2ppm~10ppm, and the solution is heated to 95℃~100℃ to generate ozone. The pulsed nitrogen gas carrying the ozone aqueous solution vapor is circulated 15 to 30 times.
[0017] Compared with related technologies, the online high-efficiency cleaning system and method for oxidation furnace tubes of monocrystalline silicon wafers provided in this application have at least the following technical advantages: By constructing a pulse-type nitrogen device that includes an MFC mass flow meter, a high-speed solenoid valve, and PLC control, and combining it with an integrated air inlet structure of a water bath heating device and an oxidation furnace tube, in-situ online cleaning of the oxidation furnace tube without disassembly is achieved, avoiding the risk of secondary contamination and the labor installation costs introduced by traditional disassembly and cleaning methods.
[0018] The multi-step pulsed steam cleaning sequence, which involves pre-cleaning with deionized water vapor, removing metal contaminants and dopant elements with SC2 solution steam, further removing metal contaminants with dilute hydrofluoric acid solution steam, passivating the inner wall surface of the furnace tube with ozone aqueous solution steam, and rinsing with deionized water vapor, can remove the metal contaminant content on the inner wall of the oxidation furnace tube to within 1E10 atoms / cm², meeting the requirements of SEMI standards and achieving rapid and efficient removal of metal impurities.
[0019] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. Attached Figure Description
[0020] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a flowchart illustrating an online, high-efficiency cleaning method for oxidation furnace tubes of monocrystalline silicon wafers, according to an exemplary embodiment.
[0021] Figure 2 This is a schematic diagram of nitrogen flow rate when the pulse period is 100s, according to an exemplary embodiment.
[0022] Figure 3 This is a schematic diagram of nitrogen flow rate when the pulse period is 50s, according to an exemplary embodiment.
[0023] Figure 4 This is a structural diagram of an online high-efficiency cleaning system for oxidation furnace tubes of monocrystalline silicon wafers, according to another exemplary embodiment.
[0024] Figure 5 This is a comparison chart of metal content detection after treatment in Example 1, Comparative Example 1, and Comparative Example 2. Detailed Implementation
[0025] To make the objectives, technical solutions, and advantages of this application clearer, the application is described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.
[0026] Obviously, the accompanying drawings described below are merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios based on these drawings without any inventive effort. Furthermore, it is understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.
[0027] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments without conflict.
[0028] Unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms “a,” “an,” “an,” “the,” and similar words used in this application do not indicate quantity limitation and may indicate singular or plural. The terms “comprising,” “including,” “having,” and any variations thereof used in this application are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units not listed, or may include other steps or units inherent to these processes, methods, products, or devices. The terms “connected,” “linked,” “coupled,” and similar words used in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. “Multiple” used in this application refers to two or more. “And / or” describes the relationship between related objects, indicating that three relationships may exist; for example, “A and / or B” can represent: A alone, A and B simultaneously, and B alone. The character " / " generally indicates that the preceding and following objects are in an "or" relationship. The terms "first," "second," and "third" used in this application are merely to distinguish similar objects and do not represent a specific ordering of the objects.
[0029] In related technologies, fabricating high-performance MOSFET transistors requires growing a thermal oxide layer on a polished silicon substrate. The oxidation furnace tube, serving as the reaction chamber for high-temperature wet oxidation, suffers from metal contamination on its inner walls, which directly reduces the insulation capacity of the oxide layer, increases interface state density, and induces lattice defects. After processing a certain number of silicon wafers, the oxidation furnace tube needs periodic cleaning. Currently, the mainstream disassembly and cleaning method involves cooling the furnace, sending it to a specialized cleaning machine, and manually reassembling it, which is time-consuming and carries the risk of secondary contamination.
[0030] Based on the above, embodiments of the present invention provide an online high-efficiency cleaning system and method for oxidation furnace tubes of single crystal silicon wafers, which will be described in detail below with reference to specific embodiments and accompanying drawings.
[0031] Example 1
[0032] Embodiment 1 of this application provides an online high-efficiency cleaning method for oxidation furnace tubes of monocrystalline silicon wafers. 1 is a flowchart illustrating an online high-efficiency cleaning method for oxidation furnace tubes of monocrystalline silicon wafers according to an exemplary embodiment. Figure 1 As shown, the method includes the following steps: S1, Seal the oxidation furnace tube and introduce nitrogen to cool it down to the cleaning temperature; In this step, the oxidation furnace door is closed to keep the oxidation furnace tube in a sealed state, and nitrogen gas is introduced to cool the furnace tube to 100°C at a flow rate of 10 slpm. The oxidation furnace tube is a reaction chamber used for high-temperature wet oxidation of monocrystalline silicon wafers. It is made of high-purity quartz, and the furnace tail has a dome-shaped structure. An integrated air inlet with a diameter of 3cm to 6cm and a length of 10cm to 20cm is welded at the center of the dome. The furnace mouth fixing flange has a built-in exhaust gas treatment device.
[0033] S2, using pulsed nitrogen gas to carry deionized water vapor to clean the oxidation furnace tubes; In this step, 35L of deionized water is injected into a quartz water bath connected to the furnace tail. The water is heated to 98℃ by a heating base to generate deionized steam. Pulsed nitrogen gas at a flow rate of 10 slpm carries this steam through the furnace tail inlet into the oxidation furnace tube. The pulse cycle is 100s, consisting of 80s of ventilation and 20s of shut-off, with a pulse frequency of 0.01Hz, and the ventilation cycle is repeated 20 times. The purpose of this step is to remove particulate matter and organic matter adhering to the inner wall of the furnace tube.
[0034] S3, using pulsed nitrogen to sequentially carry SC2 solution vapor, dilute hydrofluoric acid solution vapor and ozone water vapor to clean the oxidation furnace tubes; In this step, hydrochloric acid and hydrogen peroxide are first injected into the replaced deionized water to make the SC2 concentration in the mixed solution reach 2%. The solution is heated to 98°C to generate SC2 solution vapor. Pulsed nitrogen gas with a flow rate of 10 slpm is introduced to carry the vapor into the furnace tube. The pulse working cycle is 50s, including 40s of ventilation and 10s of shutdown. The pulse frequency is 0.02Hz, and the ventilation cycle is repeated 30 times to remove metal contaminants and dopant elements from the inner wall of the furnace tube. Subsequently, hydrofluoric acid was injected into the replaced deionized water to bring the concentration of hydrofluoric acid in the solution to 1%. The solution was heated to 98°C to generate dilute hydrofluoric acid solution vapor. Pulsed nitrogen gas with a flow rate of 3 slpm was introduced to carry the vapor into the furnace tube. The pulse working cycle was 100s, including 80s of ventilation and 20s of shutdown. The pulse frequency was 0.01Hz, and the ventilation cycle was repeated 20 times to further remove residual metal contaminants and dopant elements. Finally, ozone is introduced into the replaced high-purity deionized water. The ozone concentration is monitored by an ozone concentration meter until the ozone content reaches 10 ppm. The water is heated to 98°C to produce ozone aqueous solution vapor. Pulsed nitrogen gas with a flow rate of 10 slpm is introduced to carry the vapor into the furnace tube. The pulse working cycle is 50s, including 40s of ventilation and 10s of shutdown. The pulse frequency is 0.02Hz, and the ventilation cycle is repeated 30 times to passivate the inner wall surface of the furnace tube.
[0035] S4, using pulsed nitrogen gas to carry deionized water vapor to clean the oxidation furnace tubes; In this step, the solution in the quartz water bath is replaced with 30L of high-purity deionized water, heated to 98℃ to generate deionized water vapor. This vapor is then carried into the oxidation furnace tube by a pulsed nitrogen flow rate of 10 slpm. The pulse cycle is 100s, consisting of 80s of ventilation and 20s of shutdown, with a pulse frequency of 0.01Hz, and the ventilation cycle is repeated 20 times. The purpose of this step is to remove residual chemical vapors from the furnace tube.
[0036] S5, Metal characterization and testing of oxidation furnace tubes.
[0037] In this step, inductively coupled plasma mass spectrometry was used to characterize the cleaned oxidation furnace tubes, confirming that the content of each metal element in the furnace tubes was within 1E10 atoms / cm².
[0038] The technical solution of the above embodiment, through the cooling preparation in step S1; the pre-cleaning with deionized water vapor in step S2; the chemical cleaning in step S3 using SC2, dilute hydrofluoric acid and ozone aqueous solution vapor in sequence; the rinsing with deionized water vapor in step S4; and the metal characterization detection in step S5, realizes multi-step pulsed steam cleaning of the oxidation furnace tube in situ without disassembly, and can complete a complete online cleaning process in about 20 hours.
[0039] In one possible design, the pulsed nitrogen device includes a gas source, a buffer valve, an MFC mass flow meter, a high-speed solenoid valve, and a gas consumption terminal connected in sequence. The high-speed solenoid valve is controlled to open and close via a PLC. In this embodiment, Figure 2 This is a schematic diagram of nitrogen flow rate when the pulse period is 100s, according to an exemplary embodiment. Figure 3 This is a schematic diagram illustrating nitrogen flow rate with a pulse period of 50 seconds, according to an exemplary embodiment. (Refer to...) Figures 2-3 The pulse working cycle is 100s (80s ventilation / 20s shutdown) or 50s (40s ventilation / 10s shutdown), corresponding to pulse frequencies of 0.01Hz and 0.02Hz, respectively.
[0040] Specifically, when nitrogen is needed at the gas consumption end, the PLC controls the high-speed solenoid valve to open, and nitrogen is introduced into the gas consumption end through the MFC mass flow meter and the high-speed solenoid valve. When gas consumption is suspended at the gas-consuming end, the PLC controls the high-speed solenoid valve to close, and nitrogen is automatically switched to the bypass recovery pipeline to form a pulsed nitrogen gas with a fixed cycle frequency.
[0041] The technical solution of the above embodiment solves the problem of abnormal flow alarm caused by intermittent nitrogen flow into the MFC mass flow meter by adding a high-speed solenoid valve to the back end of the traditional MFC mass flow meter and realizing millisecond-level opening and closing control through PLC, in conjunction with the bypass recovery pipeline. At the same time, it forms a pulsed nitrogen with a fixed periodic frequency, providing a stable and controllable gas carrying method for each cleaning step.
[0042] In one possible design, the preparation method of SC2 solution vapor, dilute hydrofluoric acid solution vapor, and ozone aqueous solution vapor in S3 includes the following steps: Hydrochloric acid and hydrogen peroxide are injected into the replaced deionized water to make the SC2 concentration in the mixed solution reach 2% to 3%. The solution is heated to 95°C to 100°C to generate steam. The steam is then circulated by pulsed nitrogen gas for 15 to 30 times.
[0043] Hydrofluoric acid is injected into the replaced deionized water to make the concentration of hydrofluoric acid in the solution reach 1% to 2%. The solution is heated to 95℃ to 100℃ to generate steam. The steam is then circulated by pulsed nitrogen gas for 10 to 20 times.
[0044] Ozone is introduced into the replaced deionized water to make the ozone content in the solution reach 2ppm~10ppm. The solution is heated to 95℃~100℃ to generate steam. The steam is carried by pulsed nitrogen gas and circulated 15 to 30 times.
[0045] The technical solution of the above embodiments ensures the stepwise removal effect of different types of metal contaminants and dopant elements in the chemical cleaning stage by defining the specific ranges of SC2 solution concentration, dilute hydrofluoric acid concentration, and ozone content, as well as the corresponding number of ventilation cycles. Specifically, the SC2 solution is mainly used to remove metal contaminants and dopant elements, the dilute hydrofluoric acid solution further removes residual metal contaminants, and the ozone aqueous solution is used to passivate the inner wall surface of the furnace tube.
[0046] In this embodiment, SC2 solution is prepared by injecting 0.5L to 1L of 30% to 45% hydrochloric acid and 1L to 2L of 40% to 50% hydrogen peroxide into the deionized water after the bathtub is replaced; subsequently, 300ml to 800ml of 40% to 70% hydrofluoric acid is injected into the deionized water after the bathtub is replaced to prepare dilute hydrofluoric acid solution. The content of various metal elements in the oxidation furnace tubes after cleaning using the method of this application can reach within 1E10 atoms / cm², meeting the SEMI standard, and saving at least 20 hours per cleaning cycle compared to existing disassembly and cleaning methods.
[0047] In summary, the online high-efficiency cleaning method for oxidation furnace tubes of monocrystalline silicon wafers provided in Embodiment 1 of this application generates pulsed nitrogen gas with a fixed periodic frequency by constructing a pulsed nitrogen gas device including an MFC mass flow meter, a high-speed solenoid valve, and PLC control. A multi-step pulsed steam cleaning sequence of deionized water vapor, SC2 solution vapor, dilute hydrofluoric acid solution vapor, ozone aqueous solution vapor, and deionized water vapor is used in sequence. This achieves efficient removal of metal contaminants and dopant elements from the inner wall of the oxidation furnace tube without disassembling it. After cleaning, the content of metal contaminant elements can reach less than 1E10 atoms / cm².
[0048] Example 2
[0049] Embodiment 2 of this application also provides an online high-efficiency cleaning system for oxidation furnace tubes of single crystal silicon wafers. Figure 4 This is a structural diagram illustrating an online high-efficiency cleaning system for oxidation furnace tubes of monocrystalline silicon wafers, according to another exemplary embodiment. (Refer to...) Figure 4 The system includes: an oxidation furnace tube, a water bath heating device, and a pulsed nitrogen device.
[0050] The oxidation furnace tube is made of high-purity quartz material, and its furnace tail is a dome structure with an integrated air inlet at the center of the dome. The furnace mouth fixing flange of the oxidation furnace tube has a built-in tail gas treatment device. The water bath heating device is a quartz water bath with a heating base. The quartz water bath is connected to the air inlet at the tail of the furnace via a PFA gas pipe and a polytetrafluoroethylene fixing piece. The pulsed nitrogen device includes a gas source, a buffer valve, an MFC mass flow meter, a high-speed solenoid valve, and a gas consumption end connected in sequence. The high-speed solenoid valve is controlled to open and close by a PLC. When nitrogen is needed at the gas consumption end, the PLC controls the high-speed solenoid valve to open, and nitrogen is introduced into the gas consumption end through the MFC mass flow meter and the high-speed solenoid valve; when the gas consumption end stops using gas, the PLC controls the high-speed solenoid valve to close, and nitrogen is automatically switched to the bypass recovery pipeline to form a pulsed nitrogen with a fixed cycle frequency. The outlet of the pulsed nitrogen device is connected to a quartz water bath, which is used to introduce pulsed nitrogen into the quartz water bath to carry steam through the inlet into the oxidation furnace tube.
[0051] In summary, the online high-efficiency cleaning system and method for oxidation furnace tubes of monocrystalline silicon wafers provided in this application form a pulsed nitrogen gas with a fixed periodic frequency by adding a high-speed solenoid valve to the back end of a traditional MFC mass flow meter and cooperating with a PLC and a bypass recovery pipeline. The cleaning liquid is heated and evaporated by a water bath heating device and carried into the oxidation furnace tube by the pulsed nitrogen gas in sequence. The metal contaminants and dopant elements on the inner wall of the furnace tube are cleaned in situ in a multi-step chemical vapor sequence. After cleaning, the content of metal contaminant elements can reach less than 1E10 atoms / cm², which can save about 20 hours per cleaning compared with the existing disassembly and cleaning method.
[0052] To further verify the key influence of the SC2 solution concentration and dilute hydrofluoric acid solution concentration specified in this application on the cleaning effect, the cleaning effect of the online high-efficiency cleaning method for single crystal silicon wafer oxidation furnace tubes proposed in this application is compared and verified below with Comparative Example 1 and Comparative Example 2.
[0053] Comparative Example 1 Compared with Example 1, Comparative Example 1 only changed the concentration of SC2 solution in step S3 to 1%, while the remaining steps and parameters were completely identical to those in Example 1. After cleaning, inductively coupled plasma mass spectrometry was also used to characterize the furnace tubes for metals.
[0054] Comparative Example 2 Comparative Example 2 differs from Example 1 only in that the concentration of the dilute hydrofluoric acid solution in S3 is adjusted to 0.5%, while the remaining steps and parameters are identical. After cleaning, the furnace tubes were also characterized using inductively coupled plasma mass spectrometry.
[0055] Figure 5 This is a comparison chart of the metal content detection after treatment in Example 1, Comparative Example 1, and Comparative Example 2. Table 1 is a data table of metal content detection after treatment in Example 1, Comparative Example 1, and Comparative Example 2. (Refer to the appendix.) Figure 5 According to Table 1, the metal content of the oxidation furnace tube test pieces after treatment in Example 1, Comparative Example 1 and Comparative Example 2 was detected using inductively coupled plasma mass spectrometry.
[0056] Table 1. Metal content detection data after treatment in Example 1, Comparative Example 1, and Comparative Example 2. Do not clean 8.89 1.29 13.00 12.27 21.77 0.90 18.49 8.60 0.55 0.56 2.31 10.48 0.46 0.01 0.03 Example 1 0.64 0.53 0.15 0.68 0.19 0.47 0.42 0.65 0.21 0.62 0.43 0.96 0.17 0.00 0.03 Comparative Example 2 5.51 0.74 7.95 5.04 5.19 0.30 1.89 3.45 0.61 0.43 0.82 2.09 0.47 0.00 0.03 Comparative Example 3 5.47 0.97 7.92 5.67 6.46 0.60 1.00 3.80 0.13 0.46 0.57 3.00 0.09 0.00 0.04 Unit: E10 atoms / cm² Depend on Figure 5 The test results in Table 1 show that the content of each metal element in the oxidation furnace tube after treatment in Example 1 can reach within 1E10 atoms / cm², which meets the SEMI standard. However, the metal element content of the oxidation furnace tubes treated in Comparative Example 1 and Comparative Example 2 did not all reach within 1E10 atoms / cm².
[0057] The test results show that the concentrations of SC2 solution and dilute hydrofluoric acid solution are key process parameters affecting the cleaning effect. The concentration range specified in this application (SC2 concentration 2% to 3%, dilute hydrofluoric acid concentration 1% to 2%) can control the metal contamination content of the oxide furnace tube after cleaning within the SEMI standard, verifying the advanced nature and technical effect of the online high-efficiency cleaning system and method for monocrystalline silicon wafer oxide furnace tubes proposed in this application.
[0058] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0059] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.
Claims
1. An online high-efficiency cleaning system for oxidation furnace tubes of single-crystal silicon wafers, characterized in that, This includes oxidation furnace tubes, water bath heating devices, and pulsed nitrogen devices; The oxidation furnace tube is made of high-purity quartz material, and its tail is a dome structure with an integrated air inlet at the center of the dome. The furnace inlet fixing flange of the oxidation furnace tube has a built-in tail gas treatment device. The water bath heating device is a quartz water bath with a heating base. The quartz water bath is connected to the air inlet at the tail of the furnace via a PFA gas pipe and a polytetrafluoroethylene fixing piece. The pulsed nitrogen device includes a gas source, a buffer valve, an MFC mass flow meter, a high-speed solenoid valve, and a gas consumption terminal connected in sequence. The high-speed solenoid valve is controlled to open and close by a PLC. When the gas consumption terminal needs nitrogen, the PLC controls the high-speed solenoid valve to open, and nitrogen is introduced into the gas consumption terminal through the MFC mass flow meter and the high-speed solenoid valve. When the gas consumption terminal stops using gas, the PLC controls the high-speed solenoid valve to close, and nitrogen is automatically switched to a bypass recovery pipeline to form a pulsed nitrogen with a fixed cycle frequency. The outlet of the pulsed nitrogen device is connected to the quartz water bath, and is used to introduce the pulsed nitrogen into the quartz water bath to carry steam through the air inlet into the oxidation furnace tube.
2. The system according to claim 1, characterized in that, The integrated air inlet at the tail of the oxidation furnace tube is a quartz tube with a diameter of 3cm to 6cm and a length of 10cm to 20cm, and the quartz tube is welded to the center of the dome.
3. The system according to claim 1, characterized in that, The quartz water bath has a volume of 25L to 40L, and the heating base is used to heat the liquid in the quartz water bath to 95℃ to 100℃.
4. The system according to claim 1, characterized in that, The pulsed nitrogen flow rate is 5slpm~10slpm, the gas supply cycle is 50s~100s, including 40s~80s of ventilation and 10s~20s of shutdown, and the pulse frequency is 0.01Hz~0.02Hz.
5. An online, high-efficiency cleaning method for oxidation furnace tubes of single-crystal silicon wafers, characterized in that, The method, applied to any one of claims 1 to 4, comprises the following steps: S1: Seal the oxidation furnace tube and introduce nitrogen gas to cool it down to the cleaning temperature; S2: The pulsed nitrogen gas generated by the pulsed nitrogen device carries deionized water vapor to clean the oxidation furnace tube; S3: The pulsed nitrogen generated by the pulsed nitrogen device carries SC2 solution vapor, dilute hydrofluoric acid solution vapor and ozone aqueous solution vapor in sequence to clean the oxidation furnace tube. S4: The pulsed nitrogen gas generated by the pulsed nitrogen device carries the deionized water vapor to clean the oxidation furnace tube; S5: Perform metal characterization and testing on the oxidation furnace tube.
6. The method according to claim 5, characterized in that, The cleaning temperature in S1 is 50℃~150℃, and the flow rate of nitrogen is 5slpm~10slpm.
7. The method according to claim 5, characterized in that, The methods for preparing deionized water vapor in S2 and S4 include the following steps: Deionized water is injected into the quartz water bath and heated to 95°C~100°C by the heating base to evaporate; wherein, the pulsed nitrogen gas carrying the deionized water vapor is circulated 10 to 20 times.
8. The method according to claim 5, characterized in that, The method for preparing the SC2 solution vapor in S3 includes the following steps: Hydrochloric acid and hydrogen peroxide are injected into the replaced deionized water to make the SC2 concentration in the mixed solution reach 2% to 3%, and the mixed solution is heated to 95°C to 100°C to generate SC2 solution vapor. The pulsed nitrogen gas carrying the SC2 solution vapor is circulated 15 to 30 times.
9. The method according to claim 5, characterized in that, The method for preparing the dilute hydrofluoric acid solution vapor in S3 includes the following steps: Hydrofluoric acid is injected into the replaced deionized water to make the concentration of hydrofluoric acid in the solution reach 1% to 2%, and the solution is heated to 95°C to 100°C to generate hydrofluoric acid vapor; wherein, the pulsed nitrogen gas carrying the dilute hydrofluoric acid solution vapor is circulated 10 to 20 times.
10. The method according to claim 5, characterized in that, The method for preparing ozone aqueous solution vapor in S3 includes the following steps: Ozone is introduced into the replaced deionized water to make the ozone content in the solution reach 2ppm~10ppm, and the solution is heated to 95℃~100℃ to generate ozone. The pulsed nitrogen gas carrying the ozone aqueous solution vapor is circulated 15 to 30 times.